Hey guys and gals, I resently bought a 88 chevy 1/2 ton 4x4, it has 252xxx motor has been replaced or rebuilt not sure which. It has on the older style gm head sure the stock ones where junk.
Ok no noise from motor at start up,drive it round motor starts to have a light knock when up to operating temp. Goes away when putting in gear, and if in park or neutral you can rev it up to about 1200 to 1500 gets a bit louder but then goes away over that. Oil pressure gauge reading 60 at idle cold and hot, not sure it gauge is right, going to be doing a oil pressure test with a gauge.

My question is should I take off the pan and inspect, I think that I'm going to not sure if may have spun bearing, but seems odd that don't hear it all the time even when cold.

 

your gonna need to check the oil gap on main bearings I think.

 

Why don't you check your rockers first? If you spin a bearing you will know it.

 

Well first off it's not a tick, only makes noise after motor is warmed up. I am a motorcycle tech and diagose motors beofre I take them apart. While those if it's a knock it should always get loader when holding the brake and reving up the motor. Far as valve train noise if you do the same it goes away.
This is where this noise has got me puzzled, only there when motor is up to temp. Only there at idle and just above, you put in gear and hold the brake and nothing. One person has suggested a wrist pin/ piston/ rod, does seem to be loader on passanger side than the drivers. I took the belt off and started it and ran same test.

 

Wht engine....the GMs of old in the 350 and 454, IT was very common for what most people call 'piston slap' basically sounds exactly what you are describing, and 85% of the time you wont get rid of it....my recommendation live with it....my old Jeep does it and has been for 3 years....

 

Thanks for all of your replies on this, all is very helpful. I was just worried about it a litttle, mostly cause I hade bought it to turn around and sell it. Bought for 500 bucks need a rear brake line, I already repaired that. Then I notice the noise and wanted to get it figured out.
So it's for sale if anyone in here is looken for a cheap truck I live in Brainerd MN, it's nice and clean inside and out, some rust, good tires although someone put on 225 little small in my book. Would make a good farm/ ranch or hunting truck. I'm think about sellen for around 1000.00 or best offer