> I meant to ask this during the oil pressure thread that went by some weeks
> ago. However, better late than never. I was out for a little drive
> yesterday (about 200 miles each way) in the '77 B and noticed that my oil
> pressure would decline steadily until it reached about 30-35 psi at
> 3000-3400 RPM after a couple hours of steady driving. At idle, the oil
> pressure was about 10-12 psi. Oil pressure is typically about 65-70 at
> cold start. The temp gauge indicated well below the midline (about 165, if
> I remember a comment made last week correctly), which has been the normal
> operating temp throughout the summer.
>
> The engine was newly-rebuilt just before I bought the car in June and
> hasn't leaked more than a couple dozen drops of oil on my drive since. (I
> haven't checked to see what it does when I park it away from home.) All
> fluids levels are fine.
>
> The question is: Am I being unduly concerned or is the pressure too low
> once the car is thoroughly warmed up? I am especially worried about the
> very low idle readings, but the readings at 3K+ also concern me.
>
> Bill Singleton
>
> '52 TD (hers, in pieces in the garage)
> '77 MGB (ours, we needed something fun to drive)
Bill,
I had alway used the rule of thumb of 10psi for 1000 RPM, and hadn't
really had a problem, but after driving from Florida to Texas, I
noticed that it couldn't up even this amount of pressure at 4000 RPM.
Two week later, it was in the shop with several fried main bearings.
I can't say they were related, but I'd had the car almost a year
prior to this happening.
What was done on the "newly-rebuilt" engine. Some sellers will call
having some head work done "rebuilt", not out of dishonesty, but
rather ignorance. I understand worn cam bearings can be a big source
of lost oil pressure, and they might not have been replaced, even in
the course of an otherwise complete rebuild, becaue they're generally
pretty sturdy.
Scott Gardner
gardner@lwcomm.com
www.lwcomm.com/~gardner
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