Cascade Crew

Al Hasse · Posted: Sun Nov 22, 2009 1:50 pm Post subject: Fan Switch

Thought I'd start my own thread for the cooling fan.

I installed a new fan switch and its pigtail to replace the temp sender that was there before. With the sender, my fan ran continuous with key on. Now I can't get the fan to turn on, my connections are good, I grounded the pigtail and the fan runs with the key on. That leaves the switch. What temperature is the TBI 305 supposed to come on? I let the thing get up to 240* according to the stock gauge when I heard a few knocks (I think I have a few air pockets). I know that gauge isn't the best, but it's all I have for the moment. Maybe the sealant that was put on the threads is preventing a good ground???

chevymad · Posted: Sun Nov 22, 2009 2:25 pm Post subject:

235-240 stock I think.

There were some v/6 cars in the 80s that were set for 245!! Shocked

Al Hasse · Posted: Sun Nov 22, 2009 3:46 pm Post subject:

Thanks Brandon, I thought it was set to the warm side. I still think I have a problem with the switch, I remember there being some sealant on the threads and didn't remove it. I picked a new one up this afternoon and took a look, it had teflon tape on the threads, great insulator for a switch that uses the contact with the block for ground.

IIRC most sensors/senders have threads cut so that sealant isn't needed on them. The ones Dakota Digital sent with their gauges specifically said not to use any sealant.

Twilightoptics · Posted: Sun Nov 22, 2009 4:09 pm Post subject:

Never seen a pipe plug that didn't need thread sealant. Even if the sender is "made" that way... the head isn't. Years of wear, in and outs, etc threads aren't what they were first tapped as.

As long as you used a liquid teflon, and not tape you're definitely fine in terms of a ground. Even tape is going to seal up. Definitely make sure there are no air bubbles, cause you'll get improper readings that way too.

Easy way to check the ground is use your volt meter on a spot on the head, and a spot on the brass sender. See if it's got good continuity.

Al Hasse · Posted: Sun Nov 22, 2009 4:24 pm Post subject:

chevymad · Posted: Sun Nov 22, 2009 4:51 pm Post subject:

Pipe thread is tapered. It will cut through whatever sealant you use and ground. Never seen a sensor not ground because of sealant.

aaron_sK · Posted: Sun Nov 22, 2009 5:49 pm Post subject:

Al Hasse · Posted: Sun Nov 22, 2009 6:28 pm Post subject:

Thanks Aaron. I might go that route if I can't figure out what's going on. Tomorrow after I fix my meter, I need to check the switch continuity to the block. If that's good, it's the connector and I don't care for its design anyhow.

Quasi-Traction · Posted: Sun Nov 22, 2009 9:14 pm Post subject:

IIRC before I put the adjustable switch in, I had a A TBI switch that would come on at 225 degrees.

Al Hasse · Posted: Mon Nov 23, 2009 11:17 am Post subject:

Well, I have continuity from the switch to the block. Fan still doesn't come on even after the water starts to boil. That leaves either a bad switch or the connector. My guess is on the connector which I don't like the design of. I'm going to replace the switch with the one Aaron linked - I like the spade type connector on the end, provides a more positive connection.

aaron_sK · Posted: Mon Nov 23, 2009 11:43 am Post subject:

Just another quick thought:

When I put my S10 together, I was running some name-brand fan switch I got from Jay (JET, or Hypertech or something). Had the old-school Chebbie-style connector on it.

Truck kept overheating. Some of that was due to a junk t-stat, but even with that fixed it still did it.

Fan was coming on in the driveway, but not switching on and off consistently on the road. Would come on right at 190 sometimes, other times fluid was boiling out before it switched on.

Narrowed it down to either the switch or the connector, and ultimately decided to replace both. Works like a charm now.

When you buy from Summit, they sell two flavors: 180/170, and 200/185. You want the latter. I accidentally bought the former, and didn't feel like waiting on a return. Put it in the stock 60* location (drivers head front water jacket). Damn fan never turned off (180* t-stat). Moved it to the intake manifold to let it see cooler temps, and it switches perfectly.

Al Hasse · Posted: Sat Nov 28, 2009 4:00 pm Post subject:

Got the Summit switch in this afternoon. Spade terminal makes for a much more positive connection and works like a champ. On about 200* and off at about 185* Cool

aaron_sK · Posted: Sat Nov 28, 2009 8:30 pm Post subject:

Right on dude. Now go do a burnout in front the nearest IHOP.