1. Home
  2. Mercedes Autos and SUVs
  3. 1987 300D Turbo Issues .. Please Help!

1987 300D Turbo Issues .. Please Help!

Hi Group. I have an '87 300D (W124 300DT) Turbo. It has a couple of issues I thought you might have some advice on.

1) It runs really hot, although the thermostat and coolant sensor have been replaced. The temp guage gets up to about 1/8" below the red line often but it will go down briefly when the car drives or the engine is revved, but it climbs right back up to "scary" zone soon. It's kind of unpredictable, except definitely it gets up to that hot zone while idling or going up a even a small hill. The radiator looks shiny/newish (looks like 1 year old or so) as do the hoses. I drove it about 120 miles and although it stayed up in that high neighborhood of the guage, it did not overheat. Should I ignore it? Should I flush the radiator, buy a new one, or replace the water pump or something else next?

2) Everything in the circuit (at least listed on the fuse box as "in the circuit") for the windshield wipers does not work. The windshield wipers, headlight wipers, windows, comfort, etc., all do not work. What is most likely to be causing that?

3) I am getting a buzz/hum from the right front wheel, that increases with speed..I can hear it from 5 mph and upward. It sounds more like a something rubbing than a wheel bearing rumble, although maybe that's how it sounds in these cars. What do you think it is?

Any help would be appreciated!

Thanks! Michelle

Reply to
Michelle
Loading thread data ...

I suggest you have someone measure the temperature of the cooling system with a laser/infrared themometer... unless you have some thermometer that can handle 200 degree. Measure it at the thermostat housing. It is possible you got a bad grounding for the gauge... making it read high even though the operating temperature is normal.

Other possibility is bad fan clutch but this only works for speeds under

25MPH... after 25MPH the wind force is more powerful than the fan... so if on the highway and your temperature gauge still reads the same... it is a good probability that it might have to do with temperature gauge's grounding or the temperature sensor.

Take the fuses out... and change it to new one. These are notorious for looking normal even though they are corroded out.

Could be some bushings on the control arm shot.

Reply to
Tiger

That was it for the wipers not working! The fuse looked normal, but was actually not conducting. Thanks!

Still working on the high-heat reading and also the buzz from the right front wheel.

Reply to
Michelle

Do you have any coolant loss. That engine is infamous for cracking cylinder heads. The later replacement heads are redesigned and less likely to crack.

I've helped replace the head on two 126 chassis 300SDL cars owned by friends. One of my co-workers had the head on his 124 chassis 300D repaired by a welder after it cracked. It's unusual to see high mileage 603 engine cars without a cracked head.

How many miles does your car have on it?

Reply to
VCopelan

There is absolutely ZERO coolant loss, and runs like a dream other than the high heat reading. The engine has about 180,000 miles.

Reply to
Michelle

Under high temp, do you notice if your auxilliary fan is running? It's got

2 speeds and should give a hi-pitched howl in hi-speed mode when the temp is as high as you described.

Do you live in a cold or warm area? There are different temp values for thermostats and if your car's cooling system is tuned for winter climates and you are driving in a warm climate, the thermostat will only open and allow coolant to circulate at higher temperatures causing you to have excessively high temps.

These Benzes have a wide range of operating temp so you need not worry about damaging your engine as long as you stay within that temp range. Lastly, diesel engines run better on the hot side.

Reply to
Rico Led

Never ignore a gauge. I did that once with an oil sensor light in '72 after a mechanic told me not to worry, it was probably a bad light. I took the advice, made it about another mile, and ended up having to have the motor rebuilt due to oil pressure loss. IF you suspect the gauge, and they sometimes go bad, see if you mechanic can swap one he knows is good temporarily for yours. That will let you know if it is the gauge. You might be able to take an independent temperature reading and compare it to your present gauge and see if the readings are at least close.

Should I

Sounds like you need your mech to go over your wiring. Shorts abound in older cars. Mine had a short that killed all four power windows as soon as you used the flash. It was finally traced to a short in the seat relay. Go figure.

Hmmmm....I'm no expert, to be sure. Could it possibly be your brake pads? That's easy to check--drive a mile or so, then get out and feel the rotor of the good side. Then feel (carefully!) the rotor of the side you suspect. You will be able to tell instantly if the rotor is hotter.

Reply to
L. Cook

are you getting heat out of the heater? if not ya got an air lock.

you may also have a bad impeller on your water pump

case

Reply to
pool man

Air lock--- how can I fix that? I have an 87 SDL that had a cracked radiator... which I replaced... but ever since have had the low radiator fluid light come on intermittedly. The car also runs hotter than normal. I do have the heat problems as well. Everything I have read has pointed me towards the water pump thus far. Is that right? Is it a matter of replacing- or repair. I like to know all I can before walking into a repair shop. Thanks

Reply to
marku

What you need to do is get a coolant pressure gauge... Autozone might lend them out... Put it in place of your cap... let the car run until hot... if pressure keeps going up and past 20 PSI then you got a head gasket problem.

If the pressure remain steady below 20 PSI then your system is okay...no head gasket problem.

MB coolant system is self bleeding so it shouldn't have air lock problem. Are you sure your coolant level is normal?

Reply to
Tiger

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.