Compression Test Results

[jenks 0]

Just wondering what everyones opinions are on the following results?

 

94 Vr6 with 176k (been off road for 18 months) no running problems aware of.

 

Cylinder

1) 165

2) 185

3) 175

4) 160

5) 175

6) 180

 

93 Vr6 with 150K (daily runner) no probs

 

Cylinder

1) 155

2) 175

3) 175

4) 175

5) 175

6) 180

 

92 2.8 Vr6 with 115k and suspected Bottom end gone.

 

Cylinder

1) 175

2) 160

3) 140

4) 170

5) 150

6) 155

 

Opinions? :salute:

[Yandards 0]

Direct from the workshop manual:

 

Engine oil temp min 30 deg C

Pull 3/5 pin connector from ignition transformer

Fully open throttle valve

Crank engine

 

New 10-13 bar / 145-188.55 PSI

Min 7.5 bar / 108.7 PSI

Max difference 3 bar / 43.5 PSI

 

So they are all within the limits specified by VW although the 34 PSI difference on the last block is getting close.

[andy 0]

First results I would say are as to be expected, its a high mileage car, a bit of variation in the readings but if she's running ok, as I'm sure it would with those figures, no problem there.

 

2nd results are ok, but no 1 cylinder is obviously starting to show its age, it could be many things but you'd need further diagnosis to work out what. The fact that no 6 is still so good says to me that it probably isn't bore wear as in my experience 1 and 6 tend to wear at a similar rate. Overall though thats a good set of figs so its a shame no 1 is so low, could be early Head Gasket issues or valve trouble.

 

3rd results are anyones guess, all the figs are lower than desirable, with some that are very low, theres obviously an issue on that one especially given the low mileage.

 

I take it the engine was hot for these tests?

[Yandards 0]

First results I would say are as to be expected, its a high mileage car, a bit of variation in the readings but if she's running ok, as I'm sure it would with those figures, no problem there.

 

2nd results are ok, but no 1 cylinder is obviously starting to show its age, it could be many things but you'd need further diagnosis to work out what. The fact that no 6 is still so good says to me that it probably isn't bore wear as in my experience 1 and 6 tend to wear at a similar rate. Overall though thats a good set of figs so its a shame no 1 is so low, could be early Head Gasket issues or valve trouble.

 

3rd results are anyones guess, all the figs are lower than desirable, with some that are very low, theres obviously an issue on that one especially given the low mileage.

 

I take it the engine was hot for these tests?

 

Er, as I said above the figures are, as far as VW are concerned, all ok. Admitedly some of them are not great but even the cylinder difference still has 20-25% tolerance between the worst 2 cylinders.

[jenks 0]

woops! ok ive fecked up there, no sorry they werent warm or hot? damn i shoulda realised! :brickwall:

I take it it will make a difference?

 

thanks for the input

[Yandards 0]

woops! ok ive fecked up there, no sorry they werent warm or hot? damn i shoulda realised! :brickwall:

I take it it will make a difference?

 

thanks for the input

 

Min 30 degrees of oil temp as posted above, do exactly what I posted or it may mess the figures up a bit.

[craigowl 0]

Mind you, if oil at blood temp is acceptable, say, 37C, the engine isn't going to be scorching hot and the metal bits will not have expanded that much? Or is it not as simple as that??

[Yandards 0]

It is that simple Craig but then the figures provided will be based on what VAG decided was acceptable so as all it says is that oil temp must be above 30 deg C then any furthur thermal expansion must have little effect on the compression figures.

 

Personally I would warm the engine up until the MFA oil temp kicks in at 50 deg C and go from there.

[Supercharged 2]

I always thought you had to pull the FP relay too but maybe the ignition trans plug stops the injection?

[Yandards 0]

I always thought you had to pull the FP relay too but maybe the ignition trans plug stops the injection?

 

I've said it before on this thread and I'll say it again, the text I provided above is directly from the VR6 engine manual under the heading 'Compression Testing'.

 

So, no, you dont need to do anything more than that which I typed out ages ago :?

 

You should know better too :cuckoo: :nono: :scratch: :bad-words: ;)

[andy 0]

There you go, we've all been told now! I think the manual says something about never replacing certain parts like chains too....oh and fuel filters, it just makes you wonder why you can even buy them!