I have 1977 Volare with a slant-six that when I get the car on the road it gets hot like 210-220 degrees. I have a 160 degree thermostat in it.

Have you already check your water pump? radiator got good flow?, dist advance? (that one got me in problems with a 84 Mustang), also is standard or automatic your car?

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Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

try a t-stat like 180 or 195------- your system cannot maintain with the 160 so one that slows the flow down -so to speak should help with the cooling

I had a 68 Valiant with a 170 and later a 225 in it. I was running a 160 degree thermostat and at highway speed and idling at a stop the thing would reach for the sky temperature wise. I put a shroud on it and that stopped the running hot at a stop but I still had the problem at highway speeds. An old guy told me that the 160 degree thermostat was allowing the coolant to go through the radiator too fast to cool down at highway speeds. He suggested I go to a 180 or a 190 degree thermostat and that would fix it. Sounded logical to me and thermostats are cheap and easy to change so I changed it to a 190. After that no more overheating at all with the AC on and 100 degrees outside. It could idle all day long with the AC running and run 80 mph and never go over 190 or so. Give it a try.

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Former bent 6 owner
Mark

Ok, people one more time I need to ask for a solution for my problem in temp matter.

My 71 Duster never had overheating problems, the fact is that is alwas cold, barely and sometimes in hot seasons engine temp reach almost half of temp gauge (normal temp as far I know), all the rest of the year the gauge reads in cold sector

Gauge
\Cold "here" Temp|Normal Temp|Hot Temp/

My thermostat if 160 degrees, 4 blades fan, 50% Water 50% Anty Freeze.

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Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

The main ingredients to a good cooling system on a slant six are (1) non-clogged water passages (head. block, radiator and heater core), (2) a working thermostat (I have run 160 to 195 and all cooled fine), (3) a working water pump and fan, (4) a working radiator cap. Lots of people forget the radiator cap.

Volare320hp- replace your radiator cap with a 16 pound one from the parts store.

There is no reason to run a 160* thermostat in your slant, or in any car that I know of. The engine will not produce optimum fuel efficiency at that temperature and you will be wasting gas, prematurely fouling your oil, and your engine will suffer excessive wear and produce excessive emmissions. You should run a 180* thermostat at a minimum.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

When a thermostat is a few degrees above its set point, it should be open as far as it can go - the openings are all about the same in order to have enough back pressure to force the flow through all the passages.

Changing thermostats won't help overheating unless your thermostat is defective (which does happen). It is easy to pull it and test it in a pot on the kitchen stove.

Increasing the flow rate may or may not help much depending on where you're sitting in the cooling curve; it should never hurt unless it is so fast you have non-laminar flow (very unlikely). Removing the thermostat entirely may reduce the flow in some areas of the engine, leading to localized overheating.

There are formulas I could post giving you the relationship between flow and temperature, but if your system is stock I'd suggest you just fix the problem, rather then re-engineer it.

I use a little "candy" cooking thermometer (~$5) and a 500F IR (~$50) thermometer to check the temperatures.

I recommend you the following in this order:

1) verify the overheating- sometimes sensors and gauges go bad

2a) pressure test the system and look for any leaks - even a small leak can cause problems - sometimes the thermostat housing warps and will never seal properly (air leaks much faster than coolant)

2b) pressure test (or just replace) the radiator cap - they do go bad, especially after even a single overheating|blowing-out-coolant incident

3) test the thermostat on the stove; sometimes they don't open all the way - I even test new thermostats before installation

4) check for internal blockages in the hoses; replace if in doubt

5) have the radiator checked at a radiator shop - often, they don't leak but are corroded inside and won't transfer heat well

6) verify that the exhaust valves are opening properly

In my personal experience, the causes of overheating are #1 leaks, #2 weak radiator caps, #3 crudded up radiators, #4 bad thermostats, #5 bad hoses, #6 worn cam not opening an exhaust valve. I'm sure there are other, rare causes that I've not stumbled over (like dragging brakes, etc.)