I have a 2000 blazer. I recently replaced the head gaskets. I started it up, let it get to operating temperature. My oil pressure was 40 psi. I then took it for a test drive. I heard a backfire & lost power, then i gained power. I then noticed the oil pressure dropped to under 20, when under load & 0-10 at idle. Any ideas what could cause this? Thanks for any help.

 

sounds like the headgaskets got water in the oil,and killed the bearings,thus lowering tolerances and lowering oil pressure.

 

Distributor to oil pump shaft? Pull the oil filter and cut open the can. Look for metal

 

if water got in & lowered the oil pressure, would changing the oil correct the problem? when i changed the headgaskets the block was full of coolant & oil mix. i drained the block an cleaned it the best i could. Here are the pics.

 

Unless the head gaskets werent installed properly then you will have antifreeze in the oil once again.But its something that needs to be done soon,DONT WAIT.Antifreeze eats bearing surfaces.

 

i changed the oil & no coolant was present. no coolant on the dipstick either. still the same problem, now i also have a lifter tapping.

 

Hey ewarma, I had a 97 F150 exact same deal, anti-freeze and oil burned bearings. Coming off the highway to a stop pressure would drop to zero and start shaking.

Until your up to doing the lower end run straight 50 wieght oil with a can of motor honey. Mine went 100 grand after and I know for a fact it's still running. I asked the guy who has it and he said he never fxed it and has put 50 g's on it since.

If it's going to hold of the damage you should see it hold better pressure instantly.

 

Does sound like the distributor to oil pump shaft retainer broke.DONT DRIVE IT till you figure out whats wrong or you will be doing a bottom end job or replacing the engine.

 

1st, your thinking because he had good pressure to start and then backfire incident.
Sounds good...so you think pull the dizzy and look for breakage at the bottom of the shaft?

 

how do you check for retainer without dropping the oil pan or can i? what about the oil pressure sensor going bad?