Cooling system/Heater mystery

[kiwi]

BX19TZS (yes Petrol) fitted with Aircon

Bit of background first! Last few months have hardly been using this BX but now the wife is using it after losing the ability to reverse or overdrive in her Mitsi Auto. So now the TZS has become her drive!!!

Problem that I had was the overpressurising and usage of water through the cooling system, now I feared that as head gasket but not being in daily use after the arrival of diesel have lived with it. Few weeks ago I was fiddling with a colling hose for the carb trying to figure out why the auto choke seemed "stuck". Whatever I did seems to have removed an airlock I am figuring and now the cooling system is behaving ok! (No water added for a while)

Now the next problem is the heater dont work! Checked the heater tap and yes the tap mech seems stuck with little movement, trying to get into the linkages as you all know is a mission. Yet I found while running the car and attempting to free the linkage that warm flow was going passed the tap indicating that the tap must be open to some point? Am I correct to assume that?

Yet still got no significant warm air blowing into the vehicle This has got me a little bit confused given the only thig that is beyond that tap is the heater matrix.

Would you think that there is some connection here to the other cooling system woe?

[KevR]

Auto choke sticking was probably due to crud in the carb heating circuit - maybe you've dislodged that while fiddling (hence auto chole working) and the crud's worked its way down to the heater tap... if a little warm water's getting through, that would explain why the tap feels warm, but it may not be enough to actually warm up the heater matrix (or the matrix may be largely blocked, only allowing a small amount through).

[JayW]

As Kev says, this is the same issue i had with Mickeys meteor... it would only open a fraction which would make the matrix pipe hot but not provide anywhere near enough flow to heat the matrix itself. If your heater tap is stuck i suspect you've added radweld when you suspected the headgasket failure. Track down Vanny's "Heater tap dissection" thread if you haven't already seen it.

[kiwi]

i suspect you've added radweld when you suspected the headgasket failure.

Nope not me! I had the head off this car about 4 years ago now (a few threads in here about that), what stuck in my mind though was when the garage reassembled it there was a Radiator Leak and yes they chucked some evil in to seal it. Last antifreeze change was done with caution maybe a little to cautious allowing sediment to stay put.

I am looking forward to doing the heater tap....not. One those jobs I dont want to do.

[smiffy1071]

seriously dude, if you've not already seen the pictures, in vanny's thread, take a look and you will be amazed!

[kiwi]

seriously dude, if you've not already seen the pictures, in vanny's thread, take a look and you will be amazed!

Not exactly sure what your saying and getting at here.

Yes I have seen the thread, I actually posted in that thread and couple months later forgot about the problem being posted there.

Yes I have replaced a heater tap in the past (more than one). Whats enlightening to me is how this seems to be linked to other cooling system dramas I have had that nearly wrote the car off thinking another Head Gasket job. When someone says they have over pressurising in the cooling system the first though is head gasket!!! It seems that unknowingly I have found out its a blockage in the cooling system from the effects on the heater and Carb.

I think more of a precautionary tale of dont assume.

Like I said I still do nto relish the job of replacing/ reconditioning the heater tap.

[JayW]

It's possible that with the tap jammed (mostly) closed, the last time it was filled up there could have been air trapped in the matrix which has slowly escaped into the system over time causing your pressurising. Maybe, just maybe it's all cleared now...

I think Smiffy was referring to the crap we got out of vanny's tap (if you hadn't seen it - which you have). There is VERY little else that can foul the tap up and the radweld can sit dormant being slowly compressed into it for years.

[kiwi]

I have been thinking about that JayW. Its rare for me to actually use the heater for maybe a couple of months of the year even in winter the AC tends to get put to use. This has been going on for over a year now so possible I guess. Only reason I noticed this now is the wife is using the car and you know how women are about comfort. My reason to hardly use the heater is through fear of it being stuck open (thats happened) and the Aircon becomes in effective. Yes I have become a softy for being cold in summer

One the side effects of the carb blockage may also be the cause of a stutterring and loss of power when driving corners vigourously. Unfortuantely one the series of s bends I noticed this on has been signed as a slippery surface now (after two years of complaing) due to a truck finding its way into the paddock of the mates farm there. Last year I changed the antifreeze so if a blockage was present it stayed and actually got worse with the pressure problem.

[Vanny]

You'll likely find the heater matrix is blocked. It has i think 18 banks of 5 capilary tubes. You've likely got most of the capilary tubes blocked. The last few are enough to make the pipes warm, but not enough to make the matrix warm. What you really need to do is take the return pipe off under bonnet and see how much flow there is.

From what youve said, i bet there wont be much.

New heater matrix (it wont wash out fully so not worth trying), refurb your tap, and do a ruddy good power flush on the coolant system.

Oh, and when you've got the matrix out, cut through the inlet tank (should be the bottom, but it is french) and see how much crap is in there! It doesn't take much to block a matrix, grease will do a quick and thorough job.

[kiwi]

I have a spare matrix and I know the 19TRS has a leaking matrix so wont bother with than one. So does sound like it will be the mission of dash removal etc either way.

I am going to take a guess that a new matrix is no longer available and quite expensive as well?

[Vanny]

They've popped up on ebay from time to time, so might be worth asking a factor, also the end tank with the pipes in is removable, so you only need a core the right size (ish), you might get one from another model.

You only need to remove the steering column to swap the matrix i thought. Though if you want extra room i suspect either rotating the HVAC under the IP or slacking off the IP and lifting it would give sufficient room. (Oh, IP = Dash, sort of)