Bad Compression

[joobienooner]

Well I just compression check my 91 talon tsi and the results are 30-115-130-140 (1-4). Car was warmed up and I test at WOT. The car only has 9XXXX miles and has always been completely stock and run at stock boost. Dont really know where to start and I dont have a leak down tester. Could it just be the hg or does it sound like something worse.

Thanks,
Ryan

 

[FLiP OuT MaN]

Could be variety of things, HG, your head, piston rings etc. I believe at this piont its too much of a guessing game and you need to diagnose some more, good luck.

 

[joobienooner]

It seems weird that the compression gets better as you go to the next cylinder. Could it just have a crack in the headgasket between the cylinders or something like that. The car only has 9XXXX miles on it, I would hope that it doesnt already need a rebuild.

Thanks
Ryan

 

[DoyoFCT]

put oil in the cylinder and re-test if it stays the same then its probably a headgasket or valve. if it goes up its rings. oh and worse case it might be a combination of both, unfortunately 1g cars run pretty agressive/lean from the factory and if there are any boost leaks it can cause some damage so even if the car was bone stock without making sure it was in perfect running condition problems can occur. btw try all cylinders with oil during the re-test cause one may not change and one might. it sounds like you are in for a rebuild, altho ive had ppl bring me cars that have been running on two dead cylinders . so it might last a little while but you risk causing more damage.

 

[joobienooner]

Alright so this is weird. I Decided i was going to do a cold compression test and then add oil and do another cold test and see if it went up. But the cylinder that was 30 yesterday when i did the hot test is now 120 cold. Is there any reason why it would be a lot less when its hot? Also yesterday when i found out cylinder 1 was only 30 i tried cylinder 4 again and got 140 again, then i tried cylinder 1 again and got 30 again. So the gauge is consistant. IUNNO. I'm kinda scared to drive it.

Thanks,
Ryan

 

[Defiant]

It's done. It will neither heal, nor repair itself. You'll find out what died when you get it apart. Suspect a scorched valve or piston.