Challenga

I have an 88 with a 3.0 V6. I just replaced the head gaskets and while i started trying to figure out why it had no power I did a compression test and found that 2 of the cylinders are dead. I did the oil in the cylinder test and it didn't increase the pressure. Should I just replace the head gasket and try it again or should I go get a valve job on the head while i have it apart? i assume it is just the head gasket since the cylinders are side by side and the rest of the cylinders tested at around 140 to 142. What do you guys think?

jstluise

What prompted you to change the head gaskets in the first place?

Did you have the heads resurfaced? This is a must.

Regardless, you're gonna have to pull the head(s). If you didn't resurface the head, get it done and while you have it at a head shop have them do a pressure test on the valves if you are concerned about the valves. But, it sounds like the head gasket since the dead cylinders are adjacent to eachother.

If you did have the heads resurfaced before, then I'm not sure exactly what you should do. I don't think you'd have to have them resurfaced again...someone else chime in here.

Remember, you cannot reuse the head bolts on the 3VZE.

Challenga

I got the 4runner out of a guys field and he said it ran when he parked it. When I got it home I realized it had a blown head gasket on the pass side. It had oil all over the side of the engine. So i just dove in and replaced the head gasket. When I did that I checked the heads at a head shop and the guy said that they were flat and didn't need to be ground. So I just took them apart and lapped the valves by hand and replaced the valve oil seals and threw them back in. I used a new Felpro gaskets and new head bolts. I torqued them per the FSM and it started right up.

My assumption is that I just made a mistake installing them. I didn't clean out the holes with a tap....maybe the torque was off because of that. I don't know. I am hoping to find a smoking gun when I take them apart, but I can't really figure this one out. I have rebuilt a few engines, so this isn't my first one. I would love to blame it on being a newbie, but I can't.

Any ideas? Anyone ever had this happen to them?

yoterr

you could just retorq to a higher # by like 10 or 15lbs and see if it helps..if it does redo ur head gasket and chase ur threads

Challenga

That's a good idea yoterr. I'll try that tomorrow night.

Marc

Uh why not try a leak down test.
That should narrow it down.

TNRabbit

If you have ZERO compression, you have open valves. Broken springs, bent shaft, etc.

Did you check the valve clearances when you put everything back together? Did you put the same lifters/pucks back in the same locations?

Challenga

TNRabbit - After thinking about it a little more I think, like you said, it has to be the valves. Zero compression is different than low compression. If it was low compression it could be the rings or maybe the head gasket, but if all of the pressure is blowing out fast enough to not read on the gauge, that means there is a pretty big hole for the air to get out. To me that means that it has to be valves. To answer your question....no I did not check the valve clearances when i did the head gasket job before. That was pretty stupid of me. 20 20 hindsight. I went by a big Toyota specialty place here in Albuquerque this afternoon and ran my theory by one of the mechanics. He agreed that I should just focus on the valves. I just ordered a set of those fancy pliers to hold open the valves while I check the valve clearances and change shims. I should have them tomorrow. The only good thing about this is that Toyota dude has a box full of shims for the 3.0 and I can just get them from him instead of ordering them and waiting.

Challenga

When I rebuilt the heads and lapped the valves I could have switched the lifters/pucks between cylinders 4 and 6 by accident. That would explain why they are both having problems. I thought I was careful with the order and what goes where, but that would explain a lot actually.

TNRabbit

There ya go--I'd bet that's your problem. The deal with the 3vze valves is they actually get TIGHTER as they get worn do to the cam being directly on TOP of the valve actuators...so if you've put a shim in that's too thick, it won't let the valve close properly.

blake.nemitz

when you have the heads off put some parts solvent in the runners and see if it leaks past the valves. shimming valves sucks

Challenga

I'm not taking the heads off unless I have to. I am going to check the valve clearances and adjust the shims while it is still on the truck. I don't even have to take the plenum off the truck. Luckily the valves in question are on the driverside. I hope the tight valves are my smoking gun...

Challenga

I just pulled the valve cover and checked the clearance between the puck and the cam and the valves in the back two cylinders were riding on the puck. The cam even had lines on it where the lifter/puck was riding on the cam. I rotated it and never could put a feeler gauge between on 3 of the valves. The valves on the front cylinder (#2) was fine. That must be why it had 140 compression.

I found my smoking gun. Once I adjust the shims and update this thread with the results.

blake.nemitz

hopefully you didnt run it too long like that you might have burned a valve

Challenga

I have about 15 miles on it....I hope that is not enough to burn my valves.