Compression test results (BURNT VALVE SEAT!)

[VRTrickster 0]

As some of you may know Ive had a few running problems with my vr ,which I think Ive almost got to the bottom of now. Although yesterday I decided to give it a compression test and heres the results.

1)13 bar 3)12 5) 9.5!

2)12.5 4)12 6)12.5

The thing that concerns me is the cylinder 5 ! The rest are very good ,in the Bentley it states 11-13 for a new engine and 7.5 minimum wear limit.

Maximum permissable difference between all cylinders is 3 bar.

Im I worrying about nothing as apart from the number 5 its got pretty good compression?

Please someone put my mind at rest !

[vr6turbo 27]

warm the car up and then retry the compression test

a leak down test will confirm if its rings or valves

some times its worth doing each cylinder twice, as i have had the tester not seal correctly and give a false reading

then at least you will be 100% sure there is a problem

remember to remove the fuel pump fuse whilst testing

[6potmkII 0]

5 does seem a bit lower than the rest mate, whats the milage on...

[VRTrickster 0]

I did warm the car right up before carrying out the test. The car has done 125,500 but had a new block and pistons about 30,000 ago. The head was stripped and the valves re lapped. The face was also welded and re skimmed. This was carried out before I brought the car but I have all paper work from a main dealer.

Maybe I should redo number 5 just to make sure. Would the lower compression in one cylinder cause a noticable difference in engine behaviour?

[Eat this 2]

does it chuck oil out the exhaust when its stone cold?

[VRTrickster 0]

No, no smoke from exhaust. I thought if anything it could be the cylinder head, surely not the pistons? MPG pretty good aswell.

[Eat this 2]

not likely to be pistons/rings if its not smokin maybe a valve not sealing properly??

[VRTrickster 0]

Could be, I think I do need to do the test again just to make sure.

[antera309 3]

The next step would be a leakage test. The pressure is either leaking into the exhaust, inlet or into the crankcase.

[VRTrickster 0]

Yes I can let my dad take it to work, and give it a leakage test. Im just wondering if it would effect things that much? The cylinder compression is within the 7.5 min, but is still 2.5 bar different to the rest.

[VRTrickster 0]

Right I brought myself a comp tester today and retested number 5. It measured the same result of 9.5 ! One thing I did notice is when turning the engine whilst testing the engine was making a chirping noise that was quite loud! This noise but quieter also happens when I switch off the ignition after driving. I was just wondering if this could be the sound of air coming back up through the intake ?

[antera309 3]

I don't know about the noise, but it is quite possible that air could be leaking into the intake due to a valve not seating properly.

[VRTrickster 0]

Right Ive stripped the head and found a burnt inlet valve seat on number 5!

The valve didnt look that bad but Ill find out for sure when its inspected and rebuilt. Does anyone think that it might no be able to be re-seated as I know the seats cant be replaced on these heads?

Didnt really come across any problems when stripping apart from Im going to need a new cam sprocket bolt and coil pack bolts, along with the gaskets and seals etc.

Im probably going to go for new bronze stems, exhaust valves, multi angled seats and port polish/gas flow. He has asked me to send the lower inlet mani for port matching plus all the old gaskets for guides for porting I suppose.

The fella is based in south Ireland and will be picking in up from the ANC depot on the 24th to carry out the work and send it back. I really cant wait to slap it back on!

How do you post pics up?