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G40niko

Piston oil residue pics attached

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G40niko

So my car is burning some oil notice it when the car is warmed up get blueish smoke when at a stop idling then pulls away i.e. Traffic lights seems to be ok on the move but then noticeable on the overrun
Did a compression test with engine hot 
Cy1 180psi
Cyl 2 180.5 psi
Cyl 3 165 psi
Cyl 4 180 psi

Cyl 3 is a little low but would think is still above spec?
Then got a camera down bores to see pistons in order cyl 1 first pic etc
Cyl 3 looks the cleanestspacer.png

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Also do these look like standard G40 pistons cant really tell?

Edited by G40niko
Pictures added

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steveo3002

cant see the pics ...smoking after idling is typical valve guide and seal wear , to be expected with some milage

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G40niko
11 hours ago, steveo3002 said:

cant see the pics ...smoking after idling is typical valve guide and seal wear , to be expected with some milage

Sorry if you click the links should direct you to pics

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damunk
23 hours ago, steveo3002 said:

cant see the pics ...smoking after idling is typical valve guide and seal wear , to be expected with some milage

 

i was advised to change valve guides when doing the valves and i wish i hadnt. valve guides were hardly worn at all.

should have left them in. the seals are rubber and i bet get perished first (worn first), all them years/milage of valve stem going through it.

 

is it not worth op changing the valve stem seals first, very cheap option first?

he might even find one of them has popped off, or even the tiny spring around the seals has popped off one of them.

 

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steveo3002

certainly worth looking first ...theres specs in the manual how much wear is acceptable

 

if the guides are worn then a valve rattling about will wear the seals in no time ...but yeah seals can go hard and stop working with age , id say over 100k the guides will be worn too

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caretakerplus

Welcome to the Forum.

 

You don't need much wear on the valve guides (especially the inlet valve guides) before oil is drawn in.  Obviously, this happens when the engine is idling, rather than when the throttle is open, as that is when vacuum is at its highest.

As you say, cylinder three is the cleanest, the reason being that this is the one with the lowest compression pressure - the oil has had a cleaning effect.

Before you do anything else, I would suggest that you carry out a 'wet' compression test on No 3 pot, if the pressure remains the same, or there is only a slight increase, it is telling you that the loss of compression is due to a valve not seating. On the other hand, if the pressure does 'come up' with the wet test, it means that the oil that you have put into the cylinder (about a tablespoon full) is forming a temporary seal around the piston and you MAY have to replace the piston or rings.

 

Without a Dial Test Indicator (D.T.I.) it can be difficult to measure valve guide wear - It can also be difficult the gauge any wear by 'rocking' the valve in its guide, but try this with the valve in its normal open position and again when it is about half way open.

A simple check that you can make with a DRY valve stem and dry guide, is to place your finger over the end of the guide and withdraw the valve (fairly smartly) - this should produce a distinct 'POP'.

Note: If you do this with oil on the valve stem, even a worn guide will create the 'POP'.

 

Regards

 

 

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G40niko

Thank you all for you replied much appreciated thing is the valve stem seals were replaced not to long ago but the does not mean to say if it was be done correctly 

also I know that there are 2 sizes on the G40 7mm and 8mm so will need to check that which have been fitted,

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damunk

i once put a valve stem seal on and i popped the spring off when i were pushing it over guide,  luckly saw it

but if that was your case you should have noticed the problem more or less straight away.

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G40niko

Ok I will have to look into it the stem seals were fitted by someone else . Think I will have to check them first.

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