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I have a 96 blazer with a 4.3 I noticed I had a loss of HP the day before I was losing water mysteriously… I knew I had a bad head gasket so I turned around, but never made it. It stalled twice then wouldn’t even think about it. Anyways, I finally got it drug home and got started. It all went well til I tried to start it, it just spun freely. So i adjusted valves ( i torqued them originally) I noticed when I was adjusting the valves that one of them (I believe intake #6) looked odd as in the position and It didn’t give lash til the nut was almost completely off. I started it, it ran disgustingly rough, so I killed it the fuel pump kept priming. I waited a minute or two, it never quit so i disconnected the battery. Worried that maybe I had timing too far out, I rechecked TDC and plugs and wires and elect. connections, all good. Tried again, it cranked and ran for maybe 30 seconds and died and the fuel pump was priming til I disconnected the battery. I took off the maf sensor and cleaned it it had a lot of sludge on it I removed and cleaned the spider as best I could without removing the poppets and such with a stiff bristled brush and needle and sea foam. The ends were full of grease and crud. The EGR was pretty clean but I cleaned it anyway and cleaned the throttle body. It’s been snowing and too cold to spend hardly any time out there so I haven’t put them back on yet. So do you think that will fix it? I’m just wondering cuz I’ve already missed a month of work almost And I was told to check valve and ignition timing, if good I have a stuck valve or cam problem? He said that and I got a little worried, but I don’t know how reputable this guy is… :/
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Should replace the head gasket… You have probably lost compression…Also something to think about… the fuel pump should not run unless it is getting a signal from the crank position sensor…. Try to get a scan tool on it while running and after it dies see what rpms the ECU is getting… also see if any codes pop up/ensure the ECU is working. .
Right. I did change the head gaskets and I never felt ANY compression on my finger when we were bumping the key til after I adjusted the valves
If you are absolutely sure the timing is right, then it is time for a compression/leak down test.. maybe a jumped chain…are the valves moving when the engine turns?
I think there is a chance the chain is on incorrectly (jumped perhaps) or issues the head installation (pushrods maybe)… The crank and distributor timing may be correct, but the valve timing may be off..
Check to ensure both valves are closed at TDC ignition point… if not, your valve timing is off…
Forgive my ignorance please but
You are referring to the compression stroke which is the first upward stroke of the piston, right? Which is where both valves are closed (upright position)?Yes the valves are moving.
You mentioned the belt; you’re saying maybe the timing belt jumped? How can I tell?
Is it possible that maybe I accidentally switched heads?
[quote=”Haas C” post=87633]Forgive my ignorance please but
You are referring to the compression stroke which is the first upward stroke of the piston, right? Which is where both valves are closed (upright position)?Yes the valves are moving.
You mentioned the belt; you’re saying maybe the timing belt jumped? How can I tell?
Is it possible that maybe I accidentally switched heads?[/quote]
Yes, I was referring to the top of the compression stroke.. Also, I should have said chain (have belts on the brain today)..
The easiest way to find the compression/power stroke is with #1 cylinder TDC (you can check with long screwdriver) and the rotor pointing at #1 cylinder direction (to the spark plug that is firing)….
Remember suck (intake), squeeze(compression)at TDC, bang (power), blow (exhaust)returns to TDC to begin all over again.
I don’t know if the heads can be reversed, but I would check your timing chain at some point… A compression test/leakdown test should be done…
Another concern would be how much you tightened up your valves, if your timing was off, and you tightened them all the way, and you set the timing correctly (assuming the chain is off), you could have issues with your valves/head… Also, how did you handle the pushrods when you removed the head…
-Karl
I kept them in exact order just as they came out. Also what would I be looking for if indeed I wind up having to remove the timing cover?
Run a leak down test before you go after the timing chain… if one bank is normal and the other side is not, then you can narrow it down to one bank (head) and not necessarily the chain…
A leak down test consists of removing only one plug from one bank and checking for air to blow out throttle body right? I’ve heard of it but know nothing about it.
I think you seriously need some professional help there. There are exact procedures for adjusting valves. Before you bend all of the valves either get live help or at least research the correct procedure.
The fuel pump running issue could be either caused by a wiring problem or a pump relay with stuck contacts inside.
Naa I think I got it; after I adjusted my valves and it was the correct procedure according to Haines and I put all those cleaned parts back on it started and ran n sounded pretty good with the exception on a rocker clatter. I’m waiting for the battery to charge right now so I can crank her up again (fingers crossed). I’m prepared or the leak down if needed. And compression when done.
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