Low compression 2 cylinders

86.5Supra09 · 10-08-2010, 01:30 PM

Hey guys I have an 86.5 MKIII and did a compression check with the #4 & #5 were low. I think the #4 was 120psi and the #5 was only 90 psi. What could be the problem? Rings? HG? Any help would be great!
Thanks!

Metaphysico · 10-08-2010, 03:00 PM

If your compression tester is like most it has an air chuck fitting on it, take the schrader out of the hose and the radiator cap off and hook an air line to it while its on the worst cyl. If the coolant starts to overflow or bubble then you have a bhg. Either way with those values I would think bhg, rings are not normally a problem on these car, or at least you will have lower values in all the cyls. Also bent valves don't normally happen so that should not be an issue either. If you want to check the rings, put a small amount of oil or trans fluid in the cyls and redo the compression test, if you get a large increase in compression it will be rings..

Travis89Turbo · 10-08-2010, 06:38 PM

It's your piston rings. They don't always show low on all cylinders. 90psi. is definatly not caused from a bad heasgasket. But since it is free to test it. its worth a try. but I got 100 bucks on rings... rings wear out on any car regardless of make. Although they are not as prone to ring problems as they are bhg. They do wear out. In your situation is say rings.. especially unit has high mileage. Or has the boost cranked up above stock

86.5Supra09 · 10-08-2010, 08:12 PM

Sorry I forgot to add that its a non turbo car.. has a little under 160,XXX. Ive been told from numberous people its either the rings or BHG. I was thinking about buying that "Blue Devil" sealant for the mean time, but I was trying to confirm it was a BHG. I dont really want to have to take apart the head because I want to do a 1jz swap in a month or two. But if it is the rings then Ill have to take the head off.

86.5Supra09 · 10-08-2010, 08:13 PM

Also it has some white smoke when I start it up coming out of the exhaust, I normally only drive it around town once a day.

Travis89Turbo · 10-08-2010, 09:09 PM

Quote:

Originally Posted by 86.5Supra09

Also it has some white smoke when I start it up coming out of the exhaust, I normally only drive it around town once a day.

White smoke is a sign of piston rings. Blue smoke is sign of BHG. Like i said. bhg won't affect the compression by that much... jz swap is coming early..you will love it. I love my jz..

10-08-2010, 01:30 PM	#1
86.5Supra09 Stock Join Date: Oct 2010 Location: Ohio Posts: 10	Low compression 2 cylinders Hey guys I have an 86.5 MKIII and did a compression check with the #4 & #5 were low. I think the #4 was 120psi and the #5 was only 90 psi. What could be the problem? Rings? HG? Any help would be great! Thanks!

10-08-2010, 06:38 PM	#3
Travis89Turbo 12psi boost Join Date: Jul 2010 Location: Utah Posts: 332	It's your piston rings. They don't always show low on all cylinders. 90psi. is definatly not caused from a bad heasgasket. But since it is free to test it. its worth a try. but I got 100 bucks on rings... rings wear out on any car regardless of make. Although they are not as prone to ring problems as they are bhg. They do wear out. In your situation is say rings.. especially unit has high mileage. Or has the boost cranked up above stock __________________ 1995 Toyota Supra SE 71k miles. Master power T70 stock 2jzge 1989 Toyota Supra. 1jzgte swap 5 speed of course.. Driftmotion 60-1 single turbo kit. Cxracing FMIC. 2jz 550cc injectors... soon to come..... EMS Stinger. BC 264 cams 680cc injectors Spec stage 4 clutch and A LOT of boost!------SOLD 1999 Ford F350 diesel 2004 Jaguar XJR Supercharged If it hasnt broke you haven pushed it hard enough!!

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10-08-2010, 03:00 PM	#2
Metaphysico Stock Join Date: Oct 2010 Location: Georgia Posts: 27	If your compression tester is like most it has an air chuck fitting on it, take the schrader out of the hose and the radiator cap off and hook an air line to it while its on the worst cyl. If the coolant starts to overflow or bubble then you have a bhg. Either way with those values I would think bhg, rings are not normally a problem on these car, or at least you will have lower values in all the cyls. Also bent valves don't normally happen so that should not be an issue either. If you want to check the rings, put a small amount of oil or trans fluid in the cyls and redo the compression test, if you get a large increase in compression it will be rings..

10-08-2010, 08:12 PM	#4
86.5Supra09 Stock Join Date: Oct 2010 Location: Ohio Posts: 10	Sorry I forgot to add that its a non turbo car.. has a little under 160,XXX. Ive been told from numberous people its either the rings or BHG. I was thinking about buying that "Blue Devil" sealant for the mean time, but I was trying to confirm it was a BHG. I dont really want to have to take apart the head because I want to do a 1jz swap in a month or two. But if it is the rings then Ill have to take the head off.

10-08-2010, 08:13 PM	#5
86.5Supra09 Stock Join Date: Oct 2010 Location: Ohio Posts: 10	Also it has some white smoke when I start it up coming out of the exhaust, I normally only drive it around town once a day.