engine temp

I read that the optimum Healey running temp is 195 degrees. I get happy when I'm running cooler but the article said it not good for the mpg and that the thermostate may not be operating properly. I watch the temps go up and down as I drive my Healey. My 4 Runner's gauge goes from stone cold to midway on the dial (no dial numbers) then never moves?????

I think that 195 is a pretty good running temperature. Engine wear is less & mpg higher.

If you look at my gage, 190 is in the center with 230 at the top. This might be pretty close to the Four Runners gage which also runs mid gage. Be assured that the Four R. temp does move up & down. The gage is just made to respond very slowly so that the driver doesn't worry about it.

Folks seem to get nervous when the thing gets near 212. With 50-50 antifreeze/water & a 7 psi pressure cap your boiling point is likely to be somewhere around 240. Clear off the top of your gage.

Some newer cars regularly run at 220 to 240 with 14 lb caps. I guess that's why they don't put numbers on the gages anymore.
D

[ 11-02-2003: Message edited by: Dave Russell ]</p>

My friends 100 runs at about 175 with a 160 degree thermostat, and runs like a rocket! The temperature gauges on most newer vehicles aren bizzarely, non-linear. Something about making people more comfortable. My Miata will not go past just below normal, and, there's a whole redesign and construction article on how to disassemble and construct your temp. gauge to be linear! Nuts!

Paul B.

I compared my 100 gage to an accurate thermometer & the gage reads 10 degrees higher than actual. This makes 190 look even more alarming.
D

Tahoe

Your 4 Runner cooling system has two things the Healey doesn't: Capacity and control.

Your Healey has a thermostat that has a lower opening temperature than 190 degrees, so, when the car is moving the water can cool down to the thermostat temp and stay there, because the thermostat will close if it gets any cooler. When you're sitting in traffic or the day is hot, hot, hot your thermostat is wide open, but the water must get hotter to remove the engine heat. If your radiator were bigger or you had an electric fan (and modern water pump) the fan could turn on and keep the engine cooler. No control; no regulation, your water temperature changes.

If your Healey radiator had the capacity of the 4 Runner, you could run it at a higher temperature and rely on it staying at the "optimal" temperature for efficiency, but as we know, the cooling system was designed in England, not the Sierria Mountains, so it can't be trusted to unconditionally cool the engine if we use the optimal thermostat.

So, it the temps drop to 160 then the thermostat isn't functioning?

There is some time lag in thermostat operation which will cause some overshoot/undershoot.(check the thermo opening specification vs the closing spec.Also it takes some time for the coolant to respond to the new setting. A newer damped gage will not respond to these changes. Your undamped gage is likeky to show these variations. They are there whether they show or not. The fuel gage is another example of the undamped gages.
D

my bj8 ran "hot" at idle; crept up to 212. Solution:
1. check accuracy of gauge; mine was -6 degrees.
2. make sure the thermostat sleeve is in place; after an egine rebuild with new thermo the sleeve was not replaced; correct thero, sleeve and rad cap corrected over heating without having to resort to electric fan.

160 degrees as the lower temperature is not bad considering we aren't using digital technology to regulate the engine temperature. It could be you have a 165 or 170 degreee thermostat installed and it operates at a little lower temperature, It may also be that your temperature gauge reads a little low at that temperature or a combination of both... I wouldn't worry about it.

Neither device is a precision instrument. They kinda sorta get into the ballpark.

How can I check the accuracy of my gauge? In summer, my BJ8 pushes 220. Of course that's a Texas summer and in heavy slow traffic.

How can I check the accuracy of my gauge? In summer, my BJ8 pushes 220. Of course that's a Texas summer and in heavy slow traffic.

How can I check the accuracy of my gauge? In summer, my BJ8 pushes 220. Of course that's a Texas summer and in heavy slow traffic.

D,

On your car the temp sending unit is in the head & separated from the top tank by the thermostat. On a cool or partially warm day the thermostat may be partially closed or in the process of opening or closing. This will cause a difference in temp. between the sending unit & radiator top tank. Pick a hot day when the thermostat is likely to be fully open & put a thermometer such as a meat thermo. in the top tank & compare it to your temp. gage.

With a little more work, you can pull the sending unit, (it is sometimes very hard to get it out) put it in a can of water & heat the water to boiling with a torch. The gage should read around 212 at sea level, a little less at higher altitudes.

BTW - You can eliminate double posts by clicking on the "edit icon", pencil & paper pic at the top of your post, & clicking on "Delete Post" box.
D

[ 11-04-2003: Message edited by: Dave Russell ]</p>

Droy,
If you don't have a torch handy a hot plate and a coffee can work good.Run the temp up and down and check at every 25% of range Test thermometer aganist gauge.
CDK
PS Dave R. Chek out the vapor trail post.Whats the real reason?