Oil cooler fan death - upgrades?
07-08-2018, 09:36 AM
#1
Three Wheelin'
Thread Starter
Oil cooler fan death - upgrades?
Sequence of events at yesterday’s autocross- Noticed the oil temp touching the 3/4 mark, which never happens since doing the resistor mod to have the fan kick in earlier. No wind under the front bumper confirmed that the fan wasn’t turning on. Found the 30A fan fuse had popped and replaced with a fresh fuse. Took a ~70 second run and smelled burning wires mid-way through. Pulled off the tire and wheel liner and the fan blades required a good bit of force to turn.
So dead fan and I’m going to have to open up the wiring harness to the fan and replace the wires.
Any fan upgrades available while I’m in there? Lighter? More efficient/lower amp draw? I couldn’t find the cfm spec on the stock fan anywhere on the net. There must be design improvements on this 30+ year old part? I’ll definitely be using a lower amp fuse on this circuit...
So dead fan and I’m going to have to open up the wiring harness to the fan and replace the wires.
Any fan upgrades available while I’m in there? Lighter? More efficient/lower amp draw? I couldn’t find the cfm spec on the stock fan anywhere on the net. There must be design improvements on this 30+ year old part? I’ll definitely be using a lower amp fuse on this circuit...
07-08-2018, 10:27 AM
#2
Race Car
Wow nick. Toasted wiring? Crazy.
Call me crazy- but I've not heard of the resister mod ? What's that all about and how did i miss this one?
On the fan upgrade- there has to be a way to use the original housing and instal a newer fan type in there- or with so many coolers out there - someone has to make one that has to bolt holes in the same place.
Call me crazy- but I've not heard of the resister mod ? What's that all about and how did i miss this one?
On the fan upgrade- there has to be a way to use the original housing and instal a newer fan type in there- or with so many coolers out there - someone has to make one that has to bolt holes in the same place.
07-08-2018, 11:05 AM
#3
Three Wheelin'
Thread Starter
You’re missing out, having the fan kick in a little earlier is a treat!
https://rennlist.com/forums/964-foru...by-212f-3.html
2.2kohm between the temperature switch on the oil cooler. Fan comes on at the 50% mark instead of the ~70% mark.
Spal seems to be the quality fan of choice, I’l try contacting them. I believe that our fan motors are the same as 944 radiator fans, maybe even the same as 924 fans from 1976!
https://rennlist.com/forums/964-foru...by-212f-3.html
2.2kohm between the temperature switch on the oil cooler. Fan comes on at the 50% mark instead of the ~70% mark.
Spal seems to be the quality fan of choice, I’l try contacting them. I believe that our fan motors are the same as 944 radiator fans, maybe even the same as 924 fans from 1976!
07-08-2018, 01:47 PM
#4
Rennlist Member
Resistor mod works well. Did this on mine.
Also wired in a manual switch.
And added a second cooler from carnewal
if it were me I’d just put a new OEM fan in.
Also wired in a manual switch.
And added a second cooler from carnewal
if it were me I’d just put a new OEM fan in.
07-09-2018, 12:47 PM
#6
Technical Guru
Rennlist Member
Rennlist Member
07-09-2018, 12:57 PM
#7
Rennlist Member
The answer is it depends. on what you have done to your car, and what sort of weather you run the car in, and how hard.
Keep in mind race cars... they run harder, they focus on reliability, FOR THAT RACE!
Other than longer warm-up (you could put in place another thermostat on the 2nd cooler...) and higher oil change costs, there isn't much of a downside to more oil cooling if you're going to run the car hard. I personally like the idea of better passive cooling capacity, as that fan is critical for temp stability once you get to 9 o'clock on the gauge.
For me, I'm also going to be building the motor at some point, hence the 2nd cooler while everything else was apart.
Keep in mind race cars... they run harder, they focus on reliability, FOR THAT RACE!
Other than longer warm-up (you could put in place another thermostat on the 2nd cooler...) and higher oil change costs, there isn't much of a downside to more oil cooling if you're going to run the car hard. I personally like the idea of better passive cooling capacity, as that fan is critical for temp stability once you get to 9 o'clock on the gauge.
For me, I'm also going to be building the motor at some point, hence the 2nd cooler while everything else was apart.
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07-10-2018, 11:51 AM
#8
Nordschleife Master
Did you install a stronger fuse when you replaced the original burnt out fuse? I would expect the fuse to pop again, not push the problem to the point of melting wiring. That's what the fuse is there to prevent. Hopefully repairing the harness isn't too much of a task.
07-10-2018, 02:54 PM
#9
Rennlist Member
Fuse 2 is oil cooler fan, 25A?
07-16-2018, 09:45 PM
#10
Three Wheelin'
Thread Starter
Mine was a 20amp fuse. But- I pulled it apart over the weekend and was very happy to find that the fan pcb and an internal wire were all that melted down. The fan wiring harness and relay both survived without any problem. I opened up the fan body for an autopsy and found the bronze bearing on the rear of the fan (one of those impregnated oil bearings I believe) was frozen to the fan shaft. I have one of those cheap "JP Group / Dansk" replacement fans coming and will see how the output compares to the ~good stock a/c condenser fan that I have out. The replacement oil cooler and a/c fans are now one and the same. In fact, it's hard to tell what ever made them any different.
I didn't see anything in the Spal brand catalog that looked like a worthwhile upgrade. Here is what I found/discovered for the stock fan. Maybe someone else will come up with a brilliant 1lb fan upgrade for this chunky part:
From Bosch, specs on the AC fan: 12V, 170W (=14.2Amps), 2800RPM
4.32lbs fan motor+plastic blade
1.0lbs plastic housing
11" square, fan housing
3.5" thick, fan housing
10" diameter, fan blades
3" radius to each of the 3 fan motor mounting studs
counter-clockwise rotation
964.624.035.01 the latest p/n for the oil cooler & AC fan
0130304214 the original Bosch p/n for the AC fan
0130304213 the original Bosch p/n for the oil cooler fan
I didn't see anything in the Spal brand catalog that looked like a worthwhile upgrade. Here is what I found/discovered for the stock fan. Maybe someone else will come up with a brilliant 1lb fan upgrade for this chunky part:
From Bosch, specs on the AC fan: 12V, 170W (=14.2Amps), 2800RPM
4.32lbs fan motor+plastic blade
1.0lbs plastic housing
11" square, fan housing
3.5" thick, fan housing
10" diameter, fan blades
3" radius to each of the 3 fan motor mounting studs
counter-clockwise rotation
964.624.035.01 the latest p/n for the oil cooler & AC fan
0130304214 the original Bosch p/n for the AC fan
0130304213 the original Bosch p/n for the oil cooler fan