damn fan clutches
08-12-02, 01:20 PM
#1
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damn fan clutches
I had a bad fan clutch so i replaced it. Everything was working fine for about 2 weeks, but now im back where i was before - overheating in slow trafic.
Do you think i need to replace the clutch again ?
Or is there something else i could do?
When i open the hood with cold engine, i can tell that the fan is blowing a lot of air thru the radiator. I dont know how it acts when the engine is hot when im driving. I guess im just trying to figure out how the damn fan clutches work. Is there like a termo switch on them or something ?
Do you think i need to replace the clutch again ?
Or is there something else i could do?
When i open the hood with cold engine, i can tell that the fan is blowing a lot of air thru the radiator. I dont know how it acts when the engine is hot when im driving. I guess im just trying to figure out how the damn fan clutches work. Is there like a termo switch on them or something ?
08-12-02, 01:30 PM
#3
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Overheating – check list
1) Replace the thermostat. Make sure it fits. The spring loaded disc on the stat must close the bypass port, or guess what?
2) Replace the radiator cap. Low pressure = steam bubbles = spit out coolant.
3) Look for leaks. (same symptoms as #2) Some can be very hard to find. You may have to pressure test it. A common failure spot is the 3/8” coolant line that runs from the top of the rear housing (under the intake runners) to the throttle body, to the BAC, to the water pump. Another one is the heater hose under the oil filter.
4) The fan should pull really hard up to about 4k when the motor is hot. It should maintain about 4k as the motor revs higher. The cut-in for the series 4 fan clutch is gradual – it pulls some even when cold. The series 5 fan clutch is more on/off.
Your description sounds like a series 4 (86-88) with about 140000 miles?
1) Replace the thermostat. Make sure it fits. The spring loaded disc on the stat must close the bypass port, or guess what?
2) Replace the radiator cap. Low pressure = steam bubbles = spit out coolant.
3) Look for leaks. (same symptoms as #2) Some can be very hard to find. You may have to pressure test it. A common failure spot is the 3/8” coolant line that runs from the top of the rear housing (under the intake runners) to the throttle body, to the BAC, to the water pump. Another one is the heater hose under the oil filter.
4) The fan should pull really hard up to about 4k when the motor is hot. It should maintain about 4k as the motor revs higher. The cut-in for the series 4 fan clutch is gradual – it pulls some even when cold. The series 5 fan clutch is more on/off.
Your description sounds like a series 4 (86-88) with about 140000 miles?
Last edited by SureShot; 08-12-02 at 01:34 PM.
08-12-02, 01:53 PM
#4
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I see you are offline right now, so if the above is OK, here is another possibility.
My 87 was showing overheating symptoms. What finally fixed it? Would you believe the water pump housing? The aluminum casting behind the pump was eroded by the turbulence of the high revving pump and the previous owner using plain water for some time. The bypass valve seat under the thermostat had about a 4mm chamfer eroded away, and there was a 6mm hole eroded through the internal wall between the inlet and outlet side.
All this bypassing gives symptoms like a partially blocked radiator. I fabricated a repair with Bondo Marine Epoxy Putty Stick. It has held for a year before I sold it.
My 87 was showing overheating symptoms. What finally fixed it? Would you believe the water pump housing? The aluminum casting behind the pump was eroded by the turbulence of the high revving pump and the previous owner using plain water for some time. The bypass valve seat under the thermostat had about a 4mm chamfer eroded away, and there was a 6mm hole eroded through the internal wall between the inlet and outlet side.
All this bypassing gives symptoms like a partially blocked radiator. I fabricated a repair with Bondo Marine Epoxy Putty Stick. It has held for a year before I sold it.
08-12-02, 02:37 PM
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Well, i guess i can check everything that you've suggested. Somehow, i think tho that the fan clutch might be the problem again.
This is why :
1) the replacement clutch wasnt new when i bought it.
2) the cooling occurs whenever i actually get moving. It means that once i get some air moving through the radiator, the cooling system works fine. To me it also means that there can be nothing wrong with the water pump, rad caps or the termostat.
3) There are no leaks. Had the radiator replaced about a month ago. While i was at it, i replaced all hoses as well.
Do the reasons above narrow the problem down to the clutch?
This is why :
1) the replacement clutch wasnt new when i bought it.
2) the cooling occurs whenever i actually get moving. It means that once i get some air moving through the radiator, the cooling system works fine. To me it also means that there can be nothing wrong with the water pump, rad caps or the termostat.
3) There are no leaks. Had the radiator replaced about a month ago. While i was at it, i replaced all hoses as well.
Do the reasons above narrow the problem down to the clutch?
08-12-02, 02:44 PM
#7
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Sounds like the fan clutch. My 87 was slipping at 2500. You can get the fan clutch to bite better by bending the bimetal strip outward. That should help for a while. Food for thought - An electric fan conversion costs less than a new fan clutch..
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08-12-02, 02:48 PM
#8
Rotary Freak
The clutch fan works by a heat sesitive clutch. When cold, the fan is diengauged. You can even grab the fan when the motor is cold but I do not recomend doing so. Once the radiator becomes hot, the heat is transfered from the radiator to the fins in front of the fan. These fins are temperature pickups for the clutch.
The test for the system is to warm up the car to operating temperature and then stop the engine. Hop out and spin the fan. It should have resistence when spun over. I'd say if it spins around very freely, its time for a new clutch. If it spins like 1/3 a turn, then you are probably OK.
Have you tried turning the A/C on while in traffic??? Even if you dont have the A/C belt hooked up, turning the ac on will force the small electric fan to come on. Its a bandaid, but dont forget to do it if your car starts to get hot. That goes for everyone!
The test for the system is to warm up the car to operating temperature and then stop the engine. Hop out and spin the fan. It should have resistence when spun over. I'd say if it spins around very freely, its time for a new clutch. If it spins like 1/3 a turn, then you are probably OK.
Have you tried turning the A/C on while in traffic??? Even if you dont have the A/C belt hooked up, turning the ac on will force the small electric fan to come on. Its a bandaid, but dont forget to do it if your car starts to get hot. That goes for everyone!
08-15-02, 11:35 PM
#10
My Custom Title > Your's
If you buy an efan buy one of the expensive ones...not just an advance auto special. I used the efan off one of my mx6s (even fashioned a perfect shroud) it just was NOT enough to cool my car. I put my stock fan back on and the car stays COLD now
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