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Oil Fan cooler issue

G

grandad

New member
Hiya guys I have a query.

Does the oil cooler fan spin all the time or just at certain times when a certain temperature is reached.

I have just noticed that when I pulled up in my garage and the car was up to running temperature the fan was not running. I have currently have issues with the oil pressure dropping down to 1 bar at idle and rev counter dropping down to 600rpm between gear change.

Have I got a problem with my cooler. If so should I check the relay first. Can I interchange any other relay for the cooler one for now? How can I check to see if my coller is operational at 2 speeds?

Things which I have done to try and remedy the problem so far. New DME relay. Cleaned the ISV. Removed air box and air flow meter and cleaned both.

Any help would be appreciated.
Car spec C2 wth no air con.

Cheers in advance
Ray
 
Ray,

The oil cooler fan doesn't run all the time. There is a temperature sensor mounted on the radiator and the slow speed will be activated by the CCU when the temperature gets to a certain point (I don't have the exact temperature to hand). If the temperature reaches a higher threshold the high speed will be activated.

The relay that controls the fan is the same type of relay as is used for the rear blower. The rear blower relay is in the engine comapartment electrical panel, the oil cooler one in the front fuse box.

It is possible to check both speeds by jumpering the contacts of the relay but I'd have to check the points. Adrian Streather's book has all the details.

The 1 bar oil pressure at idle is not unusual and is perfectly acceptable when the oil is hot.

The idle speed shouldn't drop that low (as you already know) and definitely sounds like an ISV issue. Maybe cleaning isn't enough. The ISV is a strange little device which is very subtle in the way it works and it's entirely possible that it just isn't working right. Swapping to a different one would be an ideal check but it's not the sort of thing you have lying around. Maybe one of the indies might have one that could be tried.

Hope that helps.

Regards

Dave
 
Dave you are a wealth of knowledge.

I have the car booked in at Porsche on the 22nd as there is a recall outstanding so I thought I would give them a whirl.

I will swap the rear blower relay for the oil cooler when I get a chance tomorrow and see if that makes a difference.

Thanks for clearing that up though I feel a bit better. Was getting a bit worried witht he cooler fan not running. I will swap the relays and let the car idle and see if the fan cuts in at both speeds.

Thanks again. I will keep you posted to my results. I may as well order another relay just in case as a spare.
 
Hiya Dave,

I have tried changing the relay and tried letting the car run until oil temp was just about at 10o'clock but the oil cooler fan did not kick in so I turned the car off. Did I bail out too soon, or have I got a fan problem. If so how can I check to see if there is any operation in my fan. The relay was fine as I swapped the rear blower one around and rear blower worked with both relays installed.
 
Ok the next diagnosis i would do, would be take the front right hand inner arch cover off and on the oil radiator you will see the oil fan thermostat, I would link the two connections together to see if the fan even runs ....then this will proof the fan works or the thermostat for the fan is open circuit.

Sounds like something is not right is the fan will come on at approx 9:00 on the gauge .
 
OK - given that you've proved the relay is good it starts to get a bit complicated. There are several possible causes so we need to prove the blower worksfirst of all. If you remove the relay (R04) and jumper pins 30 and 87. This will apply 12 volts to the fan motor and it should run at high speed. If it doesn't it points to the CCU as faulty. Jumpering pins 30 and 87c will run the blower at slow speed. If high speed works but slow speed doesn't then the ballast resistor is toast. If neither speed works the fan motor is toast. If all works as intended with the jumpers and the relay is OK then it looks like the CCU.

Hope that helps.

Regards

Dave


 
Hiya Dave, thanks for that. I have done the test and the oil cooler fan works at high speed but not at low speed. I take it that the ballast resistor must be knackered.

I will order one tomorrow. Can i fit this myself or would I require an autoelectrician? If it is a DIY is there a write up on this somewhere?

Thanks again
 
There is a ton of information on p-car (here) about the troubleshooting and the resistor replacement. You'll have to remove the wheel arch liner on the right side and it's a bit awkward, but doable.

Regards

Dave
 
Cheers Dave. I have found the info which I need. All I need to do now is to give it a shot on the weekend. The slow speed fan should kick in at just above 9'oclock position. Which is where my car never usuallt gets to but I will replace the resistor as a matter of course.

Your a star. Thanks again.

The procedure for replacing the resistor is as follows. I have copied this, from the web site mentioned above.:-

[font=arial,helvetica][size=-1]I spent last 2 days (at least a couple of hours after work) try to replace the darn thing on my own......finally gave up and took it to my Porsche mechanic at the dealership this morning. He did exactly what I did as I watched him (no other dealerships that I know would allow their customers watch mechanics work on cars except this one....don't ask me why....no complaints from me !!) working on it, basically loosen up all the bolts that the cooler's attached to the body of the car. The cooler still wouldn't move and could see from his face expression that he was running out of patience......well to make the long story short, I learned a trick today that may help you guys a lot if you plan to do this on your own.....it basically boils down to one bolt (located at not so obviously place that is at least to me) that has be removed. [/size][FONT=verdana,geneva"]
[font=arial,helvetica][size=-1]YOU HAVE TO REMOVE THE HEADLIGHT ASSEMBLY FIRST. UNDERNEATH IT, YOU WILL SEE A BOLT THAT HOLDS THE SHEET METAL (which is attached to the cooler) IN PLACE......once he removed it, he was able to slide out the cooler w/ no effort. From that point on, all you need is a 4 mm allan wrench to take out the old resistor and put the new one back in place.....maybe 2 minutes job.[/size][FONT=verdana,geneva"]
[font=arial,helvetica][size=-1]Now the fan comes on at the low speed. It started coming on when the temp needle was approaching 9 o'clock position. As I were driving the car to home even in heavy traffic, it never exceeded 9 o'clock position. Although I am $150 out of pocket, I am happy to know that my car has no mechanical flaws now. I am also happy that I can share this w/ the fellow rennlisters. [/size][FONT=verdana,geneva"]
 
Dave I have fitted the ballast resistor and have again jumped the pins 30 and 87c and again the fan did not work. When I fitted the resistor there was a metal circular plate which I fitted directly under the resistor and attached a nut from the other side. Is that correct?
 
It sounds about rught. The resistor is switched into the circuit by the relay using the same current source. If the resistor is OK it can only mean that there is a problem with the wiring from the relay to the resistor to the fan. It sounds like it's time to break out the voltmeter!!!

I've not done the job myself but I'm assuming that there is some insulation between the resitor itself and the mounting since the wiring diagram shows 2 wires to it.

Regards

Dave
 
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