3.0 B6 A4 Compression Test

[jms2211]

Hi all,

I plan on performing a compression test on my car this upcoming weekend, Does anyone know what good results would be per cylinder?

Thanks

[customa4]

Not sure about exact numbers but I believe anywhere around the 180 mark would be pretty healthy.

Compression Check
Engine oil temperature at least 30°C
Battery voltage at least 12.7 V
Remove engine cover
Switch off ignition
Disconnect coil pack harness'
Pull out ignition coils
Remove spark plugs
Disconnect connectors from all injectors
Fully open throttle valve
Check compression with the compression tester
Using the compression tester-Operate starter until tester shows no further pressure increase

Max difference between cylinders-43.51 psi

[cschuster]

Factory specs:
New: 145psig -203 psig
Wear limit: 130 psig

Maximum difference between cylinders: 43 psig. Max difference is measured from the highest cylinder. Instead of disconnecting all the injectors, you can start the car and pull the fuel pump fuse until it dies.

EDIT: Consistent numbers are more important than high ones.

[jms2211]

Factory specs:
New: 145psig -203 psig
Wear limit: 130 psig

Maximum difference between cylinders: 43 psig. Max difference is measured from the highest cylinder. Instead of disconnecting all the injectors, you can start the car and pull the fuel pump fuse until it dies.

EDIT: Consistent numbers are more important than high ones.

Thank You!

[jms2211]

Did the test this past weekend, the results were between 126-132 psi for each cylinder. What do you think of these numbers?

[customa4]

With the wear limit being 130, the numbers don't seem to be too good. On the plus side at least the cylinders were in close range to each other. I'd recommend grabbing a can of BG EPR and run it through the car. Should bring the numbers up a bit. I've used it with great success. It requires an oil change after running it through the system.

[CyberPMG]

Those are not good results. You're at or below the wear limit. Could be just bad rings. Check for excessive cam lobe wear. If they are worn down, those metal shavings are getting into the cylinders and destroying them. Check the oil pan for any debris. Check the oil pickup tube to make sure it's not clogged. You could be looking at a rebuild at worst.

[jms2211]

I actually have had the oil pan off recently and it was perfectly clean, pickup tube was sprayed out and seemed very clean and free of clog.

When I did the compression test I took all the plugs out and performed the test, would I have gotten different results if I only pulled one plug out at a time?

[customa4]

No, you did it right, plugs are supposed to be removed. Each cylinder is separate from one another, the compression tester holds the seal for each cylinder as you test it.

[jms2211]

Those are not good results. You're at or below the wear limit. Could be just bad rings. Check for excessive cam lobe wear. If they are worn down, those metal shavings are getting into the cylinders and destroying them. Check the oil pan for any debris. Check the oil pickup tube to make sure it's not clogged. You could be looking at a rebuild at worst.

Also are bad rings common in these cars?

I am not losing any oil and may have lost a little coolant over the past 6,000 miles, (I'm not 100% sure of this because the body shop filled my coolant last and I never checked how full it was)
The main concern for this test was last time I took off my oil cap there was a white milky substance, on it. I did also notice that the rubber gasket on the oil cap is deteriorating so I am wonder if that can be a cause for moisture in the oil.

Either way I was just curious so I did the test, the car runs fine and without any problems (knock on wood)

- - - Updated - - -

No, you did it right, plugs are supposed to be removed. Each cylinder is separate from one another, the compression tester holds the seal for each cylinder as you test it.

OK I though so, thanks for confirming

[cschuster]

Here are my results from a few years ago at 137k. I did not do anything with the throttle body - not sure how that affects results. This was also a dry test, no oil added to cylinders.

1: 167 | 6: 166
2: 164 | 5: 170
3: 167 | 4: 166

Try the test again, but add a few drops of oil into the cylinder. If compression numbers go up, then its the piston ring. If compression is still the same, maybe valve seals or a head gasket?

[CyberPMG]

How many miles are on the car? Are you the original owner? How often are you changing the oil? If you're not the original owner, do you have full history of all service done? Are you always using synthetic oil and large capacity oil filters?

I would agree with csc's recommendation of running the compression test again and use a few drops of oil in the cylinder to see if the compression number goes up.

[jms2211]

How many miles are on the car? Are you the original owner? How often are you changing the oil? If you're not the original owner, do you have full history of all service done? Are you always using synthetic oil and large capacity oil filters?

I would agree with csc's recommendation of running the compression test again and use a few drops of oil in the cylinder to see if the compression number goes up.

Unfortunately I am not the original owner, nor do I have to full service history of the vehicle, The car has 129,000 miles on it, and since I've had it since (110,000 miles) I have changed the oil between 5 and 6 thousand miles and I use the Audi filter right from the dealer, I do use a full synthetic 5W-30 oil and i do all the changes myself.

I have read about dropping some oil in the cylinders to see if it makes the numbers rise, I will try that, maybe today. I read about a teaspoon of oil in the cylinder, is that a good amount to put in?

[customa4]

Yes

[SJorge3442]

I'm not sure how much of an issue it could be, but generally you want the throttle body wide open when running these tests. I'm not sure if that will help you get significantly better values, but its probably worth a shot.

Sent from my Nexus 6 using Tapatalk

[Jesus Leyva]

I have a 2002 A4 3.0l and I just did a compression test to check for a blown head gasket, when white smoke billowed fom the exhaust, and I got,

1-60 psi and it drops
2-90 psi
3-90 psi
4-70 psi
5-60 psi
6-90 psi
Is this normal?

The engine was cold, it had been sitting for about a month, Cam lobes are fine on both heads, the spark plugs in cylinder 1 and 3 we're clean the rest had normal wear, low on coolent and oil smelt and looked normal. Car turns over ist fine and ran perfect before I guess I'm asking which cylinder has the bad head gasket?