Jim B

I just bought a 92 ext cab 4x4 with the 3.0 and automatic. I have been reading these forums for quite a while and you have been a great help. I have a couple issues with this motor that i hope you can help me with.

The motor is ticking and from reading here that seems pretty normal. I have poked around with a screw driver and the best that i can determine is that the injectors are ticking. When i got the truck in addition to the ticking, it was missing and only running on 5 cylinders. I pulled all of the plugs and #'s 5and 6 were very black and oil covered and #4 was slightly black and slightly oil covered. The rest of the plugs were all good. I did a compression test and all cyliders except #4 held 155 - 160 and #4 only held 50 psi. Did a leak down test on #4 and the only place that i can feel air excaping is through the spark plug hole on #2.

Air leaking from cylinder to cylider sounds like a head gasket but, i had great compression on #2! If the gasket was leaking shouldn't i have bad compression on #2? My theory is that i have a burnt exhaust valve in #4 pushing air into the exhaust manifold. The cat looks original, could it be clogged to the point that all the air escaping through the burn #4 valve is being pushed through the partially open #2 exhaust valve instead of down the tail pipe? Any other ideas?

Thanks for your help.

chimmike

Sounds like you've done your homework. Most likely an exhaust valve as you've said.

Jim B

I re-did the tests last night to make sure i was not mssing anything and i came up with the same results. Crawled underneith and the best i can tell the cat looks to be original. The muffler has had a half ass replacement but the cat looks like it has never been touched.

Now, when i pulled the plugs on 4,5&6 they are oil covered and i have oil in the intake manifold. 5 & 6 both had good compression and i could not find any air leaking into the crankcase in #4. Any explanation for where this oil could be coming from? There is quite a bit in the intake maniflold. Any connection between all this oil buildup and a clogged cat? Any connection between this and the previous mentioned ticking noises? I am not quite sure if i am looking at 1 big problem here or 3 or 4 smaller ones.

Thanks

BC Rider

by intake manifold do you mean the "air intake plenum"? In other words the alluminum up top?

They are known to get gunged up due to the pcv and other hoses that come back into it. Your throttle body may also be gummed up a bit.

SEAIRESCUE

Appears you have multiple problems. HG and burned valves. I just did a 250k motor rebuild this winter and found the exhaust valves in really bad shape. Also, HG's were deteriorated. Pack two lunches for the repair work because those motors are a bitch. By the way, torque the head bolts to 55 ft-lbs and forget the instructions from Toyota. The short bolt is 35 ft-lbs. I highly recommed installing stainless steel exhaust valves from enginebuilder. He sells on Ebay.