Re: IML: Thermostat issue 160 or 180

[sosmi@xxxxxxxxxxx]

Some of the things you noted about that damaged engine, are not just cooling related. In order for an engine to be most efficient, the temperature should be in the 190-220 range. The lubrication oil can run 150-250 degrees higher. Just check your oil pan after a good run down the high-way. Engine components need heat to perform their duties properly, piston and ring expansion, cylinder bores, bearing clearances etc, all have an effect on performance. New engines run much hotter than 180, this for calibration of EFI,  emissions, and efficiency. Marine engines have been running 140 thermostats for years, some 440's I've rebuilt had 8000-10000 hrs at that temp.Damned if you do, and damned if you don't Dave.

 

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From: santiam oregon <santiamoregon@xxxxxxxxx>

I think the point about local climate, use, issues is important, however I'd also be concerned with the wear difference of engine components at the lower temperatures.  I have torn down and rebuilt several engines where the previous owners either removed the thermostat or left one that was stuck open.  The resulting cylinder wear was tremendous. Gouged cylinder walls around the coolest areas of the water jackets.   There are always adjuvants to controlling pinging, such as water/marvel mystery oil top end injection, retarding the timing a few degrees or making sure your plugs are gapped properly and the right heat range.  My mom had a 69' Mercury with 10.5:1 compression that I drove in high school. It sounded like a drum roll when you floored it, but doing a few things to reduce the pinging made a huge difference and it still had gobs of power compared to a low compression 351 from later model cars.   I know that 160 thermostats are used in racing, but like most racing components, they are torn apart quite often and don't show the long term effects we have in

street driving.

spicemanii@xxxxxxx wrote:

This could be for anyone who has issues with deceiding which thermostat to use, in Imperials or any other vehicle.
   Fisrt, like kenyon said, Chrysler engineered what was best, but, at that time, gas was what I use in a term as better gas. Gasoline has been altered since these were built. The closed chamber design heads, for example, 58 thru 67, do not like the fuel we have to buy today. I have experimented for years here in the desert and the cure was an open chamber from 68 and newer. And, without going thru all the other issues involved here, since this is a thermostat talk, yes, after it opens, they all flow water about the same.
   But, with the pinging issue here when an engine is forced to run hotter, as a 180 will do, I have control sooner if it opens at 160 there about, I have less of a chance for a pinging situation than waiting till it is 180 opening where I guarantee myself to ping. Their is a bad when running cooler. Less fuel mileage and you loose a bit of performance because the oil is thicker. Their is a perfect point for these all to meet. But, it will not happen with air conditioning, traffic, mountains, altitude, your foot, the weight of the vehicle, gear ratio and so many other things.
   So, I run a 160 because of the desert with way less humidity.
   When these cars were new, owners traveled thru the desert at night. My 61 Imperials all came with a 22 inch radiator. Not big enough for todays traffic and driving the desert all day or climbing a grade with these heavy cars and keeping the air on. Signs used to say, "Turn off air conditioners to prevent overheating" when pulling a desert grade. This is not the end of this, it has so many other facets, you would be bored. joe machado

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