1996 4.3 Chevy/Volvo Engine proplems

[rattana]

Re: 1996 4.3 Chevy/Volvo Engine proplems

When you do a compression test, make sure the throttle is wide open to allow air into the cylinders to get a true reading. First test do it dry no oil or anything in the cylinders. The second time squirt some oil in the cylinders and redo the test. If your low cylinder pressure comes up it could be the rings, if it doesn't it could be the valves, head gasket, etc.

 

[brianhayes]

Re: 1996 4.3 Chevy/Volvo Engine proplems

I will redo this again, but the last time I did the test the reading was 150 psi at home and when I ran the boat on the water at full temp it was 90 psi. But who knows, I could have messed this up.<br /><br />Now today, after yesterdays running with everything in order the reading on that cylinder is up (cold testing) 165, while the rest are 183 which are exceptable ranges. I ran (idle) for 5 minutes on a hose and let the engine warm up. And no change in compression. I then sprayed some WD40 into the lower cylinder and then I got a reading of 170.<br /><br />Next time I'm out on the water and I can get the engine to full temp, I will check it again.<br /><br /><br />So my question is this:<br /><br />What could cause a good reading cold and a bad one hot?<br /><br />Brian Hayes

 

[brianhayes]

Re: 1996 4.3 Chevy/Volvo Engine proplems

Thank you everyone for you help on this.. I'm not quite sure what I have going on, but It will let it self be known soon enough. I just need to pull the head and have it checked out.<br /><br />Same thing, when engine is 120 degs, the idle becomes rough and #4 drops down to 90 psi.<br /><br />When engine is cold or just a little warm #4 is 160 ish.<br /><br />I guess the problem could just about anything at this point. Gasket, cracked head/block, valve.<br /><br />I'm dumping the oil today to see if there are signs of water in oil, plus I should change is anyway because of my awsome carb rebuild job that resulted in a big time flooding condition.<br /><br />Brian Hayes