I'm planning to put electric fans on my slant. The thermostat for the fans kicks on at 185 and off at 175 deg, but my slant's thermostat is a 180 deg. Should I change to a hotter opening thermostat in my block or is my 180 deg OK? Seems to me, I should put a hotter thermostat in the block so that the fans' thermostat operates properly.

Thanks All,

BG

The fans will run all the time ask me how I know

If it's a 180 stat I'd look at least for a 190 switch. The stat starts to open at 180 and is there to let the rad do it's job. So if the stat is 180 and the switch is 180 on, once the head is at operating temp then the fans won't shut off. Had to pull the fuse on mine for now.

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

OK, so I should get a fan thermostat that kicks on, and shuts off, at temps above the 180 block thermostat, right? Say, kicks on at 200 and off at 185, something like that?

Also, if I'm putting the fan thermostat in the radiator hose, should it be in the inlet (top) hose, nearer the block thermostat so it sees the hottest water coming out of the block, or in the outlet (lower) hose so it sees the water after the radiator? I've seen them put in the lower hose, but it seems to me you'd want it closer to the block thermostat.

bg

This blurb, see: http://www.alumrad.com/fans.htm scroll down to the inline thermostat housing, says the thermostat for the fans should be in the lower radiator hose. If that's true, I think the 185 deg on, 170 degree off is correct thermostat, because it kicks on at 185, i.e. when the coolant coming out of the radiator is 5 degrees above the engine thermostat opening. Then when the fans have cooled the coolant down to 170 degrees, the fans shut off. The 170 degree coolant will enter the block, get heated back up, and keep the engine thermostat open, but it seems like the fans won't stay on because they are reading the coolant temperature after it passes through the radiator. At highway speeds, it shouldn't get to 185 degrees at the lower hose, but at idle or under load it will.

Does this make sense? I'm thinking the fan thermostat should go in the lower hose and the 185/170 deg is the correct one....

Somebody school me if I'm wrong, Pohlman is your fan thermostat in the top where the coolant is hot or in the bottom?

BG

Get an adjustable fan thermostat.

That way you can get it to turn on and off when you want, plus compensate for sensor placement.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I guess they both may be right. That is, with a 180 deg engine thermostat:

In the top hose, a 200/185 fan thermostat should work, because it's not fighting against the engine thermostat, it will turn on at 200 and off at 185, so the fan won't run continuously, but will keep the system temp in check.

In the bottom hose, a 185/170 fan thermostat should also work, because it only kicks on when the coolant exiting the radiator gets up to 185 degrees, and the fact that it shuts off at 170 is OK, because the 170 deg coolant exiting the radiator will enter the block in order to extract heat, but by the time it gets to the engine thermostat it'll be at least 180 degrees and so the engine thermostat won't close; operating temperature will be maintained.

Does this make sense?

BG

If it's a lower rad hose install then I'd go w a 190 off, that gives a slight bit more room while sitting at a light etc. so that it's not a lot of on off on off. You got the idea down. I wouldn't do an upper hose but that's me.

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

I have some time to think about it...I installed my shroud with dual 10" fans, but the power steering bracket was cracked/bent and my power steering pulley was touching the electric fan. I had a detour while I reshaped my power steering bracket, welded the (many) cracks and also welded in a strut to support the tab that bolts to the back of the pump. See: http://s785.photobucket.com/user/67dart ... sort=1&o=0

I had to move my power steering pump back about 1/4 inch so it wouldn't hit the lower of the two fans. It was too far forward anyhow, with the cracks in the bracket, the stress pulled it forward too much. It's in place now solidly, but I don't have the 1.5 inch hose inline thermostat fitting or the fan thermostat yet...Summit will have it to me by Monday. They must love me at Summit...you might guess why.

Anyway, I'd rather do the bottom hose, but I can't find a 1 3/4 inline thermostat housing, only 1 1/2, so I think I'll do the top hose with the 200/185 fan thermostat. Auto meter makes a really nice inline fitting, see: http://www.summitracing.com/parts/atm-2 ... Qgodj1wAfQ It ain't cheap, but how many times will I do this?

BG

As you can see the water pump pulley has about 1/2 inch clearance from the fans, but the power steering pulley is about 1/4 inch from the lower fan. See: http://s785.photobucket.com/user/67dart ... sort=1&o=0

Anyhow, I have to wire the relay, circuit breaker, etc. tomorrow. This work was just to get the system to actually fit.

BG

My engine is chrysler red, not orange, I had my iphone camera settings off...

OK so I'm cheap and like to try new things,does anyone know when an oem temp. lite switch opens and closes?

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81 LeBaron Salon,88 5th ave,79 Aspen SE wagon,79 W150
Don't worry, nothing is going to be alright.

This article may help: http://www.moparmusclemagazine.com/tech ... es_repair/

bg

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I got the dual 10" fans installed, I used an on at 200 deg, off at 185 deg thermostat sending unit in the top hose (with ground wire), along with a 180 deg thermostat in the block.

It works great, only turns on occasionally, like when I'm sitting at a stop light. The fans are really quiet. Temp gauge is steady. I think the triple core small block V8 radiator helps. I'll post a pic later, it was getting dark by the time I finished my test runs.

Thanks for all the input everyone.

bg

Good to hear!

My system keeps us nice and toasty in these cold temps....

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG