lost compression

[eltron3030]

my dsm's compression is at 90 psi... and it smoking out the exhuast at higher rpms, im not sure if my fuel filter is gummed up and not givin enough gas to get right compression or if my turbo is shot, or if the pistons/rings are shot.. any one have an idea maybe? let me know if u have had this problem

 

[spydreclips6]

Hmm... Sounds like it could be one of three things (piston rings, valves, or your timing is off.) I'd start with checking the timing. Then the valves, and last the pistons.

 

[95blackGsTurbo]

Is it 90 all the way across? Do a compression test first. Remove all the plugs, crank engine with throttle wide open and bring back exact results. Most likely the motor is getting weak and the rings are worn. Turbo won't lower compression and neither will a fuel filter.

 

[jrohner]

You need a leakdown test to see where the compression is being lost.

 

[eltron3030]

yeah it has 90 psi all the way across all 4 cylinders. also, it a rebuilt 4g63 engine and ran fine for a while and is now getting weak, i figure its the rings but i wanted to check around and see if anyone else has had a similar problem. Any ideas on where to start for mods, right now all i have is a 3.5" turbo back exhuast, stock turbo, cold air intake. i have a 16g evo III turbo but dont wanna put it on because i did with my other 95 talon and blew the tranny, so if you got anyideas let me know, thanks

 

[killab443]

It does seem to be the rings judging by the symptoms you give. I would do a "wet" compression test. Add a cap of oil to the cylinder before you check your compression. The oil seals off imperfections in the rings/ cylinder. It will yeild a higher compression number if the rings are the problem.

 

[TalonTsi_291]

Fuel and turbo won't effect compression! Run the car to opperating temp. Pull all the plugs. Hold the throttle open and crank it till the guage stops jumping. Do it to all 4. Then put a cap full of oil in each cylinder and run the test again. If the numbers change it's your rings. If not you need to do a leak down test and find out if you have a bad headgasket or bad valves.

 

[killab443]

Fuel and turbo won't effect compression! Run the car to opperating temp. Pull all the plugs. Hold the throttle open and crank it till the guage stops jumping. Do it to all 4. Then put a cap full of oil in each cylinder and run the test again. If the numbers change it's your rings. If not you need to do a leak down test and find out if you have a bad headgasket or bad valves.

Didn't I just say half of what you said?

 

[eltron3030]

ok so im completly rebuilding my 4g63 motor and i have pretty much everything out but is there some kind of trick to pull the motor out? iv got separation on the trans and motor but i dont have enough room to disconnect the clutch to get it out...is there a way to move the tranny over or what? let me know pleeease

ok i got the motor out and every thing so its all good. time to rebuild this son of a bi*** and ill try to post pics as i go