BX 16v Thermostat

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white exec
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Re: BX 16v Thermostat

Post by white exec »

I had thought that all 16v had twin fans. Parts seem to show this.
???

If the bottom (radiator exit) hose really is half empty, then that suggests either chronic clogging, or else a very low level of the coolant in the system. If that is the case, the car should not be driven. Probably a good idea to disconnect the bottom hose and check what water flow there is through the radiator.

The radiator bottom and the bottom hose would be the first part of the system to fill up (when filling), so what you say is very concerning. You could be close to cooking the engine, and damage may already have been done.
Chris

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Re: BX 16v Thermostat

Post by Dave_16v »

krekov wrote:
Sat Oct 30, 2021 1:09 am
I have just one at the moment, but I will be fitting a second one using the schematic I believe you gave me.

The radiator is still the original. So just to confirm, does the half-empty, squeezable hose coming out of the rad mean the radiator is at fault?
It could easily be that when that pipe is squeezed, it's just pushing coolant back into the radiator, it's a big pipe and takes very little effort to squash it. However, I will do the same with mine later and let you know what I find resistance wise. I wouldn't jump to ant conclusions about that.

As for two fans, they don't all have two. My Gti's and 16v's all had one and have and managed perfectly well In this climate. I think the valvers have temp switches set higher from memory but regardless of that, they are known to run hot anyway.
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Re: BX 16v Thermostat

Post by white exec »

So which GTi's and 16v acquired two, and when?

Bearing in mind Citroen's recommendation to fit a second fan even to diesels that were used for towing, and that petrol cars (especially the performance ones) generate much more combustion heat than diesels, having twin fans on these cars seems only sensible - and so easy to do. They also do away with the sometimes troublesome dropper resistor.

Agree about the large hoses. When the system is cold/not under pressure, they're easily squeezed, and not necessary empty!
Chris

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Re: BX 16v Thermostat

Post by Dave_16v »

Checked the lower hose, just as I expected, there is very little resistance, the majority is from the hose itself. However, if you squeeze it quickly near the outlet with the expansion chamber cap removed, it is possible to see some movement of fluid in the tank. If you can do the same, it would be a good sign.

I am not entirely sure where you stand now but if you are not seeing the red light (which is not wholly reliable), it could be OK. I know you notice a difference with the fan on, that will remove heat from the engine, it might just be keeping the engine cooler before the hotter coolant has reached the switch. As I said, they do run hot but the new stat may help, that's why people do that mod but the stat doesn't get mentioned often if at all. Perhaps see how it goes and keep a watch what happens at standstill.

With regard to two fans being fitted, the 16v's with air conditioning have two. Not sure about others, never delved into it.
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Re: BX 16v Thermostat

Post by white exec »

Dave_16v wrote:
Sat Oct 30, 2021 11:55 am
With regard to two fans being fitted, the 16v's with air conditioning have two. Not sure about others, never delved into it.
Went back to Parts, and 16v models are shown as having wide radiators and twin fans:
.
16S radiator
16S radiator
.
16S cooling fans
16S cooling fans
.
.

Other petrols (so that would include GTi 8v) shown with narrower radiator and a single fan:
.
Radiator, petrol, except 16S
Radiator, petrol, except 16S
.
Cooling fan, petrol, except 16S
Cooling fan, petrol, except 16S
So, to find a GTi 16v with only a single fan is odd, and doesn't seem to make much cooling sense.
There is no mention in Parts of anything different for early models, or RP changes.
_________

Could run a Servicebox check on a 16v's VIN number, to see what factory Characteristics shows up.
This info can be a bit limited for BX-era cars though.
Chris

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Re: BX 16v Thermostat

Post by Dave_16v »

You are assuming that just because there is a twin cage, there would automatically be fans. It makes perfect sense for Citroen to use the same cage and add the extra fan to that as required. Happens a lot in all sorts of manufacture. It's not odd at all 😉
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Re: BX 16v Thermostat

Post by white exec »

You could be right.
Just noticed that the same part number (for the fan motor) is shows as qty.01 or qty.02 in the parts listing.
.
BX 16S cooling fans - one or two.jpg
.
Flipping the Parts page into French shows "Heater" as "Climatiseur", so that would be the AC option.

Must say, if I were running a 16v, my preference would be for twin fan.
Even our old '89 19RD was given a second one. That had no twin cage, but just had the ability to slot its single fan case either centrally, or to one side, so allowing the slotting in of another – which it got from a breaker's yard.
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Re: BX 16v Thermostat

Post by krekov »

Thank you for the replies, I will be installing a 2nd fan like I said and maybe take this radiator to be recored, if twin fans don't resolve the issue.

I'm not convinced this is anything serious, possibly just an old French car being French. Maybe it's not a real issue at all! It's a project car, I've been driving it for half a year with this problem and there is no sign of head gasket failure or any actual signs of overheating, like coolant spewing from under the reservoir cap.

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Re: BX 16v Thermostat

Post by Vanny »

All Ph2 (and probably Ph1) 16Vs come with a two fan frame. Most only have a single fan and motor in. All 16Vs with air con have two motors/fans installed as standard.

I don't believe the twin fan adds a huge amount on a normal valver as the size and back pressure of the rad is considerably smaller than that of the standard diesel/turbo diesel

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Re: BX 16v Thermostat

Post by krekov »

Could it be possible to fit the rad from the turbo diesel into a 16v? They both use separate reservoirs.

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Re: BX 16v Thermostat

Post by Jaba »

Everything is possible. I don't know if they are interchangeable but I doubt it somehow. The TD has loads of torque low down that the 16v lacks so maybe it needs more cooling despite its better thermal efficiency. Its usually best to stick with standard components without proven expert advice.

I was a passenger in a duel between a TD and a 16v up an Alpine col on one of the BX Challenges. The TD got away it just had more usable power which is a demonstration of why they need such a different rad.
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Re: BX 16v Thermostat

Post by Kaapelimies »

The 16V has the rad more front as it's under the bonnet lock plate (I don't know what it is actually in english). TD has the rad more rear (like all other models of BX), as it measures more in height. So I'm not quite confident that the TD rad will fit in 16V, vice versa should be no problem.
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Re: BX 16v Thermostat

Post by white exec »

It's called the "slam panel", Kaap. Not a recommendation for what you should do, but that's it.
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Re: BX 16v Thermostat

Post by krekov »

I think I've solved the problem.
Like I said earlier, I had an 82C thermostat fitted, but I noticed after a test drive that the temp. gauge was still just barely below 90C when driving.
I grew suspicious of this behavior, as my BX 1.8 diesel has a thermostat also opening at 82C, and the gauge was in a different, lower position.

So, I took the gauges apart. Upon further inspection, it became clear someone had messed with them a long time ago. I found that the water temp. gauge needle was moved upwards and no longer giving an accurate readout.

I would've never suspected this if not for being informed elsewhere that the temp. gauge is NOT supposed to start at the first notch, the one closest to 60C.

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Re: BX 16v Thermostat

Post by white exec »

:D What you say is correct, Krek. When the IGN is switched on, the temp gauge needles rise from their rest positions to a slightly higher position, but not as far as the numbered scale. Needle stays there, until temp rises enough to get it moving further.

The pointers on all the instruments are delicate things, and the spindle/pointer can be damaged if not pulled off 'dead straight'.
The gauges on BX seem to be fairly accurate (not true of all cars, including some much newer ones), but I'm guessing the needle position can only be 'corrected' by running a check with a known good thermometer for one of the more critical temperatures - eg 90 or 100degC.
______

Something which might have got overlooked when discussing thermostat and fan cut-in temperature figures (and whether they need to be 'matched'), is that the fan thermo-switch is, on the BX, positioned near the base of the radiator, where it is sensing cooled water which is about to be pumped into the engine block. To detect overheating in that position, the cut-in figures would need to be a good bit lower than if the sensing were done at the water outlet/thermostat housing - which is where it is done (by a sensor or two) on many later PSA engines.

Glad you got your gauge reading something sensible.
Chris