Running warm

[Chris996]

I KNOW that I am asking for the impossible with as little info as I can provide but figured I would ask anyway.
Recently my T has been running warm at over 200 degrees. She never really ran over 180ish before.
Oil and coolant levels are fine so I haven't started chasing a blown head gasket and instead replaced the water pump with a HD unit, 160 degree thermostat, upper and lower radiator hoses. I have not replaced the radiator cap yet, but will be picking one up today and what appears to be an F body radiator has been flushed and looks to be pretty clean with no visible calcium or rust build up.
I have a Cottons FMIC which covers the entire radiator but have what looks to be an intrepid dual fan set up. I am also not sure on the wiring harness that controls the dual fans.
I noticed with the car idling in the driveway, the fans initially come on at 164 degrees and shut off around 162 (checking the scan master) keeping the temps in check. After a few cycles, the fans stop coming on and temps start climbing with no way to turn them on.
Does any of this sound normal or SOP for a dual fan set up? Is there a way to over ride the temp sensor switch that turns the fan on with a toggle switch?
Lastly, any other areas to check for a running warm car?
Appreciate any feedback as the down fall of purchasing a used car sometimes leaves previous modifications a bit of a question mark.

 

[Chris996]

oh, coolant temperature sensors are both new also

 

[salvageV6]

Depends upon how everything is wired, period.

The chip controls the low speed fan relay, sensor controls the high speed fan relay.

You should start with a wiring diagram of your fan system.

Check the drivers fender for the low and high speed fan relays perhaps your low speed chip controlled relay is intermittent, assuming it's still in the fan control circuitry.

The factory relays are easily controlled with a Hi/Lo fan switch available from vendors such as Caspers' electronics etc.

However actually knowing what you have in place (wiring stock and aftermarket) is very important to fan operation.

When those fans stop cycling my first test would be to unplug the harness at the fans and put power to them with heavy gauge wiring to the battery, if they don't operate then, you have found the problem.

 

[GNRick]

My fans recently stopped working. Found a loose connection in that big 3 wire harness connector located near the fans.

 

[Chuck Leeper]

A couple "things".
Short of the pump being damaged w/ either corrosion, or the impeller slipping on the shaft, the pump is not an issue.
If the belt tensioner is not keeping the belt tight, that's another issue. IE: Belt stretch to a point the tensioner is out of travel, etc.
The cap controls the boiling point of the coolant, not the operating temp.
As mentioned above, failure of the fan controls is where I'd be looking.

 

[turbo nasty]

Good info already in the thread. The ramcharger/Intrepid fans are notorious for fan motors failing as well. Listen for them starting to make the squeaky noise when they are coming to a stop or give them a spin with your hand and if the are making any noise they are dying. Any dual gans need a custom relay setup as the factory wire, plug and relays are showing their age and tend to overheat, etc.

 

[Chris996]

I sincerely appreciate the replies.
My wiring harness looks to be a Casper's going by pictures on their website. I'm unsure of how the fans operate however , meaning once the coolant temp reaches a certain number will the fans come on non stop until the temperature drops back down or will they shut off after a set period regardless of the coolant temp.
I will trace the wiring and jump the harness as recommended, and probably backflush or replace the radiator as although it seems clean, I'm not sure of it's age.

 

[Pronto]

The fan turn on and off temp is programed in the chip if you are running one.

 

[Chris996]

The fan turn on and off temp is programed in the chip if you are running one.

Thanks, i’ve a Turbo Tweak 6.1

 

[GNRick]

Should be fan wiring info here http://www.vortexbuicks-etc.com