My fuel and temperature guage will jump/twitch, sometimes independently of each other and sometime together. The fuel guage will jump less than 1/4 a tank (maybe more like an 1/8). The temp guage about 15 degrees. Do you think this is a problem with the guage, or with the sending units? I'm trying to solve a slight temperature issue, and I'm trying to troubleshoot this, as it might be the cause for my high readings, I don't know.

I actually don't know where my temperature sending unit it, as what I thought it was is probably the grounding switch for my blower fan (see post 42: Name these parts, to help new members.). There is nothing on my valve cover that could be it.

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B
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1983 300SD

Temp sending unit should be in the head on the drivers side near the IP pump. Check your ground connections.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Whack your dashboard when they do that - if it changes, you may have a connection problem on or behind the gauge cluster.

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1984 300Sd 210k

Former cars:
1984 300D 445k (!!) (Strider) Original (and not rebuilt) engine and transmission. Currently running on V80 ( 80% vegetable oil, 20% petroleum products). Actually not, taking a WVO break.
1993 300d 2.5 275k. Current 120/day commuter
1981 300SD 188k (Hans) Killed by a deer

Sounds like a classic ground problem. I'd remove the grounds and clean them. Maybe even crimp on new ends.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

ground

most likely

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

A poor ground connection is certainly a likelihood, especially if the two gauges jump together like a pair of dancers, at the exact same instant.

On the other hand, you may have two unrelated problems:

1) Fuel level wires dirty on the sensor in the tank.

2) Temperature sending unit going bad.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

I've had the exact problem after removing the gauge cluster for speedo repair - going back in and reverifying all connections cured the problem.

John

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

Check your engine-to-chassis ground especially. If loose, it will give the same symptoms.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I cannot, for the life of me, find my temperature sending unit.

I did beat on the dash last night. The fuel gauage went from between 1/4 and 1/2 tank down to 1/4 and stayed put (as in, didn't jump around) for my 40 minute drive.

The temp guage shook alittle, but maybe it was just because I was beating on the dash. It didn't seem to jump much, as I recall now, for the rest of the drive either.

How hard is it to get behind the instrument cluster?

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B
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1983 300SD

Its cake. Do a search. Pretty much you just make some hooks up out of wire and slip them behind the cluster. They pop right out their is nothing holding them in. Then just unplug the guages.

I am not 100% sure but I think the temp sensor on a 617 is on the drivers side, in the head, more towards the front.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

It's in the head on the drivers side, about halfway back, either between the 2 and 3, or the 3 and 4 glow plugs. Look for a black plastic connector.

Temperature sending unit replaced, instrument cluster removed and connections checked. Guage still does a little dance here and there.

Where are these grounds everyone is talking about? Sorry if that's a retarded question.

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B
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1983 300SD

If you have removed the instrument cluster, you should be looking right at them. There are several groups of them attached to the structure directly behind it.

Have you checked the batt.-chassis and the chassis-engine ground? The chassis-engine ground, located near the starter, is what caused my jumping guage problem.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Did it cause just a couple of guages to jump, or all of them? I'll check it out anyway, just curious though.

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B
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1983 300SD

Your oil pressure gauge is not electrical so it cannot be affected by electrical problems I believe. The speedometer is the same and operates by mechanical function. Do not forget it is a very common problem to have a bouncy gas gauge in this model. But certainly not usual to have a jittery heat gauge. For the short time it really requires doing the grounds is sound information.