View Full Version : More Diesel problems, tapping.
Since doing the headgasket it's developed a fairly prominent tap, at first I thought this might be the oil getting crap in it while it was changed and losing a bit while the head was off (levels were fine though) so changed it, it shut up for about 10 seconds til it was revved then the tap came back, so changed the 5w30 for some thicker 15w50 (although mobil 1, so it's most likely more like 10w40) and it did the same again, although this time didn't shut up quite as much. Can't seem to locate it using a big screwdriver but it doesn't get louder with the rocker cover off so I don't think it's cam/lifter related.
Head gasket is definitely not overhanging the bores as the pistons sit slightly proud of the block, so the gasket wouldn't have gone on if it was wrong.
Under the rocker did look slightly dry to me with the new oil, although that could be because it's still oil coloured rather than black, which is always slightly deceptive. Doubt it's a pump failure though as it does seem to react to new oil and shut up for a second.
Tensioner is bolted up tight so it's not that, timing is spot on the marks and engine turns freely.
Gonna get my uncle (mechanic) to look at it for me, most likely tomorrow sometime, just wondered if anyone had any suggestions?
have you got oil feeding the cam and lifters? im wondering if you have the gasket on the wrong way round....
have you got oil feeding the cam and lifters? im wondering if you have the gasket on the wrong way round....
It only fits one way and I made sure all the holes lined up. Must be an oil feed as it shut up after putting the 5w30 in it, at least for a bit.
or the oil pump is dying, or a shell is worn. is the tick from the top end area? the other thing is, it could be a ring...
Have you put the shims in the right way?
or the oil pump is dying, or a shell is worn. is the tick from the top end area? the other thing is, it could be a ring...
It sounds like a top end tap, but doesn't get louder with the oil cap off, and nor with a screwdriver to ear up against the head. In fact, it's most prominent when you stand by the drivers door... due to the diesel noise, which makes it a bugger to track down.
Have you put the shims in the right way?
Well this is certainly a possibility, because I'm gonna hold my hands up and say, the what?
oh.... also is there a bolt or owt catching the cambelt end of the motor? or is the cover rubbing/hitting. noises are a bastarrd to diag...
Oh dear, isuzu engines don't have hydraulic lifters, they have shims to set up the valve clearence which should be 0.25mm inlet and 0.15 exhaust
very common of the valves sinking into the head , thus clearence being none making it boost less and inlet get hot as the valves dont quite close... they will also start up with loads of smoke, maybe on 2-3 cyclinders for a few seconds to..
all my inlet valves were open around .1 -.2 mm all the time :/
http://www.pngclub.com/forum/showthread.php?t=127192 look at this
Oh dear, isuzu engines don't have hydraulic lifters, they have shims to set up the valve clearence which should be 0.25mm inlet and 0.15 exhaust
very common of the valves sinking into the head , thus clearence being none making it boost less and inlet get hot as the valves dont quite close... they will also start up with loads of smoke, maybe on 2-3 cyclinders for a few seconds to..
all my inlet valves were open around .1 -.2 mm all the time :/
Ah right yeah, I haven't played with the shims at all and the noise was apparent after doing the gasket, not before. Chances are mine is like that as it's high mileage and OAP owned most of its life, but I don't think it's the cause of the knocking.
Nothing I can see catching the cambelt etc, and top half of the cover is removed atm as I was double checking timing etc.
have you checked the valves clearances since you've had the head off? Edit too slow.
have you checked the valves clearances since you've had the head off?
No.. are they likely to be out of whack and causing this issue? I'm assuming they're going to be the same as before I did the gasket.
No.. are they likely to be out of whack and causing this issue? I'm assuming they're going to be the same as before I did the gasket. not neccesarily, check them and see what you've got.
Just gave a few a quick measure and they seem to be fairly consistent, 0.08ish on the inlet and just about 0.2 on the exhaust, which says they've worn by maybe 0.05 ish but not holding open etc... will give the rest a measure in a sec just to make sure theres not one miles out tapping away
have you started slackening off injector pipes yet? to work out which cylinder its doing it in?
have you started slackening off injector pipes yet? to work out which cylinder its doing it in?
No, but this would be pretty useful, I think it's 1 but it's bloody hard to hear it clearly. I take it you just undo them slightly, diesel pishes everywhere and when the noise stops you know it's that cylinder?
the amount of fuel that comes out is tiny.. just have a rag handy. get it ticking over, and simply slacken no1 and listen. if the noise remains, tighten it, and do no.2 etc. etc. it is a useful trick on a diesel
Noise persisted no matter what cylinder you slackened off, just became slower as obviously the engine is running on 3, maybe of some interest though is that 4 seemed to want to squirt fuel all over the inlet, whereas the other 3 bubbled a bit? Guessing its not a fuelling issue since the noise remained though.
Did find that inlet on 1 2 and 4 has no clearance at all, or at least less than 0.04 and 3 is down at about 0.04ish, all exhaust are at about 0.2. Would this cause it to tap? I can see decreased performance being caused by this, but if anything it seems logical that it stop it tapping, rather than cause it, since the valve isn't being sprung against the head?
No it wouldn't tap from that, get your clearences sorted, will run better then
No it wouldn't tap from that, get your clearences sorted, will run better then
Bound to I'm sure, but right now I just need a car I know isn't going to try and nuke itself or something at uni, need to find out what is causing this tap/knock :(
Well No offence but we can't tell from guessing..
Why not put a video up or get some one to look at it... Could be a million or one things
Dont know if its been mentioned yet, diesel knock?
aahhh yer, if no 4 isnt injecting it will be running lean thus knocking....
Yeah I know, like I say I'll be getting my uncle to look at that, was just after some suggestions here first as it may save him the hassle and me a day or two of waiting for it...
I always find videos of these things misleading tbh, it never picks up the sound properly, and they all sound the same, in fact 5 second search on ebay and it sounds a bit like this: http://www.youtube.com/watch?v=YdZVolqfSQA but without the V8 background lol
aahhh yer, if no 4 isnt injecting it will be running lean thus knocking....
Diesels don't 'run lean' and knock, as that's the way in which they control power, they have no throttle plate, all diesels run lean at idle, and stoich when flat out. At least as far as I know, but I don't see how it can run rich at idle without a throttle plate...
I did find the odd video on diesel knock and it sounds rather similar, but like I say any kind of video on that does :( If it is a leaking injector though, I'd imagine the sound would go away when you slackened off the injector pipe enough for it to run on 3.
edit: Could be a timing problem I guess, as this has been changed, however as far as I can see the marks are absolutely spot on, and with it lined up you can slot the bolts straight into the locking positions.
Also forgot to mention, had to go to halfords for feeler guages so did some kill or cure diagnostics, it does seem to be boosting less than before and is down on power, also it only knocks when warm, which is why changing the oil (or leaving it to cool long enough to change the oil) makes it go away for a few seconds. I guess this could fit with it being diesel knock?
timing out? the fuel pump might be out a tooth.
timing out? the fuel pump might be out a tooth.
Yeah that's what I thought, would explain everything, apart from the fact it lines up with every timing mark spot on :tard: 99.9% sure I have the right timing mark, as balley talked me through it before, there does appear to be 2 on the pulley, but one is a definite deep mark and lines up with what he told me, the other looks like impact damage or a home grown mark to me.
Pulley pic from the other thread:
http://img.photobucket.com/albums/v471/MK999/Nova/Pulley.jpg
Arrowed is what I'm using, and looks much deeper than the other mark with the arrowed "?" the pic is deceiving. ignore the lines.
this might be a bit off the wall, but i assume you removed the injectors. and if you did, did you put them in the right way round??? back in the late eighties, i worked at a tractor dealership & loads of customers fitted their own injectors & then complained that they were down on power. when the mechanic went out, it was always the injectors the wrong way round.
they have an offset spray pattern, and if they aren't squirting into the right place, it won't run right.
diesel knocks sound as though the engine is about to blow up.
fire it up and keep your foot planted, that should cure it.
im being serious, not trying to make you blow it up.
this might be a bit off the wall, but i assume you removed the injectors. and if you did, did you put them in the right way round??? back in the late eighties, i worked at a tractor dealership & loads of customers fitted their own injectors & then complained that they were down on power. when the mechanic went out, it was always the injectors the wrong way round.
they have an offset spray pattern, and if they aren't squirting into the right place, it won't run right.
Injector pipes were removed, injectors stayed put.
and I'll uh, give that a go Paul... 50/50 on a replacement if it goes bang? lol
Well it stayed alive, and the knock seems to go away at higher revs... or the diesel sound just drowns it out, but it's still tapping/knocking away, I'm guessing your line of thought is theres an air bubble playing with the injectors Paul? Would it help if it was under load maybe?
yeh im guessing theres air in the system, sounds right to me.
Just took it out for a run, definitely diesel sound drowning out the knock, it's present at higher revs, can hear it in the car. It's smoking like a real trooper considering the amount of boost it's making, it's at around 6psi, and was making 10 with a bad headgasket. Loosening off each injector definitely doesn't cure it, slackened them right off this time until they were totally finger loose. There does seem to be a lot of bubbles coming out of 1-3 but I'm not sure if this confirms what Pauls thinking or it's just the way it's coming out. Judging from that little run it's not ready to nuke itself though, it might be ok to just run until it loses all the air in the system?
Right went and bled a fair amount of air out of it, got it clean on 1 and 4, and then slackened off 2 and 3, so it was running on the 'clean' air free injectors and it didn't effect the knock, so that may be causing the smoking and performance loss, but probably not the knock? I'm wondering if one of the injectors is leaking or similar, and only now that the gasket is done, does it have the compression to ignite it or something like that.
Count Vaux Alot
15-09-10, 06:57 PM
I have a spare engine you can have for beer money lol
I have a spare engine you can have for beer money lol
The amount of times I've mentioned your engine and said it would have been easier quicker and cheaper than changing the head gasket lol
I assume it runs ok etc? If my Uncle says it could be anything and you could spend hundreds chasing it down that may well be the best option...
1.7 conversion is alot harder than people make out! And he just wants a nice reliable daily he don't wont to mess about with it when he has another project!! Am I right Mk999
does it run rough on idle, the pump could be a tooth out?! even with it pinned its still possible as the crank only has an eye line, which on needs to be half a turn out.. + the pump pulley moves a bit even with the correct stud in it..
6psi is lower than standard FFS so that really not good..
it idles perfectly, it's noticably louder than it was before, I assume because it actually has compression now rather just spraying half of it into the water system/oil/atmosphere. The only other thing that's odd about it is it has always idled high, even with the screw all the way out it sits at about 1k with a bit of extra fuel around from me playing with the boost etc trying to get it near standard. I think the rough running is probably explained by the air in the system, it will run noticeably smoother on 1 and 4 than 2 and 3 for instance, as 4 and 1 are the 'cleanest' fuel tracts air wise. It just doesn't explain the knock.
And yes, this is purely a reasonably tidy, cheap daily, as much as I keep spending more on it than I really should it's because I can't get my teeth into the project properly yet, I don't plan on any complicated big block diesel conversions.
i didn't have any fuel problems other than bleeding the filter
really cant think what could be wrong with it.
I'm at a loss too tbh, hence getting my uncle involved, I sorted all the problems with my engine conversion etc myself, but diesel I just don't understand well enough :tard: Should probably have got him to do the gasket tbh I may well have done more damage to it running it trying to fix it.
Uncle reckons it's probably a valve tapping the head from the clearances being out, and the tolerances being so tight in the engine. So will see what happens when that is sorted.
Been onto motor factors today, and there's only one size of shim that is not NLS, and they're £8.67+vat each so it'd be about £100 to reshim it even if they had the right sizes :/
sheet of glass and some emerry cloth/wet and dry. Its tedious but doable.
better yet a surface grinder would be good
sheet of glass and some emerry cloth/wet and dry. Its tedious but doable.
better yet a surface grinder would be good
Would it not need to be well polished as well to stop it wearing the cam? I could probably get my uncle to machine them down and polish tbh, but he's off work for a week now and I should have been moving into my place at uni a week ago...
you w/d them with lighter grit and get a polished finish ;)
Well I wasn't gonna jump in with some 80 grit lol I'm guessing 2000 or 3000 grit?
I'd start on 600ish and finish at 1200ish.
I'd start on 600ish and finish at 1200ish.
ah ok, I'll give that a go... if not it looks like count vauxs engine and use the head off that
you can measure the ones you have and swap em around till it measures right. also can you nt nip to the breakers and nab a load of em?
Well just remembered the studs and nuts on the cam caps are knackered too, and they're also NLS, just phoned to check... so it looks like count vauxs engine is only option, and use the head off that to save swapping the entire thing.
Can't swap them round as they're all too large, and the chance of getting the right sizes from a breakers (if you even see a 1.5 diesel in there) is slim, it'd have to be something around a 150k engine that has had it done, to have the right size shims in it, assuming the valves have worn roughly the same.
ah ok, I'll give that a go... if not it looks like count vauxs engine and use the head off that
Unless the shims have been done theres No point... There always tight... I would rather it tap than be tight.. Fords have been going on this theory for years!!
Grind yours up, you only do one side.. then place the ground side on top of the valve!!
Unless the shims have been done theres No point... There always tight... I would rather it tap than be tight..
His engine is a good runner that boosts fine, so it's neither tapping or too tight, whereas mine is both...
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