Coolant Temperature

[Cophan]

I have a 91 Fleetwood RV, that was built on a Ford E350 frame. The engine is a Ford 460 with 41,000 miles. After having some work done, I notice that the Coolant Temperature Gauge now indicates that the engine is running hotter than it has in the past. I suspect a hotter thermostat may have been installed, or the old one may have just been stuck open.
When checking for replacement thermostats I have found they come in many flavors, including 160, 180, 192 and 195 degrees. The thermostats listed on a parts site (autozone) state that the original equipment temp was 192/195 degrees.

I live in Phoenix Arizona, and in the summer, its hot as hell. Any major traveling to the north or west means that I have mountain passes to go thorugh, so keeping the engine as cool as I can is critical.

Question 1: Are there really any drawbacks to installing a thermostat with a lower temp such as the 160 deg ones? The engine has never had a problem passing emissions when it was running cooler.

Question 2: Does anyone know what the maximum safe coolant temp would be for a 1991 ford 460? .... Its understood that the needle should never enter the "red" zone at the top of the gauge. However, I would like to replace the current gauge with one that lists actual temperatures. Some of the aftermarket coolant temp gauges list temps as high as 300 degrees, however I doubt that high of a temp would not also come with some major engine damage, so it would be nice to know the maximum safe range for this size engine...... I have searched the web, but not found much in the way of engine coolant temperature listings. Any help would be much appreciated.

Thanks in advance.

[phantom_smack]

If I remember correctly to low a temperature themostat does not allow the coolant to stay in the radiator and cool off.
I would not want to get above 220-230 degrees

[throwback19]

you might drop back to 185, wouldn't go much cooler than that. your engine wants to run warm for everything to work properly. If you have overheating issues you might want to consider putting a bigger rad. in or installing a bigger fan if that is possible.

[Cophan]

Cool,

Thanks for the Info.

[ChrisH]

Stay with the 192/195 spec! I just fried my catalytic converter by putting in the 180 degree stat. The engine ran cool, however the EEC computer (thinking I was still in warm-up) ran the fuel mixture rich which caused my catalytic converter to almost melt my whole exhaust system down. I had an overheating problem with my '89 460cc RV (E-350) and I thought I would be wise to go with a lower stat, however the original problem with my stat was that it was a cheap part from China! Failer after 1 year :-P There's a rash of cheap thermostats on the market nowdays. I'd stay away from anything made in Mexico or China. The Duralast brand that autozone sells is made in Israel and thus far I'm happy with the qaulity. Also - this brand has a bypass valve in the stat (very small hole) that allows for air-bubbles to flow through and also allows the stat to react and open quicker.

Also..Lower temp stats will give your even more problems in the cooler winter months.

[BroncoJoe19]

ChrisH,
Thanks for posting that informative message. Sorry to hear that you burnt out your CAT by putting in too low a thermostat.

I don't get it why so many people think they can do better than the engineers who designed a vehicle. AS a result it is amazing how much disinformation is out there.

[theoldwizard]

Originally Posted by ChrisH

Stay with the 192/195 spec! I just fried my catalytic converter by putting in the 180 degree stat. The engine ran cool, however the EEC computer (thinking I was still in warm-up) ran the fuel mixture rich which caused my catalytic converter to almost melt my whole exhaust system down.

Never thought of this, but to quote Mr. Spock, "That is logical !"

FYI, newer engine with "tighter" OBD-II tests, "normal" engine operating temperature is monitored quite closely. While the original OBD-II tests from 10 years ago were not required to report thermostat problems, now adays they do. (slow opening, under/over normal temp).

Few people realize that OBD-II tests/monitoring actually get "tightened" also every year. We are really on something like OBD-II.12 !