LUVTruck.com

Thanks for all the replies . I figured out the problem ,finally. I took the alternator apart and found one of the tabs that the winding souters to had broken loose. I sauters it directly to the diode tab and it works like a charm . I happen to have an old alternator from a 72 mercedes benz around and found that the pump on the back off the alternator is the same ! So with a little handy work I took the oil seal out of the MB alternator and used that pump on the luv. Total repair cost of 0$.
I have another question though , on my luv the glow plug light goes off before the solenoid actually kicks out so . After the light goes out I continue to wait until I hear the click of the solenoid. About 5 seconds longer?

2.2--

Nice going on the alternator repair. Much better to do this than shopping for possibly bad stuff.

Re the glow lamp. The glow lamp is on a timer which doesn't know whether the glow plug current has retired or not and the lamp will generally go out before the glow relay opens, especially in lower temperatures.

But, the longer you glow the plugs, the shorter their life will be. So, it is best to figure out how much glowing is required to start your engine at any given temperature, and glow no more to ensure decent glow plug life. In our moderate climate here in Calif I find that 4 to 5 seconds is enough.

It is hard to understand why Isuzu did not connect the glow lamp directly to the glow plug bus but they did not.

Paul

_________________
'84 Isuzu diesel P'up

Aren't the glow plugs powered by a 6 volt circuit on these guys? That might explain why they didn't run the lamp off the same relay as the plugs. It does not explain why they used a timer instead of a relay to source 12 volt to the lamp, or a 6 volt bulb, or any number of other ways of making the light match what the plugs are actually doing. I sometimes think Isuzu engineers of the 70s-80s were heavy drinkers, it would explain a lot.

Good info on the real world care/feeding/use of glow plugs by the way.

2.2--

Yes, the plugs are marked for a low voltage. Mine say 5V on the hex head.
But, they are connected to the battery in operation and do receive nearly the full battery voltage. There is a small voltage drop in the fusible link, the relay , the wiring and in a small ( .015 ohm ) resistor. The plugs are operated at this high voltage so that they will heat very quickly. But, because of the (too) high voltage one must be careful to glow them only long enough to successfully start the engine. Or else risk an early failure.

The Isuzu glow controller does a pretty good job of glowing the plugs for good starts without burning them out. It does this by watching the voltage across that .015 ohm restor I mentioned. The plugs have a positive temperature coefficient which causes the current to decline as the plugs warm. When the current declines to a certain level the controller shuts the plugs off.

This may be more than anyone wants to know.

Paul

_________________
'84 Isuzu diesel P'up