jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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Morning all, Having some issues with oil burning on my 91 mk2 Golf GTI. I've recently finished my 2E 2.0 conversion (2E block from a mk3 with the mk2 PB head). Everything was great...for a couple of days... Engine pulls and drives very well however I'm burning a fair amount of oil in not a great deal of miles - most noticeable symptom is a plume of blue/grey smoke on gear change at high revs. I ran a compression test today to see what was going on and these are the figures (seem ok to me): Engine cold: Cylinder 1: 190 psi / 13.1 bar Cylinder 2: 190 psi / 13.1 bar Cylinder 3: 200 psi / 14 bar Cylinder 4: 200 psi / 14 bar Engine up to temp: Cylinder 1: 190 psi / 13.1 bar Cylinder 2: 190 psi / 13.1 bar Cylinder 3: 195 psi / 13.5 bar Cylinder 4: 200 psi / 14 bar The head was fully refurbed with new guides replaced and the valve seats recut. Exhaust smells quite fumey on idle but the smoke only happens at high revs on gear change. No puff on start up and no sign of smoke any other time (i.e idle, any other time driving etc). Other than the smell it's clean smokewise from the exhaust. Oil pressure on my VDO gauges looks good. Am I right in thinking if the rings had gone I'd be smoking constantly on acceleration? I'm looking towards blaming the head but would like to get a more accurate diagnosis before speaking to the guy who refurbed the head - I'm not really sure what to say and I don't want to go making accusations I don't really know much about. Any help appreciated as I'm at a bit of a loss  . |
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Sept 8, 2011 11:18:51 GMT
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The comp fig's look ok to me but what are the manufactures fig's, the blue smoke on gear change would point to valve stem seals but you would also get a lot of blue smoke on start up. But this wouldn't use a large amount of oil.
Remember there are compression rings and oil control rings so just because the comp is ok doesn't mean rings cant be ruled out.
You could take off the inlet and exhaust manifold and see if oil has run down the valve stems before you take the head off.
A test you could do would be to put some oil down the bores and do a comp test to see if it jumps up as the oil will temporally seal leaks in the rings.
And then there's the crank/head breath's check these of if you can block if off at the manifold and see if that improves things.
Good luck ;D
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jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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Sept 8, 2011 18:17:46 GMT
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Thanks for the reply. Manufacturers figs are a good GTI should be between 180 psi and 200 psi so ticks the box there. I shall try the oil down the bores trick. Bloody hope it's not the rings  |
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ChasR
RR Helper
motivation
Posts: 10,307
Club RR Member Number: 170
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Sept 8, 2011 21:19:38 GMT
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How are the breathers? It may be a Valve guide issue I admit, but if you are using a hybrid engine are the breather systems vastly different for each engine?
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jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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The breathers are a hybrid design but not vastly different to standard. The ones on the rocker cover are the same, just routed slightly differently. The only main difference is the 2.0 block has an actual outlet on the block whereas the 1.8 doesn't. It's ok to block this off but I decided to use it as it must be there for a reason. I'll try cleaning it out again. Would a leak down test be worth doing? Not even sure if garages still do those? Thanks for the help btw, appreciated. Large hose coming down the front of the block is the additional breather:  Plugs all looked clean:  |
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Last Edit: Sept 9, 2011 6:47:13 GMT by jmsheahan
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murran
Part of things
Posts: 610
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Sept 10, 2011 17:04:44 GMT
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how much oil is it burning? is the level in the sump noticablely dropping?
the breather system.
doesnt seem quite right to me. you know when the engines ticking over if you unscrew the oil cap does it seem like theres excessive vacuum in the crank case?
also i see youve fitted the 2e cam cover... the old pb tin cover has a plastic cam splash guard under it to keep oil from being splashed up on to the breather vent in the cam cover.
does the 2e one have a similar thing?
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jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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Sept 12, 2011 6:19:58 GMT
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how much oil is it burning? is the level in the sump noticablely dropping? the breather system. doesnt seem quite right to me. you know when the engines ticking over if you unscrew the oil cap does it seem like theres excessive vacuum in the crank case? also I see youve fitted the 2e cam cover... the old pb tin cover has a plastic cam splash guard under it to keep oil from being splashed up on to the breather vent in the cam cover. does the 2e one have a similar thing? A fair point on the breather system - it's been suggested it should be plumbed in differently on another forum. Going to try and get the proper hoses from the scrappy today (mk3 setup) and see if it makes a difference. I'll check the vacuum from the crank case in a bit - going to mock up a home brewed catch can and see how heavily it's breathing. Regarding the cam splash cover, yes the 2E has the same one and it's in there so can cross that one off. Cheers for the suggestions guys, appreciated. |
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jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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Sept 12, 2011 15:47:40 GMT
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Regarding the vacuum in the crankcase, yes it's noticable when cold but when up to temp not at all.
I set up a catch can yesterday to see if it was breathing heavily. Done around 60-70 miles of mixed driving with it and it's completely dry still.
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Last Edit: Sept 12, 2011 15:48:03 GMT by jmsheahan
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jmsheahan
Club Retro Rides Member
Posts: 689
Club RR Member Number: 121
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Sept 23, 2011 10:56:53 GMT
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Have redone the breather system as per the Mk3 setup (cheers RJ) just to rule that out as the current setup was a bit bodged. Looks much more tidy I have to say.
Went for a good blast around the countryside with a mate to check the smoking. I can confirm it is literally on gear changes at high revs, not all of the time having seen it from following behind. It doesn't smoke constantly on power, just a fairly large plume at higher rev gear changes when coming back onto the power which lingers for a few seconds and clears. Idle seems clean. It's definitely not down on power.
Most of the symptoms point to a block problem (i.e smoke on power), but I have good compression and it doesn't smoke constantly (I don't know what blown piston rings smoke like, never had it). This points to the head but it seems clean on idle and startup which makes me doubt the seals.
If the rings or oil control seals had gone surely it would be smoking it's tits off?
The way I see it is I've got two options:
1 - Replace the stem seals which will cost around £200 as I can't do it myself.
2 - Source a new bottom end and strip the whole thing down again.
Both are gambles and I have very very little money to play with which is why I wish for more certainty as to the route of the problem.
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