Welp...I acquired another project.

I decided to buy an extremely clean 92 pickup that was running slightly rough and had 148,000 miles on the odometer in hopes that the mechanical work would be relatively low impact. Unfortunately, that doesn't seem to be the case. But I figured, "Its a good deal and I can do the work myself. In the end i'll have a great truck." Famous last words...

I had a mechanic look it over. He did a compression check and found 0 (like zero) compression in cylinder #1. A leak down test concluded a leak in an exhaust valve seal at cylinder #1. Compression in the other cylinders seemed good. We also discovered a leaking oil pump, valve cover gasket, and power steering pump. Feelings of regret seem unproductive at this point. I just need to develop a game plan and move forward. I'd like to get feedback on the various options of tackling this.

After some research it seems possible to "simply" remove the valve cover and replace the valve seals using a spring compressor. Throw a new valve cover gasket on and be done. This doesn't seem like the ideal method as it's highly possible to destroy the head gasket while compressing the valves.

The other option would be to pull the head, replace the seals, send the head off for machine work, rebuild the injectors, ect. While I'm in there I can replace the timing chain, oil pump, and water pump. Put it all back together with new gaskets and have a new top end. I can even put a new power steering pump on during assembly and get 4 birds with "1" stone.

The last option, suggested by the mechanic, is to replace the engine. That just seems wasteful.

So I guess i'm seeking opinions, suggestions, and stories on how to proceed. I don't have a ton of mechanical experience of this kind, but I have enough to know it's possible with enough time and patients. In the end, I hope to have a reliable daily driver for putting around town and weekend camping trips. Here's the truck...



Thanks for listening.

 

If your going to do Head Work You most likely will be doing the bottom end a short time later .

I don`t know why but these engines don`t like fresh heads on top of older bottom ends.

I don`t know what kind of budget or if this can be a long term project .

Do the complete engine go a running used engine . Then you just might get lucky !!

Every Head gasket the head gets cleaned checked for Cracks and reinstalled

I have never seen 0 on a compression test you might find a surprise when you pull things apart

Are you sure the mechanic is not looking for work$$$

 

The "leak" may be coming out around the valve stem seal, but that's not the cause of no compression. You (most likely) have an exhaust valve that is not closing. The valve could be toast (actually, pretty likely), you could have a bad seat, or crud around the valve stem. None of this can be fixed (or even seen) with the head on.

The valve stem seals are there to keep oil (around the cam, rockers, etc) from getting sucked into the cylinder. They cannot hold back the pressure of the cylinder firing. Just so you know, the most common symptom of a bad valve stem seal is blue smoke on startup; the oil around the cam dripped down along the valve overnight into the exhaust manifold.

 

Do you have access to a bore scope? Just remove the spark plug in the #1 cylinder and stick the camera in there to see what's going on. Sounds like carbon build up to where the exhaust valve don't seat properly to close and seal off the cylinder during the exhaust stroke. Good Luck!

 

Thank you for the replies. I don't have experience diagnosing these problems. Thats why I had a mechanic run the tests.

It sounds like, at the very least, I will need to pull the head to see whats going on in there. Once I get the head off, how difficult is it to replace the faulty exhaust valve? And is this route worth the time? or like wyoming9 suggests, should I just find a new engine? From the limited research I've done, it seems like plenty of people replace the top ends of these engines.

Anndel, I don't have a bore scope, but that might be worth tracking down to limit the surprise factor.

 

Replacing the valve (IF that is the issue) is pretty vanilla. When I had my heads (3VZE, so two) done, the machinist called and advised 3 valves be replaced. I didn't even bother looking at the old ones, and it added about $25 to the job.

Burning an exhaust valve is actually pretty easy, as it sits in the fiery exhaust, and gets its cooling solely from sitting on the valve seat. If, for a host of reasons, you have too little valve clearance (or carbon buildup propping it open), the valve doesn't quite close and never gets cooled. It will erode quite quickly then.

Personally, I don't think a borescope will tell you much, EVEN if you know what to look for. Even if you crank the engine to open the valve, you're trying to look through a tiny space with a camera that won't turn in that direction. But electronic borescopes are very cheap, so give it a try.

What you CAN do is just measure the valve clearance. If too high, that suggests the valve is stuck open. You can even try smacking it with a plastic hammer to re-seat it, but that's not an actual fix. If you have too little clearance, it suggests the valve has eroded so far it is sitting low in the seat. But either way, the only real fix is to remove the head, pull out the valve, and look at the valve and the seat.

Good luck!