W115 300D temp resistor - secret information - PeachParts Mercedes-Benz Forum

1975300D · #1 08-27-2011, 12:46 PM

Hey Everyone,

I really need a piece of information I have not been able to find anywhere. I have scoured the internet and sent a few emails to suppliers.

The temp gauge on a 300D W115 has a resistor. Mine is blown so the numbers have been eradicated. I need to replace the resistor but can't until I know those numbers.

One repair shop local to me said he knew, but because it was his little secret, he wouldn't tell me.

Does anybody know, or can anybody check theirs?

Thanks a million.

Mark

diametricalbenz · #2 08-27-2011, 10:25 PM

Does the resistor have any color banding?

1975300D · #3 08-28-2011, 08:43 PM

No it does not. These resisting have numbers.

54dan · #4 08-30-2011, 09:35 AM

If you can point me to where this resistor is, I can try to take a look at my '76 w115 300D...

-Dan

--
1976 w115 300D
1985 w123 300TD

1975300D · #5 08-30-2011, 08:16 PM

Thanks dan, the resistor is on the back of the temp gauge. But you would have to pull out the instrument cluster. That is easy. It just pulls out, but then you'd have to disconnect the odometer cable, a couple of leads that pull out, the main electrical connection and the oil pressure cable and the glow plug light. .

LOL. I doubt you want to do that. It's actually quite quick, but that is what you'd have to do to remove the instrument cluster.

54dan · #6 09-01-2011, 10:36 AM

I got a box of spare parts with my 300D and there is a cluster in there. I remembered on the way out the door this morning and ran down to the basement to check.

Sure enough, I saw the resistor on the back of the fuel gauge, but it has no markings on it. It appears to have been hot over the years (I guess that's what these things do) but not burnt.

When I get home, I'll snip one side and measure with an ohm meter and post here.

-Dan

54dan · #7 09-02-2011, 11:11 AM

I took a look in better light and the resistor on the back of the fuel gauge is indeed marked "68 ohms," picture attached.

Hope this helps.

-Dan

1975300D · #8 09-02-2011, 08:18 PM

Thanks Dan, sorry for the delay. I forget to check this thread in Vintage. I'm always over at Diesel.

So thanks for confirming that! That means a lot.

Does it say wattage or just ohms?

54dan · #9 09-03-2011, 10:51 AM

So I went to take a look again and realized the one I was looking at was on the temp gauge. So, I clipped one end of the one on the fuel gauge (no readable value) and measured with my digital ohm meter. Measures 70 ohms ... so although I was looking at the wrong one, it appears that they are the same resistor.

Take a look at the pic ... as long as you use one that's about as big it should be fine. Too small wattage (size) and it can't dissipate the heat ... too much wattage is never a problem, but size will get to be an issue.

Hope this helps.

-Dan