New Australian BX member with cooling fan problems

[michaelr]

Hi all

I have just joined as today I got a 1989 BX19TRI Auto hatch. It has a presumably honest 122,000 km but has suffered from lack of regular servicing recently.

I know that the cooling system has had some minor leaks and been topped up with plain water... hope no serious damage. I will remove and check the thermostat and flush the system asap.

My question today is probably about an electrical problem. When the ignition key is turned on the radiator fan starts up immediately at high speed. The fan continues running even after starting. Related to this is that on cold starting there appears to be no enrichment or raised idle speed. Once the engine is warmed up it idles well. Am I right to assume that a coolant sensor is faulty or possible a wiring fault ? Which sensor and where?

An additional symptom is that the temperature gauge slowly climbs to max, illumination the red warning light and "Stop" light. However, the engine is not overheating and can be driven without problem. The oil temperature gauge remains normal. Maybe this is a totally unconnected fault?

Any suggestions gratefully received.

[Way2go]

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My question today is probably about an electrical problem. When the ignition key is turned on the radiator fan starts up immediately at high speed. The fan continues running even after starting. Related to this is that on cold starting there appears to be no enrichment or raised idle speed. Once the engine is warmed up it idles well. Am I right to assume that a coolant sensor is faulty or possible a wiring fault ? Which sensor and where?

The cooling fan temp switch sounds permanently short circuit & needs replacing. It is located adjacent to the bottom of the radiator on the engine side.

An additional symptom is that the temperature gauge slowly climbs to max, illumination the red warning light and "Stop" light. However, the engine is not overheating and can be driven without problem. The oil temperature gauge remains normal. Maybe this is a totally unconnected fault?

This would be unconnected and sounds like your water thermostat has failed closed. Oil temperature normally takes a considerable time to rise compared to water temperature.
A good idea to use "Barrs Professional Flush" on the water system to clear out the crud in the waterways and radiator before refilling with new coolant. (Take the thermostat out first before flushing with this if its not opening & before replacing it)

[mat_fenwick]

/\ You may be right, but it's possible all the faults are electrical. I'm wondering if so, whether they are all somehow connected but I can't think how without studying a wiring diagram!

the temperature gauge slowly climbs to max, illumination the red warning light and "Stop" light.

How slowly? Does it correspond roughly with expected engine warm up time, or is a matter of a minute or so. The temperature warning light is operated by a different sender to that for the gauge, so the chances of both giving spurious readings are slim. BUT, the cold starting enrichment is operated by another sender, so with that seeming to be non opertaional I do wonder about a wiring fault. I think that for the gauge and lamp senders, a short to earth would cause them both to show a hot situation, and "slowly climbing" (depending on the speed of climb) may just reflect the speed the needle is able to move at?

[Defender110]

.

My question today is probably about an electrical problem. When the ignition key is turned on the radiator fan starts up immediately at high speed. The fan continues running even after starting. Related to this is that on cold starting there appears to be no enrichment or raised idle speed. Once the engine is warmed up it idles well. Am I right to assume that a coolant sensor is faulty or possible a wiring fault ? Which sensor and where?

The cooling fan temp switch sounds permanently short circuit & needs replacing. It is located adjacent to the bottom of the radiator on the engine side.

Or just the plug has been taken off the sensor on the radiator and the plug shorted across to keep the fan on all the time wich may have been done to counteract the suspected over heating ?

[mds141]

I understand the temperatures in Oz have been regularly topping 40 degrees.

[kiwi]

I understand the temperatures in Oz have been regularly topping 40 degrees.

I doubt the OP has been working on his car in those conditions anywas they are stealing the rain there nowdays or has that not hit the british media? Not exactly been cold here in NZ temps hitting the 30s so can understand OPs angle better.

This bit raises some concern to me.

It has a presumably honest 122,000 km but has suffered from lack of regular servicing recently.

I know that the cooling system has had some minor leaks and been topped up with plain water... hope no serious damage. I will remove and check the thermostat and flush the system asap.

Water Pump comes to mind after experiances with my TZS! For some reason the australian made replacement water pumps seem to fail more often than the European or original counterparts.

Personally I would look at a flush of the coolant system first. The overheating issue may be electrical but in saying that I have had a BX thats seems ok to drive even when its overheating such is the good design of the engine. Regards to the fan on permanatly that sounds like someone has shorted the fan to stay on permantly, possibly dare I say as a result of overheating?

[michaelr]

Ah Kiwi, that is a pessimistic but entirely possible explanation, but I think the previous owners have simply watched the decline of the car without any such actions.

Thanks to all the answers and suggestions so far from many generous people! I will work through them all and report back

[michaelr]

Hi. It certainly was not 40 degs here today, that is a rare occurrence here in Sydney though we did get to 46 last month... not too comfortable!

It was a sunny 28 degs and sunny today, perfect for pottering around the BX. Thanks Way2go for pointing me at that temp switch for the electric fans. Disconnecting it stopped the fan so I will track down a replacement.

The thermostat had indeed failed and hardly opened at all at 100 degs so that is now replaced and all runs normally so the symptoms were unrelated. System now flushed and filled with proper coolant. Even the heater works

A set of plugs and a general tidyup and clean has made a huge difference but I can find no evidence of the timing belt ever having been replaced. No stickers and nothing in the service book. 122 thousand km and 24 years?? Is it possible? Better be the next priority. Any opinions about changing the water pump too? I talked to a BX owner today who has run the same pump for 450,000 km. !

[citsncycles]

A timing belt that age is possible, but it'll be very fragile so change it ASAP! General max age for a timing belt seems to be about 6 years, although I've heard of ones twice that age being used!

[hilarystone]

A timing belt that age is possible, but it'll be very fragile so change it ASAP! General max age for a timing belt seems to be about 6 years, although I've heard of ones twice that age being used!

Yeh, the one on the Visa 17RD (26 years old) my son is now using was the original as was the one on my Xantia Activa (16 years old) ...
They can last but I would not take that chance on most engines.

[mat_fenwick]

Personally, unless you fit a good quality water pump, I'd leave the original on if it spins smoothly with no leaks. Reason being there are a lot of poor quality parts out there which may not last as well as even a part worn original! A lot of people seem to change it as a mater of course though.

However, if an aftermarket part has already been fitted, then I'd change it at each cambelt change. I appreciate that you probably won't know this.

[MULLEY]

My TXD is on it's 2nd cambelt in my ownership & the water pump has never been changed, i guess the above is probably the reason why.

[kiwi]

I think I already posted my opinion of changing the water pump! Unless you get a good quality replacement and I have my doubts of any Australian factor part being quality then leave it until it breaks.

Two experiances of water pumps being changed at cambelt replacement has soured my view on replacing originals out here in the antipodes unless they have broken. My TXD kept its water pump and it is the original I have been told by previous owner of 15 years now done 190,000 miles.

Australian factor parts I am going to repeat are crap quality. Hence why mechanics here recommned changing water pumps every time you change the cambelt.

[michaelr]

Thanks Kiwi, yes I noted you comment re aftermarket water pumps. In fact I have decided to leave the existing one (original ?) in place. Thanks for your advice.

To be fair I doubt that any pumps sold in Australia are actually manufactured in Aus. There has been a sad trend over the last decade or two to sell the very lowest quality manufactured items at huge retail markups. Fastenings such as nuts, bolts and screws are a case in point... nothing but Chinese rubbish being sold by the major hardware chains.

[Defender110]

I replaced my genuine original waterpump when I changed my belt and pulleys with new genuine dealer parts and the qaulity of the genuine water pump had altered. The old water pump had a brass type impellar where the new one had plastic/nylon. Not necessarally worse quality but keeping up with more modern manufacturing processes?