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MG TD TF 1500 - Original Oil Pressure

I restored my TD back to close to what the factory did. This included putting the oil line back up on the head (1950 TD).

The engine has about 3000 miles on it and the pump was rebuild by University motor when the engine was rebuilt. I am also running a Moss Adjustable Oil Pressure regulator (it has been on the car prior to the rebuild, so it was just left on) (currently all the way in)

Oil pressure with the line off the lower block used to be 50 pounds at speed and 20 at idle.

Current pressure is 30 at speed and 20 at idle.

I am not concerned about the oil pressure. I looked in the valve cover and have a good amount of oil coming off the rockers.

Just wondering if we know what the TD ran for oil pressure from the factory (early TD)
Bruce Cunha

Bruce---just a thought
If your car used to have the gauge at the bottom----maybe it had an oil restrictor fitted in the top banjo bolt. and now with the gauge at the top and the top bolt in the bottom --If so the restrictor in the now bottom banjo bolt would be restricting oil pressure at the top (gauge)

willy
William Revit

30PSI way too low at speed. Figure 10psi/1000 RPM. Take gauge reading from lower banjo, or use a different gauge. You need to ensure main oil galley pressure is high enough. Years ago, we spent hours chasing low pressure after an engine out for oil leak, and it was indeed a restricted banjo bolt. We swapped top and bottom at reassembly, so even with gauge take off at bottom it was reading restricted pressure. George
George Butz III

Operationally 30psi is plenty of pressure. The engine will suffer no consequences. I assume George is referring to the capability of the pump out put. Modern cars, which operate at higher compression and rpm the low oil pressure/check engine idiot light doesn’t come on until 11 psi typically
Of course this post does not answer your question.
Regards, Tom
tm peterson

The W K F Wood book quotes 60psi running normal, 40psi running minimum. Fiiting the supplementary spring increase running pressure to 80psi, no actual revs quoted.
B W Wood

From"The MG operation manual midget series TD"
Third edition.
"A pressure between 25 and 40 is shown under normal running conditions.A lower figure is shown when the engine is running slowly"
The second scale indicates the cooling water temperature which should be from 80 to 90 C."
Hope this helps!
Len
Len Fanelli

Thanks all. Pressure is solid (not fluctuating), and I do have oil spurting out of the rockers. So from what len posted, it appears to be in a normal range.

I will obviously keep an eye on it.



Bruce Cunha

Fitting a supplementary spring to increase oil pressure to 80psi is ridiculous,as the oil pressure "RELIEF" valve is designed to open at 65 psi.
R E J Stewart

I feel that 30 is enough to do the job in normal driving, but 40 is the minimum that I like to see. 65 is the max I would want to see.
Steve Simmons

I'd still be removing both banjo bolts and checking to make sure the bottom one doesn't have a restrictor--
If it hasn't then all good---- but If it has it needs removing and fitting to the top bolt
William Revit

I'd still be removing both banjo bolts and checking to make sure the bottom one doesn't have a restrictor--
If it hasn't then all good, it is what it is---- but If it has it needs removing and fitting to the top bolt
William Revit

Without context, oil pressure is just a number. The number, whatever it is, has no direct bearing on adequate lubrication. Now a CHANGE to the number, now that gives it context.
The Hudson line of cars used engines of almost identical technology to the XPAG/XPEG. Both are low revving, long stroke engines. The Hudson engines dominated stock car racing for years in the 1950’s. They use zero oil pressure. There is a pump that puts out a few psi to move oil from the pan to an upper tray. The rod big ends have scuppers that just scoop oil as they splash in the trough. There is NO oil pressure. All an engine needs is oil delivered to the moving parts, hydrodynamic film does the rest. A volume of oil is required for cooling. Don’t get too focused on a number, it is only change of pressure over time that is worth noting.

Regards, Tom
tm peterson

This thread was discussed between 07/05/2024 and 09/05/2024

MG TD TF 1500 index

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