Low compression number three cylinder

TOYOTAMASTER

MEMBER
1996 TOYOTA TACOMA
2.4L
4 CYL
2WD
MANUAL
410,000 MILES

What is the best way and least expensive way to repair the cylinder and get it closer to what the other three read in a compression test? I did a compression test with about 60 psi between the number three cylinder And any one of the other three I put a few drops of oil and repeated test and number three cylinder gained 80 psi with the few drops of oil I put in. Is there any mystery oil or something I could use to correct this problem? My truck has a real rough idle and has a hard time accelerating.

Wednesday, February 7th, 2018 AT 11:02 AM

2 Replies

PATENTED_REPAIR_PRO

MECHANIC
1,853 POSTS

That usually means the piston compression rings on that number three are worn. What you would have to do is replace them compression rings, hone the cylinder.

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Wednesday, February 7th, 2018 AT 11:31 AM

STEVE W.

MECHANIC
15,237 POSTS

I would do a leak down test to pinpoint where the compression is going. If you only picked up 20 psi adding oil I would almost bet you have a valve issue and not the rings. That is because rings normally wear at the same rate in all cylinders unless they break or the cylinder gets scored. That would show up as low compression in all cylinders unless there is a failure in only one cylinder. A partly burnt exhaust valve or seat could easily cause this issue.

For a repair in this case I would probably opt for a used engine. By the time you tear the old one down and buy the parts to repair it you will have as much as a used engine from a you pull it yard, and you still need to have any machine work done.

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Wednesday, February 7th, 2018 AT 12:25 PM