Cooling System Advice

[RyanSheldon]

I am in the process of repairing my '90SE in an effort to lower the coolant temperature. At idle, the needle is right at 100 which is making me nervous on a warm day. So I thought I would try a new thermostat.

Is it necessary to drain the cooling system to replace the thermostat? I want to avoid leaking coolant on the timing belt.

Has anyone actually had a new thermostat lower the coolant temperature?

Thanks,
ryan

[GUY JOHNSON]

yes you will have to drain it.
Do you fans come on? when the engine is off but the ignition is on you should be able to hear them.

[cnh1990]

It is quite normal to go to 100 and when the fans kick in go back down to 82. The fan control is part of the ECU and there is a new chip map that cuts in the fans eariler available.
Calvin

[RyanSheldon]

All three fans are working. I had to replace one of them because it was missing a connector when I got the car. AutoZone had a near identical replacement 10" cooling fan that fit perfectly with very little modification (a dremel tool was required). The fans come on around 100, but the temperature does not lower very much, if any at all, maybe goes down to 99 at best. When driving, the temperature drops back down to 90 on a warm day and around 85 on a cool day. The car seems to run better around 85. Is it safe for the car to run with a coolant temperature of 100?

thanks,
ryan

[cnh1990]

Well assuming you do not hear gurgling sounds that indicate an air bubble in the cooling system I would go and check the thermostat. Heck they are only a few dollars anyways. Seems like you are not getting enough coolant flow. with fans on at idle it should lower to below 90c. Even on a real hot days 95-100F air temp mine falls to 82-85c while driving. Fans on in traffic on a hot day about the same. In the 80F air temps something range the temp is a solid 82c. Have you checked the V belt on the pump? Also the header cap is okay and I assume holding pressure?. Sometimes I force the radiator fans on with A/C control as I get nervous about the near 100c before the fans kick on and see the dramatic temp drop upon cooling. If you have to drain the system might be a good opportunity to back flush the system and clear some gunk out of the radiator and lines.
Calvin

[RyanSheldon]

Calvin,
The car had a new water pump installed along with a new belt just prior to my taking delivery. The radiator cap is new and is holding coolant properly. I will flush the system and install the new thermostat and see what happens. Thanks,
ryan

[cnh1990]

Don't forget to bleed the system well as air pockets will hinder circulation. It's in the manual how to do it as well as in the EFF web site. I think it is under proceedures or something like that. New belts can slip after the break in period as they stretch a bit.
Good luck you have been doing well for a new owner keep up the good work. You will be in tune with the car and you will be able to work on the car with your eyes closed soon.
Calvin

[peptidedoc]

Ok, just some advice but here is what I did to my pantera (supercharged vortech 12 lbs boost, 622 hp to the rear wheeles) to keep it cool. Remove the H2O pump and determine if a lotus pump has a a plate behind the turbine fins. If there is enough clearance you can install a thin aluminum plate to the rear of the fins. This reduces the tolerance between the back of the fins and the housing. Also, reduce the ammount of antifreeze and add water wetter, not sure who makes it. Finally increase the volume of your whole system by 10%. This would not add too much weight but can be acomplished by a high pressure tank at the front of the car which is mabey only a gallon or so.