I have a 89 camaro beater it is a 305 tbi. when I start it up in the mornings and the temp is around 55 degrees it only holds about 12 psi oil pressure but as it gets hot it will hold around 40 is this signs of a clogged oil pump screen? bad gauge? or the motor oil is to thick it is castrol syntec 20w 50.

Thanks

 

Hmmmm....you'd think with it cold, the pressure would be high and lower after warm. But it's concievable that when the oil is cold, it's thicker, so the pump kinda starves for oil. Then when it warms up- oil gets thinner, and you could pass more volume through a partaily clogged pick-up screen.

IMO, I'd run a quart of oil flush in it, then change the oil to see if it improves, if not - must be the sending unit. I've also heard of running a qt. of dextron II in with the oil to clean things up.

Works just like the flush does.

 

Unless you have excessive bearing clearance, you are using oil that is far too viscous. Try a 10W30 or 10W40. The facy that you are holding 40 PSIG when hot indicates the viscosity is too high unless you have change to a high volume oiul pump or altered the oil pump pressure relief valve spring.

Another possibility is an oil filter with undersized passages or poor filtering area. Switch to the correct viscosity and an AC, Purolator, or Wix filter.

A flush with ATF can clean up a lot of sludge and varnish, but regular oil changes will really help clear up any restrictions. Synthetic is excellent for this.

 

How bout hooking a mechanical pressure gauge up and actually seeing if that is the correct pressure reading, if the pressure is what the gauge says, I agree totally with Vader if its not you probably have more problems.

Kyle

 

vader,


Why does holding 40 psi oil pressure when hot indicate that the oil is to thick? By the way I am using a AC delco filter and the car has regular oil changes as long as I have had it.


Thanks:hail:

 

Define "hot". At full operating temperature (coolant at 223°F) the oil pressure at idle RPM (650) should be more like 30 PSIG, but there are variations.

The fact that you can't move oil when cold but appear to have more than adequate pressure when "hot" indicates a viscosity issue. Change in some 10W30 synthetic and a standard AC filter, and see what happens.

And as Twisted mentioned, if you are going strictly by the factory gauge, you may not be getting a completely accurate representation of what's happening.