cooling system puzzler

[Guest waxbgone]

I am really baffled by this problem. On my '90 convertible the coolant temperature is just fine, summer or winter, with and without the A/c running, EXCEPT when I run at low speed with the car warmed up. One of our favorite things with the convert is to "cruise" the nearby "town center-style" shopping area, which entails driving at idle speed for about 10 minutes. Even in 60-degree weather with the a/c off, the temperature will begin to climb after a few minutes, and will peak in the last block before the "red zone" on the gauge. None of my other Reattas have done this (2- '90 converts and 1-'91 coupe).

The car has a brand-new (2,000 mi)GM Goodwrench engine installed by a trusted dealer. I have replaced the radiator with a brand-new one (from e-bay). I replaced the water pump, and tried new thermostats (one of each temperature). My understanding is that the cooling fans do not come on until the temperature of the coolant is almost in the "red zone, so I have not checked the fan function.

This one has me puzzled. Any advice?

[Jim]

The low speed fan comes on at 214 degrees and the high speed fan comes on at 226 degrees. Both of these are far less that the second mark from the top.

[Guest F14CRAZY]

Could the temperature sensor be faulty? You might not be that hot.

Is the fan working at all? You may want to consider having Ryan of GMtuners adjust your fan settings. I have a 180 thermostat and he set it up so the fans keep the temperature very close to 180

[padgett]

I reset my fans to match the 180F thermostat and have yet to see it go over 190F. If a concern, turn the A/C on and that will automatically turn on the LO fans (both turning at 1/2 speed on a '90).

ps GM thinks 230F is OK. I don't.

[Guest F14CRAZY]

Padgett is right. 230F, to me, is waaaay too hot. Open the hood in the summer...feels like a blast furnace.

[Guest inthespot]

What does Ryan at GMTurners do to get the fan setting at 180. Mine is running about halfway or straight up but when it goes 90 to 95 and I am in traffic I think it will get higher. It will go up one notch as it is. All the cars I have ever had before never move once they get to operating temperature. The fan comes on and once you get rolling is goes back down to midway but I do not like the gage to get more than 1/3 the way up.

[Guest F14CRAZY]

He changes the engine computer program for the fan

[harry yarnell]

ALL the '90-93 gauges run at 12 o'clock, normal. Probably around 210-215°.

[Guest inthespot]

Well maybe mine is ok and I just think it should be more like at 10:00 or so that is where my last 3 vans have been running. That is also where my mazda pickup also runs (10:00). What does it cost to have a the chip reprogramed?

[Guest F14CRAZY]

$45. You can have other things done to it too, like have the top speed limiter removed for the long trip up your driveway

[Guest C.F.Massie]

Pray tell, by who and where can you get the chip reprogrammed?

[Guest F14CRAZY]

GMtuners.com. Ryan did the custom tuning of my ECM for the my supercharged LN3/L67 hybrid.

With a 180 thermostat and custom fan programming, the plastic and rubber under the hood is going to last longer. Pointless to have these engines running at 200+ degrees (once I did have mine in the 240 range).

[Guest waxbgone]

Thanks for the help, guys. The front cooling fan motor was dead. To make these fans have 2 speeds, they are wired in series for low speed. For high speed, they are each powered separately, and get twice the voltage. Because of this, if one fan goes bad, neither one works. I replaced the front fan motor, and all is well.

Thanks for the help