Another Cooling System Question

[kiwi]

Long story short the BX19TZS has had for a while a problem with the cooling system. I am discounting Headgasket at this time due to it having been replaced and certain other issues.

It is losing coolant more prominant when the Aircon is in use although I can not be 100% let alone 50% sure on this possible coincidence.

Basically the car is experiancing a lot of back pressure evident by the spray onto the alternator.

Other associated problems that I think may be the cause! Auto Choke staying on longer than needed. This I have swaped the over a piece in the carb (not sure of its name or function but it has to small coolant pipes attached.

Second problem is the Heater Tap is stuck or the Heater Matrix is blocked! One thing I was annoyed about the HG replacement was the inclussion of radweld into the radiator that was leaking over time I have heard this grows, probably blocking radiator or like I think heater matrix? Stuffed rads are apparently quite common in NZ mainly due I think because the see anti freeze as being only needed in cold climates.

One idea I have thought to elimate the Matrix and heater tap is to bypass and join the two pipes into the bulkhead together. Will this cause any problems? (heater not used this time year anyways Aircon could be though.)

If I still have over pressure the radiator is next of which I am hoping the spare out of the TRS dont spring a leak which seems to happen when they are moved. My new mechanics managed to get the TZD rad fixed when it sprung a leak with any radshyte.

Failing this I can only conclude a Head Gasket but before I do any of this I would like some views and experiances of looping the system without the Heater Matrix.

[mat_fenwick]

It won't cause any issues (other than cold feet!) to bypass the heater matrix. When you say the matrix is blocked or the tap stuck, can you physically move the temperature control? Don't use undue force as you may break the ceramic slider where it attaches to the actuating rod.

The apparent link to AC use may just be the fact that you're more likely to use AC in hot weather when the cooling system is under more load anyway. Plus the temperature of the air hitting the radiator will be hotter after it's passed through the AC condenser.

I'm not suggesting HG as a possible cause at this stage but I wouldn't necessarily discount it just because it's been replaced, if the original cause of it failing wasn't addressed. It may just be a leak under normal cooling system pressure onto the alternator (can you see where?) unless it's also pressurising when cold?

[electrokid]

Other associated problems that I think may be the cause! Auto Choke staying on longer than needed.

IMHO the auto choke staying on is more likely to be a symptom rather than a cause. If the feed to the auto choke is in series with the feed to the heater matrix then that could point to blocked heater matrix.

Auto choke staying on is more likely to be caused by the water in that part of the system not getting hot enough quickly enough. If you bypass the heater matrix make sure that the pipework feeding the auto choke circuit is getting nice and hot.

[Way2go]

Stuffed rads are apparently quite common in NZ mainly due I think because the see anti freeze as being only needed in cold climates.

The corrosion inhibitor contained in the anti-freeze though is even more important for aluminium engines/heads. Without this inhibitor the waterways are possibly more prone to the depletion and deposition of metals around the system which can restrict certain parts caused by the action of electrolysis. This would be even more so if earthing connections have become resistive with age.

The head in a diesel is still aluminium isn't it even if the block isn't?

[rutter123]

the part of the carb with water pipes going to it is poss the waxstat this controls the "opening and closing" of the auto choke. these can seize with age and cause the auto choke to stick usually in the on position, may be worth checking.

[ghaddon1701]

Was the head skimmed when the head gasket was done?

Regards Graham

[kiwi]

Will give this a shot of answer to individul question as best I can

Was the head skimmed when the head gasket was done?

Yes

the part of the carb with water pipes going to it is poss the waxstat this controls the "opening and closing" of the auto choke. these can seize with age and cause the auto choke to stick usually in the on position, may be worth checking.

I swaped the waxstat if thats what it is called over from a spare carb taken of a car years ago, not done a road test yet so maybe the cure required

Another thought on that on the TRS is that probably the reason the damn car dont like starting when cold so not used that ones waxstat. Will fit the one from the TZS in its place!

The heater tap is well stuck and no I wont force the dial as I am experianced enough to know what happens, plus running out of spare ones I have wriggled it from the control points on the tap with no joy.

Pretty much got through the winter without the haeater working! When you have a couple other cars to use with heaters then it was not an issue. Just with Summer I dont want to cook the engine one day although way things are going probably be a while before this gets fixed anyways. Took me 6 months to get through tank of petrol

Thanks so far given me some ideas to work with.

[kiwi]

Dont you just love long hot summer days (sorry to rub it in).

I got so used to getting up at 5am before the sun rises that this morning a sleep in 6am started work on the cooling system

Flushed the system with the hose pipe after disconnecting the heater matrix. After months of topping upp the coolant was none to healthy looking and it took a while to flush out the rad etc. Not a perfect job I will say as I did not remove the thermostat housing (thermostat already removed) or the lower hose on the rad. On reflection maybe I should have Anyways he flow seemed to be uninterrupted through the heater matrix and ended up clear flowing yet. Thats got me confused if the tap was closed (eg no heat) then this should not have flown so well?

Next job at my leisure I can work on that tap as I bypassed the matrix (not that going to need it for a while), Quick run of the engine all seems well a test will be a road test preferably on a cool day after the holidays to reduce overheating risk.

Adjusted the idle on the carb and thats not easy with the adjusting of the Aircon idle to balance the two. Will get there slowly at the moment this car is in low use so no urgency.

[electrokid]

(thermostat already removed)

The part of the cooling system that heats the auto choke is connected to the circuit that heats up more quickly because the thermostat keeps it separate from the radiator. Leaving the thermostat out will force the whole system to heat up more slowly - that's the reason your auto choke stays on longer than needed - it's not a fault - stick the thermostat in and that problem should go away.

Anyways the flow seemed to be uninterrupted through the heater matrix and ended up clear flowing yet. Thats got me confused if the tap was closed (eg no heat) then this should not have flown so well?

So here's a question...

I'm fairly sure that we all, or at least most of us, are assuming that the heater tap operates by either allowing flow through the matrix or stopping flow in that circuit altogether.

What if that wasn't the case - maybe the tap operates by either allowing flow through the matrix or bypassing the matrix. That would explain the flow despite the tap being in the 'off' position.

If the circuit flowing through the heater also flows through the auto choke then the heater tap must contol by bypassing because this part of the coolant circuit must remain hot - it mustn't be 'switched off' by the heater tap - if that were the case then the auto choke would run rich when the heater tap was turned off.

[JayW]

Having stripped a few taps now the are definitely flow-through rather than bypass. However, the feed to the tap and matrix is a branch from the cooling hoses hence the tap can be closed without backing up pressure in the closed-loop.

But, i forsee an issue with bleeding air from the system with the tap already closed. It is seldolm 100% completely closed so could indeed be introducing the matrixes stored air AFTER the system's been bled. This is why the tap should always been open when refilling & bleeding.

However, having now looped the hoses this issue would be eliminated and if it is indeed the (only) issue it should be resolved.

And as mentioned above he waxstat issue is obvious & clear.

[kiwi]

Not sure if I was clear but I think I have knocked the waxstat situation on the head. The fast running seems to have gone. I say seems to because until the ambiant air temperature dips below 20c again I am not going to know if the autochoke is working. I took the thermostat out after the autochoke problem had already started it made no differance being in or out however once again warm ambiant air temps not going to know for sure.

My main concern is getting rid of that overpressure and establishing where the cause is. If indeed the matrix is blocked then with luck I have established a viable cause. Winter running will be off the menu without a heater.

[kiwi]

Fixing the Tap on indefinite hold!

During an adventure to rescue the diesel from a flat battery the good wife decided to bring the TZS to my rescue! Proved that there was still a pressure build up total distance 20 kilometres and coolant level light on again and clear evidence of water spray from overflow. That plus possible leak from unsecured hoselip on the heater bypass.

I am startng to think either there is a blockage! When filling it felt real slow flowing into the system or the HG is gone again. I dont have the tools of funds for another HG job of which the missus will not allow. So could be terminal this time

[JayW]

Water pump impeller failure?

[kiwi]

Water pump impeller failure?

Hope not! Although thats another job I dont think I have the tools for. Water pump was replaced with Cambelt which was replaced with Head gasket which was 40,000kms ago! 4 years and 40k kms? Does sound plausible given the quality of parts these days.

However if it was water pump failure would it not show external leakage in that area?

[citsncycles]

Not necessarily - it will only leak if there's damage to the shaft or seal. If the impeller has worked loose on the shaft (for example) it'll look fine from the outside without actually doing much