compression test results

[benji mk2]

Just done a compression test on my 8v 2.1, results were:

1  dry 12  wet 13  bar
2  dry 12  wet 13  bar
3  dry 11.5 wet 13  bar
4  dry 12  wet 13.5  bar

 I have been suspecting the valve stem seals for a while, smoking at certain times, tear stain of oil below two of the plugs, using oil etc etc. Could anyone tell me if these results point to that or not? Also can the seals be done without removing the head?

 Ta 

[fused]

My mechanics did my '90 8v pb head, valve seals with the head in situ. I can check later today but I'm sure they removed the spark plug and manually turned the engine over untill the piston was TDC (so the valves couldn't drop to far) I'm not sure if they used compressed air to hold the valves up or not..... ? hmm got me wondering now! 

steve

[benji mk2]

any more info you can provide would be appreicated dude!!!! Cheers

[monzablue16v]

They can do valve seals with the head in situ by using compressed air in the spark plug hole to hold the valve in place. not too much of a job to take the head of and do yourself tbh I did all mine when I rebuilt it not long back may as well do the head gasket whilst it's off as well.

[yorkie]

You must be reading the gauge wrong, car wouldn't even run at 13psi are you sure you don't mean bar?

Won't be the valve stem seals anyway as at peak compression both valves will be shut.

I wouldn't worry about it, the readings are close enough imo.

You probably do have leaking valve stem seals as they all leak eventually but unless you are producing a James Bond style smoke screen and using a ton of oil I would'nt worry too much about that either.

Worn seals usually mean smoke when you lift off the throttle at high revs, is this what you get?

[benji mk2]

opps slight typo methinks, it was bar!!! what a dumbass

 tested it out today and it smokes a little under hard acceleration but if i floor it then back off i get a nice little explosion of oil!!! 

 I'm gonna phone machine mart tommorrow and order the bits, will try and do it with the head in place!!!! Doesnt look to bad but will i need to take the cam out???

[rowlers]

take the head off - I found it easier!

Treid doing it with head on and it was just awkward and a pain! Far easier/quicker to take head off, although it costs a gasket set!

[DarnPB]

Changing the seals can be done with the head in situ. You need to put the piston at the bottom of its stroke so that it is just about to start its travel upwards on the copression stroke. Get some cord in good condition and thread as much as you can into the cylinder through the spark plug hole. Then rotate the engine in direction of travel and the cord should force the valves against their seats. Then do the necessary with the valve stem seals.
Once finished, turn the engine the opposite way and remove the cord.
Be carefull not to turn the engine whist the valves are not captive or you will lose one. Then the head does need to come off.

[rowlers]

see what I mean - its a ballache

[clipperjay]

You must be reading the gauge wrong, car wouldn't even run at 13psi are you sure you don't mean bar?

Won't be the valve stem seals anyway as at peak compression both valves will be shut.

I wouldn't worry about it, the readings are close enough imo.

You probably do have leaking valve stem seals as they all leak eventually but unless you are producing a James Bond style smoke screen and using a ton of oil I would'nt worry too much about that either.

Worn seals usually mean smoke when you lift off the throttle at high revs, is this what you get?

Haa knew someone was going to spot that I just thought he decided to miss the zero on the end of that PSI.
thats what I thought the valves and compression is close enough after all 1.8 should be 9.5bar being a 2.1 13 bar is not bad, seen worse.