99 burb with 5.7 oil pressure issues???

[DieselEater]

Got a friend who just bought a 99 burb with the 5.7.......On cold start-up gets some upper end clatter for a few minutes, then quiets down and runs fine.

What should idle oil pressure be? right now its around 35lbs

What should high rpm oil pressure be? right now around 60lbs



if there is an oiling issue, should he go straight to replacing the oil pump?

Should he be looking to replace the noisy lifter?

This is a stock engine


Thanks for your help in advance,


A.........

[Jacfourteen]

Jow many miles is on it? Does it do it only when it is cold out?
On my 5.3 when Idling it runs about 40 and high rpm climbs to about 65-70 (has 120 k miles), my 68 gmc with a fresh rebuilt 350 runs about the same, so I would think that your pressure would be about right.
I'm not sure if the 5.7 was affected or not but I know the ls based 4.8, 5.3, and 6.0 had some piston slap noise when cold started in low temperatures. Hope I could be more help. Good luck.

[bwood]

The pressures you listed are good. The rule of thumb is 10 psi per 1000 rpm. My new (6000 miles) Goodwrench engine runs 35 psi hot at idle. I have been told that there have been piston slap noises in these engines, piston slap can happen in any engine I guess, but it was not a problematic issue like stated before about the 4.8, 5.3, 6.0 "LS" engines. You did mentioned that it lasts a "few minutes", one of the issues that came about with the above mentioned piston slap was an accumulation of carbon on top of the pistons.

Also, the lifters in these engines are hydraulic roller and they have been know to fail and get a little noisy. The roller bearing on the bottom can have a lot of wear and be rattling around until it warms up.

Another possible answer could be a bearing clearance issue on the #5 bearing. There is a service bulliten on this and, it talks about how the #1,2,3,4 Main bearings are supporting the crankshaft and that the #5 bearing clearance is a little too much. When starting the, the shaft will deflect slightly and over time the #7 & #8 rod bearing clearance will grow creating a slight low end knocking during starting lasting up to about 20 sec. Usually stops once the oil pressure gets up.

[truckdude239]

the nosie on start up sound like a bad filter not keeping the oil up top (aka a bad anti flowback valve) what kind of filter is he running? if it fram have him swap the filter for another brand and see if it helps