Incendiary

I have a '91 190E. I noticed today that the speedometer, while previously steady, was really wobbly. The needle would fluctuate by about +/- 2.5 mph whether I was maintaining a constant speed or not. Anyone have any idea what the problem could be?

Also, while I'm asking a question, does anyone know when the proper time to check the engine oil level is? When cold? After the car's been driven and properly warmed? 5-10 minutes after shutting off the engine? (BTW, I thought the little oil lamp gauge in the instrument cluster, the one with levels from 0-3, was supposed to give the oil level. Just now it read 3, or full, but when I checked the dip stick, it was actually only a little above the low mark...)

TIA.

mleskovar

My guess is the speedometer cable needs lubrication. Oil level is best checked after sitting for at least 5 minutes to give the oil time to drain to the pan (not that much actually drains down though). Hot or cold makes no difference. Don't know about the gauge....is it for volume and not pressure?

MTI

The speedometer is the only "mechanical" guage in the cluster, so the bounce is likely the cable, either stretched or in need of lube. Considering what you have to do to lube the cable (disconnect from trans under the car) you might want to consider replacement instead.

Oil. Check hot and check often. Warm engine, turn off, wait 5 minutes for gravity to do it's magic, then read dipstick. When the engine is cold, you should check for oil where it shouldn't be, in the coolant overflow tank. Milky looking coolant is a sign of a headgasket leak.

The gauge on the left hand side of the cluster, with the fuel, temp and economy gauge is the oil pressure gauge. The markings are in "BAR" not psi.

1 bar equals 14.504 psi
2 bar equals 29.008 psi
3 bar equals 43.512 psi

The low oil level warning is an "idiot" light below the cluster.

Jer

The speedo wobble is very common for VDO mechanical speedometers. Not much you can do about it.

Incendiary

Thanks for the replies, all. Jer, what's VDO? And why do you say nothing can be done? The cable can't be changed like MTI suggests?

Jer

VDO is the company that makes the instruments for MB, VW, BMW, and other European auto makers.

You can replace the cable and see what happens, but the problem is just annoying at the most.

Incendiary

True. It does still function, and at least I can tell what the speed is by the number at the center of the wobble...

Thanks again.