1979 504 Radiator Fan

7

79Arms

New member
Tadpole
Joined
Mar 10, 2019
Messages
7
Location
Los Angeles
Hello all,

I live in Los Angeles and recently purchased a 1979 Peugeot 504 saloon made in France US Model with a 2.3 liter diesel engine (XD2). I’ve noticed the fan is not spinning fast enough in idle. I have deduced that this is the cause of a slight overheating issue (when in idle and in traffic only). I’ve replaced the fan switch on the radiator and temperature sender, for good measure, on the back of the block. Still spinning slow. Flushed the entire cooling system and it’s spotless. No clogs or debris in the radiator and in the process replaced the thermostat as well. Could I have a bad fan clutch? I find this difficult to believe considering the car has 56,000 original miles. Could it be a fuse or an electrical issue? Radiator fan solenoid? Any and all advice welcome.

Thanks!
 
Check the carbon brush that provides power to the electromagnet. In the meantime, tighten the adjustment nuts to keep it permanently engaged so it won't overheat. That's going to mean the engine has about 4 HP less!
 
i have had this happen on several 504s i have had,including my current cab and have just locked the fan tight to never worry about again . Economy is still fantastic
 
The fan only comes on when temp is high. It spins a bit at idle due to friction in the bearings. You need to put 12volts on the wire to the carbon brush to see whether the magnetic clutch works. Fan is very noisy when engaged but probably not noticeable on a Diesel!
 
julian c b said:
i have had this happen on several 504s i have had,including my current cab and have just locked the fan tight to never worry about again . Economy is still fantastic
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That's what I have done on a few cars. They say that it decreases fuel economy but I've never noticed. Doing it takes away one more thing that may go wrong.
The solenoid in the hub does fail after time...probably due to heat. But as others mentioned, check the carbon brush first.
Do you know how to lock up the fan by tightening the three bolts (with locknuts) on the front of the fan ? It's pretty easy...what you are doing is decreasing the distance between two clutch plates. And they don't even have to be particularly tight at all.....just make sure the lock nuts are done up again.
 
I had the lock up fan on my 1980 504 GL, and eventually freed it up when searching for whatever hp gains I could find (which were slim!). Agree on all points on this thread, and note that wth the fan disengaged, it was quieter, and (perhaps) a bit more nippy, but it was never overly noticeable.
 
With my 1980 XD2 504 the fan only ever came on in traffic and was easily heard over the diesel clatter. It always came on when the temp gauge reached a certain point. After 34 years and 300,000 kms it was still working. I think I changed the carbon brush only once.
 
I could always notice the power drop when my Ti fan was engaged. Can recall an article stating the engaged fan robs a Ti of 12bhp! (That is only about 11% of total power available).:(
My Ti fan clutch still works after 360,000kms and 45 years! :) (Has had one new carbon brush though).
 
GRAHAM WALLIS said:
The fan only comes on when temp is high. It spins a bit at idle due to friction in the bearings. You need to put 12volts on the wire to the carbon brush to see whether the magnetic clutch works. Fan is very noisy when engaged but probably not noticeable on a Diesel!
Click to expand...

Will do. Thank you Graham
 
Beano said:
That's what I have done on a few cars. They say that it decreases fuel economy but I've never noticed. Doing it takes away one more thing that may go wrong.
The solenoid in the hub does fail after time...probably due to heat. But as others mentioned, check the carbon brush first.
Do you know how to lock up the fan by tightening the three bolts (with locknuts) on the front of the fan ? It's pretty easy...what you are doing is decreasing the distance between two clutch plates. And they don't even have to be particularly tight at all.....just make sure the lock nuts are done up again.
Click to expand...

Thank you Beano. I do know how to lock up the fan, but will this require removing the radiator as it seems very tight?
 
BIGRR said:
I could always notice the power drop when my Ti fan was engaged. Can recall an article stating the engaged fan robs a Ti of 12bhp! (That is only about 11% of total power available).:(
My Ti fan clutch still works after 360,000kms and 45 years! :) (Has had one new carbon brush though).
Click to expand...

Yes, makes a noticeable difference, I had my 505 dyno tuned after the Gas Research conversion, may have been 5kw drop.
 
The diesel has an 8 bladed fan and the power drop is far more noticeable than with the petrol with 6 blades.
I had an override switch on mine and climbing a steep hill and flicking the switch was like throwing out an anchor.
 
First check if you have the right temperature switch. Not mistaken the 504's switch turns ON at 85 or 82 degrees celcius. Which I find a little odd since it's almost nearing boiling temp.
On my 404 I opted to use a blow in electric fan and used a 65 degrees ON temperature switch. Seems to be fine for now.
 
Normally the switch will be set to turn on at the mid 90s and off at the high 80s. 88C is normal running temperature - most 404 thermostats don't even open until then.
 
79Arms said:
Thank you Beano. I do know how to lock up the fan, but will this require removing the radiator as it seems very tight?
Click to expand...

No removal of radiator required. It's a bit of a fiddle in there but not actually knuckle-barking !
Just use a small ring spanner on the locknuts and something to turn the actual bolts....which have a very small diameter head, if I remember correctly. You don't have to do up the bolts tight at all....just a few turns.
 
Hello! It was the carbon brush after all. Replaced the brush and the two 15 amp in line fuses for both fans with 30 amp fuses (a tip from my local Peugeot mechanic). Runs without overheating on hot days, in Los Angeles traffic, like a charm! Thanks again to all who contributed to this thread! I’ll be back....without a doubt.
 
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