Ok so I was changing the oil in my mom's 2k2 silverado 4x4 and I noticed on the fan guard it said that for the diesel version that damage may result if the car is started while the voltage is over 12V (jump starting & charging). Just wondering if this is also applicable to our cars, it kind of makes sense. The idea being to much juice could be sent to the plugs with the voltage set higher than it should be.

Thanks.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

BB,

Chevy trucks use 6 volt GP and a controller for faster heat up of the GP. If they are left on too long, they will burn out, I know, I replaced 8 of them. I replaced them with 12 volt GP and haven't had any burn out since.

I suppose an overvoltage could damage the GM GP, especially if the controller wasn't working perfectly.

This is not likely to happen to MB GP. They are 11.5 volt plugs and a volt or so extra so won't harm them.

P E H

PEH, Wow, You changed 8 glow plugs ALL AT ONCE ? I know how bad that hurt you ....Surprised that did not require minor hospitalization for recovery from 'consternation'....

I think my charger likes to jump start at about 15-17V, apparently I shouldn't risk it with this anymore as that is quite a noticeable increase in voltage.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

BostnBenz,

Thinking of what the voltage might be and measuring the voltage of your charger are two different things. Get a voltmeter and measure it open and under load.

Although the open circuit voltage may be higher than 12 volts, the voltage will drop significantly when the charger is cranking the engine.

I would worry more about the light bulbs, radio and other electronic equipment than the GP.

P E H

Leather,

No, I didn't replace all 8 GP at once, I replaced all 8 GP one at a time.

The GP relay failed when the truck was owned by the PO and he was too cheap to replace it. So he "hot wired" the GP with a manual switch. I was having trouble starting it one day and I left the 6 volt GP on too long and thay all burned out.

I did some checking and found 12 volt GP were available so I replaced all with the 12 volt plugs. I think they were something like $9 each. I didn't cry too much because I was fixing something that was broke unlike the guys who replace GP on a whim just because they are old.

I replaced more GP in that truck at one time than I did in MB in 35 years.

P E H

Surely the starter takes much more energy to turn than the glow plugs to glow, but they are also doing it at different times. The glow plugs would glow while the charger was waiting for the starter to kick in, which would happen seconds later. I've never seen the bulbs so bright as before I start it with that charger, never gave it much thought of how dangerous that could be to the car's electric system either. Maybe I should just use a shelf battery next time to jump start it, or maybe another car, I suddenly don't find the jump start feature of the charger so appealing.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

BnB,

Why do you have to jumpstart so often? Maybe you should invest $60 in a new battery at AutoZone. I just bought one this week, after another Exide failed. I will never buy an Exide again.

If you jump to another car, you can't hurt anything if you don't have its engine running because you would just have the nominal voltage of the battery, not the voltage generated by the alternator.

Probably the open circuit of your charger is so high is to make up for the voltage drop under starting current load.

P E H

Well I have three cars, the battery in the talon quit a year ago, then one start after the new battery (champion) then again last month. The 83 has had a MB battery in it, which age I don't know and it isn't very strong while cold. Same goes with the 84's Interstate battery which was 6-7yrs old and the wrong size, so I've been phasing out these old batteries and got a new Duralast (nice battery, like the idea of a reserve) for that car. I'm just going to sell the 83 with the MB battery in it, it is fine in the summer but don't even think of starting it in the wintertime.... So I really won't have to jump start a car for a while now (knock on wood) but before it was almost everytime I had to start one and boy was that irritating.

Yea I think I'll try to do that next time either a non running car or a shelf battery just to keep the voltage down. Maybe just charge it off of a running car to start it too, not just start it off of the other car.

I see your point about the charger, but the GPs only pull like 80A max right? So they wouldn't drop the voltage that much, I can't imagine it dropping very much until the starter kicked in.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

BnB,

Only one way to know how much voltage drop: measure it. But of course GP drop wouldn't be nearly as much as the drop from the starter cranking the engine.

P E H