hello all,
Let me first say that this isn't my vehicle its my cousins, and ive encountered a lot of engine problems and have rebuilt a lot of engines but i have never seen this problem and i am hoping someone can help me out. the vehicle is a 1977 Chevy K5 Blazer with a 350 and a 4speed trans. Now the problem is that with the engine running it has oil preasure, 45-50 PSI cold and 25-30 PSI hot at idle. now while it isn't knocking, its tapping like a SOB. so i looked in the valve covers and dry as a bone. its getting something cause it was running for a good 10 minutes without siezing up and it ran so smooth. He said he replaced the oil pump but i wasn't there and he said he primed it, and it has oil in it, so im stumped, what could cause an engine to have somekind of oil preasure but not get any oil to the top end? thanks for any help

 

anyone?

 

My 4.3 in my truck ended up like this. Sounds like it might have spun a cam bearing. Someone told me before that chevy you have to line up the hole in the cam bearings to the holes in the block. Or it will not flow oil to the top of the motor. If they run dry and move their position they'd cause the symptoms you're seeing. I believe.

 

i was suspecting that, im trying to get a definate answer as to what can cause this

 

Mechanical fuel pump? I've heard fuel pumps that were bad that sounded like a rod knock.

Does it have headers? Are they a cheap (or old rust pair)? I had a truck where one of the tubes had rusted away from the flange. When the piston would come up on the exhaust stroke, it would push the tube away from the flange. Once the exhaust vavle closed the tube would spring back into the flange. Sounded exactly like a knock. I was ready to pull the motor. Had I not bumped the header when taking it off I would have never figured it out.

 

UPDATE: pulled the motor out and apart.....every bearing was shot....it in the process of being rebuilt

 

Plugged oil galleries sounds like. Need to clean them out. Try some oil flush first. Didn't read last post sorry never mind.

 

better late then never haha, its never a good thing when you can see the copper in the bearing haha......every main bearing was shot and one cam bearing was spun around

 

straight up if you have pics post em lol that will make a funny story one day

 

lol yes spun or bad bearings will cause oiling problems. My wife melted the cam bearings shut in her grand am. It lost oil pressure but she continued to drive it anyway /facepalm

 

i do not have any pics, mainly because i was so filthy and i didn't want to grab my camera