Club 80-90 Forums

Hiya folks,
I've had a few cooling issues with my 1987 2.1 petrol bus recently (from broken thermostats, cracked header tanks, leaky hoses to stuffed head gaskets) so thought I would change my thermo-switch for good measure as I can't remember the last time I heard the fan kick in. The fan definitely works as I completed the test suggested in the Haynes manual by connecting the wire terminals together. I know the fan is supposed cut in between 89-94 degrees C., but even when stuck in traffic I still haven't heard it come on. Unfortunately, my temp gauge doesn't work so I have no idea how hot the engine is getting - there just seems to be a great deal of heat emitted from the back of the van from the vents when I stop (this has become something of a paranoid habit now - immediately 'feeling' the warm air around the back of the van when I get out!!!! ) I know there is supposed to be heat , what the exhaust and everything being back there too, but would like to know what your experiences are...?
Cheers all, Mark

I have a 1.6 diesel and I have only heard mine a couple of times.

fix yer temperature gauge.. coz "feeling" how hot isnt very accurate is it....

My early caravelle, takes a lot before the fan kicks in (1st stage), prob 2/3rds accross gauge..
My late Syncro, low speed comes on and off in the middle and gauge doent go up much more than that...

Remember there is 17L of coolant in the system and a lot of surface area, the fans generally dont come on that often compared to a normal car...

Oh.. and get yer gauge working.... then you'll know what temp the engines at...

[quote="toomanytoys"]fix yer temperature gauge.. coz "feeling" how hot isnt very accurate is it....

Ha! I have a 'feeling' you may be right there!

My fan kicks in at 89 to 94 deg c
thermostat opens at 85 and is fully open at 105 deg C

Ayup Kev....I think it's more like the thermostat is fully open (stays open) when all the coolant around the thermostat housing reaches 85C.. it may well get hotter after this happens...
I agree.....get the gauge fixed lol

Martin

sorry Martin but it's progressive from 85 it doesn't fully open then, it is fully open at 105, it has 8mm of travel from shut to fully open.


I'm surprised you didn't know that

E D I T..
I just checked the haynes and it's there too.

Hi Kev,
I can see why you would think that from the Haynes description 'As the temperature of the coolant rises the thermostat opens, allowing partial and then full circulation of the coolant through the radiator'
But what the Haynes describes is a point at which the cold coolant from the radiator mixes with the hot coolant from the engine and the opening and closing action of the thermostat until all the coolant reaches the thermostat 'pre-set' temperature at which point the thermostat stays open.
Having discussed this with two of my collegues we all agree that you may be thinking about old fashioned bellows or alcholol filled thermostats which were 'linear' and do indeed progressively open (the hotter the coolant the wider open they get)
Those particular types have long since been replaced by the waxstat which doesn't open progressively but opens fully as soon as it reaches it's pre-determined temperature.
To explain this I'll quote directly from the Hillier's book 'The wax type element depends for it's operation upon the considerable change in volume which occurs in certain types of wax at around melting point in laymans terms: when the wax within the capsule melts from a solid to a liquid it rapidly expands pushing the pin outwards opening the thermostat...this isn't a progressive action just the difference in volume of the wax between it being a solid or liquid.

Martin

I've no idea on actual temperatures but when warmed up, my guage always sits just to the right of the red light (about 1 o'clock).
I bought a new fan switch from JK 2 years ago and the fan has never kicked in (never been in a traffic jam or situation why it would) but I bought a new one from Brickwerks last week and went for a run. Guage at 1 oclock as usual and then let it tick over for 10 mins on the driveway. the guage moved marginally to the right and the fan kicked in.
So It could be a duff radiator fan switch you have as well.

California Dreamin wrote:Hi Kev,
I can see why you would think that from the Haynes description 'As the temperature of the coolant rises the thermostat opens, allowing partial and then full circulation of the coolant through the radiator'
But what the Haynes describes is a point at which the cold coolant from the radiator mixes with the hot coolant from the engine and the opening and closing action of the thermostat until all the coolant reaches the thermostat 'pre-set' temperature at which point the thermostat stays open.
Having discussed this with two of my collegues we all agree that you may be thinking about old fashioned bellows or alcholol filled thermostats which were 'linear' and do indeed progressively open (the hotter the coolant the wider open they get)
Those particular types have long since been replaced by the waxstat which doesn't open progressively but opens fully as soon as it reaches it's pre-determined temperature.
To explain this I'll quote directly from the Hillier's book 'The wax type element depends for it's operation upon the considerable change in volume which occurs in certain types of wax at around melting point in laymans terms: when the wax within the capsule melts from a solid to a liquid it rapidly expands pushing the pin outwards opening the thermostat...this isn't a progressive action just the difference in volume of the wax between it being a solid or liquid.

Martin

All well and good if it was a "waxstat" type... but... it's not.
It's a bi-metal spring type, you can open them with your hands even when cold, I doubt you can do that with wax, as you say, that's solid.
I'm sure that my schoolboy physics is still correct with bi metal strips and springs being progressive with temperature.

I also think dumping the contents of a cold radiator into a hot engine sounds really wrong.. hence the gradual cooling from a lower temp as indicated by the Haynes.

ohhh thermostat summit i dont have fitted to my engine (and haven't since fitting it,hence no problem with it ever sticking!) but i have a slightly different engine!

kevtherev wrote:

California Dreamin wrote:Hi Kev,
I can see why you would think that from the Haynes description 'As the temperature of the coolant rises the thermostat opens, allowing partial and then full circulation of the coolant through the radiator'
But what the Haynes describes is a point at which the cold coolant from the radiator mixes with the hot coolant from the engine and the opening and closing action of the thermostat until all the coolant reaches the thermostat 'pre-set' temperature at which point the thermostat stays open.
Having discussed this with two of my collegues we all agree that you may be thinking about old fashioned bellows or alcholol filled thermostats which were 'linear' and do indeed progressively open (the hotter the coolant the wider open they get)
Those particular types have long since been replaced by the waxstat which doesn't open progressively but opens fully as soon as it reaches it's pre-determined temperature.
To explain this I'll quote directly from the Hillier's book 'The wax type element depends for it's operation upon the considerable change in volume which occurs in certain types of wax at around melting point in laymans terms: when the wax within the capsule melts from a solid to a liquid it rapidly expands pushing the pin outwards opening the thermostat...this isn't a progressive action just the difference in volume of the wax between it being a solid or liquid.

Martin

All well and good if it was a "waxstat" type... but... it's not.
It's a bi-metal spring type, you can open them with your hands even when cold, I doubt you can do that with wax, as you say, that's solid.
I'm sure that my schoolboy physics is still correct with bi metal strips and springs being progressive with temperature.

I also think dumping the contents of a cold radiator into a hot engine sounds really wrong.. hence the gradual cooling from a lower temp as indicated by the Haynes.

Kev...now you are confusing me, you are talking about a thermostat like the one fitted to markbikerider's 1987 2.1 wasserboxer?
like this one on Simons site?:
http://www.brickwerks.co.uk/shop?page=s ... lypage.tpl" onclick="window.open(this.href);return false;
Certaily looks like a waxstat to me......
Pretty much every water cooled car engine dating back to the 70's has a waxstat fitted, I'm sure there are acceptions but I can't think of any.

As for 'dumping the contents of cold radiator into a hot engine, it doesn't! the thermostat opens and closes as many times as it takes, letting a little cold water in, shutting as the wax re-sets, heating up again, opening, letting a little more cold water through until all the coolant surrounding the stat is above it's pre-set at which point it stays open.

Some Peugeot's and Renaults had dual temperature waxstats fitted, effectively opening in two stages but still not progressive.
Of course your schoolboy physics is correct and bi metal strips and springs are progressive with temperature but thermostats fitted to watercooled T25's have always been waxstats, as shown on the Brickwerks link..

Martin