Radiator fan speed

[Yoni_d]

Hi All

I was wondering if the electric radiator fan has 2 speeds or only one?
I was looking at the part catalog and I have noticed that there are 2 switches:
75 deg
92 deg

Are they both installed on the radiator?

My friend told me that he thinks that the mechanical fan has also a temperature switch...I couldnt see it...is that true? or he was mistaken?

Thanks for your help!

[rhjames]

Originally Posted by Yoni_d

Hi All

I was wondering if the electric radiator fan has 2 speeds or only one?
I was looking at the part catalog and I have noticed that there are 2 switches:
75 deg
92 deg

Are they both installed on the radiator?

My friend told me that he thinks that the mechanical fan has also a temperature switch...I couldnt see it...is that true? or he was mistaken?

Thanks for your help!

the mechanical fan is just that--mechanical, with no method of adjustment. As long as the hydraulic oil is intact in the fan hub, it will operate as it should.

no switches installed on the radiator that I know of--all temp switches are on the engine, or HVAC system.

--Russ

[Yoni_d]

There is a sensor on the radiator. See the atatched picture.
Maybe someone has an electrical schema for 1980? I have only of 1985.

[MPDano]

Temp Sensor is for the Electric Fan. RHJames is correct. Mechanical is mechanical. The Fan Clutch is what adjusts it's speed. Engine cool, less rotation, Engine warm, more rotation.

[Danglerb]

Mechanical fan is temperature sensitive. When cool the clutch lets it spin freely, no drag on motor and slower rotation speed. When hot the clutch locks and the fan spins at full motor speed.

Radiator has a temp switch on the front for the Aux electric fan, and replacements for it are available in many temperature settings, but it's supposed to only come on to prevent over heating. I don't advise using a lower setting to accommodate a failing mechanical fan.

[JK McDonald]

I might mention a couple of tests that I made to modify the operation of hydraulic fan clutch. If you remove the center pin that is under the bimetallic strip - it will measure approx. 9mm in length and .8mm thick. Assuming your radiator is in good condition, have added enough silicon oil inside the clutch assembly and your aged bimetallic strip is operating reasonably well, adjusting the length of this pin is the key to modifying the engagement or coupling up of the fan to the engine driven pulley. With a little experimentation I determined that if you shorten the pin by .5mm the fan not only begins to engage slightly earlier but satisfactorily moves much more air in relation to the sensed air temperature coming through the radiator. The removal of .25 mm from the pin in several increments continued to make significant changes to the cooling performance of the hydraulic fan but as you approach 1mm I feel the lockup was then too early.

NOTE: Instead of modifying your original center pin, use the solid end of an old drill bit that is approx .8mm thick. I used a harbor freight digital micrometer and a fine-grained grinding wheel to help keep track of the length of the new pin being made. Save the original pin in reserve in case of a MM (major malfunction). In order to make sure the center rubber cap seals everything up I used a drop of clear sealant on the pin tip just before the final installation of the bimetallic strip. After a couple of weeks in the Texas July heat, this seems to have helped Miss Purdy – (84 Red/Blk Interior)– good luck….. Michael

[Normy]

Yoni-

Many people remove the belt-driven fan all-together. Porsche did it 22 years ago in 1987, there is nothing wrong with that idea.

-You can buy a kit to remove all your fans and convert to 100% electric fans with the latest technology at www.928specialists.com. Or you can retire to eBay, and do a search for a similar product, which usually uses Ford Mustang parts, for a little less. Or you can do a cheap replacement and use parts from Haden available at Pep-Boy's and eliminate both your belt-driven fan, and your aux fan on the front.

OR...

You can do like me, and keep your belt-driven fan, and when your air-pump seizes up, you can obtain the correct riding lawn-mower belt and drive your engine-driven fan directly off your crankshaft.

Your electric aux fan? That is designed to give extra cooling to the a/c condenser when the airco is engaged. It works at ONE speed only. It is either on or off. Where it gets weird is the '82-'86 cars, where there is a sensor built into one of the "spider" legs that tells the fan to come on for a few minutes after shut-down if the under-hood temperature gets too high.
This is a factory response to hot-start problems on other cars that employed L-Jetronic or LH-jetronic injection. Many VW Golfs and Jetta's of the same vintage do the same thing. Shut it down, and 1 minute later, the fan suddenly runs for 5 minutes.

N!

PS: The '92-'94 VW Corrado SLC not only had a fan that ran for a few minutes after shut-down, it had a second electric water pump that continued for up to 10 minutes! This second water pump is a source of THOUSANDS of problems, since it was made of plastic. Along with the stupid plastic thermostat housing~

[Yoni_d]

My electric fan starts working regardless the A/C. it starts working at about 90C.
My problem is that my car gets hot when idling...when driving the engine temperature is a little below the middle so the problem is only when idling...people have told me that the radiator is good since if there is a radiator problem / water pump problem - the car will over heat during driving on the high way. so, in my case it's either the thermostat (I am not sure it is the case) or the mechanical fan...I thought that maybe the electric fan has 2 speeds but if it has only one, then I think I need to check the mechanical fan as well...

[rhjames]

if it's hot when Idling, but cool when cruising down the road at speed, I would suspect the fan hub is on it's way out. they are notorious for leaking hydraulic fluid out of them requiring rebuild or replacement. the hydraulic fluid will react (become less viscous causing the fan to freewheel) when the hub/engine compartment is hot, but at idle/cool temps the would will tend to be thicker allowing the fan to "lock up".

only one speed on the aux electric fan, stimulated by high head temp on the A/C system.

--Russ

[porshapower]

If you would like to try to change out your thermostat and fan switch let me know. I have a thermostat and o ring and a fan switch that I bought to try to fix a problem with over heating on my last 928 and had it on the car for 3 weeks before it was totalled. Ive got a coolant sensor for top of your coolant reservoir if you want to change that too. Send me $25 to cover shipping and post office run and they are yours! Hope this helps. Nel

[Yoni_d]

That fan looked suspicion from the moment I looked at it
Is there any rebuild tutorial for the fan hub?
Or I must replace it?

[Danglerb]

Once the mechanical fan starts to leak, it generally will leak again if refilled, the seals have gone. You can try fixing it, searching on toyota in this forum should find the directions since Toyota sells the replacement oil.

Most reliable fix, replace with new, but they are not cheap.

[Yoni_d]

Originally Posted by porshapower

If you would like to try to change out your thermostat and fan switch let me know. I have a thermostat and o ring and a fan switch that I bought to try to fix a problem with over heating on my last 928 and had it on the car for 3 weeks before it was totalled. Ive got a coolant sensor for top of your coolant reservoir if you want to change that too. Send me $25 to cover shipping and post office run and they are yours! Hope this helps. Nel

Can you please send me your email in PM I think I would like to have those parts.


I checked the fan when the car is cold...well...33C outside
Anyway, when I try to spin it by hand, it has resistance. it doesnt spins freely.
Does it mean that the clutch is good? or it is better to take it off anyway and put the silicone oil and maybe adjust the center pin like Michael described?

By the way, is there a certain silicon oil that is used?

[928forlife]

What Normy said above about the spider leg sensor making the aux fan work is correct, at least on euro's.

There is a correct fluid and it is available from toyota I think, bought it once years ago, Do not waste time with it..

These cars do NOT like idling in hot weather. The mechanical fan is useless.

In fact no fan is needed once moving on the highway, just a FYI.

Get an electrical fan that mounts on the radiator with a good shroud, that is what you need. Normy was right on that too.