Help!!!! No compression......

[jimlaw3]

Hello all,I need help.I bought a 1990 4runner v6 with 290k.The head gaskets were replaced by previous owner a while ago,I noticed the engine running rough at low RPMs but as the engine got over 3k rpm it smoothed out and ran fine.The engine burns no oil and leaks no coolant, but I did a compression check and noticed no compression on cylinders 1 and 3 (same head passenger side).I don't understand how the engine even runs at all with 0 compression on two cylinders,can it just be the head gaskets again or a valve issue,the engine sounds ok, please someone help me from going insane........

 

[flyinhawaiian01]

Only way to have no compression on cylinders is from bent or broken valves. Try pulling the spark plug wires one at a time on those cylinders and see if it changes the way it runs over 3000rpm. If it doesn't, then its bent valves and probably not actually running that smooth.

Even with a blown head gasket, you'd still get a reading, but it would fail a leak down test immediately.

Try re-checking those cylinders again, I would think the gauge wasn't set up correctly or something. Maybe the tool wasn't screwed all the way into the spark plug hole?

If its still the same outcome, squirt a little oil down the spark plug hole and re-test, see if that changes it. I doubt its what I'm thinking here, but cracked rings would let enough around the piston, although you'd definitely know it by the smell of the oil on the dipstick! It would be pretty stinky with gas and you'd definitely hear it in the engine like there was a ball bearing floatin' around in the cylinder!

 

[jimlaw3]

I was thinking the same thing,so I checked compression again,all cylinders over 170 except 1 and 3,they are both at 0. Since there is no loud noise coming from engine maybe the valves are too tight and never fully closing.How the hell do you adjust valves on this engine.Thanks for your input.

 

[jimlaw3]

......UPDATE.......
removed valve cover and noticed exhaust valves have zero clearance.Now I got to find a place to buy shims and adjust valves properly.

 

[flyinhawaiian01]

LOL! Guess you already figured out how to adjust the valves!

I think I saw the shim kit on RockAuto, but don't quote me on that. Its not an easy job to figure out, but the online manual for the 3VZE explains the procedure. Sounds like the shims may not have gone into the proper spots if you tore the head apart for repairing the blown head gasket. You'll want to check every one for proper clearance.

 

[jimlaw3]

Guess I'm just going to sell the truck. I work on Hondas all day and don't feel like working on this thing my day's off.....Called Toyota and they quoted $650 parts and labor to do valve adjustment, I can buy a reman head for that. I tried to remove shim with two screwdrivers,no luck with that. I believe I will be done with this truck.I can help you guys fix any Hondas y[all may have though. Dang Toyota design.:jaw: