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MG TD TF 1500 - What causes higher than normal oil pressure?

At start up today, my 52 TD had oil pressure of 80#. After driving ten miles, 45MPH, it dropped to 70# but when increasing the speed to 50 it went back up to 80#.

After engine was completely warmed up, at 50MPH, the oil pressure was dead on 60#.

At idle the pressure was dead on 20#.

What would cause the higher than normal oil pressure?

I've never had this issue before.
R C Flowers

Possibly an issue with the bypass valve? PJ
Paul S Jennings

Thank you Paul. My thoughts were in that direction too. I'll check into it later today.
R C Flowers

I remember reading an article from a gentleman in France that had an issue with the bypass valve, but his problem was low oil pressure and found out the ball and seat were worn badly. As I remember he had a tough time finding a tool to re-furbish the seat. But of course your problem is the other way. Maybe the valve is sticking? Only way to see is to pull it apart. Like to know what you find. PJ
Paul S Jennings

These figures exactly match our 1947 MG TC. The other XPAGs all run between 20 and 60 depending on oil temp and engine speed.
D. Sander

I'll let you folks know what I find when I pull the bypass valve parts.

The complete bottom end was rebuilt and I just got it back on the road about 250 miles ago.
R C Flowers

R C, your figures are very close to matching those that I've been looking at for about 18,000 miles. The only 'problem' that I see is a messy engine bay. Bud
Bud Krueger

Bud,

I broke the crank last August. Ordered a new forged crank from John Esposito, and then opted for the Ford T9 five speed from John as well.

Did a complete rebuild of the bottom end. The top end looked like a brand new motor. The cylinders retained the original cross hatching from the factory.

Also installed was the Moss crank seal, front and rear, the latter consisting of 400 lines of instructions. Patience required and two trips to the machine shop for slight milling. End result is a dry engine. Nothing like the original marking it's spot where ever I parked!

I thought being the bottom end was rebuilt with all new seals, upgraded gaskets, all new parts, bearings and such that that might have something to do with the increase in pressure.

I will note as well that the engine had great oil pressure prior to the crank failure and subsequent rebuild.
R C Flowers

Defective oil pressure gauge will also read incorrect oil pressure. As you probably know, but if not..seals on the supply side will effect oil pressure if leaking previously and now you have a good seal..or vice versa. Regards, tom
tm peterson

This thread was discussed between 06/07/2014 and 08/07/2014

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