Heater and Roof Lining

Just thought i'd share with you a couple of helpful points I found when rebuilding the heater box.

1: The adjusters on the side for the flap mechanism are slacked via undoing the tiny allen headed grub screw and not the nut. Discovered this after breaking one! Doesn't mention this in the haynes manual.

2: Obvious but you'll regret if you don't. The position of each of the levers in relation to the flaps and operating arms are vital so mark them before removal. I didn't and even though I had another heater for reference I got the main control out by a couple of splines. I think a saw cut in the end of the shaft and dot punch on the ally/mazac arms would be the best way.


I actually think you can change the matrix without removing the control levers but it's a bit of a struggle however you do it.
 
A trick which a lot of you probably already know for a mediocre heater is backflushing which I normally do by disconnecting the heater & pushing a hosepipe connected to the mains to the outlet pipe of the heater & then run the tap until the water runs clear. A mechanic of many years recently suggested that I reverse the heater inlet & outlet pipes on our rather chilly V8 (at the heater end of the hoses as the engine ends are different sizes) & use the car as normal. This gives a more prolonged treatment than 10 minutes with the hosepipe. After approx a month empty the radiator of any debris that the water-pump has deposited there (The radiator is a lot easier to remove than the heater Matrix). As long as the hoses are in good condition they will cross quite easily. As soon as I did this & warmed the engine the difference in heat output from the vents was marked which must mean our heater was not too badly blocked. Obviously if the heater matrix is blocked solid then there will be no improvement but it is well worth trying first as a few trips with the reversal in place should dislodge any crud that CAN be moved. Whether you change the pipes back is up to you as it should have no adverse effect on the running of the car, but periodically swapping them would seem sensible. I'm going to try this on my 2000TC too but don't know if the hoses are as amenable as the V8's yet.
Airlocks are another point to consider If you have poor heater performance & another trick is to warm the car with the heater set to HOT & the radiator cap off, until the thermostat opens & the coolant starts circulating/overflowing. Then get your assistant/Wife to rev the engine to around 1500/2000 rpm & hold it there & you'll be able to get a fair bit more water into the rad' which should help push any air out of the system. Put the cap back on while the revs are STILL UP & then NEVER, repeat, NEVER take the cap off unless the engine is completely COLD & switched OFF or you'll have a fountain of boiling coolant to contend with. Obviously you shouldn't ever do this anyway, but with the extra coolant pressurising the system you're asking for trouble if you attempt it. I think this is mainly a V8 trick but it may work on the 4-pots too. The same warnings apply of course.
If none of this works then a matrix re-core must be on the cards. :)
 
Had to take my rebuilt heater box out again yesterday as the matrix started leaking the second time I ran the engine. Bit irritating but when I took the matrix out I discovered that the leak was along the seam on one of the end tanks. I tested the other three matixes I've got and they were all the same: perfect apart from the seam had broken open.

(I tested them by blanking off one of the pipes and using a domestic plumbing pressure tester on the other, you pump this up with a bicycle pump and they only cost about £20)

I repaired one tank by resoldering the seam. This was a complete pain in the backside as it was very difficult to get the seam clean and the solder to take. Also to get enough heat to solder I had to put it end up on a gas stove to pre-heat it and then use a blow torch to solder. Anyway it took about 5 goes to get it to seal completely.

I then tested the matrix by connecting the hot tap to it with a bit of hose. Problem: it doesn't really seem to get hot suggesting it's still a little blocked inside even after cleaning.
Out of interest I tried one of the other matrix and this time it gets hot instantly indicating that I have repaired the wrong matrix.

Having had enough of soldering I decided to try trusty araldite on this one. I cleaned out the seam and then filled it to the brim with araldite. Pressure testing when the araldite was not quite set revealed a couple of air bubbles which I filled again and then put it on the radiator to set overnight. Tested it this morning to 20psi and it seems perfect. Only one more hurdle now and that is explaining to my wife why I have pulled a large patch of wall paper off where the tank had lent against the wall and araldited itself on.
 
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