Low oil pressure after recent rebuild

[vitaman2]

Purchased a 80k mi short block, cross hatches in cylinder walls looked great, took out crank-had it polished & used micrometer to specs on high side for standard bearings, rolled in standard clevite both on rod/mains & installed High Volume front cover & run a PTE Turbo saver-felt that everything was done correctly even thru break-in w/10w30 dino oil.

I'm in Florida & while driving after awhile, guage would be a consistant 10 psi @ idle.
Decided to change to 20w50 last weekend & it holds a little above 10 psi @ hot idle.
But today while running A/C in 90 degree city traffic water temp raised to 200 & while idling @ traffic light I was observing oil pressure dropping to near ZERO.
I have no chatter noise/knock(piston/rod noise) or smoke, scanmaster reading are great as well as EGT temps.
No excessive bearing material while changing oil using a magnetic drain plug.

Did I miss something here? Clearances on oil pump or spring type(purchased HV cover from Hartline who suggested spring color for my stock block)

 

[ThikStik]

Have you double checked the oil lines for correct connections? That would move trash around in engine if wrong. Good luck. I have a new engine with Chevy clearances on rods thanks to machine shop goons. My o press can go low as 8 on 20-50 at hot ildle..

 

[scgnx]

The colored spring has nothing to do with hot idle pressure. It controls how high the pressure can go. Try removing oil pump cover and going to a thinner gasket. There are different thickness available. The thinner gasket will raise oil pressure at idle. Had a similiar problem when I swapped covers. Pressure fell to 5psi. Went with a thinner gasket and its now 14psi at idle.

- Scott

 

[Adrian87]

Wow where can I get one of these thinner gaskets? My psi is around 5 hot idle.

 

[Nick Micale]

There are 2 items you have not mentioned, what is cold/start up oil pressure, and what did you do for cam bearings?

 

[RICHIE HIGH PSI]

Are you using a mechaincal guage?

 

[Adrian87]

My cold/startup pressure is 70 or so but if the car is really hot and been driven for a while, it will be at 5 in drive stopped...and I assume my VDO in dash guage is mechanical. I believe it has an oil line from the motor to it..

 

[NC87GN]

Did you mic the crank? Did you mic the mains with bearings installed without crank. What do you mean clearances are on the high side (.002", .0025"??) Low oil pressure hot, at idle, is directly related to bearing clearances. I would definately run a mechanical gauge just to verify.

 

[turbosam6]

DO NOT just put a thinner oil pump gasket in there. It was assinine to even suggest that without checking clearances first. If you get it too tight you will F it up.

Also, bearing material is non magnetic. It won't be on your drain plug.

 

[vitaman2]

Thanks for the replies
I'll drop the oil pan, check bearings & clearances

 

[vitaman2]

Thanks for the replies
I'll drop the oil pan, check bearings & clearances

 

[ThikStik]

Clearances be darned, the fact remains that you had 10 psi at one time. My 1.9-2.4 rod clearances give me 8-10 psi. My mains are 1.5-2.0.

 

[Red Regal T]

I guess you could check your bearing clearances, but if they are wide, you can't do much about other than to decide to rebuild. I'd go right to the oil pump. Make sure you have the proper tight clearances on that. With a hi-volume pump, you should be able to get some liveable oil pressures. Also, make sure the cover isn't scored.

 

[ThikStik]

One possible route couldbe to buy bearings that have been coated. It adds 1/2 a thous. to clearance. I may try it in my motor. Calico Coatings 888 236 6079 Jerry