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MG TD TF 1500 - Oil Pressure Gauge - not at zero

The oil pressure gauge in my '55 TF1500 has stopped returning to zero when the engine is shut off. After a number of hours It will drop to about 30 pounds. It reads about 70 pounds when running.

I believed that it started after I changed oil (Valvoline VR1) and changed the filter (Moss 950-530).

Previously it returned to zero when off and the pressure when running was mid-gauge.

Could it be a piece of crud in the tube to the gauge? I haven't disconnected the copper tube at the union of the "fabric" line or at the gauge yet.

Any suggestions?

Thanks,

Lonnie
TF7211
LM Cook

Start first by disconnecting the fitting at the gauge. If it does not drop to zero after you disconnect it then its in the gauge and will probably have to be repaired. If it does drop to zero then you can blow air through it to clean it out. I would bet its the gauge.
Chris Couper

Chris -

Thanks for your suggestion. I disconnected the fitting. No change - needle still at 25 pounds. I tapped on the back of the gauge. The needle immediately fell to zero. Started the engine and the needle moved up to normal position, but didn't fluctuate with engine RPM. Turned off the engine and the needle remained at operating reading. Tapped on the gauge. Fell to zero again. Happy - I believe that the gauge is OK.

I also did a fast job on the ammeter while I was under the the dash. Although the needle barely moves in normal operation, it shows a CHARGE when the headlights are on and ignition off. Previous owner had not changed the wires when polarity was changed to negative ground.

So I switched the leads to the ammeter. Turned on the headlights and needle moved to discharge but did not return to zero with lights off. Tapped on glass and needle moved to zero.

CAUSE IDENTIFIED: Looks like the needles on the oil pressure and ammeter are rubbing the glass on the instrument cluster. The ammeter needle looks bent. Can't tell if the oil pressure needle is too. The temp gauge looks like a replacement and doesn't rub the glass.

There is a gap between the glass and the bezels on all three clusters - speedo / tach / oil-temp-amp. But the glass is solidly in place. I tried to move it with a suction cup.

THE FIX: I won't know the fix until I remove the clusters from the instrument panel. Hope that the resistance by the glass on the needles doesn't damage the gauges before I can remove and adjust.

Thanks for your help,

Lonnie
TF7211
LM Cook

It might just loosen up once its used a number of times if not rubbing. The bezels twist off if you need to remove the glass.
Chris Couper

Chris, Lonnie,
I am pretty sure that the three small gauges are removed from the cluster by undoing fixing screws at the rear. Each gauge can be taken out separately leaving the glass behind. That would make if easy to delicately bend the needle if needed.
Max Irvine

Lonnie

Max is spot on how you remove the 3 cluster gauges on a TF. I have had my ammeter out many times, just ensure you disconnect your battery prior to commencing the task.

The mechanisms are fairly primitive however there are facilities to set the pointer shaft pivot clearance. If the adjustment has come loose it could be the reason the pointer is rubbing on the glass. After adjustment use a little nail polish to lock it in position.


Graeme
G Evans

A few years ago I went through the same thing. what I found was that the inner workings had oxidized a bit. I remmoved the gauge gave the guts a liberal dose of very light machine oil and carefully worked the pointer several times and lastly let the oil drain back out. Been working great ever since.
MG LaVerne

I failed to read the TF statement :-)
Chris Couper

I had a few more "issues" pop up, so it may be a while before I remove the gauges. I'll let you know what I find and the results.

Lonnie
TF7211
LM Cook

This thread was discussed between 07/02/2014 and 10/02/2014

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