SilverBulletAMG

The only difference was outside temp. Drove to/from work about the same (not hotroding around) and there was very light traffic, so not much stop/go. Left this morning and it was cold out (40s) and left from a heated garage. Left work and it was in the 60s outside and car sat outside all day.

c32AMG-DTM

His modified t-stat is always "open" to some degree, because of the holes drilled in it. I'm thinking that causes the car to take a good bit longer to get up to temp vs. a stock or PTE t-stat that remains fully sealed until the appropriate opening temperature is achieved.

Silver - sorry, upon re-reading it, my first comment was indeed obvious... sounds like you're already doing it, too. Maybe add a min or two to your idle time to see what happens? Those weather patterns do sound pretty crazy.

Phil C55

Why on earth would you have a thermostat with holes in it? I'm no kid, at nearly 50 and working on cars and bikes for 35 years, it makes no sense at all. A thermostat should be closed until the motor gets up to temp and then it opens to maintain a constant temp. There are 600+ hp cars out there and they use a regular thermostat.

SilverBulletAMG

According to TVT Designs, who knows far more about this stuff than I do -

"We've aimed to modify the stock thermostat to allow coolant to flow in before it is fully open, but still allow for cooling running temps.
We've left the stock opening temperature as to not interfere with the fan or heat."

Phil C55

That completely undermines the function of the thermostat. It stays closed until the coolant is up to temp for a reason, it needs to. Once a proper operating temp is reached it opens and will flow plenty of coolant, if the coolant cools too much it will close. The temp that the thermostat opens is the temp the engine needs to be. Overcooling an engine is a bad thing.

I'm still not convinced you don't have some other problem. I ran the C55 last Saturday and it was 30 F out. After a few miles the temp gauge settled in as always at a tick above 80 C. I have also been stuck in traffic around Indy when it was 80 F outside with the AC on and it stayed at the exact same point on the temp gauge. It never got hot or had any issue.

SilverBulletAMG

I'm assuming your NA 55 was stock as well. I'm slightly modified and as I'm sure you now, the blower is a big heater. The 55s don't have near the heat issues the 32s have. Even bone stock 32s have heat issues if thrashed in the slightest.

I do agree with you on the t-stat and how it should function. The problem with the stock t-stat is that once the engine gets up to temp and t-stat opens, temps continue to rise....and doesn't stop until it's pulled a ton of timing and has the get-up and go of a lawn mower. With the small holes in the modified t-stat, it flows a little more and helps prolong heat soak. At least that's the rationale explained to me.

Phil C55

Yeah my 55 is stock and I fully understand an engine roughly 60 percent the size making the same or more power is under some stress. It sounds to me more like a radiator issue than thermostat because it isn't dissipating the heat generated by your engine. That can also be a function of the water pump.

No matter how the car is driven, the radiator, water pump and fans should keep the temp in check. The thermostat is really only there to control the low side of temperature because when it's wide open, it flows a lot of coolant.

SilverBulletAMG

I agree whole heartedly. That is also why most of us 32 owners are running the upgraded heat exchanger, CM30 pumps, split cooling systems, and modified t-stats. All pieces to the cooling puzzle....