horrible compression

[25391tally]

so we tested my buddies compression today on his 90 gsx and it came back 4=0 3=0 2=30 1=0 what is wrong with it blown motor or really messed up head ?

 

[TwoLiterLaser]

What procedure did you follow to test the compression?

 

[25391tally]

took out the spark plug screwed in the tester and cranked it over i forgot to specify the car has been sitting for around two years but compression that bad seems like it either horrible valves or a really messed up bottom end we also checked for the rings with the oil and nothing changed except #2 went way up

 

[TwoLiterLaser]

So you did place a cap of oil in each cylinder then repeat the test?

Is the cam timing correct? A 180 degree out cam will cause incorrect compression but will not cause the pistons to hit the valves.

 

[25391tally]

ya we did like i said only a jump in two it went from 30 to 90 the timing has never been messed with the car is completely stock and still if it was 180 out would it honestly be that horrible ?

 

[nuclearr]

Could be timming is out bent valves or bad rings. Dose it run?

 

[25391tally]

in no way shape or form does it run barely cranks over

 

[bento]

Defenetly sounds like the timing belt skipped and bent all your valves. It's very hard to have all piston rings bad.

 

[25391tally]

not so good but its what ever he is thinking of doing a 2.3 stroker i believe . would that mean the bottom end is still good ?

 

[tqmx1]

If he is going to build a 2.3 who the heck cares about the old engine! How is the body and every thing else?

 

[25391tally]

the body is a dime piece if he got the green stuff off it other than the motor its emaculate

 

[253gsx1g]

Since this is my car, the body is in great condition. I just need to wash the car to get the green stuff off it and fix my driver side door handle. Other then that I have been thinking about building the 2.3 stroker. If my funds are not up to that i will just bore it out 40 over and go from there.

 

[tqmx1]

Well I guess it's time to pull the lump and start the overhaul. Good luck & take your time do it once and do it right It will save a lot of heartake down the road as a lot of other posters have found the hard way.

 

[TwoLiterLaser]

if it was 180 out would it honestly be that horrible ?

Yes. When a cam shaft is 180 degrees out then you have open valves that are supposed to be closed during the compression stroke, it just so happens that the timing is enough off with our cams that you do not have contact between the piston and valves when this happens. But you will zero compression because all the air that was sucked in during the intake stroke is shoved back out by the piston through the open valves.

If the car ran before being parked then I think you boys need to look into it more.

 

[25391tally]

ahh very true i honestly thing the valves are dunzo

 

[MY1GDSM]

So how Bad was it?