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Oil Pressure problem

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Brit

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I am having a problem with oil pressure on start up. Instead of registering 60lbs +/- when cold my pressure is only 38-40 lbs at idle or even when the engine is revved to 3000 RPMs. After the car warms up to operating temp the oil pressure slowly rises and then settles at the normal 50lbs at 3000 RPM and 35-40 at idle. Can anyone offer an explanation or solution. Only mods to my BJ7 is an oil cooler and spin-on filter. I guess I shouldn't be too concerned but odd that on startup pressure is so low. Before I installed the spin-on filter and oil cooler pressure was 65-70 lbs at start up.
Thanks,
 
Hi Brit,

How have you mounted your oil cooler? If you have mounted it high you will get drain-down and will require the lines and radiator to be refilled. How long does it take for the pressure to build to normal? Have you installed a cooler thermostat?

Ray 64BJ8P1
 
Ray, Cooler is at bottom of radiator and it takes about 10 minutes of driving to get oil pressure up to normal. I am running a 180 thermostat. I switch to this from a 160 a few years ago and didn't notice any issue then. This drop in oil presssure at start up started last year. Oil pressure is fine when the oil is hot, just not cold. I would expect much higher oil pressure with cold oil. Very weird.
Brit
 
The cooler adapter plate may have a thermostat actived bypass. If the cooler isn't designed for a spi. n on filter, it might be bypassing both the cooler and filter until the temps get high enough. Bypassing the filter would explain the pressure drop.
 
Hi Brit,

I concur with GregW on the effects of a cooler thermostat causing the oil flow to bypass the filter since your pressure returns to normal when at normal operating temperatures. Have you changed the type of oil filter being used or switched from original to spin-on type? If no changes have been implemented since before this condition started, I would consider looking closely at your filter (maybe change brands), filter adapter, or cooler thermostat for a cold oil bypassing issue.

Sorry I can’t be more specific.

All the best,
Ray 64BJ8P1
 
Ray,Greg,
Thanks for your ideas. I don't think my cooler has any by pass switches or thermostat. However, the point about a change in the filter might be it. When I first installed the spin on filter adapter I used a K&N filter. Last year I put on a Wix filter and I think that is around the same time I started to notice the lower oil pressure. I will get a K&N and put on and see if that solves the problem. Can't to this until the spring as the car is going into winter storage this weekend. I will repost in the spring with the results.
Thx,Brit
 
You should change the oil before you put it away for winter

My 2 cent

Cheers

Mark
 
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