cylinder compression

[mr.oogieboogie]

hello everyone. Can anyone tell me what the compression should be on the cylinders as i will be testing this evening.

Car is a 1994 s4

[Bibs]

Search = awesome

[troutrou]

According to the Turbo SE workshop manual, which should therefore apply to the S4 engine just the same, it is specified: " 9.5 Bar (140 PSI) minimum ".

Edited April 13, 2010 by troutrou

[mr.oogieboogie]

well the compression test :-

cylinder 1 = 140

cylinder 2 = 150 (this is the cylinder with the noise)

cylinder 3 = 150

cylinder 4 = 140

so i have ruled out a combustion issue, next take the alternator off and get it checked

[lotus4s]

Bibs,

Is there any way of finding out from the factory what psi range a new/rebuilt SE-S4s engine should be? It would be nice for those of us that rebuild engines to know if 145psi is a good number or maybe it should be more like 160 or 170. I have no clue but would be nice to know. As you know, the manual only gives a minimum number...

Jim

[Bibs]

I'll ask tomorrow Jim

[robdaniel]

peter i know you have a charging issue which was pointed out by looking at your freescan logs, but i cant see how this would cause the problems your having. did you have this problem before you changed your manifold or was it cracked/blowing and you did not notice. has the manifold been designed in such a way that the gasses are exiting abnormally or has it not been welded quite right and got a small pin hole where gasses can escape causing this noise.

[mr.oogieboogie]

hello robin no noise before, no leaks, the only difference on the tubes is that i had this one dressed, slighty flatter on the end of the bend to fit it i cant see that making the noise difference. Im sure i will get to get to the cause soon, the alternator will bw checked friday hope to get it repaired or replaced on the spot. Then i will give it a good bitchin to see if anything occurrs

[waynef]

What Milage is the S4 mine is running sweet as a nut (touch wood) with 96000 miles on the clock and is reading

150

145

150

145

Strangly enough mine had a strange noise and has just had the manifold sent back to lotus, a small pin prick hole was found straight through between cylinders 2 and 3. The manifold had never been right since fitted new two years ago and has been on and off numerous times. Luckily for me they have found this small hole now and I should have a replacement shortly.

From what I have heard from independent Lotus grages a rebuilt engine is about 170 ish

Edited April 16, 2010 by waynef

[mr.oogieboogie]

hello wayne. the s4 has around 84k on it. had the alternator fixed today it was tested and was putting out 17volts so regulator replaced checked and put back on noise still there, took it for a small run cars sounds great when going but noise still there. brakes binding and i think one of the oil coolers may have a leak as when washing there was a rainbow from the front wheelarch so i will need to check that over the weekend

[Bibs]

From the guru

For a Esprit 910 Turbo Engine we would expect Compression Figures to be approx 150 PSI.

This is typically what we recorded on our development engines when fully Run In and in good condition.

A tolerance of +/- 10 PSI could be expected.

The figures could vary slightly depending on the Temperature of the Engine and the Cranking Speed (battery dependant)

The engine build specification (final compression ratio) could also have a small influence.

The figure of 140 PSI Min is stated in our Service Notes.

Anything below this indicates some wear within the engine.

The most important thing is that all the cylinders are registering similar pressures - within 10 PSI.

It is important that the battery is in good condition and fully charged while doing the checks.

The engine in question is showing what we consider as satisfactory figures.

[waynef]

Wow that is lower than i expected so mine at 96000 miles is pretty good then.

And the good news my exhaust manifold arrived today hoorah!!!!!

Will get her back in about a week so hopefully all will be ready for Castle Coombe

[lotus4s]

Bibs,

Thanks a million for that info, it will be most helpful.