Heater Motor Problems Solved

stormcrow · stormcrow's Garage

The heater motor on my 78 911 Sc went out last week and I was going to order a new one. However, I decided to take it apart to find out what was going on with it.

Well, the front bearing was washed out and the and the shaft was loose as a goose. It just so happened that I had another motor around that I salvaged parts from awhile back and low and behold the bearing from that motor, fit the shaft of my heater motor.

What I ended up doing was removing the worn bearing from the front housing. There is a ring over the bearing that has to be removed first - the collar around it is dimpled so I used a nail punch to flatten them out to remove the collar.

The inside diameter of the new bearing is tight, so I had to press it onto the shaft.

Once the old bearing was removed, I placed the housing on a flat area and set the new bearing in the collar where the old bearing was.

The new bearing was smaller in diameter, so after making sure it was centered, I mixed up some epoxie and epoxied it in place. Once the epoxie cured, I slid the shaft into the housing to mate to check rotation. worked great. Reassembled the unit, put it back in place and won't have to worry about that motor for awhile.

For those of you who want to do this you can get a bearing from McMaster Carr. The bearing # that I used was MNB 608D. This is for shaft dia 8mm rated for 38,800 rpm. It was pretty tight getting on the shaft so I would recommend measuring your shaft first. Other sizes are 627 for 7MM shaft, 629 for 9mm shaft.

Steve

Roy M · 12-21-2001, 01:46 AM

Related but not specifically.

My '88 motor started to squeal recently so stripped it out (is this the easiest job on a 911?) pulled it apart and checked lubricated the whole thing. Had been out before as a nut was missing - replaced this. Whilst I was on the heating theme stripped out the footwell motors (no this is the easiest job!!) and lubricated them as well.

Heating system is now almost silent - didn't realise previously that it was making a noise but I can tell the difference now!