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Old 06-29-2013, 06:49 AM
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thermostat and fan issues

I am running a sbc350 with a Holley 750 Double pumper in my rod. I think I have a 195 degree thermostat. My problem is that my fan wont kick on until 240 or so and then only comes down to 210 at idle. Should i have a thermostat that is lower in temperature and why does the fan kick on so late. just seems that running the engine over 200 all the time is real hot.

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Old 06-29-2013, 07:33 AM
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hi temps

what ever runs your fan is messed up... thats the first place to go.. i am no fan of 195 stat's.. drive in summer only i always run 160's and yes it does go up in temp when in traffic, but not something major. i am also a fan in drilling a 1/8" between the stat hole and the gasket area to allow air to escape when filling.
ck to make sure no air in cooling sys, lower the stat temp's and ck the turning of sys of the fan..
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Old 06-29-2013, 11:37 AM
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with a 195 thermostat your always going to run in the 200 range
i'd change it out to a 185 thermostat and check why your fan is coming on so late.
check your fan operation by grounding the sensor wire, the fan should turn on immediately.
if the circuit is working ok, look at your sensor location, in the thermostat housing is ideal
but you don't want the same temp switch and thermostat or your fan will always run
if your running a 185 thermostat use a 195 switch

i have a 185 thermostat and a 185 switch that came with my spal fan
if i mounted the switch in the block the fan would always run even in the winter because the thermostat is keeping the motor at 185
i mounted my switch in the lower hose to allow the thermostat and radiator to do it's job
i added a separate ground wire since the rubber hose insulates the tube
if the radiator can't keep up, then the fan turns on. all has been fine for 20,000 miles

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Old 07-01-2013, 06:22 AM
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sorry for the delay. I think i found the issue. I touched the two wires for the fan together and they run when the key is on. So I know that it works. First thing I thought is that my sensor is bad. So i decided to just connect the wires and leave them so that the fan was on when the key is on. Then I decided to check the thermostat. I removed it and put it in a pan of water. It is a 195 stat and I had to run the temperature of the water up to almost 220 to get it to open. tried it again and realized that if I tapped it , it would open faster. Finally after messing with it for a while it started to work better. It is a new stat but I guess still a POS. So i put in a 180 stat. I think that will work. the fan probably was not kicking on when it should because the stat was not opening. tonight i will fill it with anti freeze and check things out. Probably will hook the fan back the way it was.
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Old 07-09-2013, 11:26 PM
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I agree, there is something really wrong with your fan controller if it's not coming on until 240!

I run a 160 t-stat (drive it all year like that)
BUT, I run two electric fans, and two fan controllers.
controller one turns both fans on, with the big fan on 'low' (two speed fan) that happens around 185-190. This gives me the advantage of being able to come to stop, and idle for a minute or two before the fans actually turn on.

the 2nd controller is really just a 'oh s**t' back up.. at 220F it turns the big fan on high. - with this setup, I have NEVER gotten to 220F even idling in the staging lanes at the track for an hour when it's 90+ degrees outside.

http://home.comcast.net/~kc8oye/Engine/DSCN1150.JPG
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Old 07-10-2013, 05:15 AM
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That is an excellent idea. I called painless wiring and they told me they are having issues. They sent me a new sending unit or controller. i hope that one works.
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