i have a 2000 3/4 ton chevy p.u. with a nasty lifter tick ONLY after an overnight cooldown and its multiple lifters. the noise is awful but goes away within 30 to 40 seconds. i can’t imagine that many lifters failing all at once so my thought is the oil pressure relief valve is sticking on the oil pump leting the top of the motor drain down overnight, otherwise oil pressure is good. this is my truck so throwing parts at it is out. any thoughts?
Some of the other people on the Forum have come up with info about GM engines and piston slap, perhaps your truck is so affected.
How many miles did it take for problem to develope? Will a mechanic give a estimate and a guarantee on a repair? (this shows confidence all around).
What is your oil type and specs on the oil (along with filter)? This info. is more for developing a base when other people complain of a similar situation. (not much help to you).
no the problem is not “piston slap” its definatly a lifter noise!
problem came on nearly overnight wasnt there one day, scary noisy the next. but only for 30-40 seconds then fine till the next day.
tried a motor flush noise went away for about a week then came back
I will ask a GM heavy line mechanic what they have been seeing.
The pressure relief valve on the oil pump does not have anything to do with a lifter rattle. Rattling lifters are bad lifters; sticking, worn, sludged up, etc.
Try adding a can of SeaFoam or Berryman B-12, etc. to the engine oil, drive it around, and see if it clears the problem up.
well i replaced all the lifters (after trying multiple engine flushes and adding seafoam etc) and ofcorse the problem is still there with the exact same conditions, goes away within 30 to 40 seconds on on the first start up in the a.m.
I have to believe at this point that somehow the oli is all draining back into the pan over night, allowing the lifters to drain as well, gotta be the oil pump i guess
Have you measured the oil pressure with a mechanical gauge on startup? How is the oil pressure from start to fully warm? Does the oil pressure stay low for those 30-40 seconds? Look at the oil circuit diagram for your engine and see if there is a way to check the oil pressure in the lifter galley. I am thinking that something is blocking the oil flow to the lifter galley so check the oil circuit diagram to see where the problem could lie.
BTW a lifter that is holding a valve open when the engine stops will eventually bleed down – that is the way hydraulic lifters work. When the oil pressure comes up again the bled lifters are refilled and the valve clearance is taken up. The problem you are having is most likely that the oil pressure is not coming up quickly in the lifter oil galley.
Hope that helps. Get back to us with additional information.
The oil filter in your vehicle has a bypass valve which means not all the oil passes through the filter media as it does in a full flow oil filter. If this bypass valve is stuck shut, it will take longer for the oil pressure to build after the engine has sat for an extended period of time. Try installing a new oil filter to see if this eliminates the lifter noise.
replaced the oil filter several times durring the flush and sea foam trials thanks though