Lotus Elan

Is your Elan heater motor noisy or screeching? An easy fix.

PostPost by: Graham B » Wed Mar 10, 2021 9:25 am

I have owned my 1968 Elan S4 DHC for 40 years now and for a good part of that time I have put up with screeching and coaxing the heater motor to run silently, by pulsing it on and off. I have recently finished getting the car back on the road after 4 years “rest” following a water pump failure. It had to happen eventually and no amount of coaxing would stop the noise. After studying LotusElan.net (a wonderful resource) and contemplating the prospect of removing the dashboard, it started me mulling the problem over for several weeks before I might succumb to one of the worst jobs hiding away in our Elans.
It’s funny how the brain works but, for no particular reason, the image of doctors doing keyhole surgery transitioned into depositing oil onto the shaft between fan and bearing. I investigated the heater box with a light shining into one footwell vent and observing through the other. No light and a growing concern I could damage the heater matrix by probing further kicked the idea into touch.
I have found over the years that mulling things over is an underestimated tool in all of our toolboxes. “Eureka”, as somebody exclaimed many centuries ago. “Have a look behind the ashtray!” Sure enough the heater box was there and holding the support bracket to the heater box was a single pozidrive screw. Photo 1.

1 Where to drill the Heater case.JPG and
1. Where to drill the heater case.

Removing the screw leaves a 3mm hole on the centre line of the heater. With a carefully straightened piece of stiff steel wire, I started investigating. I could certainly feel the top half of the motor and could touch the fan blades but not the shaft. With a dog leg added to the wire, I could move up the side of the motor, in over the end face, make out the spherical shape housing the bearing, the shaft and the fan on top. The shaft was about 120mm in from the face of the box. Proof that this could work.
A search on eBay found 320mm long, 2.5mm od. 1.6mm id. straight brass tube used by model makers. Rather than try to bend the tube in the shape of the steel probe, I decided to drill a hole 16mm vertically above the screw hole and blank it off later with a self taper, mine was 2.9mm dia. for a 4mm self tapper. See photo 1. Warning, the drill chuck is close to the edge of the ash tray cut-out. Before you gasp and cry “What about the heater matrix!”. The matrix is in two sections, one each side by the footwell vents with a joining pipe across the front of the box, well away from the drill.
To apply a controlled quantity of oil, I found a syringe and refilling needle from a printer cartridge refill kit. The needle was a tight fit in the 1.6mm id. of the brass and the 5ml syringe was ideal for dosing a small quantity of engine oil. The brass tube was cut to 160mm long with one end filed like an oilcan nozzle, the other deburred and the needle pushed in. Photo 2.

2 Heater motor oiler.jpg and
2. Heater motor oiler.

Mark the tube 120mm from the end, this is approximately the distance from shaft to the heater casing.
I recommend that you practice finding the shaft before dosing the oil. Probe for the motor body, move up to find the shaft and probe both sides to reassure yourself it really is the shaft, it’s about 6mm dia. The mark should be close to the heater case. See photo 3.

3 Heater Motor.jpg and
3. Heater motor.

When confident, fill the syringe with 2ml of oil and prime the brass tube. You only need to dose 0.2ml max. of oil on the shaft facing you where it enters the spherical bearing housing, so it runs down the shaft into the bearing. The shaft end face of the motor has a ring of large holes around the bearing to allow the fan breeze to cool the motor. If you inject too much oil it will run into the motor, not good for the brushes. See photos 3 & 4.

4 Oiler touching the shaft.JPG and
4. Oiler touching the shaft.

I found it took ten minutes, after pulsing the motor on and off a few times, before oil soaks into the bearing and the motor stops screeching and quietens down, so be patient.
Fit the blanking screw, refit the housing screw and ash tray. Now enjoy the peace and quiet, the thought that you won't have to remove the dashboard and thank the pioneers of keyhole surgery.
I was fortunate that it was the shaft end bearing making the noise. I expect the better protected, lightly loaded bearing at the other end will usually be ok but I believe a similar method could be used by drilling a small hole (2mm) in the spherical bearing housing part of the motor case and using the syringe & needle only. Access would be below passenger side footwell vent.
Although this was on a 1968 Elan S4 DHC, looking at dashboard layouts, the S3 ashtray looks in the same position. Unfortunately, the S1 and S2 were non-smoking.
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PostPost by: rgh0 » Thu Mar 11, 2021 11:10 am

Hi Graham
Thanks for the post
Great analysis of the problem and write up of the solution. This sort of ingenuity is what this site is all about.

cheers
Rohan
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PostPost by: Graham B » Thu Mar 11, 2021 11:43 am

Hi Rohan,
Thanks for your comment. I thought Elan owners would like the solution.
Its my first post, I thought I would contribute having used the forum quite a lot recently to solve some other problems.
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PostPost by: baileyman » Thu Mar 11, 2021 12:36 pm

Well now there's a new tool for the road kit.

John
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PostPost by: ericbushby » Thu Mar 11, 2021 12:52 pm

Hi Graham and welcome to the Forum.
It looks like you have worked out a solution to a long standing problem which I have not yet worked up the courage to tackle. Excellent. I will now check it out and start gathering the stuff together.
Eric in Burnley
1967 S3SE DHC
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PostPost by: nmauduit » Thu Mar 11, 2021 1:17 pm

Graham B wrote:I have owned my 1968 Elan S4 DHC for 40 years now and for a good part of that time I have put up with screeching and coaxing the heater motor to run silently, by pulsing it on and off.


Thank you for your tip - I must admit "easy fix" caught my attention...

I will certainly give it a try : if only I can take that excuse to postpone a bit more the removal of my dashboard, I will count that as a success.
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PostPost by: ericbushby » Sat Oct 23, 2021 2:43 pm

Hi Graham.
Your idea worked for me, although it and I took a long time.
On my S3 the fan motor seems to be tilted with the top of the motor more towards the front of the car than yours.
I don`t know why because I have not been there.
This made it difficult to identify the shaft by feel.
I could not use a tube as you did and tried a drop of oil on a thin wire and wiped it off on what I hoped was the shaft several times. It needed a larger hole in the casing.
I used a silver solder stick just because I had some.
At first I did not think it had worked and then after some time the noise reduced. Now it is quiet and I can use the fan properly when I wish.
An absolutely brilliant idea which has solved a problem easily.
Thanks
Eric in Burnley
1967 S3SE DHC
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PostPost by: Graham B » Sun Oct 24, 2021 9:22 pm

Hi Eric,
Good to hear it has worked for your S3. I had assumed the heater boxes were the same as an S4.
But it is so much easier than taking the dash out!!
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