I've been working on my 98 Blazer and I found a bent exhaust valve on my #3 cylinder. The intake manifold gasket was leaking on that side also. I am debating taking the cylinder head to a machine shop. It may cost $350 to rebuild.

 

Hi Brian,
my blazer had 204k miles when it bent the exhaust valve. Here's what I did and it may help you out a bit. I am a machinist but you do not have to be to repair your heads. First, check if your heads are square using a straight edge. If you see no gaps then you are golden. Make sure you clean them really
good with a scotch brite and some WD-40. You will need to replace the bent valve, you can get that at your local auto parts store. Check your other valves and make sure they are straight. That's as simple as looking at them. You'll want to clean the carbon off using a wire wheel, don't worry you will not damage the valves they are very hard. Last of all you need to lap your valve to your valve seats. Buy some valve lapping compound from the auto parts store and spray the shaft of your valves with lube. Your going to put the end of your valve in a drill and your going to spin it and pull it back and forth with the valve lapping compound in between the valve and valve seats. This will allow them to seal better. You can check how well they are sealing by cleaning and closing the valve, and then filling up the combustion area of the head with water. Spray compressed air from the backside, if you see any bubbles you need to grind more. Good luck and let me know if you have any further questions.

 

Thanks for the info Jlp06. I took the head to the machine shop and decided to just have them replace the valve, cut the seat, and clean it up. I'm going to replace the valve stem seals and lap the valves in when I get it back. I'm hoping to have everything done before the end of May. Thanks again!

 

Thought I would give an update on the bent valve issue I had with my 1998 Blazer with the 4.3L. I took the head with the bent valve and had them replace the valve and recut the seat. I then lapped all of the other valves and replaced the valve stem seals. I cleaned everything up and put it all together. It's running great now! Definitely a project!

 

I managed to get a little over 1,000 miles on the Blazer after replacing the bent valve. I was towing with it and lost oil pressure. I'm pretty sure the engine is blown. I'm going to take it apart and evaluate the damage. I'll keep you posted.

 

That sucks man, sorry to hear that. At least you caught it as soon as it happened. Did your engine lock up? Best case scenario your oil pump went out (fairly common) and you caught it before any real damage occurred. Worst case scenario your bearings are completely gone, but I doubt it. Check your dipstick make sure there is no bearing material, you'll see tiny glittery metal specs and the oil will smell burnt.