glow plug relay - PeachParts Mercedes-Benz Forum

davidh · #1 06-13-2009, 12:28 PM

more dang problems. is it possible to repair / recondition a glow plug relay ?
mine clicks but no glow or glow light.

im trying to not need to lay the car up for a week while waiting for parts.

the alternator problem was the battery connections i believe. whomever installed the battery last fall did not tighten the cables. i did not even try to start it until april and the batt was dead then and a good charge seemed to make it work again.

but the relay thing, do they come apart ? i did see some small screws but have not taken it off the car yet

kerry · #2 06-13-2009, 01:02 PM

Have you checked for voltage at the plugs with the key in the glow position?

davidh · #3 06-13-2009, 02:33 PM

not yet. good way to troubleshoot. the relay does click but the plugs do not warm up the engine. (it all of a sudden just would not work) hard to start for the first time in its life.

looks like im on my own on this one. we'll start from scratch.

spock505 · #4 06-13-2009, 02:55 PM

They come apart pretty easy, this is from a '94 C250D but I think most are similar -

kerry · #5 06-13-2009, 02:59 PM

I think it's premature to condemn the relay without testing for voltage output. Have you checked the strip fuse in the relay?

pelon · #6 06-13-2009, 03:02 PM

i replaced the glows but couldn't hear the relay click. i took it apart and used an old point file to clean up the contacts on the relay.
now it works great. much cheaper than a hundred bucks for a new one.

davidh · #7 06-14-2009, 12:10 PM

so i checked the voltage at the five prongs on the relay. . . . zero. i took the relay off, took off the cover and disconnected the tiny spring on the side of the relay.

now we can really get at the burned points. scuffed, brushed and buffed them clean, re-assembled and put it back on. yea ! ! ! ! good for the rest of my life i'd bet.

thanks for the helpful information again.

davidh

mtbguy · #8 09-12-2009, 01:35 PM

I just went through this exact problem. Suddenly the car wouldn't start quickly. It was very hard to start unless totally warmed up. I replaced all of the glow plugs, tested continuity, everything. My relay even clicked.

When I took the relay apart one of the smaller contacts in the row of five was blackened and not working anymore. The relay would click but never energize the glow plugs. I cleaned it with 1000 grit sandpaper and the car starts and runs okay again.

I think I may go ahead and buy a new relay from ******** or get another from a parts car and keep this one as a working spare. Thanks for the helpful posts everyone from a frequent forum searcher!

Olivier · #9 09-12-2009, 03:27 PM

you might need to file the contacts?

spock505 · #10 09-12-2009, 05:44 PM

Quote:

Originally Posted by Olivier

you might need to file the contacts?

Are you competing with me for best close up photo Olly

I think mine adds a certain realism with my greasy thumb almost in view

Olivier · #11 09-12-2009, 06:17 PM

OK, here is one with the thumb too

Oh, and the fuse blade too, they might be burned, no thumb tho...

mtbguy · #12 09-14-2009, 09:41 PM

Oh well, for me cleaning the contacts worked for about two days. The glow plug light quit working again and the relay is screwed up again, so I ordered a new one from ********. The circuit board has a burn mark near a resistor, and there is no longer any voltage to the glow plugs (which are all new and continuity test was good on wires.

I guess it DID last for 19 years so I cant complain.