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Discussion Starter #1
Over the last view days i have noticed that oil is leaking from my engine, from the filler cap and from a sump bolt hole, and tonight I noticed it coming from the dipstick slightly.

I started her up the removed the dip stick, not much blowing through, then I removed the oil filler cap and the dip stick really started to blow hard, I put the dip stick back in and the oil filler cap remained the same which was more blowey than it should be.

The car drives 100% perfect, throughout the whole range, so i'm hoping I have a blocked oil Breather pipe, the rings and infact the whole engine was renewed just last year, so I'm hoping this is all still perfect,
Has anyone else experienced this or gonna be able to give me a few pointers on what to check first.

Its on my Astra with the C20 LET engine,
Regards Bren
 

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mine used to blow a small amount out the filler cap at high revs, replaced it with a metal one and its fine now.
the sump bolt needs a new washer each time you take it off, so try changing that @ next oil change.
 

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Discussion Starter #4
yeah, thats what i'm hoping,
I havn't took the cam cover off yet, really pushed for time, do you reckon it will be blocked up there, either the big pipe coming up from the sump or the little pipe that feeds it back into the turbo?.
It would be nice and easy if it was one of these.
 

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Mine had a melted piston once when it was breathing heavy like that !!!!:( Hope not for your sake though !!

May be worth a compresion test.

Richard
 

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Discussion Starter #6
Hmm, with the nos fitted I tend to think the worst,
The car really does perform without fault though.
I can normally tell straight away when something is wrong though so I think the piston will be fine, I havn't got a compression tester for this engine..i'll ring a few mates though and get it done anyway,

The guy where I bought the nos from said it would be worth while doing a blow through test (think thats what its called) its where they take the sparkplugs out the connect a compressed air pipe into the spark plug area, then as they blow in the air you listen for the valves leaking. sounded a bit bodgy so I never had it done.
Have you heard of this Richard?
 

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Yeah as 16vastra said. Cylinder leakage test is better then a compresion test but its whatever you can get your hands on. A cykinder leakage test will need a compressed air supply.

I used to to regular compression tests so you can get a idea of when things are going wrong!!!

Richard
 

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aahh, my favourite subject ever since I made my own leakdown tester :)

You're right Bren - to avoid this, each pot is put at TDCc (little c for compression) - you must not let the cylinder go past TDC or the rings move in their groves and can muck up the readings - the idea is that the rings are sat on the bottom of the lands so cannot move.

then you attach the tester and open the valve - the more complex type actually has two gauges - the first in regulated to give, say 10psi - then you have a restrictor (basically a little hole) - then the second gauge.

due to the laws of fluid (or in this case pneumatics) dynamics - the second gauge will read lower, proportional to the amount of leakage escaping out the cyclinder by whatever means (gasket, valves etc. etc) - and hence the two readings together give you your percentage.

e.g 9 psi on the second gauge would give a leakdown of 10%.

muggins here went and built the whole shooting match - which worked perfectly, except that his little paint gun compressor didn't have anywhere near enough flow to overcome the leakage - so I had to resort to the simpler leakdown method of watching how fast the pressure dropped with the restrictor and 2nd gauge removed.

whilst doing this you also listen at the oil cap, crankcase breather etc for 'wind' - and hence as well as an idea of the leakdown rate, you also know where it air is going.

generally, expect 5-10% leakdown on a good engine, and make sure the air escaping is going past the rings, obviously.

ok I'm done :)
 

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Gary said:
aahh, my favourite subject ever since I made my own leakdown tester :)

generally, expect 5-10% leakdown on a good engine, and make sure the air escaping is going past the rings, obviously.

ok I'm done :)
:( :( :( i had this done just last week during my rolling road session and all 4 cylinders were reading around 30%. - exhaust valves are shot :( :( :(

rodgerq
 
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