Oil Pressure

[Adambul]

I know there have been loads of posts over oil pressure and recommended oil viscosity but I thought I'd share my readings to see if anyone has any thoughts.
When warm, oil pressure is between 25 and 55 psi which although I would prefer it to be higher appears to be within the normal acceptable limits (mileage is 46,000), but when cold the pressure is between 35 & 40 psi and only rises to 55 when warm. Has anyone experienced similar?. I would expect it to be higher when cold not lower. It's as if the oil viscosity is too high when cold and when the oil thins more get through hence the pressure increases.
I'm running Mobil 1 10-40, I have changed the oil pressure relief spring and it made no difference. Any ideas?

[gruffalo]

I had a very similar issue with my car, thought strange so stuck a test gauge on it and found that the car was lying.

I can only put it down to the small bore of the capillary that feed the pressure gauge and thick cold oil not getting down it well.

Mine would read 50 cold and semi warm 60, the 65 was more like it cold when tested properly.

[Cyclone1]

Change the oil pressure relief spring and see if that makes a difference. Very cheap to and provides reassurance that all is well. Common problem on Cerbs where the spring cracks over time and the reading drops.

Jules

[NilsP]

Hmm weird.
Mine reads about 70-75ish when cold
And then drops to 45-55 when warm.

[gruffalo]

NilsP said:

Hmm weird.
Mine reads about 70-75ish when cold
And then drops to 45-55 when warm.

Sounds about right.

Mine would behave like it did on cold mornings, if it was a cold start but a warmish day it was fine.

I put SPA digital gauges in the old girl as the original oil gauge started sticking.

Edited by gruffalo on Monday 16th March 07:17

[Adambul]

Good idea about the gauge, I have a test gauge so I can easily check.
I've changed the spring but this didn't make any difference, although I did notice that the piston on the oil pressure relief valve was quite scored and I may change to see if this alters the pressure reading. Although I presume the bore will be equally scored so may not make any difference. The symptons do fit with a weak spring as it would pressure relief more with thicker oil when the engine is cold. Has anyone tried packing the spring in an attempt to increase oil pressure. Just a thought...

[greenracing]

Could be an oil and filter combination issue.

Have you always run the same oil brand, rating and filter brand?

Could also be the filter that's clogged or damaged internally.

[gruffalo]

The pressure relief valve opens at 75psi so if you have replaced the spring it is unlikely that packing it will make any difference.

These engines should have 20-40 psi at tick over when properly hot rising to around 55-65 at 3000rpm, if yours is in this range then don't worry about it just enjoy it.

[Adambul]

greenracing said:

Could be an oil and filter combination issue.

Have you always run the same oil brand, rating and filter brand?

Could also be the filter that's clogged or damaged internally.

I've only had the car two years and only noticed this after last years oil change so the filter is a definate possibility. Its due this years oil change so I'll see if it makes any difference

[yosini]

I was quite worried by mine as it would drop to around 10, sometime almost lower when properly warm, but no warning lights would never come on. Had it checked out by Bespoke and the gauge was apparently under-reading by almost 20psi. So now I just don't bother looking at the gauge any more...ignorance = bliss.

My t25 air cooled camper van doesn't have a temperature gauge, and is the only vehicle I have ever owned that didn't, and consequently the only one I never worry about it overheating....