compression test

[vauxluva]

What should i be looking to see from my lump, 1.4nv SR.

[Steve0011]

i would say 12psi +

:)

[bmw156]

yeh about 12psi.

on my redtop i saw 4 on one cycl and the other 3 had none!

[Steve0011]

anything less than 12 is considered 'unhealthy' less than 10 get a new engine ;)

[Royston]

Surely compression should be nearer 120psi+ not 12psi ? per cylinder

Pressure depends on compression ratio, wear, and whether throttle body/carb is open/closed (iirc should be open when done) and engine hot or cold

Variation between the cylinders is also important, i.e. even or weak cylinders

why are you testing it, what is the problem?

[WBC]

Was gonna say,, 12psi,,, get a new engine,,,

120 psi is bit more realistic.......

[vauxluva]

Surely compression should be nearer 120psi+ not 12psi ? per cylinder

Pressure depends on compression ratio, wear, and whether throttle body/carb is open/closed (iirc should be open when done) and engine hot or cold

Variation between the cylinders is also important, i.e. even or weak cylinders

why are you testing it, what is the problem? A bit of blue smoke only when you put your foot down?

[vauxluva]

I am reading 105 psi all the way across the board,Witch is not bad for a 1989 lump imo. Looks like it may just be worn vavle stem seals.

[bmw156]

Sorry i mean 12 bar.

as per this tester.
http://www.amazon.co.uk/dp/B0001K9TV0/ref=asc_df_B0001K9TV02714858?smid=A3P5ROKL5A1OLE&tag=googlecouk06-21&linkCode=asn&creative=22206&creativeASIN=B0001K9TV0

[vauxluva]

12 barr on mine is 175 psi? surely all engines are difernt?

[bmw156]

check the haynes manual, it should give a accurate figure as what is needed.

edit - compression PSI of 1.0, 1.2 and 1.3 engines is about 135psi i cant see if differing much for the 1.4 engine

[vauxluva]

Edit. cheers

[Royston]

sounds like stem seals!

[Dayle_]

oil down the bores to see if it goes up,

[Royston]

oil down the bores to see if it goes up,

it will due to the additional sealing at the ring/bore but might show ring issues I suppose. At 105 the bores/valve seats will be worn as it isn't a new engine.

Worn stem seals normally show after the engine has stood over night on the first start up....puff of smoke.

If the heads coming off for the stem seals, get the valves lapped in, you can then inspect the bores, and it isn't a great deal more work to remove the pistons, deglaze the bores and and re ring;)

Then nearly a new engine:thumb:

[bmw156]

it will due to the additional sealing:wtf: at 105 the bores/valve seats will be worn.

If the heads coming off for the stem seals, get the valves lapped in, you can then inspect the bores, and it isn't a great deal more work to remove the pistons, deglaze the bores and and re ring;)

you make the oil sound like a pointless task. it will give extra sealing on the PR as you know, so if it does go up, i would say the PR are on their way out. and the valve seats etc are fine!

[Royston]

you make the oil sound like a pointless task. it will give extra sealing on the PR as you know, so if it does go up, i would say the PR are on their way out. and the valve seats etc are fine!

Sorry I have just rewritten while you commented, after thinking about it:tard:

If the head is coming off anyway I would lap the valves as a matter of course

[bmw156]

lol, either way something is wrong with the engine with that compression.

just swap over the engine for another :)

[Steve0011]

ooops! major typo by me, so heres some extra 0's to go on the end of 12

00000000000000000000000000000 ;) :d

[Royston]

just swap over the engine for another :)

That is an option as long as you know its a good 'un:thumb:

Personally I'm a great believer in the devil you know, i.e. identify what is wrong and fix rather that chancing a £50 ebay special.;)

[vauxluva]

That is an option as long as you know its a good 'un:thumb:

Personally I'm a great believer in the devil you know, i.e. identify what is wrong and fix rather that chancing a £50 ebay special.;)
couldent have said it better? as i say its fine you can leave it half an hour ticking over no smoke @ all go past 3000rpm it turns into a blue smoke screen. Ok if i was looking for a getaway car.