This resistor is aluminum with heat sinks on three sides. The fourth side is for mounting, with a flange and two screw holes. I bought thermal adhesive so that should help with the contact. Just need the opportunity to install it.
I think earlier installers didn't realize it was important to mount it in the fan's airflow. If it is just in the car's airstream when the car is moving, it's not getting cooled under low fan conditions (sitting in traffic). I can do that... just needed to be convinced that leaving the resistor in the loop was important, especially considering its potential impact to reliability of low fan. I am now convinced that it is important. I also get to keep a short 'bypass wire' in the trunk next to my spare DI cassette.
This thread is not about the SAAB's Oil Pressure.
Re: This thread is not about the SAAB's Oil Pressure.
You could wire in an LED across the resistor (with another resistor). That would act as a "low speed fan engaged" light. If the resistor is dropping voltage, it is working in low speed.
Re: This thread is not about the SAAB's Oil Pressure.
So I finally got around to installing that fan resistor today. I was itching to do it but just didn't have the time during surviveable temperatures to do it.
Pics may come tomorrow... Or not. It's not a pretty install, but it works.
I checked the resistance on the the three leads to the resistor once I removed it. Dead short between two of them (Fan HI to Motor lead) and no connection between the other two (Fan Lo to Motor lead). So I did indeed have a bad resistor.
I made a sheet metal bracket, attached with 'Speed Nuts' to the fan shroud. This allowed me to put the resistor in the path of the fan. I used thermal adhesive and two tiny screws to attach the finned aluminum 0.2 Ohm resistor to the bracket.
I soldered the Fan Hi and Motor lead to each other and to a lead to one end of the resistor. I soldered a lead from the lo fan to the other end of the resistor.
Result:
I checked the fan by removing the hi and lo fan relays. I then bypassed each relay. Conveniently, these work off of non-switched power so I didn't even have to put the key in the ignition for the test. Fan spun fast on Hi and a bit slower on Lo. Perfect.
I performed a test drive with the OBDII scan tool plugged in to check coolant temps. I couldn't help but feel a bit like Kevin when doing this. I watched the coolant temps. On mixed city/highway, it seems to settle around 180F plus or minus three degrees. I had to sit it in the driveway for a bit to get it high enough to kick on the low fan. The fan kicks on at about 208F. It brings the temp down about 15F, then kicks off.
The best part: My oil pressure was above 14psi throughout the test, and was mostly above 15psi. The loop was only about a half hour of driving, combined with five minutes or so of unexpected engine-off time (see my booooost thread in a couple minutes for that one....)
Of course, I wont be sure if this is improved until I do a full commute or two in it. But the results are pretty promising. Remember, the coolant temp used to get up to 235F or so before the hi fan kicked on. At that point, oil pressure would be hovering between 9 and 13 psi.
Pics may come tomorrow... Or not. It's not a pretty install, but it works.
I checked the resistance on the the three leads to the resistor once I removed it. Dead short between two of them (Fan HI to Motor lead) and no connection between the other two (Fan Lo to Motor lead). So I did indeed have a bad resistor.
I made a sheet metal bracket, attached with 'Speed Nuts' to the fan shroud. This allowed me to put the resistor in the path of the fan. I used thermal adhesive and two tiny screws to attach the finned aluminum 0.2 Ohm resistor to the bracket.
I soldered the Fan Hi and Motor lead to each other and to a lead to one end of the resistor. I soldered a lead from the lo fan to the other end of the resistor.
Result:
I checked the fan by removing the hi and lo fan relays. I then bypassed each relay. Conveniently, these work off of non-switched power so I didn't even have to put the key in the ignition for the test. Fan spun fast on Hi and a bit slower on Lo. Perfect.
I performed a test drive with the OBDII scan tool plugged in to check coolant temps. I couldn't help but feel a bit like Kevin when doing this. I watched the coolant temps. On mixed city/highway, it seems to settle around 180F plus or minus three degrees. I had to sit it in the driveway for a bit to get it high enough to kick on the low fan. The fan kicks on at about 208F. It brings the temp down about 15F, then kicks off.
The best part: My oil pressure was above 14psi throughout the test, and was mostly above 15psi. The loop was only about a half hour of driving, combined with five minutes or so of unexpected engine-off time (see my booooost thread in a couple minutes for that one....)
Of course, I wont be sure if this is improved until I do a full commute or two in it. But the results are pretty promising. Remember, the coolant temp used to get up to 235F or so before the hi fan kicked on. At that point, oil pressure would be hovering between 9 and 13 psi.
Re: This thread is not about the SAAB's Oil Pressure.
Nice. It's almost like you...care about the car.
Re: This thread is not about the SAAB's Oil Pressure.
I guess I must care. I've had it since March 2004!
Re: This thread is not about the SAAB's Oil Pressure.
Yes, the temps, pressures, enabling and disabling conditions do seem like my kind of thing. It's not totally unlike the kind of thing you deal with while tuning.Fast_Ed wrote: I performed a test drive with the OBDII scan tool plugged in to check coolant temps. I couldn't help but feel a bit like Kevin when doing this. I watched the coolant temps. On mixed city/highway, it seems to settle around 180F plus or minus three degrees. I had to sit it in the driveway for a bit to get it high enough to kick on the low fan. The fan kicks on at about 208F. It brings the temp down about 15F, then kicks off.
Re: This thread is not about the SAAB's Oil Pressure.
After a month of regular driving of this car, I have yet to see the oil pressure drop below about 12psi. Even during continuous stop-and-go traffic.
This means that if I knew what I know now, and had replaced the fan resistor when I first saw the low oil pressure light, I'd be driving a 200k Viggen instead of a 168k Viggen. I would have replaced the resistor for about 10 bucks, never seen the oil pressure light again, never installed an oil pressure gauge, and never have pulled the engine/head/timing cover all those other times. Also, I would have no roadmaster, which would be sad.
I guess all in all, the years of saab horror really worked out for the best?
This means that if I knew what I know now, and had replaced the fan resistor when I first saw the low oil pressure light, I'd be driving a 200k Viggen instead of a 168k Viggen. I would have replaced the resistor for about 10 bucks, never seen the oil pressure light again, never installed an oil pressure gauge, and never have pulled the engine/head/timing cover all those other times. Also, I would have no roadmaster, which would be sad.
I guess all in all, the years of saab horror really worked out for the best?