Cyberpunky

Today I was stopped for a minute and saw my temp rise dramatically, as soon as I moved off the temp dropped back to normal. Every time I stopped I would see the temp rise again. At first I thought this was just from air but as I wasn't going very fast I wondered if it was the air. The next set of lights I increased the revs to about 1200-1500 and the temp dropped immediately.

I nursed the car home this way and when I got home noticed the water pump was working after switch off but not the fans. I checked the fuse, and it is fine so am thinking it is the relay. Any ideas on if this is the only possible reason fans would not be working or there other things that could cause them to not function or other things I should check ?
TIA
peace
Cyberpunky

Thom

Check the fan temp switch, in the radiator below the upper hose.

ausgeflippt951

When you say water pump was working you're referring to the aux pump for the turbo correct?

That is on a different circuit than the fans. First thing I would do is check your fan relay. Also, how is the shape of the connectors? Over time they can disintegrate. If all else is working you may need a new fan switch. They're cheap and easy to replace (though you will have to drain a bit of coolant beforehand).

Cyberpunky

Yes I mean the aux water pump for the turbo is still working.

Connectors ? do you mean at the fans ? how do find/inspect them ?

I have used relays for years but not sure how to test this relay, as
1/ there is no diagram on it like anormal relay
2/ it looks like it is actually 2 relays inside a metal cover (G10) on my 952
3/ it sits flush onto fuse box

Can I check fan switch by playing with setting IE turn it ? in both directions to see if activates fans ?

I just spent a fortune replacing turbo so don't want to damage the engine, so all help is appreciated, as I can't afford another melt down

86 951 Driver

Do the fans kick on when you press the A/C button? They should at least run at low speed with the A/C button on.

http://www.clarks-garage.com/shop-ma...tefanoperation

Best troubleshooting guide for the cooling fans. If you think its the fan switch(very common) then you can jumper it like they show on clark's. If it doesn't pass that then it is for sure the relay or wiring. The relay is very expensive. If I remember right you are an audio wiz that can solder. If you can you might be able to fix the solder joints in the relay and go on your way.

cruise98

Here is another cooling fan test procedure you can use.

During normal operation, and you have the factory rated thermostat, the coolant temperature gauge should read at or near the lower white line (80 degrees C) and will creep up to the mid-point between the upper and lower white lines when sitting still in traffic. The upper white line represents 100 degrees C. If the temperature normally runs above the mid-point, you need to investigate immediately.
There are several temperature ratings of the thermo switches, so it is hard to say at what point they should turn on for your car. If they are not both running at high speed when the temperature is above 90, you might have a problem.
The fans are controlled by the cooling fan relay which is in turn controlled by the thermo switch, and the a/c system. Whenever they are closed, both fans should run at the same speed at the same time. If only one is working or you only get high speed operation, there is a problem.

You should always have power available to the relay, so the fans can run at any time. Remove the cooling fan relay. It is the large rectangular silver relay in the back of the panel. Check the diagram on the fuse panel cover for the exact location. All of the following checks can be made at the fuse panel. You will need a bright light to see the markings on the fuse panel.

1. In the Bosch world, a terminal designation of “30” means it is un-switched battery voltage. Check for voltage at positions 30 M1 and 30 M2. You should get 12v + at both positions. If no voltage, check the wiring from the battery, the connections to the fuse panel, and the fuse panel itself. You will have to pull the fuse panel up, but disconnect the battery before messing around under the fuse panel.

2. Check for continuity between ground and the temp switch positions "TS" and "TF" on the fuse panel. If you have continuity, the thermo switch is calling for fan operation. If the car is cold, the thermo switch is bad.

3. Fabricate a jumper wire with flat blade connectors on each end, and a 20a fuse in the middle.

4. Connect the jumper between M1 30 to M1, the drivers fan should run at high speed. If the fan does not run, check for voltage in the connector at the fan motor, if you have voltage but the fan does not run, replace the fan motor.

5. Check the passenger fan by connecting the jumper between M2 30 and M2, the passenger fan should run at high speed. If not, the same drill.

6. Next connect the jumper between M1 30 and V1, the drivers fan should run at low speed. If not the resistor or wiring is bad. Check for voltage at the radiator fan connector and then check the resistance across the resistor.

7. Next connect the jumper between M2 30 and V2, the passenger fan should run at low speed. If it does not run, check the wiring and resistor.

If the car is still running hot and the fans are working properly, you have other issues, like a clogged radiator, water pump failing, air bubbles, bad thermostat, or a bad head gasket.

The other positions on the fan relay are:

X = battery power to the logic board in the relay
31 = Ground for the logic board in the relay
AC = AC freeze protection switch

Cyberpunky

OK ran relay test as per clarks garage and relay is good and fans work so it must be thermofan switch.
I found an article on how to replace the thermo-fan switch but if anyone who has done this has any tips or things to watch for, that would be great
cheers

Cyberpunky

OK so car is sitting on ramps ready to do thermo switch swap, but I cannot remove fans, as I cant get to centre top bolt and even if I could get it out I doubt I could get it back in. It looks like I have to pull so much stuff out to get to it
Clarks says it can be done without removing fan assembly so I think that is how I will have to do it. I am waiting for auto shop to ring me and say 29mm deep socket is here, so I can get thermo fan switch out.
Has anyone done the swap with fans still installed ?
is it do-able ? I cant see why clarks says he has no luck that way as removing the fans doesnt look like it will make much difference to me. Going to be tight either way by the looks of it
any way any info is appreciated
peace
Cyberpunky

Thom

On an S2 there isn't the coolant hard line that also works as the airbox bracket used on turbos so there should really be nothing in the way to reach the center top bolt. Can you post a pic?

URG8RB8

I replaced mine last year, hardest part is draining the radiator. I suggest buying or making the LR drain kit. That way you are golden the next time you have to drain. I did not have to remove anything just need the correct wrench for the switch. There are also multiple temp range switches available now I'd you need to lower cut on temp in a hot climate. If you search under my name you can see the makeshift drain solution I used that worked pretty well.

ehall

Hey Bruce,

If the new switch doesn't fix it, it could be as a result of bad electrical cables. I just had that happen, as a result of jiggling a known messed up battery terminal/cables. I'm putting in the Iceshark cables this month, but yeah, anyway, I was surprised but that was the cause both of my fans not running, at any temp and my engine light and ABS warning light were triggered. These old wires are pretty crappy at this point.

Seattle944

That's what I was thinking.. I would look at the wires for the fans before putting the new switch in. I think the switch your talking about goes into the rad, correct? If yes they also make switches that turn on about 10 degrees cooler for both low and high speed. Might consider pick one of those up.

Cyberpunky

Hey Thom. It's an 86 turbo (952=RHD) not an S2, so yeah its that hard line that makes it so hard to get top centre bolt. Got job done with fans in place. I may upgrade to the V12.com fans later and when I fit them will probably just not refit that centre bolt.

Couldn't find your post regarding make shift drain solution but after now having done it(what a mess lol) I will be ordering the LR kit, ready for next time

Hey Elliot
Looks like the new switch has fixed it. The fans kicked in after I replaced coolant, but the real test will be on way to work tomorrow.

Thanks for all the advice everyone, it helped a lot. It's not that hard a job, just tight and messy. Will be getting the LR drain kit as it will make things sooo much easier/less messy, once fitted. Anyway was great to do it myself and I saved a lot of money compared to paying someone else to do it and I now own a 29mm socket that I probably won't ever use unless I do this again lol
peace
Cyberpunky