Heater (late square type) Overhaul

[svenedin]

Another heater thread I know. I did search the forum first and there are useful old threads to read but they have lost all of their pictures like so many older threads that would be really useful otherwise.

I took my heater out today. At one stage I wished I hadn't started......Anyway, it is out and rusty and nasty. I am going to strip back to bare metal, de-rust, prime and re-paint. I have a new matrix from ESM and new 1 1/4" air tube from Holden.

The motor did work after a fashion but it is now with an electric motor specialist (Robson and Francis) for a complete overhaul. Given the effort of removing the heater and de-rusting and repainting there is no way I am going to put it all back together with a motor on its last legs. Off topic: the motor specialist showed me round the workshop. Absolutely fascinating. They had the starter motor and dynamo from a 1925 Rolls Royce Phantom on the bench. Beautiful. Apparently the owner drove from Glasgow to South London to deliver these parts!!

I have self-adhesive foam, medium density, for car heaters from an eBay seller to replace the foam around the matrix and on the baffle plate that controls where the air is directed. Many screws were missing entirely and the knob on the baffle was snapped in two and held together with wire. I will replace with stainless steel screws and a new knob.

What I don't have are the larger blocks of foam in my picture. These are now rock solid and useless. Shall I just build up the foam I already have in layers to match the thickness or do I need a different type of foam? It looks like it was a high density foam.


Stephen


One rusty matrix. Not the original but a very old replacement.

IMG_8510.jpeg (3.13 MiB) Viewed 1853 times

Heater box showing foam inserts now totally hardened

IMG_8508.jpeg (2.53 MiB) Viewed 1853 times

[svenedin]

I found an eBay supplier who will sell a 4"x8" piece of high density foam cut to 1" thick for 99 pence with free postage. I think I can afford to experiment!

Looking at my photo I am already a little concerned about the large plastic air intake pipe. It is riveted on. Drilling out the rivets is not difficult but I hope it does not crack when riveted back.....

[svenedin]

Charles Ware Parts used to sell stickers for the lettering on the front panel: Car, Screen, Off but that business is now in liquidation. I have read on this forum that people used white transfer letters successfully. I am not sure I can get the right font or font size as transfer letters are not as commonly used as they once were. I measured the letters at 3.5mm high with my caliper. 4mm letters are available but not 3.5mm. The alternative is a vinyl decal that covers the whole front panel and is pre-printed with the letters from "Sticky Fingers". I am not sure that would look right. I would prefer the proper wrinkle paint finish.

[ManyMinors]

Try some Mini parts suppliers? The Mk1 Mini used the same heater and Mini owners/restorers are generally much more particular about such details

[svenedin]

Try some Mini parts suppliers? The Mk1 Mini used the same heater and Mini owners/restorers are generally much more particular about such details

I have found somebody who can print the letters on to my pre-painted fascia panel for £5.

[svenedin]

Well this overhaul has turned into quite a job. The heater box was so shabby and rusty that I decided it really needed stripping back to bare metal. I used paint stripper and then a bath of Evaporust. I am gradually painting the various panels but it takes time for everything to dry and I don't have much space for painting (I have a small painting booth tent thing which I use in the junk room in the house; it is too cold to paint outside).

Ready for zinc primer

IMG_8531.jpeg (3.03 MiB) Viewed 1763 times

The fan is a devil to get off. The fan is made of nylon I think and the prongs holding the fan onto the spindle are part of the fan. There is a metal circlip as well (in this case a very rusty circlip).

IMG_8535.jpeg (1.5 MiB) Viewed 1763 times

I decided these demister vents should be refurbished (and replacement hoses too)

IMG_8527.jpeg (2.47 MiB) Viewed 1763 times

Cleaned fan with arrow showing direction of rotation

IMG_8540.jpeg (1.99 MiB) Viewed 1763 times

De-rusted demister vent

IMG_8541.jpeg (869.97 KiB) Viewed 1763 times

[NETTIE]

Nice work Stephen this is going to look good when finished.

[svenedin]

Freshly roasted from the oven. The refinished front fascia panel. This will go off to be printed with the letters.

IMG_8544.jpeg (2.73 MiB) Viewed 1725 times

[svenedin]

Just a picture of the heater fascia showing a strip that has the original finish preserved, largely unworn, where it has been protected.

IMG_8551.jpeg (1.24 MiB) Viewed 1708 times

[svenedin]

Parts painted and reassembly started. The plastic air inlet pipe was originally riveted in. My rivet tool cannot get so close to the tube without riveting at an angle (which makes for a loose rivet) so I used nuts, bolts and washers instead (M3 x8mm). As there is vibration I used a good dose of thread locker.

IMG_8560.jpeg (1.45 MiB) Viewed 1693 times

IMG_8559.jpeg (1.15 MiB) Viewed 1693 times

IMG_8561.jpeg (2.49 MiB) Viewed 1693 times

[svenedin]

Testing the Smiths motor this evening. It will run on a 9 volt PP9 battery which is handy for testing on the bench.

This particular motor is a permanent magnet motor. It will run in either clockwise or counterclockwise direction depending on the polarity. By fitting the fan a strong draft is felt when it rotates in the clockwise direction (as marked by an arrow on the fan). However, if rotating in the wrong direction the "blow" is very poor.

I also have another motor from another late type rectangular heater. This motor is also Smiths and looks almost identical but it is not a permanent magnet motor, it has field coils as well as armature coils. This motor always runs clockwise regardless of the polarity (series connected motor).

I mention this because I found a lot of old threads with arguments about this. Nobody seemed to realise that some of the Smiths motors are permanent magnet and some are not so some motors will reverse direction with polarity. Also many people argued that it does not matter if the fan rotates in the wrong direction. It really does matter! Anybody who has changed from positive earth to negative earth (which will change the polarity to their blower motor) might do well to check whether their fan connections have been swapped round. It easy to swap them round and it just might make the blower work much better......

Another bit of info for anybody doing an overhaul. The screws for the case are No 4 x 1/4". I am going to replace all of mine with stainless steel as the old ones are very rusty and beyond saving.

Lastly for this evening, the motor mount grommets will almost certainly have hardened and perished. They are available from sellers on eBay. 3 are required and they also need a metal bush that goes through the centre of the grommet. The rivets are 3/16" but bolts could be used instead.

Stephen

[svenedin]

The new rubber motor grommets, bushes, washers and rivets. These rivets are quite hard work to install with a standard pop riveter. Need to be quite strong.

IMG_8571.jpeg (1.3 MiB) Viewed 1630 times

The motor needs a foam seal underneath it or otherwise there is a gap that will leak air. This seal is no longer available but you can cut one yourself from medium density foam sheet.

IMG_8572.jpeg (1.82 MiB) Viewed 1630 times

IMG_8573.jpeg (1.47 MiB) Viewed 1630 times

IMG_8576.jpeg (1.15 MiB) Viewed 1630 times

[svenedin]

Ready to go back in the car.

I had the stickers made to show the exact correct details. Off the shelf ones were not correct. I refurbished the fascia plate myself and then had it printed with the lettering. The motor is new from Clayton.

IMG_8586.jpeg (1.8 MiB) Viewed 1602 times

IMG_8586.jpeg (1.8 MiB) Viewed 1602 times

[NETTIE]

Thats a very nice job well done.

[svenedin]

Thats a very nice job well done.

Thank you. The improvement in function is dramatic. It blows warm air within 5 minutes of a cold start into the car. Demist function is not marvellous but much better than it was. Another bonus is the car is now remarkably rattle free.

[svenedin]

Finished. Heater reinstalled. Not a job I would repeat in a hurry.......

IMG_8589.jpeg (3.04 MiB) Viewed 1563 times

[svenedin]

Somebody said to me that I had incorrectly finished the heater front plate and that it would not have had a crackle finish originally. I was rather convinced that it did have a crackle finish because it could be seen on the parts of the plate that had been protected whereas the exposed parts had worn smooth. Anyway, I chanced upon this photograph in Paul Skilleter's book "The World's Supreme Small Car Morris Minor". Even though this is a photograph of a photograph in a book, I think the textured finish is clearly seen.

Stephen

IMG_8973.jpeg (1.82 MiB) Viewed 1358 times

IMG_8974.jpeg (2.23 MiB) Viewed 1354 times

[ManyMinors]

Those heaters did indeed always have a black crackle paint finish. The plastic ends are moulded to give a similar finish.
The Mini of similar age uses basically the same heater, which were made by Smiths of course, and Mini specialists are a good source of parts for them as well as providing completely reconditioned heaters. At a price!

[svenedin]

Those heaters did indeed always have a black crackle paint finish. The plastic ends are moulded to give a similar finish.
The Mini of similar age uses basically the same heater, which were made by Smiths of course, and Mini specialists are a good source of parts for them as well as providing completely reconditioned heaters. At a price!

I am not surprised that fully refurbished heaters are expensive. If done properly (including the motor) it is quite a lot of work.