brian in buddina Posted 2June, 2018 Report Share Posted 2June, 2018 I have a 1988 944S Last night my radiator fan continued to run on after the motor was switched off. I tried removing the fuse. fuse #10 no response, the fan continued to run on fuse #15 stopped the fan I googled and found a response from Rennlist that its the thermo switch failure. On the katalogue item 29 thermo switch part number 930 606 118 00 A couple Questions: 1. Is there another test I should do to make sure its the thermo switch and not a relay or other electrical issue? 2. is this a standard part or porsche only bit? Link to comment Share on other sites More sharing options...
TINGY Posted 2June, 2018 Report Share Posted 2June, 2018 Hi @brian in buddina, this happened to me late last year i think. I just bit the bullet and got the thermo switch and luckily this was the problem. To investigate the other option requires another relay and i am not sure who is close to you to be able to borrow one, it is also way more expensive. All up i think it cost about $40 for the switch and i had to buy a 29 mm impact socket to do the job because you need the extra length to get over the switch. A fairly easy job once you get going and work out how to get your hands up to the switch from underneath, just take your time, it's a bit frustrating at first but it all comes together. From my experience there is no way to do the job from above easily so to save wasting time just empty some coolant, preferably to just below the switch as it comes running out all over, or just take out the switch and get the new one up there as fast as possible whilst coolant runs out all over you, yes this is what i did. I got everything from Bursons which @Corki944 was kind enough to organize for me, and the cheap socket i got to do the job was $10. There are a couple of different heat ranges to choose from and i dropped mine 5deg to 87-97deg i think it was and the brand is Tridon. Link to comment Share on other sites More sharing options...
Buchanan Automotive Posted 3June, 2018 Report Share Posted 3June, 2018 Hi Brian, the part number 930 606 118 00 is incorrect ,, from memory I think its 191 959 481 C , there are two fuses for the rad fans ( 2 circuits ) hence the two fuses & the large relay that control them has two outlets , one to each fuse & then onto the electric fans ( BWA sells the correct radiator fan switch, and they are not expensive ) Note } Both rad fans run at the same time & at the same speed to each other , if one fan motor drops out the fan control relay ( double relay ) senses that and switches the one remaining working fan onto max speed to try to compensate Note 2 } The fan switch in the rad side tank ( 191 959 481 C ) can cause a few interesting issues when they fail , and because they are inexpensive its always a good place to start Note 3 } In the last few years we are seeing more & more of the old fan control relay's fail ( the double relay in the CEB ) & they have three or four different failure modes Note 4 } in old age its quite natural to have one fan motor fail before the other one & yes as these fan motors get older & older they put more and more amperage load on the reasonably expensive double fan relay ,which in turn causes amperage heat/burning damage to the double relay Note 4 } When diagnosing under the car , remove the push on 2 pin multi plugs that go onto the individual fan motors , if you see the white plastic 2 pin plug that goes into the individual fan motors discoloured to a light brown colour ( instead of white ) pull back the ribber insulation boot to uncover the wiring going into the 2 pin plug , if its quite discoloured then this is heat / amperage damage to the wiring ( at the plug ) this only increases the amperage spike to the expensive fan double relay Note 5 } CEB = central electric board or fuse relay board UPDATE , my part number ( at home ) memory was incorrect , I just checked our parts dept ( as I am now at work ) and the correct part number for the correct BEHR rad fan switch is 951 606 481 00 Regards Bruce B Link to comment Share on other sites More sharing options...
brian in buddina Posted 6June, 2018 Author Report Share Posted 6June, 2018 thank you gentlemen, much appreciated. @TINGY944 @Buchanan Automotive the deep 29mm socket is a really a tight fit. Ran out of light this avro. I have an outdoor wall less shed/workshop. Will try again tomorrow to finish up. Is the radiator meant to jiggle around a bit? I see it has 2 rubber stops at the top locating the radiator. On another issue with the cooling system I've noticed a new small puddle under the car just between the exhaust manifold & the power steering pump. I've tried to identify where the leak is coming from and it looks like around where the rubber coolant line feed to the interior car heater. Pretty tight in there. The last time I used the car, it was so cold here in Qld, that I used a little cabin heat. I noticed that I left the temperature control knob on the dash in a mid to low temperature setting. Could this be a cause for my coolant leak? As this knob would rarely be used in a Qld car. I've checked all the rubber hoses in that area and they look ok...to a apprentice I tighten a couple of hose clamps in the area. We will see if I still have a leak tomorrow when I, hopefully, finish up. Link to comment Share on other sites More sharing options...
brian in buddina Posted 13June, 2018 Author Report Share Posted 13June, 2018 Last week I installed the new thermo switch, I needed to loosen the fan shroud just a few millimetres to get the socket on the thermo switch. I didn't over tighten when installing the new one. I had to do it twice to stop a drip so as to not over tightened it and crack the plastic radiator tank. Unfortunately I still had the fan run on. I did a test from Clark's Garage web site where I put a jumper between socket 2 & 3 from the fan connector. Looks like the relay? As I had an important engagement for the weekend at Lennox Head and was running out of time to make a fix, I pulled the fuse for the fan. Luckily no over heating issues over the weekend. Well, I will try to sort out a solution this weekend. Among a few other P car preservation projects. I think its on Clark's Garage that they mention you can check for hairline cracks in the solder joints on the circuit board inside the relay. Then re solder or just heat up the solder joint to remove the hairline crack. Has anyone done this? As a new relay is relatively expensive, is there anything else I should check or test? Link to comment Share on other sites More sharing options...
OZ930 Posted 13June, 2018 Report Share Posted 13June, 2018 5 minutes ago, brian in buddina said: Last week I installed the new thermo switch, I needed to loosen the fan shroud just a few millimetres to get the socket on the thermo switch. I didn't over tighten when installing the new one. I had to do it twice to stop a drip so as to not over tightened it and crack the plastic radiator tank. Unfortunately I still had the fan run on. I did a test from Clark's Garage web site where I put a jumper between socket 2 & 3 from the fan connector. Looks like the relay. I think its on Clark's Garage that they mention you can check for hairline cracks in the solder joints on the circuit board inside the relay. Then re solder or just heat up the solder joint to remove the hairline crack. Has anyone done this? As a new relay is relatively expensive, is there anything else I should check or test? Check the connectors are clean and If you take the cover off the relay, check that the contacts are clean. Link to comment Share on other sites More sharing options...
TINGY Posted 14June, 2018 Report Share Posted 14June, 2018 6 hours ago, brian in buddina said: I think its on Clark's Garage that they mention you can check for hairline cracks in the solder joints on the circuit board inside the relay. Then re solder or just heat up the solder joint to remove the hairline crack. Has anyone done this? I have fixed a DME relay, well, my electrical fitter son fixed it by just re-soldering all connections, it never missed a beat after that. I think most can be repaired but will depend on how much heat they have seen i was told. Link to comment Share on other sites More sharing options...
Peter M Posted 14June, 2018 Report Share Posted 14June, 2018 http://www.911chips.com/dmerelay.html Link to comment Share on other sites More sharing options...
TINGY Posted 14June, 2018 Report Share Posted 14June, 2018 3 hours ago, Peter M said: http://www.911chips.com/dmerelay.html This explains why my son put heaps of solder on, trust me he said. I am about to pull the brain out for the cruise control for him to do, another frustration of mine. Link to comment Share on other sites More sharing options...
Peter M Posted 14June, 2018 Report Share Posted 14June, 2018 My vague recollection is the cruise controls commonly fail because of a faulty capacitor and maybe a microchip at worst. If you do some searches there should be a thread or two on Pelican. I understand they - 911's, 944's and 928's - shared the same unit. Link to comment Share on other sites More sharing options...
TINGY Posted 14June, 2018 Report Share Posted 14June, 2018 My unit has a part no. that starts with 944, i wonder if they are all like that? I have only been looking at the basic fixes so far and it seems that one of those didn't work. Link to comment Share on other sites More sharing options...
Peter M Posted 14June, 2018 Report Share Posted 14June, 2018 I understand the same control unit was used until '88. Just realised your car is '89! Sorry EDIT: Just checked. The pre '89 cars used 928 617 127 00 Link to comment Share on other sites More sharing options...
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