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karls59tr
06-05-2012, 09:18 PM
I just finished a hard run with the car and the red dash light is on. The fan belt is not loose. I was wondering if the generator can get too hot if a header is installed? The header is wrapped and I even have some thermal insulation between the Gen and the closest pipe. I'll have to check the wiring in the morning. What's the best method to track down the fault?

TR3driver
06-05-2012, 10:01 PM
Definitely a possibility. Did you see what the ammeter was doing before it quit? If the current stays too high, the generator will roast itself without any help from the exhaust!

Here is the Lucas procedure:
https://docs.google.com/open?id=0B2H2NJt34OffNTc3ODkwYzAtYjRlYS00NDNmLWI0Y TYtNjY5ZjQxZTA2NGFm

You can use a digital voltmeter or DMM in place of the specified moving coil voltmeter. However you may need to move a little slower to give it time to update when the reading is changing.

Note that the rpm values are given in generator rpm, which for the TR3 are about twice crankshaft rpm. In other words, when the book says to run up to 3000 rev/min, you only need to rev the engine to around 1500 rpm.

Also, it's probably best not to let the open-circuit voltage go too high. I try to keep it under 20 volts.

karls59tr
06-06-2012, 01:00 PM
Randal It seems the problem was two fold. The lower rear Gen bracket bolt had fallen out. Secured it with locknut and lockwasher. Those generator bolts sure like to do the hula and fall out. The main issue was the Yellow wire where it connects to the Gen. A year ago I had spliced in a new female connector at the spade terminal. I had twisted the wires at the connection and used one of those heat shrink tubes. Well the heat from the exhaust pipes cooked the connection and seeing as how I hadn't soldered the wires together there was a meltdown. I'll do a proper wiring repair this time and maybe try to get some thermal insulation down in that area as well.

TR3driver
06-06-2012, 01:39 PM
Those generator bolts sure like to do the hula and fall out.
That they do. I believe what happens is that, at certain engine speeds, the belt hits some kind of resonance and starts flapping around, which vibrates the generator even harder than being attached to the engine does. Some things I do that seem to help:

1) Use hardened flat washers (aka "setup" washers) against all of the generator ears. They help spread out the load, making the relatively soft aluminum less likely to deform and let the joint go loose.

2) Use bolts with shanks long enough to go at least partially into the generator ears. You don't want that soft aluminum to touch the bolt threads. In some cases, this requires using a bolt longer than would be otherwise required (I sometimes cut off the excess thread length).

3) Always tighten all 3 bolts firmly after any generator adjustment. Kind of tricky to do, but very important. If you can move the generator, the bolt is too loose for operation.

4) Use new lock washers if there is any doubt about their condition. Lock washers should have sharp edges at the split and be spread by at least a full washer thickness. I added a lockwasher to that rear bolt, even though it appears the factory didn't use one.

5) Use a new Nyloc nut, every time you reinstall the pedestal.

6) My generator ears were all waddled out to some extent, so I reamed and sleeved them with thinwall brass tubing. They need to be a fairly snug fit on the bolt shank. The threaded ear has a Helicoil in it.

7) On the adjustment link, use a heavy flatwasher and nut on the forward side of the generator ear to lock the bolt against the threads inside the ear. Also be sure to use a flat washer between the slotted link and the ear on that side. No lockwasher is required.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I'll do a proper wiring repair this time and maybe try to get some thermal insulation down in that area as well. [/QUOTE]
Good! I really despise twisted wires as, even with tape, it's just a matter of time before you have problems with that joint. No matter how tight you twist them, copper is not strong enough to hold a good, gas-tight joint by itself.

MMC sells some high temperature sleeving that can be used to help protect the wires; if you can't find anything locally. So far though, I've gotten by with just some standard heat-shrink tubing at the end, and routing the wires as far from the manifold as possible.

bobhustead
06-06-2012, 05:57 PM
Don't twist wires, solder every joint and heat shrink over them.
Bob

karls59tr
06-06-2012, 09:26 PM
I've learned my lesson. I'm coming across roadside wiring repairs that I had meant to get back to and forgot about. Deja vu all over again. :-)