Low Compression - Toyota Nation Forum : Toyota Car and Truck Forums

medicstudent01 · 11-19-2006, 06:22 PM

Just picked up a 2001 Prism and have a problem. The CEL is on and flashing, diagnosed it to low compression on cylinder #2. 1,3,4 all have 160+ psi, and cylinder #2 has 50 psi with no improvement when adding oil to the cylinder. Any suggestions on what the problem could be?

Bitter · 11-19-2006, 07:25 PM

stuck rings, bent rod, damaged piston, burnt valve, stuck valve, or some other things i've forgotten.

94_Rolla_Guy · 11-20-2006, 02:34 AM

oil will usually fix bad rings or poor valves, might wanna do a leak down test and check the intake and exhaust for air noise also check adjacent cylinders for a bad head gasket

Bitter · 11-20-2006, 10:18 AM

no, the oil wont help the valves any and can only do soo much for stuck rings. do a leakdown test to get a better idea of where the compression is going. is you oil extra black and does it smell like fuel?

diver9000 · 11-20-2006, 10:42 PM

Head Gasket...

medicstudent01 · 12-08-2006, 10:51 AM

Figured I would repost since the car is now fixed. The car had a burned/leaking exhaust valve on cylinder #2. I pulled the head/turned it upside down and sprayed the #2 valves with some pb blaster. One of the exhaust valves let all the fluid through almost immediatly.

BTW, I got a 11K head off a 2004 Pontiac Vibe for $106 at a local salvage yard. Cleaned it up, checked for warpage and checked the valve lash on it. Got a head set on Ebay for $50, and a head bolt set from Headbolts.com for $46 shipped. After some misc. supplies/clamps I was at about $225 for the entire job.

I also found a shortcut on this job. Alldata lists book time @ 8hrs, I got it done in 6. It tells you to pull the front cover off to get the head off. What I did was pulled the valve cover, pulled the upper front cover bolts and 2 studs that go into the head, set the engine at TDC, pulled the timing tensioner and then the cams. There was also a bolt that held the timing chain guide in place that I carefully removed without dropping it down into the engine. It was accessable after the cams were pulled. Then the head came right off.

When I went to install the head, I added a little RTV to the exposed front cover and slid the head into place. Bolted it down and reinstalled everything and I was golden.