Bizarre cooling/heating issue.

[jonathan_dyane]

I fitted the ex GTI temperature gauge to my dash today (thanks Mike) which was most satisfying. As far as I am concerned, a temperature gauge is an essential piece of kit for any water cooled car, and why Citroen chose to neglect most models of the BX with regard to this is rather unfortunate.

Now, I was pretty sure that the gauge would reveal a dodgy thermostat, as a couple of weeks ago on a sub-zero gentle cruise, I had found the heater to seem to go cool, so was somewhat perplexed to find that the thermostat seemed to open as expected, and maintain the temperature at a constant 90 degrees.

I've just driven the thing from Newcastle to Shropshire, and was pleased to note the stable temperature regardless of right foot application, and generally enjoying the drive. *But* as I approached Wolverhampton, going at a 'reasonable' pace, I felt cold and turned up the heater, yet it still felt rather draughty. Feeling the heat emanating from the heater, I discovered that although toasty heat was still exiting from the floor vents and the R/H 1/3 of the demister vent on the top of the dash, the left 2/3 of the vent was throwing out icy cold air. Temperature still a dead-on 90 degrees.

I continued until the next junction (which I had to take anyway) and came to a stop to have a glance under the bonnet. Removing the cap from the expansion tank (the dodgy one fortunately, thanks David...) revealed the level to be up to the seam, exactly where it was when I set off. I started the engine, and gave it a bit of a rev; no bubbles were apparent. On continuing through Wolverhampton, within a couple of miles the heating returned to its normal toasty self.

Any ideas? Cooling system in need of flushing perhaps, or is my head gasket on borrowed time My last BX went somewhat funny in the heater department just before the HG died

[docchevron]

Thats odd!
If you're getting heat from one side of the vent but not the other, and if this seems more prevelant when the car is in motion it could point to ambient temp air entering the heaterbox above the matrix maybe?
I'm sure how but....
Er, I assume all the various outlet pipes from the heaterbox are attached in good condition?
The demister vent in the dash has a rubber bellow that seals to the heater box, I guess it could have come off one corner maybe?
Other than that duno really.
If the guage is sitting at 90deg and the water level is constant then I cant see it being a HG TBH..

[Way2go]

Any ideas? Cooling system in need of flushing perhaps, or is my head gasket on borrowed time My last BX went somewhat funny in the heater department just before the HG died

Maybe a build up up Crud in the vicinity of the heater valve or in the matrix itself which is then circulating through again. Best to flush it while circulation still occurs but because the heater is not easily flushable use 'Barrs Professional Flush' or something like it to break up and dissolve the crud. This is also beneficial in the cylinder head because it can still red light I found even with the temperature gauge reading 90 degrees.

[jonathan_dyane]

Wow, super quick replies

The reason I went straight down the 'woe is me, must be the head gasket' route is that the engine doesn't have the best of providences; now at 130000 it suffered big end failure about 40000 miles ago and was rebuilt, and although it starts and runs well uses a good bit of oil (about 2 pints per 1000 miles) which is never a good sign in an XUD IME. Good bit of blueish smoke too. Oh, and it had no anti-freeze in when I got it...

But that could well be all incidental, and as you say Chris, the lack of disappearing water and/or bubbles does bode well. I guess the problem could be to do with the heater pipes, but it is bizarre that the problem is intermittent; one would assume if there was ambient air leaking in due to a gap of some kind it would be a permanant rather than ocassional fault

Way2go, there is obviously some crud in the system as the heater valve is stiff (improved with antifreeze in tho...) but thinking about it if it was a load of crud moving around surely it would make the heater generally cool rather than in very specific locations?

I can feel taking the heater to bits coming on Better than the HG tho...

[M]

I fitted the ex GTI temperature gauge to my dash today (thanks Mike) which was most satisfying. As far as I am concerned, a temperature gauge is an essential piece of kit for any water cooled car, and why Citroen chose to neglect most models of the BX with regard to this is rather unfortunate.:

Hear Hear.

Not Just Citroen though, I have a 12 month old Zafira with the Fiat JTD donkey, that too has no temp gauge, just a spanner lamp of death. Uber crap for a £16K as new car. ( I didnt pay even half that price).

Looked into having one retro fitted and its a mare and a half on this car, simplest option is some OBD system that plugs into the diagnostic and I can get the coolant temp read out from that. Not cheap though at nearly 300 notes....

[Geoffrey Gould]

Hello it sounds like some crud may be floating round the system, it might be a good idea to check to see if the radiator is hot all over with out any cold spots. Give it a jolly good bleed just to shift any air and if you want to, get the garage to 'sniff' the header tank with the gas analyser that will tell you if there is a leak from the HG. Combustion gasses in the header tank. Hopefully that will put your mind at rest.
Good luck.
Geoff.

[jonathan_dyane]

I have a 12 month old Zafira with the Fiat JTD donkey, that too has no temp gauge, just a spanner lamp of death. Uber crap for a £16K as new car. ( I didnt pay even half that price).

Looked into having one retro fitted and its a mare and a half on this car, simplest option is some OBD system that plugs into the diagnostic and I can get the coolant temp read out from that. Not cheap though at nearly 300 notes....

I confess that I am completely ignorant with regard to the dark art of multiplexing and suchlike, but what's to stop you fitting a simple pod gauge and taking a live feed from, say, the radio?

[jonathan_dyane]

Hello it sounds like some crud may be floating round the system, it might be a good idea to check to see if the radiator is hot all over with out any cold spots. Give it a jolly good bleed just to shift any air and if you want to, get the garage to 'sniff' the header tank with the gas analyser that will tell you if there is a leak from the HG. Combustion gasses in the header tank. Hopefully that will put your mind at rest.
Good luck.
Geoff.

Cheers Geoff.

I shall be going down the flush route (hopefully not causing the heater matrix to disintegrate ) The cooling system had clearly been rather neglected in the past, and I should really have flushed it rather than just adding anti-freeze, and indeed would have normally but when I discovered it had none the car was on stands waiting to get the hub back from my mate with the press, and out of reach of a hose, so I just opened the radiator bleed and tipped in the required amount of anti-freeze as the coldness was upon us...

Will get the header sniffed and check the rad out too. Hopefully all will be well

[toddao]

Sounds like crap in the system, rust etc. The weird thing is that, even with anti-freeze, when there's crap in the system it seems to emulsify and freeze on the particles when it's really cold - I've experienced it this week. The inlet for the heater had blocked/frozen and even after half hour's driving was freezing though the inlet pipes were warm.
With the wife and kid in the car and -12 this was not funny. I stopped and manipulated the whole unit, til the blockage freed thankfully.
I don't know if this bears any relation to your problem Jonathan - mine didn't work at all, then did, rather than degrees. My system desperately needs a flush it looks like the Missisippi in there - no anti-freeze/anti-corrision in there from the previous owner.

[DavidRutherford]

Does sound like the heater matrix is partly blocking every now and then.

The fix: remove the feed and return pipes to the heater matrix, and belt mains water through it. Then reverse the pipes (IE backflush it) then reverse them again, and so on until you get clean water coming out of the return.

I'd do the same with the radiator, and also maybe flush the engine block through as well. I've done this on a number of cars now, and the crap that can come out of a heater matrix is quite remarkable.

Many many years ago, I tried flushing a car's cooling system through with a domestic detergent. That didn't go so well. Actually, I lie: It worked amazingly well, just created a rather large amount of foam too....

[jonathan_dyane]

Indeed, I'm now sure it is an internal crud issue; on the return leg the heater knob went back into very stiff mode, so there is now clearly a load of crappy silt nestling in the heater valve...

A thorough flush will be done soonish, but likely not for a few weeks until I have a chance to do the timing belt and waterpump at the same time; makes sense to coincide it with when I have to drop the water anyway...

Cheers,