Car getting real hot....

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Mattax said:
@Yellowrose, your concept about the t-stat setting the minimum temperature is basically correct. But your numbers don't work out if the shop manual is correct, and I think you are wrong to dismiss it. The thermostat openings have a plus minus of 5 degrees to crack open enough to get a feeler gage in. Full open is around 20 degrees hotter - plus minus some. Surely you're not saying those shop manual specs are incorrect.
This is what my post was referring to.
Also when tech goes out of their way to say that the 1968 Chrysler system does not pressurize due to coolant expansion, then someone says that cooling systems pressurize due to liquid expansion; that person either didn't read the explanation, or doesn't believe Chrysler knew how their own system worked.

Now, why run a hotter rather than a cooler engine?
On a low compression street setup I would give two reason:
1. To get rid of the condensate in the engine, especially the oil.
2. To more completely vaporize the gasoline.
Now that second can be argued about. I don't have numbers or test or any of that. But this is what Shrinker was always writing about and I buy it. When we set up relatively low compression situations we need to get enough heat in the chamber so light and medium portion of the fuel vaporizes and distributes evenly before spark.
On some engines this isn't going to apply because the heads, piston and cam are doing the work. So on some engines more heat could hurt. I get that.
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The opening point of the thermostat depends on the manufacturer. The Stewart Components thermostat is fully open by it’s rated temperature. That’s why I keep saying there is a difference in thermostats. If you have a 180 degree thermostat and it’s not fully open until 200 degrees it’s junk. That means the rated number doesn’t set the minimum operating temperature. It’s basically a guesstimate.

1. I agree, but I will say this. The oil temp isn’t much lower if the coolant is 180 than it is if it’s 200 degrees. IMO, short drives is what keeps the moisture from being cleaned up.

2. I also agree, with a caveat. Any time the intake manifold is heated with exhaust gas, coolant temperature means very little in vaporizing the fuel. The exhaust gasses are much higher in temperature than the coolant ever will be.
 
69hemibeep said:
The thermostat is for minimum operating temp, too cold an engine is bad news. Every water cooled car on the road will run warmer than the stat depending on conditions that doesn't mean the cooling system is inadequate.
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Uhhh, no. My junk doesn’t run warmer than the thermostat rated opening point. Was at a buddy’s house yesterday. He runs a 160 degree thermostat. On 90 degree days it stays at 160 because his cooling system is correct.

His brother has the same stuff in his rig. He is going from a single 4 to a tunnel ram so the intake was off when I was there. He has about 5 years on the engine and it’s clean like new inside. It runs at 160 all day long too.

If you want to make horsepower you lower the coolant temp. If your engine runs dirty after that you need to work on the tuneup.

Of course, if someone believes that their carbon footprint makes a difference, then maybe keep the coolant temps up. And give away some power. I don’t believe that so I run my stuff colder.

If an engine runs better with higher coolant temps it needs a better tuneup.
 
ir3333 said:
here's my 2 cents...and i've been wrong before.
The thermostat sets the maximum temperature and starts to open when that temperature is reached.The temperature will continue to rise about 5 or 10 degrees until coolant from the rad lowers the temperature in the heads and cylinders.The thermostat never fully closes after the initial opening and the temperature will not change from then on.The speed of the coolant must be reduced to a level that keeps it in the rad long enough for the heat to be dissipated by the rad, usually about 30 degrees (Delta T) If your cooling system is not adequate the temperature will rise when conditions become more severe like a stop and go traffic.
The heat exchanger or rad and fan are the only items cooling the engine temperature if all else is working correctly
Monkey around changing flow ,thermostat or other components is like throwing darts and you may end up with a system that works great or a whole pile of grief!
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Nope. None of that is correct. Leaving the coolant in the block longer just makes the coolant temperature coming out of the block higher.

Again, if the thermostat isn’t fully open by it’s rated number it’s garbage. If the thermostat sets the minimum operating temperature (and it does) then if it’s 180 but it’s not fully open until 190-195 the MOT is now that number. And that’s what the thermostat should be rated at.

I will beat this horse until there is nothing left because this nonsense needs to die. Air flow and coolant flow is what controls engine temperature AFTER the thermostat is open. If it’s not within a few degrees of the thermostat’s rated temperature it is straight crapola.
 
77796FA9-729D-476B-AC70-CCCA2AC8693B.jpeg


This is from the 1973 FSM. From left to right it’s the 198, 225, 318 and 340. It’s interesting that ALL the water pumps are over driven with the exception of the 318. The 318 is only overdriven with AC. I have no clue why that’s the way it is, but that’s what the FSM for 1973 says.

The AC cars had the pump driven faster than the non AC cars, but they are still 20% overdriven without AC.

And virtually ALL the aftermarket junk pulleys out there are UNDERdriven. I cobbled my stuff together with some CFV pulleys and I’m at a paltry 6% overdriven. And I have 4 hours of phone calls to get that.

What happened between 1968 and 1973? I can’t say. What I do know is they are overdriving the pumps. They damn sure were no longer worried about the coolant not staying in the block long enough. I see 7, 10, 20 and 30 percent overdriven water pumps on OE stuff. 1973 was low compression.

The water pump should be overdriven as much as the belts will stay on. The issue is finding pulleys to do that is a real beeeeeeeeeooooooootch.

It is interesting that March Performance told me they would make up a set of pulleys for whatever I wanted as long as they would physically fit. I just don’t want to invest any money in that when the vast majority of guys out there STILL believe this slow the coolant down crap. And March wasn’t interested in doing the work and adding a part number.

One other interesting tidbit occurred when I told the guy on the phone that I know for a fact with steel pulleys you can get 30% overdrive. He said I was crazy. So I sent his the above picture. His rough math said if that was true (and it is as anyone who can read can see) they could do 24-25% overdrive with aluminum pulleys.

Maybe if enough of us call and ask for overdrive pulleys they might make them. But that would require a massive change in the thought process of many folks.

BTW, if you overdrive the pump and you still want 195 degree engine coolant temperatures, just run a 195 degree thermostat. It’s what sets the MOT.
 
Some guys remove the thermostat to move coolant faster and claim that is best.
i have never tried that but maybe that will work better for some.
 
yellow rose said:
Uhhh, no. My junk doesn’t run warmer than the thermostat rated opening point. Was at a buddy’s house yesterday. He runs a 160 degree thermostat. On 90 degree days it stays at 160 because his cooling system is correct.

His brother has the same stuff in his rig. He is going from a single 4 to a tunnel ram so the intake was off when I was there. He has about 5 years on the engine and it’s clean like new inside. It runs at 160 all day long too.

If you want to make horsepower you lower the coolant temp. If your engine runs dirty after that you need to work on the tuneup.

Of course, if someone believes that their carbon footprint makes a difference, then maybe keep the coolant temps up. And give away some power. I don’t believe that so I run my stuff colder.

If an engine runs better with higher coolant temps it needs a better tuneup.
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I said depending on conditions. Come on down here and try one our 6% 5 mile long climbs at 110 degrees and the temp gauge will get your attention no doubt. A higher temp keeps oil pollutants down also and 165 is fine for a race car they dump the oil so often. My toys I tune for maximum horse power, my daily drivers I tune for maximum efficiency
 
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yellow rose said:
Air flow and coolant flow is what controls engine temperature AFTER the thermostat is open. If it’s not within a few degrees of the thermostat’s rated temperature it is straight crapola.
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Air flow, coolant flow and the radiator......but I guess the radiator falls under air flow, huh? lol
 
ir3333 said:
here's my 2 cents...and i've been wrong before.
The thermostat sets the maximum temperature and starts to open when that temperature is reached.The temperature will continue to rise about 5 or 10 degrees until coolant from the rad lowers the temperature in the heads and cylinders.The thermostat never fully closes after the initial opening and the temperature will not change from then on.The speed of the coolant must be reduced to a level that keeps it in the rad long enough for the heat to be dissipated by the rad, usually about 30 degrees (Delta T) If your cooling system is not adequate the temperature will rise when conditions become more severe like a stop and go traffic.
The heat exchanger or rad and fan are the only items cooling the engine temperature if all else is working correctly
Monkey around changing flow ,thermostat or other components is like throwing darts and you may end up with a system that works great or a whole pile of grief!
Click to expand...
ir3333, the thermostat controls the minimum operating temperature in a running engine. At startup the thermostat is closed. To allow circulation and prevent hot spots the bypass allows coolant to circulate. When the coolant gets up to the thermostat opening temp, it begins to open allowing a bit to flow to the radiator.The full open temp is generally about 20°above the advertized temp. The design Delta T across the radiator is generally 10°F to 20°F.
After searching more, the A/C water pump has fewer vanes but the pulley ratio is different to speed up the fan speed to draw more air. The lower vane count on the WP impeller keeps the coolant flow similar and prevents cavitation in the pump.
For the problem that started this, it appears from his photos that the shroud and fan spacing is a major factor. Making a "die" and rounding the inside diameter to bend the aluminium toward the engine will help airflow. This should be just 1/2" around the perimeter of the fan hole. The the fan should be spaced ahead a bit or the shroud spaced back a bit, to get the fan 1/4 to 1/2 inside the shroud and the rest outside. If it still gets warm the A/C WP and pulleys should be installed.
 
As a note, I had a 69 Chev heavy 1/2ton with a 292. In winter the heater would not put out heat. Now you need to know we get minus 35°C to 45°C in January and February. Looking at the bypass hose on a 250 six, it was 5/8" hose. The bypass on the 292 six was 3/4" or 1". Driving on the hyway the rad coolant was getting over cooled and windchill on the block kept the thermostat almost closed. All the coolant was bypassing, and the little that went to the heater bately took the chill off. I took the bypass hose off and put a flat washer in that would be trapped and restrict the bypass. Then I got heat!
Another problem on that used truck was poor previous maintenance. I flushed the cooling system once a week for a month and it kept getting rust red. I finally put a remote oil filter in the heater hose line with valves so I could change the filter without draining the coolant. It did not take long for the turbulence to pick the settled rust out of the block and filter it out. Then the coolant stayed nice and clear.
Just a maintenance tip for those with a similar problem. Once the cooling system is cleaned out, the filter can be removed.
 
69hemibeep said:
I said depending on conditions. Come on down here and try one our 6% 5 mile long climbs at 110 degrees and the temp gauge will get your attention no doubt. A higher temp keeps oil pollutants down also and 165 is fine for a race car they dump the oil so often. My toys I tune for maximum horse power, my daily drivers I tune for maximum efficiency
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It gets damn near that hot up here.

No one I know gets dirty oil from less than near boiling coolant temps. My question is have you ever lowered the coolant temps and made the tuning changes to benefit from it?

You can call ANY oil manufacturer in the country and they will tell you engine coolant temp has zero affect on oil life.

I don’t even believe that hotter engine temps make less pollutants. The OE’s have to worry about CAFE standards (what a crock of crap that is) and getting the cats fired off and making them live over 100,000 miles. I don’t give a single crap about ANY of that. And I’m not talking race cars either.
 
Dale Davies said:
ir3333, the thermostat controls the minimum operating temperature in a running engine. At startup the thermostat is closed. To allow circulation and prevent hot spots the bypass allows coolant to circulate. When the coolant gets up to the thermostat opening temp, it begins to open allowing a bit to flow to the radiator.The full open temp is generally about 20°above the advertized temp. The design Delta T across the radiator is generally 10°F to 20°F.
After searching more, the A/C water pump has fewer vanes but the pulley ratio is different to speed up the fan speed to draw more air. The lower vane count on the WP impeller keeps the coolant flow similar and prevents cavitation in the pump.
For the problem that started this, it appears from his photos that the shroud and fan spacing is a major factor. Making a "die" and rounding the inside diameter to bend the aluminium toward the engine will help airflow. This should be just 1/2" around the perimeter of the fan hole. The the fan should be spaced ahead a bit or the shroud spaced back a bit, to get the fan 1/4 to 1/2 inside the shroud and the rest outside. If it still gets warm the A/C WP and pulleys should be installed.
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That’s exactly what I said many posts back. You just contradicted yourself BTW.

I said there was about a 20 degree difference (I could have said Delta T but everyone and their mother got what I was saying) between the coolant temp coming out of the block and at the engine block going back in.

Now that you agree with what I said, how does leaving the coolant in the block longer do anything? It doesn’t. You still get about a 20 degree reduction to coolant temp IF your system, the ambient temp and pump speed is high enough to do it. If it’s not then you get a big temp increase from thermostat opening point to coolant temp while operating.

The longer the coolant stays in the engine the hotter it gets. If it comes out hotter it’s going to go back in hotter.

As for cavitation, I hear all about it and I’ve never seen it. Not once. Evidently Chrysler didn’t see it either because they damn sure started turning the pumps faster by at least 1973.

It’s time to kill this stupid myth. And all of this discussion has little bearing on the OP. His shroud is garbage. That’s the first thing to fix. After that work can be started on fixing anything else that could be wrong.
 
Dana67Dart said:
IIRC...The water pumps are different, number of vains etc.
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Our discussion revolved around the fan speed. Standard cooling has a faster fan than air conditioning does according to the way it is written in my service manual. I was a little confused by that.
 
ir3333 said:
Some guys remove the thermostat to move coolant faster and claim that is best.
i have never tried that but maybe that will work better for some.
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Road ractes will remove the thermostat, but put a restrictor plate in place of it. They are worried the thermostat could fail on the track. The restrictor would be about the same ID as the thermostat plate and basically be with the temp sensor and valve removed.
 
yellow rose said:
That’s exactly what I said many posts back. You just contradicted yourself BTW.

I said there was about a 20 degree difference (I could have said Delta T but everyone and their mother got what I was saying) between the coolant temp coming out of the block and at the engine block going back in.

Now that you agree with what I said, how does leaving the coolant in the block longer do anything? It doesn’t. You still get about a 20 degree reduction to coolant temp IF your system, the ambient temp and pump speed is high enough to do it. If it’s not then you get a big temp increase from thermostat opening point to coolant temp while operating.

The longer the coolant stays in the engine the hotter it gets. If it comes out hotter it’s going to go back in hotter.

As for cavitation, I hear all about it and I’ve never seen it. Not once. Evidently Chrysler didn’t see it either because they damn sure started turning the pumps faster by at least 1973.

It’s time to kill this stupid myth. And all of this discussion has little bearing on the OP. His shroud is garbage. That’s the first thing to fix. After that work can be started on fixing anything else that could be wrong.
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As I stated ,"after researching more" I have changed my mind. I have seen evidence of pump cavitation. Generally I believe that to be a result of poor maintenance. Twice were on cheapskate farm trucks brought in when they could not figure out the problem. Four were on hiway haulers that also had not had the coolant changed in a long time. Eventually the aditives break down and the coolant does not have the neucleate suppression any more. This also pertains to cavitation. Cummins especially were prone to liner erosion on the major thrust side and to a lesser degree on the minor thrust side. When those bubbles collapse the oolant slaps the liner hard and eventually erodes pits. Water pump impellers the same. I did pull wrenches as a proffession for 25+ years. Then I got into instrumentsation for about 15. You can get cavitation on process valve trims as they com off their seat or even more so just as they close.
Then there was sand erosion on the trims for underground gas storage. They drill into tight porous geology. With no presure downhole when they drill sand and stones get left down there. They purchase gas when the price drops a bit and sell it when it goes up. They can store and sell 6 to 8 times a year. For the first year or two, when they open the valves to sell the gas, it brings the sand up each time and sand blasts the trim. $ 10,000 for 6" trim for each valve. Eventually the sand is all gone.
 
69hemibeep said:
Yes but double check with Yellow Rose he knows everything :rofl:
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I don’t know much, but bet you’re *** I know slowing the pump down is grade school stupid. Arguing about it is idiotic. It’s time that myth died a quick death. But there will always be those who don’t think things through and will continue to say dumb **** like that. And there will always be those who support the guy who says crap like that. Birds of a feather flock together.
 
part guy sold me a motorad cap #10234, i ask for a 16 pound,but in the center its stamp 18, wrong cap? my car almost overheated yesterday.thanks for the high jack.
 
Snake said:
ask for a 16 pound,but in the center its stamp 18, wrong cap? my car almost overheated
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18 lb cap vs 16 lb cap would have made it harder to overheat, it just pressurized the system more increasing the chance of a ruptured hose or blower gasket.
 
Snake said:
could a lean mixture cause an over heating .
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Yes, but IMO, if it does, it was on the ragged edge of over heating to begin with. In other words, if the cooling system is RIGHT, no running lean alone will not cause it.
 
Snake said:
part guy sold me a motorad cap #10234, i ask for a 16 pound,but in the center its stamp 18, wrong cap? my car almost overheated yesterday.thanks for the high jack.
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A higher pressure rad cap wilnot make an engine overheat. It does raise the boiling point of the coolant. The addition of antifreeze also raises the boiling point, but caution needs to be exercised here. Water transfers heat the best but you need other aditives for the cooling system. Corrosion inhibitors and something to lube the WP seal.
Yellow rose is mostly correct; the thermostat controls the minimum operating temperature of your engine. How hot it gets is a composition of a number of factors such as ambient temp, compression, air/fuel ratio, etc. The bottom line is if the cooling system is designed correctly it should not overheat. That term is not exactly a temperature factor. What temp can the rings tollerate without loosing tension, before the pistons get tight in the bore, etc. As long as the radiator is large enough to dissipate the generated heat, that is good. But then airflow to remove the heat from the radiator is required. This entails a large enough fan and in most cases a shroud. Fan speed and design are also factors. To a point the faster you can spin the fan the more air it will draw, but centrifugal force limits that. On an A/C equiped vehicle, the condenser transfers heat to the air that subsequently is required to cool the radiator. Increasing the airflow solves this problem with different pulley ratios to turn the fan faster. Because the pulley also turns the WP it also turns faster. This could cause cavitation in the WP. This I believe is why the pumps have fewer vanes. It would be interesting to know what the actual flow rate through the cooling system is between the large diameter WP pulley and more vanes and the smaller pulley and fewer vanes on the same vehicle would be. Seems I remember the A/C cars generally can with a higher capacity radiator, so that would have to be installed. A turbine flow meter and a totalizer could be installed in the upper rad hose with the totalizer remotely in the cabin. Turbines are sized by a number of volumns with gallons per minute being one. Knowledge of the approximate GPM in the cooling system.would be required. The turbine size is basically turbine diameter in inches or millimeters. The spec may be in GPH but is easily converted to per minute. One popular turbine on oil sites is 27 to 270 gallons per hour, which if memory serves me is a 1". There are many more sizes. If the flow rate is lower than the minimum, fluid will pass through without spinning the turbine appropriately. Too high a flow rate will damage the turbine.
 
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