Haven't had any problems with temperature until getting my A/C to work finally. It's a four seasons compressor. Was running 185d F through the summer w/o air conditioning and now it runs up to 197d F with the compressor on. I've been running with my current thermostat a MotoRad 71d C/160d F without a problem. Can I resurrect a thermostat discussion by asking what your opinions are? I have an aluminum radiator, two 11" electric fans, a digital device to turn on the fans at a settable temp (currently 175d F). I know what the upper hose reads in digital degrees F as that's where the sensor is. So I have a true reading. My analog temp guage is on the L when it's 197d F. I'm running 50/50 coolant.

 

My experience with thermostats would lead me to believe that they set the lower limit for an engine, with heat built, to operate at.

Since you are worried about the engine overheating, a properly functioning thermostat shouldn't be a concern. If you are worried that the thermostat is not opening fully, then remove it and test it outside of the car.


How confident are you that your radiator/cooling system:
1: Has no blockages
2: Is fully purged of air
3: Can build psi without leaking off


I also have done an electric fan conversion and have tried various digital sensors that trigger the fans, I had varying degrees of success with the sensors triggering properly and at the right temperatures. Do you have a trusty water temp gauge installed to confirm that the fans are indeed turning on at the correct temperatures?


And if it seems like you still haven't found the problem at this point, is the water pump still flowing as much coolant as it should?

 

All great questions. Thought all was well until taxing the engine just that little bit more with the A/C compressor. I guess I would have to pressure test the coolant system to answer the holding pressure question. Don't know how to answer the air lock in the system question. As far as blockage, I've never flushed the system, so I guess that task might be ahead of me. I have shot the upper hose at the digital temp sender and they do match, so I'm confident in the correct temp readings and that the fans are doing on at the set temp. And since I am adding another digital temp gauge inside the car so I can see what the temp actually is while I'm driving, that would be the time to check and flush the system. The current device for setting fan on/off temps and monitoring temp in is the engine Bay where I can't see it underway. So I am adding another transmitter into the upper hose and running the wire inside and putting a remote LED little rectangle gauge mounted into an unused ash tray. I don't want to spoil a new wood dash. Question is - do I change put the thermostat? And if so, to what?

 

Does the temp drop back down to 185F with the compressor disengaged? If so then it seems to verify that nothing in your cooling system has changed....and what your seeing is just your engine's response to the extra load.

Also, to clarify, will the temp keep going up-up-up past 197ºF? Or does it stabilize there? Does traffic driving versus open road make a difference? Hotter temps only in traffic driving suggests lack of air flow.

I'll add also that 197º is not dangerous or extreme in and of itself. However, increasing from 185 to 197 just because of the A/C suggests the cooling system is being over-taxed a wee bit.

I'd be tempted to replace the thermostat and flush the system and see what happens. But, you may be in a "it is what it is" situation. If 197ºF is as high as it gets, it really isn't a problem.

Cheers
DD

 

Doug - many questions; no answers yet. I don't have enough empirical data yet. But, as time goes on I will figure it out. You and Mad Hatter (oh to be 27 again!) have given me a lot to think about and drill into. Many thanks.

Also, I've followed LnrB's advice and ordered 12 cans of propane/R134A mix to put into the A/C system instead of the straight 134A I have now. We'll see if indeed it does get colder in the cabin, and... see if it taxes the engine any less as it is purported to do.

I'll report back.

Bill

 

Anyone have a part number for the proper thermostat that I can buy here in North America?

 

Propane in your AC will NOT further tax your cooling system! If anything, in my experience, Propane transfers heat SO well the system has less work to do.

However, still on hot days, in heavy traffic in town, AC on Max, the needle will sit at nearly half scale ('O' in NORMAL for Series 2), dropping back down as soon as we're on the road with good air flow past the condenser. At Doug's suggestion I got an Infrared thermometer, which tells me that engine temperature at those times is a hair over 210F.

I *Never* believe printed numbers on temp or oil pressure gauges. I use them for ball park reference only.
(';')

 

Yes, I'm counting on both cooler inside and hopefully a bit cooler running engine. I'm awaiting the arrival of the "good stuff" before I try any other "fixes" on the coolant system. I too bought a HF infrared temp gun and use it all the time on engine, etc. I also find it REALLY handy in the kitchen, shooting frying pans to see if they are up to temp. Want to try something cool? Go shoot clouds and then the blue sky - You'll be amazed!!! Never tried shooting the sun. I should try that too.

 

Clouds! I never thought of that!
I'll keep that in mind.
(';')

 

do the 12 cylinder mod: wire one of the fans to run whenever the compressor comes on, as opposed to thermally.

it gets noisy, like Maserati noisy, assuming you've heard a Maserati engine in traffic. But the noise is only outside, not inside the cabin.

in winter, when you want the opposite, just disconnect the 1-wire mod.