Should I try the headgasket first? Or just rebuild?

[Novablue454]

I recently did a compression test on my 90tsi, and the results were not good. 90 across the board. I did a leak down test. On cyl 2, there was air coming out the dipstick tube, and the intake on all the rest. The car has overheated numerous times. Should I bother just doing the headgasket and seeing if it helps? Or just pull the whole thing out and rebuild it?

 

[EagleTalonTim]

It could be more than just your head gasket. Since you have overheated it several times, I would pull the head and get it milled since our motors don't like alot of heat and the head warps easily. Before you pull the head, put a cap full of oil down each spark plug hole and do the compression test again. If the compression is higher, look forward to replacing your rings too. After you pull the head, check the cylinders for ring wear towards the top. You may feel a small lip about 5cm down from the top of the cylinder. That is where the rings stop when the piston is at TDC.

Good luck!

 

[oldman]

Crankcase = rings and intake = intake valves, did you see air bubble in coolant to implicate the HG? What were the leak %?

 

[Novablue454]

I didnt use an actual leakdown tester, so i dont have a percent or a drop number. I did the oil test at the same time, and it jumped the compression back up to 160.

So now I guess is the engine easier to pull with the head on or off?

 

[oldman]

So now I guess is the engine easier to pull with the head on or off?

It's much easier to pull everything, intake manni, exhaust mani, turbo, tranny......etc.

That said, I have some questions for you before you start to pull anything.

1. Was the compression test done with the car fully warmed up, battery fully charged and throttle plate fully opened? I always asked these questions when results are low but consistent across all 4's.

2. How much oil did you administer during the wet test? Was it done on all fours and all of them got back up to 160.

Without using a real leakdown tester, it's hard to gauge how much air is being lost, remember, you will always lose some through rings especially if the car is not up to operating temperature. Many things do not make sense in your test results either, if all for rings are EQUALLY damaged as indicated by your wet test, why didn't the other 3 cylinders leak through rings during your "leakdown"? Furthermore, your "leakdown" implicated intake valves in 3 cylinders, how were you able to bring it up to 160 by adding oil?

There are simply too many conflicting data from your tests, something must have been overlooked, whether it's testing equipment, procedure and/or interpretation. What was the reason for the compression test in the first place?

 

[Novablue454]

the compression test was because the car has just been acting really funny. Slower then usual and the engine is making some very wierd noises that neither I nor anyone else that has looked at can begin to figure out.

I dont remember for sure, but I believe that the numbers were 104 for cyl 4, 92 for cyl 2, 90 for cyl 3, and 91 for cyl 4. Air came out the crankcase noticeably on 2 only, yet I did the wet test on cyl 4.

The car wasnt fully warmed up, but pretty close. I did the test cranking only because im scared of the noises its making when its running.