: Anyone sells lower temperature thermostats?

05-25-08, 10:09 PM
It's for a '97 deVille limo. I'm going to change the coolant and thermostat and wondered if there is a 170 or even 160 degree 'stat I might experiment with.

05-25-08, 11:07 PM
Why would you want to do that? Recommend sticking with the OEM thermo for your ride, change coolant with what color you currently have. NorthStar wants the OEM thermo. K_C

05-25-08, 11:12 PM
A lower temp thermostat will prevent the fuel computer from going into closed loop and turn the SES light on. It'll drink gas like crazy.

05-26-08, 11:21 AM
Your thermostat is set to begin opening at 188 and be fully open by 206. The entire drivetrain is set for those parameters. As dkoz said, if you keep the engine and systems below design operating temps you'll create far more problems than you imagine. And, yes, it will drink gas. A Deville limo in DC is not, ever going to be thrifty on gas..............

05-26-08, 04:49 PM
Don't try to reengineer it. There are many reasons for it being designed to run at the temperatures it does.

05-27-08, 07:37 AM
Don't try to reengineer it. There are many reasons for it being designed to run at the temperatures it does.

Mainly for passing emissions, not for the longevity of the engine. Sure, a stock 180 degree thermostat wont damage the engine while still under warranty, but may reduce it's life over the long run. Why do head gaskets fail so much on these cars? Maybe because of the higher temperatures they run at cause the heads to expand and contract much more than other cars causing the head bolts to fail. The engineers designed the engine and spec'd a thermostat for regular passenger car use, not for limo use.

And I'm not talking a hugh differance, just a 10 or 20 degree cooler thermostat. The 500F+ degrees temperatures inside the cylinders won't be affected much if any by a 10 to 20 degree cooler t-stat. I'm just looking for a greater reserve in cooling capacity.

So question still is does anyone sell lower temperature thermostats for this engine? If it doesn't work out I can always put back a stock one.

05-27-08, 10:48 AM
If it doesn't work out isn't really what you're looking for. HG failure is a product of head bolts loosening out of the block. Problem was finally addressed in post 2000 NorthStars by an insert thread redesign. Cooling system is a well engineered system. Still not sure what's making you uncomfortable. Is it the digital temp read out? I know I've never been able to see temp swings in a vehicle like I can in my NorthStar. Drive me up the wall till I accept the fact I'm seeing real time temp swings - not engine problems. Have confidence. I'm sure, however, you can monkey with the thermo, but dollars to doughnuts it's not going to do anything for you. MHO K_C

05-27-08, 10:29 PM
atikovi, You made it to DC from Florida..........With all your posts concerning changing this and draining that it's a wonder the car runs at all. Keep it clean, full of gas, change the oil/filter twice a year, and drive it. Trying to re-engineer what ain't broke will put you squarely in the ranks of the other frequent posters who can't keep their hands out of the pie and then come here to fix a screwup.

If relatively higher internal temperatures mattered one whit in an engines' longevity, why aren't the crankshaft, connecting rods, pistons, camshafts, valve stems, and gosh-knows-how-many other parts water cooled instead of by 225 - 300 degree oil splash? Because water cooling primarily removes wasted heat of combustion while circulating oil removes heat generated by miniscule amounts of friction.

Don't forget that a fair percentage of the Northstar engines utilize radiator wetted oil coolers in the high temp side of the radiator, so the oil temps at highway speeds never go below 210 - 225 degrees. By engineering design.....