thook

Hey guys....

A buddy of mine hired to me to fix a fustercluck on a '94 3vze/4rnr. Long story short, he'd hired a fellow to work for him at his shop and, during his short time there, was assigned to fix a blown headgasket on the thing. When the fellow reassembled the heads to the motor, he'd reinstalled the shims in the wrong locations. He never bothered to note which cylinders/valves the shims came from! Hence, the valves were way out of adjustment. It was not discovered until my buddy had fired the guy, finished assembling the motor himself, returned the vehicle to the customer, and the customer had driven it some 50-60 miles.

So, I tore everything apart to check the clearances and found all intake valves to be in spec, but on the looser side of things.....(.010"-.011"). So, no worries, there. All the exhaust valves were too tight except one at (.010"). That was number six, as I recall. Don't have my notes on hand. Anyway, number four was at (.030") whilst the rest were (.060"-.080"). I don't know, but I would guess it would take some real driving before the latter would burn. Number four is what really concerns me.

We didn't have time Friday to run a compression test. It took me all day just to tear down the top and front end, check the clearances, remove the cams (found the right hand side to have a broken guide), and then pull the shims to measure them. We deliberated on the best/easiest/least costly way to check for any burned valves concluding that we need to yank the balancer and timing belt and then run a comp. test while all the valves are closed since the cams are out. That won't happen until Thursday, though. He's all tied up with other jobs on Monday and they close up for the holiday on Tuesday and Wednesday. In the meantime, I'm just curious what the likelihood really might be.

Wish we had a borescope .......

pennswoodsed

Hi,
A leakdown tester , borrowed or assembled ,will tell you if valve faces or seats are leaking , I would expect valve face to burn first . This will save timing and balancer removal if not needed .
How far was it driven ? I would expect popping and poor running ,almost immediately.
Regards,Ed

thook

My buddy doesn't have a leak down tester and in about 15min's or less I can have the balancer and belt off. I've got it all torn down that far, already. IOW's, the extra removal or the balancer/belt is not a big deal vs doing the leak down. It'd take less time to do that than borrow or assemble a leak down tester, at this point.

The customer wasn't clear on how many miles the vehicle was driven like this. So, we can only assume atleast 50-60 miles. Possibly a little more, but Fayetteville....where the vehicle was driven to.... is a bit over 20 miles from here in Winslow where we are/the customer lives.

Of course the vehicle was running poorly immediately...haha! The exhaust valves were way out! And, since the motor's all apart, we won't know anything from how it runs until I get the shims back in order and it's all back together. But, that's not gonna happen. We need to find out before I put it all back together. If any valves are burned, I gotta pull the heads and all that jazz.

I could slap my buddy in the head for the letting the thing go out the door before it was fixed, but....*sigh*.. he's a busy man, he'd just fired the guy leaving himself without a mechanic, and it's hard for him to stay on top of everything since he's not really a mechanic himself......more of the body work guy. S'why he needed/needs a mechanic. Still deserves a hard time, though, dudn't he? I mean, he had to notice the thing ran like crap. I just don't think he realized it was the valves until well after the customer had already driven off with it and called back to complain. Hmpffthh....

Anyway, I gotta get ready for work, so I'll be back later.

arlindsay1992

iTrader: (8)

You can't check compression if the valves don't open. Valve timing plays affects compression PSI.

thook

So, what do you think will happen if we try to run a compression test with all the valves closed?

vital22re

iTrader: (2)

I think your numbers will be really low if you try it without cams moving as you won't be able to achieve the intake part of the stroke to fill the cylinders with air. Go for it though.. see what happens

thook

Low to zero.....exactly. But, what if one of the valves is leaking.....ie. burned?

thook

Well, anyway.....it'll be low, too. Difference is the air will escape and that's what we're looking for....not necessarily compression readings. So, I suppose, in a way, it's a leak test without the equipment to do a "proper one".

Meh...I guess I'll just wait until Thursday and see what we get. I was just curious with anticipation and all that crapola. No biggy....

I hope nothing's wrong, though. The heads have already been pulled once. Man, it's a lotta wrenching! I thought all I'd be getting into was a valve adjustment. Had no idea they'd be this way off. Nobody did, of course. Pftth.........

vital22re

iTrader: (2)

well if your "compression test" read 0 on all of them it wouldn't tell you anying. Even if the valve was bad it would still read 0. Were the valves lapped in by the PM? If they weren't then i'd be concerned of a proper seal at the seat to begin with. I hope you don't have to yank the heads. Not a fun day.

thook

Well, you're right, Vital. Zero on all 6 wouldn't indicate anything. But, my theory/idea is, even though it may a weak one, is that there should be some air in the cylinders. Atleast enough to give some reading though it may be low.....hopefully more than zero. And, if it's zero....won't build up any compression at all....then, theoretically the valve is burned. I don't know, man....lol! We're just trying to do this within the current means. What's got us a bit screwed for accomplishing anything more quickly is the back log of customer repairs and the holiday. I talked to my buddy a bit ago. We've got another idea to try if this'n turns out a bust.

Oh..... I don't know if the valves were lapped. If so/not, the ex-mechanic had nothing to do with that happening. They usually send heads down to Ft. Smith at the machine shop where I've sent my heads before. I'll have to ask. Thanks for mentioning it. I honestly hadn't thought of it.

TNRabbit

I'm pretty certain the clearance is as much to ensure lubrication between the cam & shim as it is to proper valve actuation.....

Sucky situation

thook

Yep! It sho' is! Ha!

There wasn't any abnormal wear/damage to the cam lobes due to tight tolerances, though. Maybe if it'd been driven more....dunno.

Due to circumstances, nothing happened with the engine on Thursday. But, so far, the upside (kinda) is that my buddy found a complete replacement head for the right bank.....the side with the fubar'd cam. (Incidentally, the broken part of the cam is called the "thrust flange", as I've recently learned). It's a used head for $75 vs $85 for another cam. We'll just have to see if the valves on the original head aren't damaged, first. If they aren't, then check bearings tolerances to see if simply swapping the cam would work. Certainly cheaper and less labor vs swapping the head just 'cause he has it.