Low compression

Tiny
BUDDY HURD
  • MEMBER
  • 1984 PONTIAC FIERO
  • 4 CYL
  • AUTOMATIC
  • 74,000 MILES
I bought this car for a toy. The man said he just had the head redone. The car shuts off when put in gear. I checked for vacuum leaks. Found none. Found 90lbs compression in 3 cylinders and 130lbs in the other one. Engine does not smoke or have blow by. What should I do.
Saturday, October 5th, 2019 AT 5:32 AM

1 Reply

Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

First thing you can do is perform a a "wet" compression test. Add a small amount of motor oil into the 90 lb cylinders and see if the compression readings come up. If they do that means the piston rings are worn. If you do that and they don't come up I would suspect a faulty head rebuild. Hope this helps and thanks for using 2CarPros.

Danny-
Was this
answer
helpful?
Yes
No
+1
Saturday, October 5th, 2019 AT 4:08 PM

Please login or register to post a reply.

Related Engine Compression Content

Engine Compression Test
VIDEO
Engine Compression Test
In­struc­tional re­pair video
Compression Test
GUIDE
Compression Test
A com­pres­sion test is a valu­able di­ag­nos­tic pro­ce­dure that helps de­ter­mine the health of an en­gine by mea­sur­ing the pres­sure gen­er­ated in each cylin­der. The fol­low­ing is a...
VIEW MORE