Engine Temperature

anthonyventry · Jul 4, 2008

Hello, I have been trying to get to an optimal (lower) engine temperature and would appreciate your advice.

I have a ''66 Mustang 289 convertible with automatic transmission and an after-market A/C. The car was rebuilt about two years ago and now has a 302. I have been having concerns that the car is overheating. On cool days, the car is running between 160 and 180. The problems start when I am in stop and go traffic, or driving in 90+ degree weather (at any speeds). In those cases, the car temp can get as high as between 210 and 220 I have a gauge that measures directly to the engine. The engine may even go higher if I don''t drive gingerly or keep the A/C off; I don''t know. I am concerned about overheating. I have seen conflicting information about the appropriate temperature range and was wondering whether I should be concerned. How hot is too hot for this car?

Next, what can I do to get the temp down? I keep the A/C off, which sucks on hot days. I also keep the speed below 60 mph when it is really hot outside. That helps but isn''t a permanent solution. The cooling system has been flushed. The water pump and thermostat have been replaced. I replaced the fan with a five-bladed fan and added a fan shroud. I even put in a 2-core rad. Coolant mix is 50/50. Any thoughts on what else I can do?

I appreciate your help and ideas.

D.Hearne · Jul 4, 2008

210-220 is not overheating. It's quite normal. Just make sure you've got a good water/antifreeze mix and a good pressure cap on the radiator. Both the engines in my 89 Ranger (roller 5.0) and 77 Comet regularly get up to 230 and sometimes higher and no damage has occured. Turn your A/C back on and enjoy.

anthonyventry · Jul 4, 2008

I will. Thanks!

rc4mike · Jul 4, 2008

i have a 65 with 302 plus ac. Have flex-a-lite fan and c4 trans. New northern alum radiator. I run at 210 to 220 in the texas heat with ac. I thought this was high, but from reading around, sounds normal.

mike

Fast63 · Jul 4, 2008

As long as it doesn't continue past 230 you're fine, if it maintains temp ok anywhere from 210-230, that is fine. You're 160 reading is too low though. At that temp you are burning more fuel and there is more wear going on in the engine. What is your thermostat rating?

anthonyventry · Jul 4, 2008

I am not sure what the thermostat is rated, but I will check.

It doesn't really maintain at 160 in the cool weather. Eventually, it goes up to 180 but it takes about 5-10 minutes of driving to get there. I plan on getting the thermostat and rad checked out for a second opinion on whether they are sufficient.

Thanks for the advice. I will make sure that it does not go over 230 at any point --- it has not made it there yet.

rbohm · Jul 4, 2008

i agree with the others, 210-220 is fine. my el camino runs at 200-205 in the heat here. you can stablize the temps if needed by use a high efficiency three core rad, and an electric fan from a later model ford taurus, preferably the one with the 3.8 engine. otherwise as long as your temps dont go any higher you are good to go.

klg · Jul 6, 2008

i think 190 + is a little too hot .it may not blow the engine but i think the cooler the better. i would take the thermostat out . i take mine out in the summer and they run about 140-180 even in 90+heat

1967project · Jul 6, 2008

I agree with the better radiator. You can even go with a 4 core heavy duty.
As stated you can run an electric fan which will also free up some drag on the engine. Just be sure to use the fans right, its easier to pull in cool air than it is to push it through. Also two fans are better that one.
There are different coolants out there as well. There is something that RV owners use, I think its purple in color but cannot remember the name, it helps to keep the temp down as well.
Last but not least you can remove the thermostat (this in itself will raise eyebrows and might spark debate, its just a suggestion). I used to work at an auto parts store and alot of guys would do this in the summer due to overheating issues.

D.Hearne · Jul 6, 2008

Removing the thermostat almost always causes an engine to run hot. It takes it longer to reach operating temps, and then it will run hot, due to the coolant moving thru the radiator and engine too fast for heat transfer to occur. If you removed the T-stat and it didn't you just got lucky.

rbohm · Jul 6, 2008

klg said:
i think 190 + is a little too hot .it may not blow the engine but i think the cooler the better. i would take the thermostat out . i take mine out in the summer and they run about 140-180 even in 90+heat

i would agree with you except that it has been proven that running a higher temperature means less engine wear, better power, and better fuel economy. while i prefer my engines to run at around 185, i dont mind if the engine runs at around 215-220 especially when the outside temps are in the 100+degree range as they are in tucson these days.

Fast63 · Jul 6, 2008

rbohm said:
i would agree with you except that it has been proven that running a higher temperature means less engine wear, better power, and better fuel economy. while i prefer my engines to run at around 185, i dont mind if the engine runs at around 215-220 especially when the outside temps are in the 100+degree range as they are in tucson these days.

You're absolutely right. Also check out this few paragraphs from an article. This guy knows what he's talking about:

Coolant Flow

Different coolants require different minimum
flow rates, but contrary to popular belief, you cannot
make the coolant flow too fast. This rumor was
started because people removed the thermostat to
gain flow, because they had an over heating
problem, and it only aggravated the problem. The
real reason they ran into problems is that removing
the thermostat also removes the restriction that
builds pressure in the engine, so they gained flow,
but reduced the boiling point of the coolant in the
block.

Running a higher flow thermostat and a
higher volume pump to maintain pressure, will give
no such problems. If you think about it, making the
coolant flow twice as fast will also make it flow
though the engine twice as often, so there will be
more even temperature across the engine.

There has been, and still is, the rumor that
of the coolant flows too fast, it will not have time to
pick up heat. That is nonsense, as long as there is
coolant contact a surface, the rate of heat transfer
will be the same. Coolant that flows twice as fast
also flows through the block twice as often.

http://www.grapeaperacing.com/GrapeApeRacing/tech/coolingsystems.pdf

Read the rest of the article to find out more about the system pressure.

D.Hearne · Jul 7, 2008

The pressure built up in the system isn't from the thermostat restriction. The pressure is from the coolant expansion. Heat any liquid and it expands, confine that liquid and it builds pressure. The pressure also raises the boiling point.

SadbutTrue · Jul 7, 2008

rbohm said:
i would agree with you except that it has been proven that running a higher temperature means less engine wear, better power, and better fuel economy. while i prefer my engines to run at around 185, i dont mind if the engine runs at around 215-220 especially when the outside temps are in the 100+degree range as they are in tucson these days.

I'm pretty sure that running a 'little' hotter does help as far as engine wear goes, and perhaps with economy (and definitely with emissions, there's a reason cars run hotter today than they did in the 60s).

However, there are a ton of engines that are reknowned for making less power when they're hot as opposed to when they're cold (the 'heat-soak' effect... most engines notice a loss when they are running a bit hot... in a few cases its a big loss, see GM LS2 and others).

So I'm not sure about the 'better power and fuel economy' claim. I think when you're arguing 185 vs 215, 99% of engines will make more power when at 185. When you get down into the 160s, thats different, that is definitely too low.

Fast63 · Jul 7, 2008

D.Hearne said:
The pressure built up in the system isn't from the thermostat restriction. The pressure is from the coolant expansion. Heat any liquid and it expands, confine that liquid and it builds pressure. The pressure also raises the boiling point.

It comes from both. If you notice in the article, the pressure in the engine is higher than it is past the thermostat and down to the water pump again. It's simple physics that trying to move a larger volume of water than will flow through a hole fast enough will build pressure.

D.Hearne · Jul 9, 2008

The only place the coolant could have more pressure is between the pump and thermostat. That pressure doesn't add to the pressure at the cap. It's not likely anyway to have more at running temps between these points, it's not a positive displacement pump. And the bypass hose will relieve any excess pressure back to the pump.

Fast63 · Jul 9, 2008

D.Hearne said:
The only place the coolant could have more pressure is between the pump and thermostat. That pressure doesn't add to the pressure at the cap.

Yes, that is exactly what I said. Only, the block is between the pump and the thermostat, hence, more pressure in the block.

I'm not quite sure what you mean about the pump not being a positive displacement pump and the bypass hose bleeding off pressure.... can you elaborate on that?

rbohm · Jul 9, 2008

SadbutTrue said:
I'm pretty sure that running a 'little' hotter does help as far as engine wear goes, and perhaps with economy (and definitely with emissions, there's a reason cars run hotter today than they did in the 60s).

However, there are a ton of engines that are reknowned for making less power when they're hot as opposed to when they're cold (the 'heat-soak' effect... most engines notice a loss when they are running a bit hot... in a few cases its a big loss, see GM LS2 and others).

So I'm not sure about the 'better power and fuel economy' claim. I think when you're arguing 185 vs 215, 99% of engines will make more power when at 185. When you get down into the 160s, thats different, that is definitely too low.

actually most race engines make better power when they run up around 210-220 degrees. street engines also if the computer doesnt pull the timing back to eliminate detonation. at the drag strip most guys trick the engine into thinking it is running colder to get more fuel into the cylinders.

D.Hearne · Jul 10, 2008

Fast63 said:
Yes, that is exactly what I said. Only, the block is between the pump and the thermostat, hence, more pressure in the block.

I'm not quite sure what you mean about the pump not being a positive displacement pump and the bypass hose bleeding off pressure.... can you elaborate on that?

Look at the pump. The impeller doesn't fill the cavity it's in completely, even when it does have the largest impeller, it still has room to spare, hence it's got room in there that makes it impossible to build pressure. All pumps built like this are not positive displacement pumps. A positive displacement pump has two gears or vanes that mesh tightly so that when the pressure is built on the pressure side of the gears or vanes, it cannot escape back around the gears or vanes. (or pistons in the case of an air compressor) Hydraulic pumps are built like this. As for the bypass hose, that's self explanitory, I would think. When the thermostat is closed, the coolant still flows thru it back to the water pump. So most( if any )pressure built by the pump is relieved by the bypass hose.

Fast63 · Jul 12, 2008

You don't need an air tight seal to build any pressure. Just look at piston rings in a bore, there is a gap in all of them, yet they still build a lot of pressure. The impeller is moving fast enough to build pressure even if some is being forced back around it, such as when the thermostat is closed.

Engine Temperature

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