Two problems with my E300D
 

On a trip right now and a couple of problems have arisen that maybe someone here has info about.

1. Blower motor is making a continuous whistling sound almost like air infiltration at speed, but it happens all the time when the motor is on, even at idle. It stops when the motor is turned off. The climate control seems to be working okay. It's just the annoying whistling sound that it makes. When the radio is on, the sound is not noticeable, but when all is quiet in the cabin, it is definitely making noise.

2. Two or three times when I last drove the car, when going up a hill under load, the engine/transmission seemed like it was reving excessively. There did not seem to be a big power loss and the car kept up its speed, but the reving sound was quite evident. I'm driving home tomorrow, so I'll see if this was an anomaly or if occurs again. I'm guessing there is a problem and I'll see it again. My guess is that it is transmission related - hope not serious?

Hope someone hs some input.

Thanks.

In regards to the first item make sure all of you dash vents are in the full open position. I would suggest at least checking the transmission fluid level. Check it with the vehicle running, in part after it has run at least 20 minutes.

I had a similar experience regarding issue #1. When I first got the car from the prior owner, it made a whistling sound as you describe. I decided to pull the cabin filters out to take a look, and they were in terrible shape, covered with debris and a fine black dust. Changed both of them out, and have not had the sound since then. There is also a carbon cabin filter, but that one is not engaged unless you have its button engaged. Hope this helps.

Thanks for the replies. I am due for service in about 4000 miles. I change my cabin filters every 10,000 miles, so I'll take a look at them when I get home. That and making sure all the vents are open are good places to start.

Also have a dipstick tool at home. so I'll give the transmission a check. It's also due for a 50,000 mile service in 5000 miles. No apparent leaks though, but it sure would be nice if the problem is only being a little low on fluid. Have to check the electrical connector and see if it is leaking again. I've changed it twice, but not in a long time.

Made the 300 mile drive home with no repeats of either issue. Before I left I checked and exercised all of the air vents and there was no reoccurance of the whistling sound. Didn't check the filters, but they ought to still be okay after 7,000 miles based on my previous experiences with them. On the transmission, I checked the fluid hot as soon as I got home and the level is midway between the high and low 80° marks. So assuming nothing else happens, I'll be changing the dust filters and doing a transmission service in 3000 miles. Will certainly look a little closer at the transmission fluid, pan and electrical connector when I do the ATF service.

You report that driving up a hill, under load, you heard a "revving" sound but with no real change in speed or apparent power... That does not sound like a transmission problem, since you don't mention any real change in engine speed to suggest the transmission was 'slipping.'

My guess is that the radiator fan 'engaged' when the temperature rose from the additional uphill load. When higher temperature air reaches the viscous fan coupling drive, it will 'lock' the fan to the shaft and begin spinning at full speed to increase airflow, which can make a lot more noise. My Suburban has an aggressive fan clutch, and the fan makes a lot of noise right after a re-start on a hot day until it pulls enough air through to cool the fan drive and let it spin slower.

You can also hear this effect on semi-tractors - when that fan pulls in you'd swear there was a airplane taking off somewhere... :D

Make a mental note of your temperature gauge reading if you hear this noise again. If it occurs with rising temperature, relax it's normal and your fan is doing its job.

Thanks Jim - I REALLY like your possibility. Makes sense - never thought of that. I'm going with that. :)

Len - Next time you hear the "trans roar", check your engine temp using the CCU display. The idiot dash gauge has a designed dead spot in it somewhere between 90 and 100C where it stops reporting until coolant temps exceed the 100C mark. The digital readout on the CCU always reports correctly. At low speeds the Aux fan will come on around 95C and once moving agian the fan clutch will begin to lock up. The fan clutch does sound kind of like a 747 taking off; hopefully that is what you werre hearing.

Thanks for the reply Terry. You bring up some interesting points. I don't ever remember hearing that sound before and I've owned the car for nine years. Just six months ago I replaced the original thermostat. I thought it was running too cool at 160°F (71°C). The new thermostat takes it up to 170°F (77°C). There are times now when under load or idling in traffic it gets up to what I would estimate to be 187°F (86°C). I have never seen it get beyond 194°F (90°C). But even though I check my gauges often, I may have missed the temperature rise this time and hopefully all I did hear was the auxiliary fan coming on.

My '95 would whistle when the far right vent was closed. Simple, but took me a little while to find it....... :o:o