QuestionQUESTION: First, I would like to thank you for your time and effort.
Problem:
22r from an 81 Toyota Pickup with no compression.
I have a 22r motor which will not start, and is producing around 15 PSI in each cylinder. The motor has around 40,000 original miles. Here is the work I have done to date:
1) Removed Valve cover, and compared TDC/Timing mark on my Harmonic Balancer to TDC mark on cam sprocket. With the engine at TDC on the #1 cylinder, notch on balancer at 12:00 position, found cam timing to be 30 - 60 degrees retarded.
2) Removed timing chain cover, found stretched timing chain and and stuck chain tensioner. Removed timing chain, sprockets, chain guides, and chain tensioner. Replaced chain sprockets with new sprockets, aligned Cam and Crank to TDC. Replaced timing chain, being careful to correctly position indicators to marks on sprocket and head. Re-installed all components, resealed gaskets, re-assembled.
3) Re-tested compression, found to be at 10-15 PSI in every cylinder.
Here is my thought process. There would seem to be few problems that would cause this kind of compression loss across all cylinders without being catastrophic. My suspicion is, this being an interference engine, that when my timing chain jumped a few links, I may have damaged or destroyed my valves.
In any case, I can't think of any other cause that I can troubleshoot without removing the head and doing in-depth investigation into rings, valves, and valve seats, as well as inspecting for cracks and blowouts in my head, cylinder sleeves, and head gasket.
I guess my main question is: is there a problem with my thought process? Is there a piece to this puzzle that I have missed, or should I go ahead and pull the head?
Thanks again for your time and consideration.
-Bryan
ANSWER: I think you are going to have to remove the head and inspect for bent valves, yes it's an interference engine, the valves were probably bent when the timing was retarded 30-60 degrees.
---------- FOLLOW-UP ----------
QUESTION: Well, I pulled the head, and found no bent or damaged valves, no indication of damage on the pistons, no cracks, and no obvious problems. I poured about 3 Oz. of 10w40 down the #2 and #3 cylinders (which are at the bottom of their strokes with the #1 at TDC) to see if my rings were blown, 1 hour later the oil was still there.
The only thing left that I can think of is head warpage, or a blown head gasket. There was no obvious damage to the head gasket when I pulled the head, but it stuck to the head (obviously), and I couldn't get a real good look. When we started to release the head bolts, we noticed a real high carbon / exhaust in the engine oil smell. When I pulled the bolts physically out, there was a fair amount of carbon residue/slag on the threads and bottom of the bolt. This seems to confirm to me that something was wrong with the seal between the head and the block.
My next step tonight will be to clean all the gasket material off of the head, and check it with a straight edge. I know this is less than scientific, but I am figuring that any warpage that would cause a 100 PSI drop in cylinder pressure should be fairly visible. If the head is not visibly warped, the last thing that I can think of to do is replace the head gasket and re-assemble.
Am I missing a step, or wrong about my process?
Thanks again for your help.
-Bryan
AnswerA warped cylinder head will usually not affect all cylinders unless there is a lot of warpage, the compression has to go somewhere and in order to affect all cylinders the same it has to be something that is common to all of the cylinders, just make sure the chain timing is set correctly after reinstallation and rotate the engine by hand before starting to check fo any possible interference.
