ahickman

I have been struggling with a rebuild on a 94 3.0 Runner. After putting it all back together, it fires up but runs poorly. Stumbles, low power, etc. Started a thread thinking I had an spark issue owing to intermittent timing light flicker on all wires. Nothing seemed to pan out and all items tested out individually. Stumped! So I went back to basics and took out the plugs, noticed most of them were fouled. Running very rich so say the least. Went on to do a compression test and blew me away when #1 and #2 cylinders were 0 and 25 psi, respectively. All others are 150 or so.

The heads were both machines and the valves were ground by a shop. What I did not do is adjust the valves/shims. I had read in one or more threads that the shims need not be replaced. Now that I think about it, they must be adjusted/replaced since the valves and seats were ground, correct?

Any advice on what to do now? I have no experience with the shims on the 3.0, but have read through the FSM and can probably manage. Could the low compression be anything other than a shim/bucket stuck and/or misadjusted?

Help!

MonsterMaxx

Shim adjustment will not cause a complete loss of compression.

Why did you do the heads? blown head gasket?
Did you do anything to the bottom end?
Have you done a leak down test?


If it's a blown head gasket and you didn't do the bottom end, it's likely those cyls were dead when you tore it down and didn't notice the pitting of the cyl walls. Now you need to rebuild the bottom end.

Set it up for a leak down test, pull the oil fill cap and the coupler off the throttle body (wedge the throttle open) then do the test. If you have air rushing out of the oil fill cap...rebuild. If you have air rushing out the throttle body something's fubar with the valves. If it's venting out the side of the block you didn't get the heads/gaskets seated right.

ahickman

MonsterMaxx, I did an entire rebuild. New rings, pistons, gaskets, etc.

thook

Oh man.....sorry, ahickman. I know it's a pain. MonsterMaxx has a good plan for testing. Did you try running the compression test with oil in the cylinders, though?

ahickman

Just went out and poured a bit of oil in cylinder 2. Only shows 12 psi after about 7 cycles. If the rings were put in incorrectly (gaps line up), could this account for no pressure? I hate to think that I have yank the block back out and tear it down.

ahickman

Thook, what do you suggest I do now?

toytech76

Completely untrue. If the machine shop did not set the valve adjustment correctly or didnt adjust them at all, its VERY likely you have extremely tight valves or valves being held open giving you little to no compression. I have literally done hundreds of 3.0's, rebuilds and valve grinds and know that the machine shop will not adjust your valves if they wernt asked to and if they didnt have the cams and everything else. Leakdown will confirm where you are losing compression. Check your valve clearance before condemning anything else

dcg9381

I agree.. The setup is like motorcycles. When they cut the head for the valves, it likely sinks the valves a bit more. Your cam is likely opening the valves very slightly on the base circle.

You can't "try" to adjust the valves - you either measure, shim, then buy new ones or you dont.

The shims themselves don't wear out (they're harder than the cam) - but you need to find which shims you you need to get the clearances right.

ahickman

toytech76...thanks for the input. Good to hear I still have a chance at making this right without tearing it down to the cylinders. The shop did not have the cams. Only the heads and the valves. I read through the FSM and see that there are special tools for extracting the shims. Two questions for you: 1.) I can still check clearance without SST's, right?, 2.) the decrease in valve clearance would be caused by the valve sitting deeper in the seat after both having been ground, correct?

thook

Well, if I what I read is true, then little to no change in compression ratio when testing with oil means valves. And, to me, that's good news....considering the alternatives.

I've never had machine shops touch the valves unless I asked. The 4cyl valves I like to do myself, but I leave the V6 up to them. They have shims on hand....I don't. It's a convenience thing.

About the rings, though.....you DIDN'T line up the gaps, did you?

toytech76

If they didnt have the cams then they definately didnt adjust your valves. I would bet thats your problem. Personally I set my exhaust valves at .012-.013 and my intakes I set at .009-.010. All you need is feeler gauges to check your clearance. Dont run it anymore untill those valves are adjusted correctly

ahickman

Thanks guys. I am a little less stressed now. Blew my mind thinking about having to get back up in there and back those bellhousing bolts out again. No fun at all when you don't have a shop or lift. Much easier to take the plenum and valve covers off!

thook

The ring gaps?

toytech76

ring gaps would cause a loss yes, but not that severe

ahickman

Nope, I did manage to follow the instructions on ring placement. Actually recall pulling one of the pistons back out because I thought one of the rings rotated while tightening the compression can around the piston.

Like you, I prefer to do the 22re valves myself, but have now learned that I should let the shop do the shims while doing the heads.

Thanks thook for your attention on each of my threads. I would be at the mercy of the dealerships without Yotatech! Makes me want to go purchase a Yotatech decal

thook

That wasn't the problem I was concerned with.....

Goodluck, hickman. You're welcome and I'll check in tomorrow.

Ganoid

If you have the valves hanging open on cyl 1 and 2 you will need to buy a very small shim to use as a reference since you will not be able to get a feeler gauge into the the 1 and 2 spots. In order to measure the clearance you must first have some clearance to measure so this may be a problem for several of your valves. Most machine shops will just grind the stem of the valve to make them work with your existing shims but this will not work in your case so you will need to take a pile of measurements and probably end up buying 8-12 shims. I buy shims at "1st toyota parts" and if I remember correctly they where about half the cost of my local dealer. I think the dealer wanted $12-14 per shim but 1st yota got them to me for $5-6 a shim.

I don't envy you on this job having adjusted the valves on my truck 8 to 10 times already. With the amount of shimming you are going to need you can probably count on half a day tearing it down and measuring then another half to full day swapping shims and putting it back together.... Good luck

toytech76

Its a shame you dont live in norcal. I would do it for ya and save you time and money. It would be done for you in a couple hours and I even have shims. lol Remember, shims come in .002 increments. Meaning, if the shim you measure, measures at say 2.75mm and you need .006 thinner, you would need a 2.60mm shim. .006= 3 shim sizes smaller

ahickman

After duty tonight I am going to take off the plen and get two work on figuring out what shims I need for all cylinders. Should be lots of fun to dissasemble what I just finished putting together Oh well, if I didn't enjoy this kind of torture, I guess I would be giving the dealership my hard earned $$$. Thanks again to all that walked me through this.

ahickman

Ganoid/Toytech76 or anyone else....I pulled the plenum and covers off this morning. Found only one valve/shim that would even allow a .006 feeler through it. The rest were too tight to get a feeler guage through. Looks like the machine shop did not even attempt to grind the ends of the valve stems to make up for the lower seating valves.

Did a couple of searches for the SST which will allow the shim to be extracted out of the buckets and found one on Amazon for $12. Ordered it, but am wondering if I will even be able to get shims thin enough to provide clearance on lifters. Going to follow Ganoids advice and get the thinnest shim and go from there.

If I end up with zero clearance using the thinnest shim, is my only option to pull the heads off and have the valve stems ground down?