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MG TD TF 1500 - Hot Generator

I've recently noticed that after driving my 53 TD for even a short distance (5 miles) the generator becomes very hot. It is way too hot to touch. I've made sure that the oiler has been lubed, and I don't think the belt is too tight to prevent distorted shaft spin. Any thoughts? I assume this is not normal. Thanks! Bill
William Metevier

Bill, how much is showing on the ammeter?

If there is too much current going to the battery the genny will get hot and eventually chuck all the solder out of the commutator which will be an expensive fix.

Cheers,

Paul.
Paul van Gool

William Metevier There is definitely something wrong. Give us more details of what the ammeter is showing and the circumstances for the readings.

Where in New Hampshire are you? Maybe we could get together.
Cheers,

Bob
R. K. (Bob) Jeffers

Bill - If you have a non segmented belt, it ca be stiff enough to cause excessive wear on the rear bushing of the generator (I know this from experience). After checking for excessive current draw on the generator, and if that is not found to be the problem, remove and disassemble the generator and check to see if the armature is rubbing against one of the field poles. this situation will definitely cause the generator to run hot and it will not necessarily make a lot of noise that can be heard over the regular engine noise. Beyond that, you are in good hands with Bob Jeffers, listen to what he has to say. Cheers - Dave
David DuBois

Thanks for the feedback. The ammeter show a slight discharge when the engine is at idle, (-3) At driving revs, (tach drive is broken) there is about a +7 reading. With the headlights on it stays dead center. I have a non segmented belt. With the belt loose, the armature spins easily. Haven't had a chance to pull the generator apart yet. Another symptom of my electrical issues is a frequent dead battery. Purchased a new battery a couple of months ago because the 10 year old battery didn't seem to hold a charge. Clearly there is a drain somewhere in the system as the new battery will also be flat if the car hasn't been driven in after several days. How would I begin to find a short in the system when it is not severe enough to create an obvious failure in a component? Thanks, Bill
William Metevier

This will not diagnose the hot generator, but might help in tracking down a dead battery.

Try disconnecting the ground terminal of the battery and hooking a 12 volt test lamp between the battery terminal and the strap. If there is any lamp glow, then there is a draw on the system. Even the clock will make the lamp glow. If there is light, start pulling the fuses and/or disconnecting wires to components until the glow ceases. The TD has only 2 fuses, so it is rather easy to narrow down the search. There are several wires hooked to the output of each fuse. Once the proper fuse is located, un-hook output wires from that fuse until the guilty circuit is located. Then track down the unwanted draw. Possibly one of the coils inside the voltage regulator? A sticking set of points can allow the battery to discharge thru the generator windings, yet the generator will function properly when the engine is running.

I once had a truck in the shop that continually had dead batteries. As long as the truck was run every day, it was fine. Only when left sitting for a few days or over a weekend did the battery go down. When I finally tracked down the problem, it was one wire on the ignition switch that allowed the dashboard gauges to stay on all the time. No one noticed that the electric temp gauge and gas gauge held their readings after the engine was shut off.

John Masters

Bill You probably don't have one but a clip-on DC ammeter will find the drain on your battery real quick.
If you can get it here I can find it for you real quick.
Cheers,
Bob
R. K. (Bob) Jeffers

This is about the Hot generator.

Went up to Bill's this PM and we checked out the electrical part of the regulator with the ohmmeter. It passed with flying colors. Then we checked the output voltage and saw 17 volts once. Way too much, so we backed off the voltage adjustment to about 14.5 volts. Then we checked the ability to regulate the voltage, not too good. The side lights caused the ammeter to drop some and the headlights brought the charge rate to zero.

The season for 'T' series is close to over here so we elected to not go further at this time. Wait until the car is put up for the winter then convert the regulator and tear down the generator to see if it needs rebuilding.

Conclusion:-- The regulator was cranked up trying to get the charge rate on the positive side with the headlights on. The mechanical adjustments of the regulator are not correct so it does not regulate very well. With enough fiddling it could probably be made to work more nearly like original but who has the time and inclination to fiddle and fuss with it?

Time will tell whether we corrected the 'hot generator' problem but my guess is that we did.
Cheers,
Bob
R. K. (Bob) Jeffers

Even though the RF95 and derivatives worked, there are better regulators around now, either some with three coils or the electronic one by Bob Jeffers. I think you spare yourself generator problems if you update the regulator.

Denis
1950 TD
Denis L Baggi

This thread was discussed between 03/09/2007 and 16/09/2007

MG TD TF 1500 index

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