Electric radiator fan conversion

[michaelovitch]

Originally Posted by m-reg

hi you can try top hose from ford escort zetec from 1990`s has built in switch , just need to cut the hose and sleeve in the part with the switch . I think fan uses 30 amp fuse happy wiring

Thank you for the info !

i will try to find one in my local junkyards or new but i need to find the opening and closing temperatures first.
i plan to use a 92°c opening one.
the thermostat open at 89°c so it should be just higher.

i would like to use it very close to the head here where it should be the hotter

what do you think ?


oh shit !!
i just see that the thermostat housing AND the thermoswitch is in a separate box

it could be very interesting to use the all system and delete the factory d24 thermostat .
on the d24 it's on the colder spot of the block .

[michaelovitch]

Originally Posted by piper109

Michaelovitch,

You may want to look at this product.

http://www.x-eng.co.uk/X-Fan.asp




I use it with a two speed Volvo fan and relay from a 92 745 turbo. I have is set so that the low speed runs with the a/c otherwise the temperature switch turns on the low or high fan speed based on coolant temp. The instructions say to put it in the lower radiator hose.
There are other ways to do it but this is clean and tried and tested. I have it on a 300tdi but I'm also going to put it on my D24T converted from gas and get rid of the viscous clutch and fan.

Bon chance, Steve
PS I appreciate your postings on the Bosch VE pump etc on Scribd. Really good stuff.

thank you !

the lower radiator hose ?
damn it's the colder spot of the circuit ! (if i'm right the head create the more heat)




i plan to use it at the upper hose the one of the head to avoid the lag of the heat radiation


on the redblocks and 850 tdi the thermostat housing is on the head and those blocks last a loooonnnnggg time

what do you think ?

thanks for the link.

Yeah about scribd !

i will make a post on that here
i forgot it could be useful here

[piper109]

Well I was also wondering about why they say to put it in the lower hose but if you think about it, you only need fan help when the radiator is not rejecting enough heat without it. When coolant is too hot coming out of the bottom of the rad, its time to add the fan.
If you look at the switch temps that X-eng uses, it makes complete sense.

Pas bete ces anglais ;-)

[piper109]

Looking again at the Volvo fan and relay you plan to use, it is exactly the same as the one I use in the 300tdi Disco. If you hadn't worked it out already, the relay is switched on the ground side. The X-eng temp switch has reed switches in it which are fine for switching ground signals instead of positive signals.

Steve

[michaelovitch]

Originally Posted by piper109

Well I was also wondering about why they say to put it in the lower hose but if you think about it, you only need fan help when the radiator is not rejecting enough heat without it. When coolant is too hot coming out of the bottom of the rad, its time to add the fan.
If you look at the switch temps that X-eng uses, it makes complete sense.

Pas bete ces anglais ;-)

I understand.

But the problem is that the thermostat is at the colder spot of the block.
So when it opens, it's yet a way more above 89°c( of the thermostat) in the head because the head is always hoter than the engine block.
as i think the problem, the head will be hotter than the block and the E fan will run a bit too late each time.

but i ask myself too if it's really a problem because according to the cooling system on the drawing the pump move the coolant all the time and the head should have constant flow even if the thermostat is closed.


i would install a thermostat very near from the head and remove the bottom one and in this case the thermoswitch would go at the lower hose as it shoul be.
i could be sure the head is always at 89 ° c max. or 92°c if i use a 92°c thermoswitch.
i should have a quicker cooling if the temp rise no ?

[piper109]

I don't think it matters that the thermostat is in the coldest part of the block. When the engine is so hot that it needs the cooling fan to run to supplement the radiator, the thermostat would normally already have been wide open for a long time.
The role of the thermostat and the role of the fan switch are at opposite ends of the cooling requirements.
The role of the thermostat is to gaurantee the minimum working temperature of the engine is reached and it can limit coolant flow to achieve this.
The role of the fan switch and the fan is to gaurantee the maximum working temperature (with conventional coolant) is not exceeded.

On the D24 engines, the water pump circulates the coolant very quickly from the top of the engine to the bottom and the pipe going through the cold start on the IP is only a few centimetres long, carrying the hottest coolant to the thermostat.

I think the VW engineers put the thermostat where it is for good reasons and it probably allows the engine and heater to get up to working temperature faster.

In a conventional way, the coolant is coolest at the bottom of the radiator. The coolant flow in the D24 conforms to this convention in spite of the fact that the thermostat is low down, as it is in many VW engines.

When moving along a road, with unassisted air going through the radiator, the coolant would normally not reach the temperature hot enough to turn on the fan, even at 88 C.

If the fan switch is in the top hose with the switch in the kit at 88 C, it could conceivably turn on before the thermostat was fully opened and prevent the engine from reaching correct running temperature or at least make it take longer to reach it.
Also, if the fan switch was in the top hose, when the engine was turned off, residual heat would continually rise and keep the fan running for some time until the whole engine and cooling system was cooled down to the point where the fan turns off.
With the switch in the bottom hose, the fan will stop running as soon as the coolest part of the engine reaches the turn-off point and then the engine will cool down albeit slower, but without any battery drain.

Incidentally, the way I have it installed, the low speed fan turns on at 88 C and the high speed turns on at 92 C, as suggested by X-eng.
I dont think I have ever seen the high speed come on yet but then diesels tend to run cool anyway.

I know other manufacturers probably run fans in a different way but the way X-eng chooses seems to make sense to me and I am comfortable with it.

cheers, Steve

[michaelovitch]

Originally Posted by piper109

I don't think it matters that the thermostat is in the coldest part of the block. When the engine is so hot that it needs the cooling fan to run to supplement the radiator, the thermostat would normally already have been wide open for a long time.
The role of the thermostat and the role of the fan switch are at opposite ends of the cooling requirements.
The role of the thermostat is to gaurantee the minimum working temperature of the engine is reached and it can limit coolant flow to achieve this.
The role of the fan switch and the fan is to gaurantee the maximum working temperature (with conventional coolant) is not exceeded.

On the D24 engines, the water pump circulates the coolant very quickly from the top of the engine to the bottom and the pipe going through the cold start on the IP is only a few centimetres long, carrying the hottest coolant to the thermostat.

I think the VW engineers put the thermostat where it is for good reasons and it probably allows the engine and heater to get up to working temperature faster.

In a conventional way, the coolant is coolest at the bottom of the radiator. The coolant flow in the D24 conforms to this convention in spite of the fact that the thermostat is low down, as it is in many VW engines.

When moving along a road, with unassisted air going through the radiator, the coolant would normally not reach the temperature hot enough to turn on the fan, even at 88 C.

If the fan switch is in the top hose with the switch in the kit at 88 C, it could conceivably turn on before the thermostat was fully opened and prevent the engine from reaching correct running temperature or at least make it take longer to reach it.
Also, if the fan switch was in the top hose, when the engine was turned off, residual heat would continually rise and keep the fan running for some time until the whole engine and cooling system was cooled down to the point where the fan turns off.
With the switch in the bottom hose, the fan will stop running as soon as the coolest part of the engine reaches the turn-off point and then the engine will cool down albeit slower, but without any battery drain.

Incidentally, the way I have it installed, the low speed fan turns on at 88 C and the high speed turns on at 92 C, as suggested by X-eng.
I dont think I have ever seen the high speed come on yet but then diesels tend to run cool anyway.

I know other manufacturers probably run fans in a different way but the way X-eng chooses seems to make sense to me and I am comfortable with it.

cheers, Steve

Thank you for the explanation !

i can see more clearly the role of each component on a global way of thinking now.
the place of the thermostat is still strange for me but eh ! i think the dudes wich built the d24 knew what they did at the vw factory.
the redblock have the thermostat in the head, but like you said ,the diesel work a bit cooler than gas ones and the warm up period on a long big diesel engine was certainly in their mind .


i think i'm going to do this system : the X-eng stuff : a T with 2 thermoswitch for safety and the volvo fan and relay with the high speed automatic and the low speed manual maybe.

i finish my build http://d24t.com/showthread.php?712-d24-NA and i adapt the E fan.

i've changed the bearing on it and it spin better now !

[m-reg]

you got me thinkin now yeh i got 940 2 speed fan an relay the ford zetec switch got 2 circuits so i thought `splice in the switch and off we go ` but never studied the water flow of d24 so was going to put in top hose cos all cars have stat at top hose right lol. also got to do some school boy experiments like dunk hose in bowl of hot water & see which circuit switches first or if junk yard switch even works ha.

[m-reg]

makes sense really cos when u think about it most cars with the switch in the rad have it mounted low down so that would agree with having it in bottom hose