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Discussion Starter #1
Wondering if the correct thermostat for a non-tow package Fleetwood with electric fans (and auxiliary thermostat housing mounted where mechanical fuel pumps once lived) is 195 degrees? I'm seeing 180 AND 195 degree thermostats listed as "OE temperature".

Would there be a difference between tow package and non-tow package? Just pulled a 10-15 year old 180 degree one out and replaced it with a 195 degree Stant.
 

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No answer, but I am curious as well, according to my codes on climate control my car stays right at 175 all the time.

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Discussion Starter #5 (Edited)
195. LT1 temp is 180, and your car is not LT1, it is LO5.
Thanks. Everything is back together and test driven, will recheck antifreeze level overnight.

I'm thinking an incorrect temperature thermostat and fuel injection/ECM's don't mix.

So on my 95, 175 plus 2 or 3 is normal?

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Sounds good to me, but I think the LT1 is supposed to operate at over 200 degrees? Maybe someone can chime in as to why or why not 175 degrees is healthy.
 

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I personally try to find thermostats that open at a colder temp than stock, but too cold and you WILL have issues with cooling fans "overcooling", and your PCM will never see an operating temp, firing off CEL and running fans constantly.
 

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Discussion Starter #7 (Edited)
Not sure what temperature the car was operating at with the 180 degree thermostat, but with the new 195 degree it basically is at 195 once warmed up, then stabilizes at around 210 on a 100 mile mixed driving condition trip. 85 degree day, near 100% humidity.

This is using the "OFF" and "TEMP UP" buttons on the HVAC control panel, option 08.

The cooling fans never came on with the 180 degree thermostat, unless the heat was turned on. Fuel economy ranged from about 15MPG (7 miles to work, barely getting to 50 MPH), to just under 27MPG on long trips in fall/springtime weather. Generally it gets 18-20MPG on average daily driving.
 

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Thanks. Everything is back together and test driven, will recheck antifreeze level overnight.

I'm thinking an incorrect temperature thermostat and fuel injection/ECM's don't mix.



Sounds good to me, but I think the LT1 is supposed to operate at over 200 degrees? Maybe someone can chime in as to why or why not 175 degrees is healthy.
We shouldn't confuse the original issue here, it is discussing the LO5 1993 with the 195 stat.

However, the LT1 uses the 180. It also is reverse cooled, so the head temps stay lower. Much higer compression than the LO5, so the lower operating temp is desireable. Although you can get a 160 for the LT1, most now agree it is too cool, and results in decreased mileage and increased engine wear. Additionally, there are two separate temp sensors. First, the one in the water pump/stat housing. That one is the one the PCM uses for data. The other one is the sensor in the right side head, and the sole function of that is to provide the gauge readout.
 

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Discussion Starter #9
We shouldn't confuse the original issue here, it is discussing the LO5 1993 with the 195 stat.

However, the LT1 uses the 180. It also is reverse cooled, so the head temps stay lower. Much higer compression than the LO5, so the lower operating temp is desireable. Although you can get a 160 for the LT1, most now agree it is too cool, and results in decreased mileage and increased engine wear. Additionally, there are two separate temp sensors. First, the one in the water pump/stat housing. That one is the one the PCM uses for data. The other one is the sensor in the right side head, and the sole function of that is to provide the gauge readout.
That being said, would 210-212 degree coolant temperature in a TBI/LO5 350 acceptable? I'm getting a 230 degree reading on the intake manifold/water outlet using a infrared gun.
 

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In general 210-212 is acceptable. GM in a number of cars let the engine run hotter then some may like for emmision reasons.
Remember may GMs in the 90's where the primary fan turned on per manuals at 220 and a secondary almost at 240.

There is 2 ways to alter the operating temp on an engine without major parts upgrades.
Lower temp thermostat. It's a starting point to keep the temp lower. But wont do everything after driving under heavy cooling load conditions.
That's where the electric fans kick in. The sooner they turn on the the cooler it runs.
Keep in mind if there is 2 fans or 2 speeds the primary wont do everything and when the 2nd kicks in also makes a diference.

For example I had a different car that had 3 fan speeds. But for the summer in Vegas I found it was just better to wire the high speed to be on when the ignition during the summer.
A but noisier outside the car. But the temps never had a chance to get too warm. It also Helps the A/C work better.

If the L05 used the ECM to control the fan you have 4 options.
1. Reprogram the computer.
2. Wire the fan on with the ignition in the summer
3. Wire the fan to an aftermarket additional temp sensor.
4. Add an additional electric fan wired like #2 or 3.

There may be some maintence that cold help a bit.
Flush the cooling system, block, & radiator. Change the antifreeze. I like to add the coolent enhancer like water wetter or super cool. Sometimes the radiators need to be cleaned by a radiator shop or replaced. Sometime the hoses get barnicals & buildup. Temp sencers can get a bit out of calibration. Look for loose / missing air deflectors or damaged fins.
Trouble is there is no guarantee this would make a difference if your looking for resualts. It's more good maintence.

For improved cooling perhaps look for parts off models that had the heavy duty option. I thought all the 5.7 Caprices had mechanical fans those years.
 

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Discussion Starter #11
Well, as it turns out, I do believe the 180 degree thermostat is correct for the 1993 Fleetwood w/o tow package, w/electric cooling fans.

The GM part# for the correct thermostat is 180 degree, 12555290. The 195 degree may be correct for 95% of 1991-1993 B/D bodies with conventional thermostat location and mechanical clutch fan, just not the electric fan cars.

I'm having both cooling fans turn on in 57 degree weather, on a 15 minute trip.
 

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Discussion Starter #13
Thanks for the update.

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No problem. I knew I heard or saw/read somewhere about the 180 degree thermostat in the electric cooling fan cars. There was a reason a 180 degree was in there, though the old one may have been staying open.

It also goes to show how parts store cataloging is constantly evolving and mixing in incorrect information. Unfortunately, as these cars keep getting older, even GM dealer information gets sketchy/one size fits all for replacement parts as room is made for newer vehicle parts cataloging. It's the Fahrenheit 451 effect...
 

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Discussion Starter #14 (Edited)
So far, the 180 degree thermostat is allowing the car to hold steady at 195 degrees in 85 degree weather on longer trips. The car also drops a degree or two when up to speed.

That's about a 20 degree lower operating temperature. Seems a bit safer for an older car with a fair amount of mileage. The cooling fans came on more, and at a higher speed with the 195 degree thermostat, but just maintained 215 degrees, sometimes reaching 217-218.

Why the aftermarket doesn't care and prunes correct information and acts like it never existed is a mystery.
 

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My 2002 Northstar (9 years later), using the stock 188 > 206 degree 'stat, runs at 190 - 205 all day every day.

Somewhere in the 185 - 210 degree range is good for just about any "modern" engine, especially the tight emissions-controlled ones.
 
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