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, Mon, 15 Jul 2002 13:13:52
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Adam,
I have recently installed a new cooling fan thermoswitch on my '84 900S. I simply had to use a large thumb adjustable wrench (carefully, and from lack of a correct size open-end wrench or socket) on the switch (after removing the two wires, that is). I did the job after draining my cooling system (unknown time of last service + I wanted to switch to Mercedes-Benz type anticorrosion coolant), but I guess you can do it w/out flush/fill if coolant isn't turning rusty/murky/grainy feeling. I saw a post the other day that 31mm is the correct socket size for the fan switch, if you can get your hands on one.
It doesn't matter which wire connects to which terminal on the thermoswitch, as the switch "closes the circuit" across the two contacts anyway.
NOTES:
1) I switched out one other fan switch, w/out draining the cooling system. I used this trick to lessen coolant loss: Open the coolant reservoir cap, squeeze a radiator (upper or lower hose), then, while still squeezing hose, screw cap back on. This trick will help "suck" the coolant back toward the reservoir--for a little while at least--when you start to remove the fan switch.
2) I would recommend doing this job ONLY if you can catch the antifreeze spilled and dipose of it safely (toxic to many animals). Have plenty of old rags handy (absorbent, clean ones, not oily/greasy rags).
3) Tip: when you get the old switch out, take a moment to peer into the hole vacated by the switch. Look for whitish/reddish deposits, rust, or scale. These may indicate a neglected cooling system and a radiator in need of a flush/acid bath cleaning (or, at worst, a new rad.).
4) Have extra antifreeze/distilled water mixture to top off the coolant reservoir to offset the (inevitable) spill.
5) DON'T OVERTIGHTEN! The radiator is aluminum or brass and both are softer metals, so don't wrench too tightly (just snug!) when installing new switch or you may ruin the threads! Make sure new switch came with gasket, too.
6) You'll need to bleed the cooling system to get out all those pesky air bubbles which might have entered. Bleeder screw is on the upper side of the thermostat housing.
BLEED PROCEDURE, as per Townsend Import's page:
[Bleed screw] has two 11 mm (7/16") hexes. Hold the lower one and loosen the top one to allow trapped air to escape the system. Fill with the coolant/water mixture until the reservoir is to the max line on 9000s and until a steady stream of coolant comes out of the air bleeder port on a 900. Then shut the bleeder port on a 900 and fill to the max line of the reservoir. Check for leaks. Then start the car and let it idle. Pay attention to the reservoir. If air comes up (it will), re adjust the level. Run the car until the fans cycle once. You might want to reopen the bleeder screw on a 900 after the car runs a few minutes just to make sure there is no trapped air. After the fans cycle, recheck and adjust the level at MAX if necessary. Replace the radiator cap and run the car until the fans cycle again and shut it off. Let it sit for 15-20 minutes and check for leaks after the system builds all the pressure it should. After a complete cool down, recheck the level. Do this again just to be sure after another temperature cycle.
I had to remove my air intake snorkel to get at the switch, but my '84 8V non-turbo is a different setup than your 16V Turbo. I don't know if the Turbo induction pipes are in the way on yours or not.
Hope this helps!
Micah in NC
'84 900S, 215K mi.
'90 900, 65K mi. (Mom's, bad starter at present)
posted by 216.77.233...
, Mon, 15 Jul 2002 10:35:29, Mon, 15 Jul 2002 13:13:52
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