Until about 2 weeks ago, my 300E was blowing very hot, ice melting air out of the vents. Now it's just blowing warm-ish air, only after the car has been running 5 or so minutes. The enigine temp seems to be holding normal even after 15 minute highway trips, so I'm assuming the coolent is doing it's job.

To correct the problem, I replaced the thermostat. I thought it may be stuck in an open possition. After a couple days of driving, this doesn't seem to have fixed anything. I've kept an eye on the cooloent levels, and that is still holding normal.

The next thing I would think about is the controller for the air conditioning. It's an arrow shaped part that electrically cuts off or releases coolant into the radiator. Since my AC doesn't work anyways, and this control has already failed on me, I took it out months ago. So now the coolent travels straight to the radiator regardless of the control panel settings.

Any advise of what I should look for next? Can the radiator be clogged or a fan not working? Winter in Michigan is not very comfortable in winter.

Thanks -Joe

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'86 300E (241K)

So you have removed the mono valve and you always have coolant flowing to the Heater core, and you still dont have heat? What does the temp gauge show? If the coolant is getting up to temp, and the valve that stops the flow of coolant to the heater core is not there... the aux water pump could be clogged.. follow the heater lines around under the hood until you find it. I forget where its located at the moment.. Its a pump with heater hoses coming out both sides.. Maybe the pump is what you have already removed... There is a valve over near the batter that would have been my first guess.. Its just an electric solenoid that opens and closes to regulate the flow of coolant to the heater core... Sorry for the ramble I was just typing as I thought out loud.. Hope this helps.. Let us know.

Bill

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Bill

Backyard Shadetree Mechanic, 30 years running.

1987 300TD
1988 300E (sold, sniff)
1999 S320
1981 Volkswagen Rabbit Truck (Diesel)
2001 Ford Expedition
1988 Suzuki Samurai
On my list to buy: R129, for me, and a R107 for my wife.

To clarify my last post, it was the electric solenoid by the battery that I remove each fall as it gets cold. I know it's only a $100 part to replace, but it's worth changing twice a year. Everything else is in place the way it should.

It's hard to say if I'm getting optimal coolant flow because it has been so cold around here. The weather alone could be cooling the engine, which would worry me that it could overheat on longer trips or in the spring, if not resolved.

Temp levels are reading normal, forget what the acutally number is in Celcius. I am getting warm air though, so something seems to be working. It's just not hot enough to really melt ice like it used to do very well. If there is a clog somewhere, maybe a just a small amount of water is moving through the piping. That would in theory keep the car at a relative normal temp on short drives, and also prohibit coolent from filling up the heater core.

If this is the case, is there a good way to flush out the system? Or any probable places where a clog might be and how to deal with it. You mentioned a 'aux water pump'. This is something different from the water pump near the thermostat.

Thanks for your ideas. I've felt it might be a clog the whole time, I've just never come accross the problem before. Didn't think it was a common problem.

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'86 300E (241K)

Yes there is a small electric water pump that is designed to do nothing but pump water through the heater core at low speeds. It could be clogged and/or not working.

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Bill

Backyard Shadetree Mechanic, 30 years running.

1987 300TD
1988 300E (sold, sniff)
1999 S320
1981 Volkswagen Rabbit Truck (Diesel)
2001 Ford Expedition
1988 Suzuki Samurai
On my list to buy: R129, for me, and a R107 for my wife.

That's a start at least. I'll do some investigating. Thanks -Joe

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'86 300E (241K)