Citroen Visa Thermostat, or just a standard replacement one?

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Daniel B
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Citroen Visa Thermostat, or just a standard replacement one?

Post by Daniel B »

Gents,

I want to get a new thermostat for the old girl, and know that when it was serviced at PTS developments, Pete stuck a Visa Diesel thermostat on, as he said it would cut in at lower temperateures.

Does anyone happen to know, either the type/make/model for this part, or the standard one?

Edit: GSF seem to sell three BX thermostats:
BX PETROL EXC 16V - 176PC0040
BX ALL DIESELS >92 - 176PC0060
BX D/TD 92> (PLASTIC HOUSING) - 176PC0080

Could I use any of the above - first one excluded I am assuming.

Cheers

Dan
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Adrian E
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Post by Adrian E »

Dan

It'll depend mainly on the diameter of the stat, I would assume. All stats I can recall looking at have the temperature at which they open stamped on them somewhere (88C springs to mind for the BX 16V as standard, so maybe the Visa diesel is 82C?)

If yours is knackered and out of the car, probably worth taking it to an old school motor factors (if you can find one!) and compare a few PSA options to find one that fits.

I wouldn't imagine the stock stat would be a problem, as yours has twin fans IIRC? So long as the fan switch is a diesel one that'll more than cover you for cooling protection :D
Last edited by Adrian E on Mon Jun 14, 2010 2:16 pm, edited 1 time in total.
Daniel B
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Post by Daniel B »

Hi Adrian,

thanks for your reply :)

It isn't off the car yet, but maybe later this week.

Looking further on GSF, if searching for a Visa thermostat, it comes up with the same part number as BX all Diesels >92

And yes your right, she has twin fans.

82C rings a bell as well :D

Anyone know the make of the thermostat, that might be handy if I do go into a motorfactors?

Cheers

Dan
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jayw
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Post by jayw »

BX diesel stat is a fairly common swap. Works a treat too!
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Adrian E
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Post by Adrian E »

Sounds like the BX diesel one will do the job then, although imagine the housing is different, so worth checking the physical dimensions still.

Don't think there's any particular brand for these - just pot luck what they have on the shelf I imagine.

Like I said above, if you've got the diesel fan switch that cuts in lower I wouldn't worry too much about the stat - if you think about it, the stat is designed to help the engine get up to temperature quicker when cold by shutting off the flow to the rad until the engine is warm. Once engine is warm it should stay open. Can't imagine even with twin fans cutting in early you'd get the water temp dropping below 82 or 88C, especially in the summer months that you're using the car. I guess only advantage of the lower cut off is that the stat will stay open even if the water temp drops below 88C?
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Post by Vanny »

jayw wrote:BX diesel stat is a fairly common swap. Works a treat too!
Diesel fan switch is common, not so sure about the thermostat.


My thoughts are similar to Adrian's, petrols are meant to run warmer, just not too warm. The thermostat controls the rate the engine warms more than it controls the water temperature. If you have the diesel fan switch, and a healthy radiator, i'm not sure you will gain much from a diesel thermostat.
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Post by ollie »

I agree with the last 2.
Getting the stat open sooner will make it warm up slower (bad) and potentially make it run cooler and not as efficiently at normal speeds, if the car overheats then you need to look at the rad and check the fan cut in temps,
Just get the switch out and then put it on the stove with a thermometer and a multimeter attached and test them! Diesel ones can be usefull but really if everything is doing what it should then standard is best!

incidentally how do you know what temp its running at? I'd test the overheat switch as well, they can vary enourmously with age and tell you your engines **ucked when its not! ditto the sender/ guage, only way to be sure is compare with a separate probe.

incidentally a spurious motorfactor visa stat may be rather worse quality than the orig 16v one anyway!
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jayw
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Post by jayw »

I'd find it unlikely that the 7 degree difference between 16v & Diesel is going to be detrimental in any way to running and to describe it as running "too" cool under those circumstances is a bit o.t.t.

Keeping any hot headed engine that few degrees cooler can only help. Fair enough, taking the stat out completely is something completely different...

But, as Vanny rightly said, the temp switch IS the common swap, I just misunderstood the question... I personally would do both.
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Post by Vanny »

What are your thoughts on thermal shock Jay? IE thermostat opens, huge amount of cool water enters the system, drops the temp a fair bit, then it all has to warm back up. I've seen it cause problems on bigger (3litre +) engines, with turbo's and super chargers, and i guess that the BX doesn't have that much coolant all in all. I wonder what effect it would have to the BX.

Excuse me for asking a numpty question, my understanding is that the stats open pretty quickly once they go (in a matter of seconds), but is this right or do they open slightly more gently. I've seen temp traces of cars that open quickly, but does the BX?
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Simran
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Post by Simran »

I would also agree with most of the comments on here, if the engine is getting too hot, it points to other problems like a gunked up radiator or a leak somewhere. The engine is meant to run pretty hot, and the standard thermostat is designed to keep the engine around its happy operating temperature. I would say 8 degrees change is a fair amount as well to change it by if you look at it as a percentage change. Your twin fans will do a good enough job of keeping temps steady.
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jayw
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Post by jayw »

Vanny wrote:What are your thoughts on thermal shock Jay? IE thermostat opens, huge amount of cool water enters the system, drops the temp a fair bit, then it all has to warm back up. I've seen it cause problems on bigger (3litre +) engines, with turbo's and super chargers, and i guess that the BX doesn't have that much coolant all in all. I wonder what effect it would have to the BX.

Excuse me for asking a numpty question, my understanding is that the stats open pretty quickly once they go (in a matter of seconds), but is this right or do they open slightly more gently. I've seen temp traces of cars that open quickly, but does the BX?
I don't think the 7 degrees we're talking about is enough to cause thermal shock, really i don't. I've always believed that almost all thermostats open progressively over an operating range. I'm pretty sure documentation i have somewhere says the BXD thermostat begins opening at 82 oC and is fully open at 87 oC, this along with dual stage fans is what prevents thermal shock. Fully opening instantly at one specific temperature would cause thermal shock on any engine.
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Post by ollie »

Stats do open in a controlled manner, just watch them on the stove! thermal shock comes from dumping it through a big puddle not a little dribble of cool out of a Radiator.
In the general scheme of things jay 8 degrees doesn't sound much, but its enough to screw up the emmissions and fuel economy on most newer cars, even old astras and corsas with a slow stat running at 80degres genearlly do about 30% less mpg than one which is at 90 as designed! sounds insignificant, but the MAP on these seems to leave them in a warm up mode longer than most just done 2 and the difference in driveabilty and fuel is immediately obvious!
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jayw
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Post by jayw »

ollie wrote:Stats do open in a controlled manner, just watch them on the stove! thermal shock comes from dumping it through a big puddle not a little dribble of cool out of a Radiator.
In the general scheme of things jay 8 degrees doesn't sound much, but its enough to screw up the emmissions and fuel economy on most newer cars, even old astras and corsas with a slow stat running at 80degres genearlly do about 30% less mpg than one which is at 90 as designed! sounds insignificant, but the MAP on these seems to leave them in a warm up mode longer than most just done 2 and the difference in driveabilty and fuel is immediately obvious!
I'd agree with that, i don't doubt it's significant with more modern engines/fuelling systems, but this is the 20+ year old BX we're talking about (most of which don't even have o2 / MAP sensors). And i think the initial concern at the start of this post was longevity/disaster oversion not mpg. Besides, there's less likelihood of it leaning out (not that it's usually a problem).
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