Electrical interference between temp gauge and taurus fan?

[Jimmybeam]

This is a followup question to a problem I posted about before. What happens is that the truck warms up to normal temp, and then climbs right up to 260. Everything with the cooling system is new, including a Corvette radiator (the Taurus fan is used however). The gauge is a Cyberdine digital gauge, which is also brand new. After playing around with it a bit, and trying different things including changing the thermostat and moving the heater hose right up next to the thermostat, I still have the problem. What I just noticed today, is that the temp stays normal until the fan clicks on. Once the fan clicks on, the temp climbs. If it's reading high and I go pull the fan wire, the temp drops right back down to normal. I'm not good with electrical stuff, so what can I look for that would be causing this problem?

[Mike]

get yourself a mechanical gauge and see what it reads compared to the digital one, also check to make sure the fan is operating correctly and not running in reverse

[Knanthrup]

That's really funky... doesn't sound like the gauge is correct and just scaring you. I don't know how you could have wired it to do that really. Is the fan pulling air through towards the motor? Are you running it on high speed or low speed?

[jameskirk1]

You might want to make sure that the gauge sender is the correct one (some of the aftermarket gauges are programmable for different senders) and also make sure you didn't use any thread sealant on the sender either. Also if the ground for the fan is running through the block and not directly back to the battery that may affect things as well. just some thoughts http://www.s10v8.com/images/smilies/icon_biggrin.gif

[Scotty_S-15]

On 2008-01-13 16:56, jameskirk1 wrote:................................. Also if the ground for the fan is running through the block and not directly back to the battery that may affect things as well. just some thoughts http://www.s10v8.com/images/smilies/icon_biggrin.gif



That'd be my first thought. If you disconnect the fan and the temp IMMEDIATELY drops? Then yeah, a wiring problem, probably a ground issue.

......... But first it'd be good to confirm the temp gauge is really right or wrong. Can you buy or borrow a mechanical gauge like Mike suggested.? Or how about an infra-red temp sensor. They sure are handy.

[Mike]

Or how about an infra-red temp sensor. They sure are handy.





those are very handy

it's hard to believe how many things you can use one for

i used to use one to check the water temp on my fish tanks, i used mine today to check the temp in the audio cabinet and if my truck was acting like the one in this post, you better believe i would have my ir temp sensor out

[Jimmybeam]

Mechanical gauge says its at 200. The sender I have in the head is the correct one for the cyberdine gauge (its the one that came with it) and the fan is wired correctly and blowing in the right direction (pulling the air in). I have the fan grounded to the radiator support and the gauge grounded to the firewall, think I should have the fan grounded directly to the battery? I have a factory digital dash (that actually works correctly) and the digital temp gauge just matches the scheme nicely so I'd like to keep that if I can without going to the mechanical gauge.

[jusbo]

the current that the fan is drawing is wreaking havoc on your sender...do you have the sender hooked up right? (sorry don't mean to sound condescending)



Is something touching that shouldn't be touching? Like is the sheathing stripped too far back on the wire? What happens if you tap the ground wire and hook another ground to the engine block? On the gauge that is....if you have already done this, then i am outta ideas.

[Scotty_S-15]

obviously you have the battery-to-engine grounded well, otherwise you'd have starting problems. But do you have a ground jumper between the engine (or battery negative) and the cab? And one to the radiator support is good too.