The original round Smiths heater keeps the inside of the Land Rover cosy on cold days… surprisingly so give its small size. The motor in mine has always been noisy. This is less surprising, given its age. One option would be to strip it down and replace the bearings and bushes but I’d end up with the heater on the bench waiting for parts for ages. Not ideal in the current weather. I found an new OEM Smiths motor on eBay for a reasonable price in the UK so I ordered and fitted one of those. I’ll keep the original motor for a rainy day project.

Exchanging the heater motor is pretty straightforward… disconnect the positive and negative cables, remove the face plate, remove the fan and the three mounting bolts and withdraw the motor. Install new motor. Simple… you’d have thought so anyway.

On on…

The new motor
The first thing to do is remove the 4 spring clips from the cardinal points of the face plate and pull the windscreen de-mister pipes free.
With the face plate removed, the fan is exposed.
This is removed by unscrewing the small grub screw on the brass boss and sliding the fan off.
Once the fan is removed the 3 mounting posts can be seen. These unscrew and the motor and wires can be pulled free.
The heater matrix can be left in place, so there’s no worry about loosing engine coolant
It’s very important to ensure the rubber grommets and bushings are swapped over to the new motor.
(Seen here fitted to the new motor)

Up until this point, I was a bit concerned that something wasn’t right. As soon as I unpacked the motor, I knew I was in for more work than planned but not sure what…

Ah ha…. that’ll be it!

It’s not uncommon the motors to have a myriad of uses. I suspect the new motor on the left is for a Clayton heater. Very similar to a Smiths but slightly deeper. Some research proved me right. Clayton actually sell the same motor with the advise the shaft needs to be cut down.

Fortunately, the three mounting posts that hold the motor can be adjusted to move the whole heater matrix fore and aft, thus allowing the longer motor to fit without touching the bulkhead behind.

I didn’t take any photos of adjusting the posts so we’ll move to the next problem.

With the matrix in the right position, I was still unable to push the motor fully home on the posts. Something was getting in the way.

Same picture as above but this time we’re interested in the gland around the 2 wires where they exit the body of the motor.
This was of such a size, if was fouling the back of the matrix.
This plastic gland was removed and replaced with a rubber grommet.
New wiring grommet. Far more discrete.

Next I needed to establish how much to cut down the shaft. Using the mounting flange as a reference point, I measured the distance from the flange to the end of the shaft on the old and now motors.

The difference between the two figures would be the amount to be cut off. It was really hard to hold the motor vertically, user the callipers and take a photo of the whole thing so the following will have to do.

Using the depth gauge on the callipers, the distance from the flange to the end of the shaft on the old motor was (roughly) 77mm
This was repeated on the new motor with a distance of (roughly) 90mm.
(In general my thumb nails are not this grubby)

Therefore, the shaft on the new motor needed to be trimmed down by 13mm…

The shaft was marked with some tape where to cut (left hand side of the tape) and mounted in a small machinists vice

With the motor now able to fit into the matrix without fouling anything and the shaft the correct length, the wiring needed to be extended.

I reused some of the wiring I used when I fitted the old motor 3 years ago.
The round eye fixing is the earth post and the push fit connector fits on the rheostat.
All connectors were crimped, soldered and shrunk wrapped. Same as everything else on the vehicle
Ready for business.

Now everything can be put back together again.

New motor is installed.
Fan is fixed and checked to ensure it’s not rubbing on anything… which is was but they’re easy adjusted.
Note of caution; be very gentle with the grub screw. It’s made of steel and the boss is made of brass. It doesn’t require a lot of force to strip the thread.
Then the wiring is connected. Female spade connector to the rheostat (the blue thing top left) and the eye to earth (brake pipe clip)
I used a short length of cable wrap to tidy things up.
The 4 spring clips were given a brisk rub down with some a Scotchbrite pad…
… and the faceplate refitted. The rather obvious wires in this shot have since been tidied out of site.

All in all, it was perhaps a bit more work than expected but the motor is a lot quieter. Unfortunately the rheostat (the rotating switch used to regulate the speed of the motor) refuses to work as intended so that needs to be replaced, but this is a very quick and inexpensive swap.