I am dealing with a 1999 Dis II 4.0, I am experincing valve train noise when the engine reaches operating temp. Engine has had new mains, rod bearings, cam bearings, lifters, rocker arm assemblies, and engine continues to knock. I have bypassed the oil cooler and put manuel oil pressure gauge, when cold engine has 55 to 60 psi pressure, at operating temp pressure drops to 8-10 psi. Also, checked the flywheel for cracks. Can any body tell me what is causing the continue knocking?

Thanks,
Desperate Paul

 

You pretty much nailed it, low oil pressure, enough testing, you are just eating metal.

Prime suspect would be oil pump, you'll see a number of fairly recent posts, some with tick, some without, and when front cover removed the pump was split into several sections. It continues to run, but oil PSI is all over the place.

When front cover is off, other items to do on that same trip include water pump, oil pump, timing chain (some one said $30 GM cross to this), and front crank seal ($5) (by default). Also can install sender for an after market oil PSI gauge.

Pix by Deepbluewater

 

You need to be more exact with the oil pressure readings, should be taken cold at idle and 2000 RPM's and again when hot at idle and 2000 RPM's.
Get back to us with those numbers. By the way, did you replace the cam when changing out the lifters, should have.

 

Oil pressure @ 2000 RPM when cold 55-60 psi, hot @ 2000 RPM 19-20 PSI @ 204 degrees, Yes cam shaft & bearings all new & checked for proper tolerance. Oil cooler has been blocked off for test purposes only.

Thanks,
Desperate Paul

 

Sounds like your oil pump is toast.

 

Unless you are running some really, really bad oil. Might consider drain and refill and new filter. This is cheap, and might (rare) be filter, and might (due to engine work) be a gasket leaking coolant into oil, which could sit toward bottom of pan until stirred up... use 20W50 cheap stuff, not seven bottles of Marvel Mystery Oil. Any coolant loss? But oil pump looms large. Cooler not a performance issue so much, was not supplied for all D2s except a particular VIN range.

Speaking of "sounds" - mechanic stethoscope or broom handle to the ear might show changes in pump noise from front cover cold and warm -careful the belt does not grab something when doing this. Some posts have suggested this as one of the tick sounds, suppose fragments of pump moving around might do something.

Better to be Desparate Paul and catch this before the rapid transformation to Part-out Paul....

 

it looks as if you have replace all your bearing and valve trian that only leaves the oilpump. thats unless you got a batch of bad oil, you could try an oil change for $25 if your preasure dont come up i think its oil pump time.

 

And if you drain the oil, let it run thru a sceen. You are looking for chunks of metal (bad) and blobs of Oklahoma grade RTV. If RTV sealant has been used, and a little extra cracked off and circulated, that would be bad.

 

Which you would have given us the information I asked for in the form of 4 oil pressure readings, there is a reason for my asking for them.
At this point, your hot oil pressure is too low.