View Full Version : stupid headgasket!!!!
well, its pv this weekend ahead, and the headgasket went on friday nite, got it stripped down with paul and the chicken shed crew, a big thanks to milton for the new parts:) , problem is its being skimmed thursday, and the chances of it being back together is nil, so big fail on me, and even if it was fixed, ive blown all the money fixing it!!!!!:mad: :mad: :mad: :mad: , rant over:(
Find somewhere to skim it before Thursday?
yea surly you can find somewhere to get the head skimmed quicker.
Skimm it yourself with a electric plainer lol
L33 LEG
07-06-10, 07:09 PM
It will rain anyway so dont worry about it :wtf:
would be nice, but im at work long distance all week, and as i said, pv money went on the rebuild, so epic fail time, oh well, always next yearlol
General Baxter
07-06-10, 07:40 PM
pv money, head gasket set with bolts £20, skim £20, thats only a bacon sarnie at pv anyway lol
Jon_nova1
07-06-10, 07:43 PM
or a nights doughnut session while drunk:wtf:
craig green
07-06-10, 07:49 PM
pv money, head gasket set with bolts £20, skim £20, thats only a bacon sarnie at pv anyway lol
Better for it to last beyond PV though. Or pop a hose off in the queue due to it being rushed......
PV sucks anyway, esp by 3pm on the sunday afternoon if ithasnt already peeved (no pun) you off.
pv money, head gasket set with bolts £20, skim £20, thats only a bacon sarnie at pv anyway lollollollol
Why does the head need skimming? Did it overheat?
Why does the head need skimming? Did it overheat?
Took the words out of my mouth. Bar unless the mating surface was damage i'd not have skimmed it.
total head job including strip down takes no more than 3 hrs labour on your own.... and head skimming is 99% myth so that garages can make huge money
The headgasket on my mk4 went big time! And i never had that skimmed. Its done 8k miles since without one issue
my view on head skimming is that the tiny amount that they take off is nothing compared to the expansion under heat & the actual distortion under the bolts clamping it down
i got told by an old tech i worked with, follow the torq procedure, then run it to temp, then nip it 5 more deg. i had a 1.poo nova that blew its gasketin notts. i nipped the bolts a bit further and ran it for 3 more months....
just noticed this and what a bummer.
Hope its sorted soon mate.
and head skimming is 99% myth so that garages can make huge money
Finely more people who have a clue.
I've been saying it for years.
When you put a straight edge on the head tho and its all over the place, then that is worth a skim.
When you put a straight edge on the head tho and its all over the place, then that is worth a skim.
the bloody thing gets clamped down by 10 bolts, each with approx 120lbft torque, with the angle of thread, that equates to about 1200-1500 lbft clamping pressure per bolt!!! it can withstand 50 explosions per second... skimming is to clean up any damage, or raise compression if thats your thing..........
the bloody thing gets clamped down by 10 bolts, each with approx 120lbft torque, with the angle of thread, that equates to about 1200-1500 lbft clamping pressure per bolt!!! it can withstand 50 explosions per second... skimming is to clean up any damage, or raise compression if thats your thing..........
Thank you. Everything i've always said.
I forgot my spurs, never mind we'll go and water Tonto Alex.
i assume that you are casting doubt on our mechanical abilities.........
i have been rebuilding all sorts of engines for years. and only once have we sent a head for a skim. cos the gasket had blown really badly & the head was actually damaged.
i just can't get my head round why people put a straight edge on the head & announce its in need of a skim, when it is not actually in its running state, ie 92DEG C & clamped down solid. if you do skim it at room temp & then refit it, it is actually more distorted once clamped down than it was before...........
i once watched a documentary about race engine builders & they were actually heating blocks & bolting down dummy heads before they bored & honed the blocks to make sure they were actually machined correctly. when people were messing with x flows & a series iron block & iron head engines, they did need more work & with the old copper gaskets, the faces would get pitted. but with decent fibre head gaskets & ally heads, i just think its an old fashioned practise that garages just havent grown out of.
what about rovers k series, where the head does visibly bend?
what about rovers k series, where the head does visibly bend?
all because of piss poor development budgets & crappy o-rings.... the heads were fine, but the cooling systems were marginal at best.
I knew Paul would take the piss.
If a heads so warped it needs skimming how the cam gonna turn?
You never seen any one getting the block skimmed and that will take most of the heat...
Im not taking the piss Ben (hugs lol)
but the fact you and him are sitting hundred of miles away behind a computer screen and that my pal has said its needs a skim after physically taking it off, i reckon he might be in a slightly better position than you to decide whether or not to bother skimming it. Do you not agree?
I knew Paul would take the piss.
If a heads so warped it needs skimming how the cam gonna turn?
You never seen any one getting the block skimmed and that will take most of the heat...
you never heard of getting the block skimmed?
all because of piss poor development budgets & crappy o-rings.... the heads were fine, but the cooling systems were marginal at best.
3 words: liners incorrectly set
btw rovers k series is waaaay o.t so i'll leave it there.
block skimming, i've done it, but it was a long time ago.
3 words: liners incorrectly set
btw rovers k series is waaaay o.t so i'll leave it there.
block skimming, i've done it, but it was a long time ago.
rob, a huge number of diesel engines have been produced with wet liners, and have always been reliable, the main problem with the rover engine was not the basic design, but the finishing off of the development. the k series now fitted in the freelander is sorted out, and reliable.
when it was first designed in the early eighties, it was basically a 4 cylinder f1 engine, such was its advanced characteristics. and still mechanics have trouble with them.... with the long studs from top to bottom.
i know mate, my uncle was at rover when they came out, and i've rebuilt more than a few. ive always found, if you set the liners 0.3mm higher than the blockface, use the saver type gasket, and the landy uprated girdle etc, and fit a cooler running stat its fine. dependant on the year of the engine depends on its issues. a mate has a 25 with a 1.8 turbo from a 75. makes 270bhp, and is utterly reliable.
i was brought up on shimming liners... these tractor boys are the best mechanics by far. turbos, intercoolers, semi auto boxes, active diffs, air con, air suspension, computer management were on tractors long before they arrived on cars
MattBrown
08-06-10, 11:25 AM
i was brought up on shimming liners... these tractor boys are the best mechanics by far. turbos, intercoolers, semi auto boxes, active diffs, air con, air suspension, computer management were on tractors long before they arrived on cars
True true.
You should see my year in school.
135 people, im on the tools as an apprentice industrail spark.
And theres 1 mechanic.
Thats it, the rest are fking useless with there hands.
Glad im not useless tbflol
Glad im not useless tbflol
thats open to debate......:p
MattBrown
08-06-10, 11:50 AM
thats open to debate......:p
lol
I haven't had many fails recently, only buying a 20let, that was a massive phaillol
lol
I haven't had many fails recently, only buying a 20let, that was a massive phaillol
that word says it all
how is buying a let a fail? oh wait.......
steveboyslim
08-06-10, 07:10 PM
total head job including strip down takes no more than 3 hrs labour on your own.... and head skimming is 99% myth so that garages can make huge money
That statement about the head skimming is bollox.
Steve
remind me who not to let work on any of my engines , myth skimming, slap it back on, and silicone it back together? if this is the case, i offer my second hand headgasket blown up, stretched head bolts and all used gaskets for any takers, ill even toss in the used oil if u want! if your fixing something, do it right or its a waste of time!
That statement about the head skimming is bollox.
Steve
Please back this up with facts.
Please back this up with facts.he builds engines for a living, so id say he knows a fair bit
steveboyslim
08-06-10, 07:17 PM
the bloody thing gets clamped down by 10 bolts, each with approx 120lbft torque, with the angle of thread, that equates to about 1200-1500 lbft clamping pressure per bolt!!! it can withstand 50 explosions per second... skimming is to clean up any damage, or raise compression if thats your thing..........
How the hell do you work that one out, the standard head bolts are stretch and tightened up using to the correct procedure each bolt torque is only about 80ft/lbs.
It is not related to the individual bolts it is the area.
If you over tighten you will pull the thread out of the block or collapse the head.
Your statement is one of the most incorrect I have read on the internet for many years, keep it going I need a good laugh.
Steve
he builds engines for a living, so id say he knows a fair bit
I know that, that is why i want his answer.
steveboyslim
08-06-10, 07:21 PM
i assume that you are casting doubt on our mechanical abilities.........
i have been rebuilding all sorts of engines for years. and only once have we sent a head for a skim. cos the gasket had blown really badly & the head was actually damaged.
i just can't get my head round why people put a straight edge on the head & announce its in need of a skim, when it is not actually in its running state, ie 92DEG C & clamped down solid. if you do skim it at room temp & then refit it, it is actually more distorted once clamped down than it was before...........
i once watched a documentary about race engine builders & they were actually heating blocks & bolting down dummy heads before they bored & honed the blocks to make sure they were actually machined correctly. when people were messing with x flows & a series iron block & iron head engines, they did need more work & with the old copper gaskets, the faces would get pitted. but with decent fibre head gaskets & ally heads, i just think its an old fashioned practise that garages just havent grown out of.
Paul might not be casting doubt on your mechanical abilities, but after your posts on this thread, I am.
Also about the abilities of anyone who backs up what you have stated.
Steve
steveboyslim
08-06-10, 07:26 PM
he builds engines for a living, so id say he knows a fair bit
No I do not build them for a living, but I know many people that do.
You do not need to be any form of engineer to see what is right and what is wrong just basic common sense.
Steve
I skim heads at work, and I know for a fact that if you don't do a warped head (say Punto) it will go by the end of the week as we have had customers who have had it happen!!
the bloody thing gets clamped down by 10 bolts, each with approx 120lbft torque, with the angle of thread, that equates to about 1200-1500 lbft clamping pressure per bolt!!! it can withstand 50 explosions per second... skimming is to clean up any damage, or raise compression if thats your thing..........
My boss thinks every one on here knows nothing,.. I back this website 100% but reading ****e like this does make me wonder!!
steveboyslim
08-06-10, 08:21 PM
I skim heads at work, and I know for a fact that if you don't do a warped head (say Punto) it will go by the end of the week as we have had customers who have had it happen!!
the bloody thing gets clamped down by 10 bolts, each with approx 120lbft torque, with the angle of thread, that equates to about 1200-1500 lbft clamping pressure per bolt!!! it can withstand 50 explosions per second... skimming is to clean up any damage, or raise compression if thats your thing..........
My boss thinks every one on here knows nothing,.. I back this website 100% but reading ****e like this does make me wonder!!
I will agree with that.
Steve
the basic concept of a screw thread is of a circular wedge, google archimedes, if you have a wedge with a 1 in 10 gradient, if you push it inwards with a force of 10kg, it exerts a sideways force of 100kg, this is the principle of how wedges cut wood, rocks etc, and how a cold chisel works.
every head bolt i've ever actually undone has had about 120lbft of torque needed to remove it. thus that is pretty much the actual torque holding it. and head bolts are fine thread, usually 1.25mm pitch.
on a 12mm thread, this equates to approximately a 1 in 10 gradient. so back to the wedge analogy, and a bolt thread does the same.thus if it has been tightened to 120lbft, then it is clamping 10 times that.
head bolts really are on ridiculously tight, you expect 2 cheap 16mm bolts to hold a towbar on & pull 3.5t at 60mph, so a set of high tensile 12mm head bolts are actually more than capable of holding the cylinder head down with a force of several tonnes,
the head needs to be torqued down by that amount simply to get it to survive the evil process that is a 4 stroke cycle. on a 2 litre engine, each firing is hitting the head & piston with a force of maybe 100hp (before inefficiency, and internal frictions, power drains from pumps, belts etc.) and the weakest link is the gasket. the gasket is an item that is designed to compress and seal. by its very nature, it will fill any minor imperfections that occur. skimming a couple of thou off it will not make it seal any better. and exerting a force of several tonnes onto a cylinder head made of aluminium alloys means it will actually bend slightly when it is torqued up. personally, i think that most heads warp because a lot of people just undo them from one end to the other as opposed to doing the opposite of the torqing up procedure, and doing it in stages.
when i clean up a head, i actually do clean it right down, i clean the block face too, i use lint free materials, because any form of contamination will ruin the seal. i actually use straight edges.
i just dont hold with the 'THOU SHALT SKIMMEST THY HEAD' school of thought.
if the head is the original from the engine, it will have evened out any stresses that may have occured in normal usage, and be an exact fit for the block. so why skim it as opposed to just giving it a bloody good clean.
i appreciate that heads do get damaged, and pitted, with foreign objects, and massive overheating causing proper head gasket failures, but the vast majority of head gaskets get swapped because they have just started to leak a little.
if you are rebuilding an engine, then so many major components are being swapped about, the valves are going to get recut, you may want to raise the compression, so skimming has its place there.
MattBrown
08-06-10, 10:14 PM
lol lol lol at this thread, its more epic than most.
I have rebuilt loads (30+) 2 stroke engines, and I popped my dtr125 head gasket last year, was experimenting with differant jets etc, apaently its a weak point but anyways.
It boiled over, I only noticed when i looked at the dials, and it was out of the blood zone, I was like meh, got 2 spare engines, ill cool it down, top up, then home.
Got home, changed gasket, put head on a glass model car set-up board, and it was fine, took 4k of abuse afterwards aswell.
I personally would check before assuming a Skim is needed.
you never heard of getting the block skimmed?
Not after a hg going no... Only people decking it for cr reasons.
And me talking about your mates one, i didn't. But just cause the Hg has gone doesn't mean you have to skim a head is what i ment.
steveboyslim
08-06-10, 11:14 PM
the basic concept of a screw thread is of a circular wedge, google archimedes, if you have a wedge with a 1 in 10 gradient, if you push it inwards with a force of 10kg, it exerts a sideways force of 100kg, this is the principle of how wedges cut wood, rocks etc, and how a cold chisel works.
every head bolt i've ever actually undone has had about 120lbft of torque needed to remove it. thus that is pretty much the actual torque holding it. and head bolts are fine thread, usually 1.25mm pitch.
on a 12mm thread, this equates to approximately a 1 in 10 gradient. so back to the wedge analogy, and a bolt thread does the same.thus if it has been tightened to 120lbft, then it is clamping 10 times that.
head bolts really are on ridiculously tight, you expect 2 cheap 16mm bolts to hold a towbar on & pull 3.5t at 60mph, so a set of high tensile 12mm head bolts are actually more than capable of holding the cylinder head down with a force of several tonnes,
the head needs to be torqued down by that amount simply to get it to survive the evil process that is a 4 stroke cycle. on a 2 litre engine, each firing is hitting the head & piston with a force of maybe 100hp (before inefficiency, and internal frictions, power drains from pumps, belts etc.) and the weakest link is the gasket. the gasket is an item that is designed to compress and seal. by its very nature, it will fill any minor imperfections that occur. skimming a couple of thou off it will not make it seal any better. and exerting a force of several tonnes onto a cylinder head made of aluminium alloys means it will actually bend slightly when it is torqued up. personally, i think that most heads warp because a lot of people just undo them from one end to the other as opposed to doing the opposite of the torqing up procedure, and doing it in stages.
when i clean up a head, i actually do clean it right down, i clean the block face too, i use lint free materials, because any form of contamination will ruin the seal. i actually use straight edges.
i just dont hold with the 'THOU SHALT SKIMMEST THY HEAD' school of thought.
if the head is the original from the engine, it will have evened out any stresses that may have occured in normal usage, and be an exact fit for the block. so why skim it as opposed to just giving it a bloody good clean.
i appreciate that heads do get damaged, and pitted, with foreign objects, and massive overheating causing proper head gasket failures, but the vast majority of head gaskets get swapped because they have just started to leak a little.
if you are rebuilding an engine, then so many major components are being swapped about, the valves are going to get recut, you may want to raise the compression, so skimming has its place there.
More bollox.
The force exerted is related to the area, in simple terms.
Turbo boost is able to lift the cylinder head and can cause the gasket to fail.
As little as 2thou (less that the thickness of a piece of paper) can and in most cases will cause problems.
Both the block and head faces need to be true (flat).
You will find that on most XE/LET block they either dip between the cylinders (as do the heads) or there is a very slight twis in the block face.
All the comments you have made are utter rubbish, this thread rely belongs in the muppet section.
Steve
im stuck in the middle, simply cos i have the vauxhall reports herefrom my uncle (a vaux tech and workshop manager for 15 years) that state xe and let heads can be skimmed a max of 0.10 and xev and x18xe heads cannot be skimmed. now i for one know that my local machine firm will and do reccomend a skim, if the gasket blows. but on the flipside, my fathers manta gt/e turbo's head was flat when the gasket blew, as was his pinto engined escort when that went. the reason i think is due to the fact the head is iron on both. heres my point. if i was building an xe or let, i would have the block decked and checked, and the head tested fully and skimmed a max of 0.05 if needed. i, and other techs i know belive that alloy heads on iron blocks warp more readily because iron cools at a different rate and speed to alloy.
oh and to the o.p, my comment about silicone sealant was serious, keith black racing engines and alot of pro engine builders use this instead of a gasket, as it seals better and, seen as nasa invented it to bond tiles to the space shuttle and withstand re-entry heat, works perfectly.
david dixon
09-06-10, 12:03 AM
I can not believe what i am reading here, what a load of old bollox! anyone that has had gasket failure and does not skim the head (at least the head) before refitting is off their rocker.
David.
chrisnovaturbo
09-06-10, 12:07 AM
you dont want to skim the head loads, you want to get it re-faced (very very light skim) just so its flat and gets a good seal to the gaskit. give the head a clean off when you get it back (make sure no swalf anywere in the head). clean the face of the block up put the head back on with new gaskits and new head bolts and job done. simples :thumb:
so far not one person who sides on the arument that you must always skim your head has given me a single piece of evidence to back it up.
i get flywheels skimmed, brake drums refaced because they are necessary when operating HGV's, but all of your arguments are that it needs doing and thats as far as it goes.
show me evidence.
More bollox.
The force exerted is related to the area, in simple terms.
Turbo boost is able to lift the cylinder head and can cause the gasket to fail.
As little as 2thou (less that the thickness of a piece of paper) can and in most cases will cause problems.
Both the block and head faces need to be true (flat).
You will find that on most XE/LET block they either dip between the cylinders (as do the heads) or there is a very slight twis in the block face.
All the comments you have made are utter rubbish, this thread rely belongs in the muppet section.
Steve
so i explained how a bolt works and how it clamps down. ok, that is rubbish.. fair enough i give up you your argument..
so explain to me please how removing differing amounts off a cylinder head face will make it stay straight in relation to such things as the camshafts.......... because a skim doesn't remove the same amount from front to back, cos if it did, it would not be worth doing.
how many people remember to remove the burr at the top of the threads on the block?? i suppose thats rubbish too........
alistairolsen
09-06-10, 08:31 AM
Sealing faces on either side of the gasket should be flat when its torqued down, not because it wont pull flat, btu because when it does, you wan an even clamping pressure on the gasket.
Some gaskets are more tolerant of imperfections than others, MLS inp particular almost demands that you skim both head and block wwith ever fitment. Modern fibre gaskets are in most cases very forgiving.
Moving away from doing it by the book, I have, and will again use heads without a skim, but only they check out with a straight edge and have no major damage. Also it tends to be OE spec low powered engines like standard 8vs on 9.5:1 cr. I wouldnt think about it on a 16xe for instance at 11.5:1!!
Yes, when you skim the head and bolt it down the crank bores are out of true, genrally any head with more than a few though of distortion is only fit for scrap anyway!
Personally Id strip it (its ****ed anyway) and check out the head and block faces. You migth get away with a clean up and chucking it back together, if not then dont make PV and fix it properly afterwards IMO. As said above, there is only about 3 hours labour in a gasket change on an XE.
steveboyslim
09-06-10, 08:36 AM
so i explained how a bolt works and how it clamps down. ok, that is rubbish.. fair enough i give up you your argument..
so explain to me please how removing differing amounts off a cylinder head face will make it stay straight in relation to such things as the camshafts.......... because a skim doesn't remove the same amount from front to back, cos if it did, it would not be worth doing.
how many people remember to remove the burr at the top of the threads on the block?? i suppose thats rubbish too........
De-burring should be standard pratice, head or the block or anything else that gets machined.
The idea is that when you skim the head or block you ensure the face that sits against the mill or grinder is also flat, correcting with shim stock if needed, if the two faces are not parallel then an angle plate is used.
I am glad you do not do any work for me, because from the statments you have made on this thread it is obvious the your engineering knowledge is zero.
Knock yourself out.
Steve
De-burring should be standard pratice, head or the block or anything else that gets machined.
The idea is that when you skim the head or block you ensure the face that sits against the mill or grinder is also flat, correcting with shim stock if needed, if the two faces are not parallel then an angle plate is used.
I am glad you do not do any work for me, because from the statments you have made on this thread it is obvious the your engineering knowledge is zero.
Knock yourself out.
Steve
steve, i have had heads skimmed before.....
so you admit that they clamp it straight before they skim it............ so in effect they are bolting it down, so far so good......
so how different is that to actually just making sure its clean and then clamping it down onto the clean block?, in my humble opinion, there is very little, if any difference at all.
and i'm prepared to leave it at that
General Baxter
09-06-10, 09:18 AM
I am glad you do not do any work for me, because from the statments you have made on this thread it is obvious the your engineering knowledge is zero.
Knock yourself out.
steve, ill make you a head :thumb:
i took a grinder to mine with a spirit lvl, lol
i dont even torque mine down, or go in order of the book, i just go around and do them FT, its a ****ing bolt and two points to bolt down the end of the day, how many of you torque your wheel nuts on, or your seat frames lol
heres my 10pence,
if it has not over heated, but just got hot, **** it, slam a new gasket on and be done, old school engines rock, only the newer craper cheap alloy heads are crap lol
farmertom
09-06-10, 01:17 PM
im with the no skimming on heads, i rebuilt my deisel van that had gone through a puddle sucked up water it bent a conrod, replaced conrod cleaned up head. put it all back together worked mint till 3 weeks ago, 40 thousand miles later it went bang. pumps gone tits up so vans no gone to scrappy in the sky :)
GRUNT 16V
09-06-10, 01:29 PM
feck me why is this thread still going !!!!! if my head gasket went i would be on the road the next eveing max stop bitching and get it done mo fo !
lol
I'll believe Steve as he looks like Chips dad lol
I've done work on engines in the past, had the head off and just cleaned up and back on as that wasnt the bit that was faulty. I have also had heads skimmed in the past.
both worked for the right faults.
oh and the K isnt fixed properly in the Freelander.... it merely lasted a bit longer and LR have a better warranty procedure than Rover ;)
lol LR have a better warranty procedure than Rover ;)
because they still exist???
because they still exist???
rover still exist (of sorts) :p
I mean in terms of they dont want a single person bitching about their products so butter them up nicely.
dhdev (Oli)
09-06-10, 02:36 PM
Mowgli if you are relying on the torquing of the cylinder head bolts to pull the head straight then the force is used in distorting the head, you will therefore not get an even seal between head and block and risk failure. Obviously the amount of distortion is directly proportional to the force required to bring it true, hence you may get away with it for a small distortion as the relative clamping loads inparted by the bolts will bring it true and still provide force to seal the combustion chamber. However relying on this to provide the seal is IMO foolish and skimming should be carried out to provide the seal. The strength of the joint between the head and block relies on the bolts having a much lower stiffness coefficient than the head and block, by including distortion in the head you are reducing the stiffness of the joint and increasing the chance of seperation and failure.
rover still exist (of sorts) :p
I mean in terms of they dont want a single person bitching about their products so butter them up nicely.
i should send you my brothers mobile no & get you to ask him how his range rover sport is doing & what he thinks of the dealers service backup... that'll keep you busy for about an hour...
it leans on one corner, they keep swapping air suspension components randomly to try to fix it, and last week, they removed the dog guard & floor mats & they have magically vanished................
Thats what you get for paying massively over the odds for a discovery though lol
I'll ask my friend who is in engineering warranty if he knows about that little beasty :)
Mowgli if you are relying on the torquing of the cylinder head bolts to pull the head straight then the force is used in distorting the head, you will therefore not get an even seal between head and block and risk failure. Obviously the amount of distortion is directly proportional to the force required to bring it true, hence you may get away with it for a small distortion as the relative clamping loads inparted by the bolts will bring it true and still provide force to seal the combustion chamber. However relying on this to provide the seal is IMO foolish and skimming should be carried out to provide the seal. The strength of the joint between the head and block relies on the bolts having a much lower stiffness coefficient than the head and block, by including distortion in the head you are reducing the stiffness of the joint and increasing the chance of seperation and failure.
thankyou for a reasoned answer, with thought in it.
my problem with skimming the head is still that if it is straight when clamped onto the bed for skimming, even if it gets shimmed, it will be straight in relation to the bed & not the actual engine. when turned over and torqued up, it will still be bent, however slightly to compress the gasket & create the seal, unless you have one of those super duper automated 10 headed air wrenches that will clamp the head down evenly. then the engine warms up and everything moves about until it settles for use..
as an exercise in cleaning the surface, skimming is excellent, but i just don't get the argument that it must at all costs be skimmed or it will fail, because it frankly isn't true.
and i still stand by my point that the head bolts actually exert a force of several tons on the head, or the gasket would get blown clean out upon firing. if every bolt only put down 80lbs as was earlier put, then 800pounds of clamping force to try & hold back 100hp explosions is engineering suicide.
have a read mike
http://www.ferriday.co.uk/copper/copper.shtml
dosent need much force to get the fire rings to seal and stay put.
oh and I'd hope to NEVER have explosions in an engine ;)
stu, every time that funny metal thing goes up & the little sparker sparks, it is an explosion
and the word i kept reading on that page was sealant......
of course a metal head gasket would need perfectly flat mating surfaces for some super duper high output engine.... even if it is actually coated in sealant on both sides as in that link... but a standard head gasket in normal roadgoing useage is actually meant to crush into position.
its not an explosion!!!!!!!!!!!!!! det is an explosion!
when the air/fuel charge is compressed and ignited its a controlled burn! You can actually out WALK the speed of the flame front, its just the cylinders are so small it appears to be fecking fast (imagine how fast you appear to travel over 90mm when walking)
The fire rings crush... with not a lot of force... not 8 billion pounds of force.
The stiffness of undoing the bolt is where the different metals will have corroded, releasing the strech force, the general friction etc.
Have you had some sort of stroke of something mike? you certainly arent your usual sound engineering self today..
Jon_nova1
09-06-10, 05:41 PM
I'm with Mowgli on this (on the skimming part) in most cases it is a preference to get more money from customers, you can skim the head and make it flat, but surely for both surfaces to be flat in comparison to each other you'd effectively have to deck the block on the same machine you did the head on.
Personally i've only ever had one head skimmed, i also had the block skimmed so the surfaces were flat in relation to each other.
Heres a car i had a few years ago that i bought as a headgasket failure, the only thing i did was clean the surfaces, put a tap down the threads and gave it a service, the car was still running when i sold it a year later
http://img.photobucket.com/albums/v166/Unicorn007/oil2.jpg
http://img.photobucket.com/albums/v166/Unicorn007/oil1.jpg
oh and agreed that a garage will probably just do it for the hell of it, rather than if it truely needs it or not.
mowgli, are you steven hawkins or something, ive only been on here a little while, and you seem to know everything and think your right on every subject and post! the head got skimmed , my bad! ive never heard such rubbish in my life!
craig green
09-06-10, 06:09 PM
oh and agreed that a garage will probably just do it for the hell of it, rather than if it truely needs it or not.
They can't really offer a guarantee on the work & parts used if a skim isnt performed I guess. Seeing as probably 99% of motorists would use a garage rather than DIY the job, you can see where the strong belief in a head skim being necessary comes from.
Knowing Mowgli a little myself, I'd say his opinion is totally founded, he's a pretty handy chap & definately knows one end of a spanner from the other & certainly has the benefit of a little more age/wisdom over most of us on here.
Horses for courses. :confused:
mowgli, are you steven hawkins or something, ive only been on here a little while, and you seem to know everything and think your right on every subject and post! the head got skimmed , my bad! ive never heard such rubbish in my life!
alex, i am prepared to accept reasoned argument with facts to back it up...... nothing more, nothing less.
i know all about cleaning a head & block & using new gaskets & bolts & then changing the fluids as a basic part of doing a head gasket, but i just don't accept that every time one gets done, a skim is a necessity. that was the basis of my argument,
you announced that you weren't going to pv because the head was away for skimming.....and if you have managed to fix it in time to go, then brilliant, i'm pleased for you.
mowgli, im just in the process of bolting my head back on. Do you have any more top tips?
Nova_Sean
14-06-10, 08:24 PM
You just now mowgli is gonna come and out wit you!
Alex, take a chill!
no, i'm not. i hope the engine runs fine for you. that is all.
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