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Bryan59EC 04-27-2008 01:20 PM

Fans not kicking in 'til 237* on a 218* switch
2 Attachment(s)
I'm kinda wondering if anyone here would know where to get a
bushing for a 3/8 switch to a 1/2 intake??

The bushing I am using now shrouds the sensor bulb to the extent that only the bottom of the sensor is exposed to flowing coolant.

Do you suppose this is why the fans do not come on when theya re supposed to?? The first time they are activated by the fan switch, is around 237.
Then the engine will get down to 215 and the fans will shut off. Subsequent cycles will kick the fans on around 228 and off around 210.

This is on a NAPA FS118-----on @218--off@205 switch

Kinda wondering where I could get a bushing that does not have the hex on it. Dakota Digital has bushings for 1/2 to 1/8 and 1/2 to a 1/4 that are only about 3/8" tall. Whear this bushing from Spal (and any others I have been able to find) are close to an inch or better.

Any insight to this?? Is it the bushing shrouding the bulb causing the fans not to come on when they are supposed to??

I have tried 3 different switches (fs118 2x --and a chevy switch once) and get the same results with all of the switches.

This is on the 59 Elky, and temps have been verified by the Dakota Digital gages AND and infared temp meter. (gage and meter match at all temps)


curtis73 04-27-2008 02:05 PM

Depending on sensor locations, coolant temps can vary up to 30 degrees throughout different places. Often times there is a 10-15 degree difference between the manifold and the heads.

I wouldn't worry about the shrouding of the sensor. Water is an excellent conductor of heat, plus there is plenty of turbulence around that fitting. Plus, the fitting is probably brass and its almost as good as the water at conducting heat.

Bryan59EC 04-27-2008 02:14 PM

The fan switch is located in the intake----directly opposite of the temp gage sender.

If the fan switch is working correctly----then the 1,3,5,7 side is running much hotter (15-20*) than the 2,4,6,8 side.

Guess I could swap the sensors around and check for that.
Not gonna do it today tho :D

not too worried about an overheat at all, runs around 200-205 on the hiway, and that is acceptable to me----(probably could use a bit more timing tho)

carsavvycook 04-27-2008 03:26 PM

Put it in the cylinder head, either side you can. The thread size should be the same as your sender. You will find it will work as advertised temp wise.

Bryan59EC 04-27-2008 03:55 PM

3/8" pipe sender
1/2" pipe intake, heads

carsavvycook 04-27-2008 04:00 PM

What heads do you have on it?

carsavvycook 04-27-2008 04:03 PM

We are assuming it is a SBC any different?

carsavvycook 04-27-2008 04:35 PM

The fitting you are looking for you can find at a hardware store. It is called a Close Pipe Adapter. It will have no hex and the shortest one will be in cast iron metal. Install it in the cylinder head so it reads right.

Bryan59EC 04-28-2008 05:46 AM


Originally Posted by carsavvycook
We are assuming it is a SBC any different?

454 HO

Close pipe adaptor?
I'll be looking for one this week then.
Have one on my pool----1/8 to 1/4---even if that was the size I needed---I'd have to fight Susan for it---She wants her pool working :D

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