Engine won't cool off!!

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Gandy Dancer

Gandy Dancer

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Hello - I have gotten to the point of getting my 318 to fire up relatively easy. Eveyrhing seems to be working well however the temperature always gets hot after about 10 minutes of running. I have taken the thermostat out, and she'll come back down to about 3/4 of the way and hover back and forth. My combination is a 318 with at Weiand Stealth 8022 intake. Does anyone have any ideas on how to cool it down? Thanks in advance!!
 
How do you know "3/4" is hot?

Is that 10 minutes of idling in the driveway?

You may not have a problem at all.

A thermostat is not an optional part of the cooling system. Put a 180 in and leave it there.
 
and the factory gauge does not tell you temp-- you need an actual gauge with degree markings or a heat gun to tell what the actual temp is.

Read the above posters comments & explain the detail of your cooling system, thanks Lawrence
 
If you take it out, and the engine runs cooler, that probably means you have a stuck thermostat. Get a 160F Fail Safe thermostat so that if it sticks again, it sticks open instead of close (Less than $10) and be done with it.
 
Who ever came up with the idea to "take out" the thermostat, not a good idea, you need some restriction in the system otherwise the water circulates to fast and will not cool anything, and the degrees of the thermostat makes almost no difference either all that does is open temp. 160 opens sooner that a 180 but it doesn't cool the engine ANY better. I have a high flow water pump and that requires a high flow thermostat, I have a Mr. Gasket high flow the first one I had didn't open so I returned it and bought another one IMO I would test any thermostats in a pan of hot water to make sure they are in fact opening. just my .02
 
412 Stroker said:
I have a Mr. Gasket high flow the first one I had didn't open so I returned it and bought another one IMO I would test any thermostats in a pan of hot water to make sure they are in fact opening. just my .02
Click to expand...

xs10. 180* or 195* is just fine. i always test them first. there was one day i was at oriellys 3 times before i got one that actually worked
 
Gandy Dancer said:
Hello - I have gotten to the point of getting my 318 to fire up relatively easy. Eveyrhing seems to be working well however the temperature always gets hot after about 10 minutes of running. I have taken the thermostat out, and she'll come back down to about 3/4 of the way and hover back and forth. My combination is a 318 with at Weiand Stealth 8022 intake. Does anyone have any ideas on how to cool it down? Thanks in advance!!
Click to expand...

Buy/borrow a cheap temp gun and go from there. take temp readings of the radiator hoses, engine block etc. after warmed up to get an idea what "3/4 of the way" really means. These old gauges and wires can't be trusted. Could be as simple as your little temp sending unit going bad ($6 fix). I had two that read completely different.
 
I had a 66 Sport Fury with the old Poly 318. It had over 100K miles and ran hot. A Chrysler mechanic I knew rebuilt the engine and it still ran hot, 190 to 230 and sometimes boiled. I went through thermostats, bigger radiator, clutch fan, you name it and no luck. It usually ran hot but did not boil although got close. After moving to Missouri, it only got worse. I took it to a shop in Lee's Summit I won't name on the forum. They had it for months and told me they could find no problem. I started it up and water gushed out like a garden hose. They told me it was condensation from sitting so long. Right. I got it home and a buddy and I decided to adjust the valves. Ha! Green radiator fluid came squirting up through the oil galleys in the heads. We clamped it down and made calls. We were told, it could be a blown head gasket and or a cracked head/block. I had too much money in this engine to have it all done again so I decided to junk it. I sold the Weind intake, the custom cam, carb, custom throttle linkage and all that. We found radiator fluid under the intake, on top of the pistons, and when we dropped the oil pan, green radiator fluid sitting on top of the oil. What I'm getting at is I was able to drive this car running hot, borderline boil over, took it one garage after another, spent a fair amount of money with these garages who could not identify the problem (it could have been one that started small and grew bigger over time), spent a lot of money on radiators, tranny coolers, you name it, and still lost the battle. I would begin a systematic look at each part of the cooling system ruling out each problem as I went. Of course start with the thermostat, hoses, and all that because those are a cheap fix and move out from there including a block flush. A head gasket is not the end of the world but you don't want to end up cracking heads and blocks. I hope this helps a little.
 
412 Stroker, in my experiences, if you put a 180, it will run about 200-220 and if you put a 160, it will run 180-200, and that makes a big difference when you are stuck in traffic.
 
67 273

This is theory but fairly sound. The reason people run 160 degree thermostats is to open the water jacket to external flow earlier in the warm up. Usually for racing. Cooler engine equals more dense fuel charge. And with a good water pump and radiator the temp can be held down longer. So basically what you are saying has merit. But from a different standpoint. If lets say I have a car that has a 195 thermostat and I have a high volume water pump and a big crossflow aluminum radiator with some big electric fans set to go on at 180 degrees, my engine will stay right at 195 all day long. On the other hand if you have a car with a 160 degree stat and you have a stock water pump with a stock radiator and stock fan, in traffic provided all else is equal my engine will run cooler than yours. In fact it is possible that my engine might even close the stat or restrict the flow a bit just to keep the engine at 195. It is all about thermal transfer. And as one member pointed out. The stat is not just to open and close, it is a flow restrictor. You need that to maintain a certain amount of back pressure against the pump to maintain an even flow through the engine. So while what you offer may indeed be valid, there is a bit more to engine cooling than just the temp of the stat. Modern engines have the high temp stats to get the engine up to optimum temp as fast as possible. All about that ugly word we all hate. Emissions. Just like a cool engine has a denser charge, a hot engine has a less dense charge. It is not about rich or lean actually. It is about density. HOT AIR like the type I am full of, is lighter and thus less dense which some might accuse me of as well. LOL !!! Being dense that is.
 
But the thing is, I dont want my engine sitting at 195 all the time, because then you get in traffic on a 110 degree day, and with the AC running, it runs the temp up a bit. Im not quite sure why you would want your engine to run that hot anyways.

If the engine is a cool running engine, and it has a 195 in it, it cant very well stay much below that because the thermostat closes before it gets a chance.

Also, I dont have to deal with emissions on older cars. When they are 25+ Years old, they are exempt.
 
67 273

The temp of the stat has little to do with how cool the engine will remain once it opens. That is my point. Most engines run at over 200 degrees normally. That is why you have a pressurized cooling system. Water under pressure boils at a higher temp. Water boils at 220 degrees. Ever watch Nascar? They are always reporting their engine temps over 220 degrees and they run fine.

You are looking at this as somehow the stat is the big controlling factor for how cool an engine runs. It isn't. All a stat does is help an engine to get to operating temp faster or slower by only circulating coolant through the engine when it is cold.

And as I said. I can run a 195 stat on a engine that has a high efficiency cooling system with high cfm fans and that engine will stay at just above 195 to 205 all day long with 110 degrees and the air on at full blast. But put that same engine with a 160 degree stat, stock water pump, stock radiator, stock fan in traffic on a 110 degree day and not only will it run over 220 degrees, it will likely be necessary to turn off the AC and turn on the heater. I know because we had a 1985 Pontiac Grand Prix that would overheat in the summer. In traffic on the way to LA we had to turn off the AC open the windows and turn on the heat to get just a bit more cooling from the heater core. Stat was indeed a 195. Put a 180 in and made no difference at all other than when it was cold we waited a bit longer for the heater to work. But I put a big electric fan and pulled the crappy viscous fan and that sucker would run cool all day long in the worst heat and traffic ever. Heat transfer only happens for the most part in one place. The radiator. Some heat radiates from the engine, but that is minor. The big transfer occurs at the radiator. And since it is all about potential much like a battery, the transfer is more or less efficient based on how heat conductive the metal that the radiator is made from. How much surface area is available to the two fluids and or gases involved in the heat transfer, The potential or variance in temperature between the two fluids and or gases and the actual volume of flow of each. So in our case we did not change the fluids or gases. We did not change the variance in temps of the said fluid or gases. When we shut down the AC and turned on the heater we did drop the temp of the fluid by reducing the load and increased the surface area by turning on the heater. But the big change was when I put in a high cfm electric fan. That changed the volume of one of the fluids and or gas. In this case air. The volume of coolant did not change. The surface area did not change. But the amount of air and of course the velocity of that air increased dramtically. So the same stat, the same engine, same coolant and pump, same climate conditions. In one case engine boiling over and the other engine runs below 210. All because of one component and it was not the stat.

One other thing. A engine running cold is subject to increased wear. Tolerances in all bearings, cylinders, pumps, etc are based on normal operating temps. If you design your cooling system to run a 160 stat and have a big radiator with a big fan set to come on at 160 degrees, you will defintely have a cool running engine, but you will also be wearing out engine components at a increased rate. Why? Because heat makes things expand. So when cold, all tolerances on a engine are too wide. One reason not to race an engine when it is cold.

The best running engine is one that runs between 195 and 205. That is the sweet spot in general. Build a cooling system to achieve that and you get the best perfomance. Best mileage. Best longevity on the engine. You can put in your 180 stat, but if your cooling system is not able to deal with the variables of altitude, humidity, ambient temperature, etc, the stat will mean diddly squat.
 
67 273 said:
412 Stroker, in my experiences, if you put a 180, it will run about 200-220 and if you put a 160, it will run 180-200, and that makes a big difference when you are stuck in traffic.
Click to expand...

I run a 180* stat and my engine runs 180 - 185 all day long in 90 degree temps.
 
67 273 said:
412 Stroker, in my experiences, if you put a 180, it will run about 200-220 and if you put a 160, it will run 180-200, and that makes a big difference when you are stuck in traffic.
Click to expand...
This is exactly why you have to or at least you should put the new thermostat in a pan of water with a thermometer, to see at what temp the new thermostat actually OPENS, my guess would be that the thermostat you had that was making your engine run at 200 - 220 was not in fact opening at 180 but probably closer to 200.
 
I once had a heating problem where my car would run anywheres from 200 up to 225. So what I ended up doing was moving my fan further back from the radiator so I could get more air flow over more area of the rad, added a fan shroud along with a flex fan and a 180 degree thermostat. No more problems. Temp will run anywheres from 165 to 190 depending on the outside temp and on a hot day in traffic it may creep up to 195 - 200 but once moving it drops rather rapidly...
 
if it's overheating at idle...radiator, waterpump(is the water circulating at higher rpm ??) and or airflow issue....Best combination I ever used was 7 blade steel clutch fan...schroud...alum or copper rad...fan should go halfway in schroud...blades half in...half out..
 
everyone kept telling me it was because I had no fan shroud. It never came with one and, although it might help, I realized I had to get to the root of the problem. I had to ask, is it running hotter than normal and what is the cause? Like I said, in my case, and I hope for no one else, cracked heads, block...
 
Save yourself time and put a shroud, it helps much more than you think.. In fact it could be the problem. There is NOTHING wrong with running 200* over that I would get weary, but in no way is 200 too hott. Another thing that some do is change the water/antifreeze mixture. 50/50, 25/75, 75/25
 
Msbaugh,

I can support your theory to some degree. Pun intended. I have been working on my 340 and in the process I removed the shroud and clutch fan. Yesterday I had it back together and left the shroud off. I can only say that the temp guage was showing a higher temp than the last time I drove the car with the shroud. Not an exact science result by any means, but I do think the shroud creates a vortex effect witht the fan. In computers, fans are always shrouded. My guess is that the shroud reduces blade wash of the tips of the fan. Ducted fans are generally more efficient than non ducted fans. This and the fact that the shroud helps to pull air from the entire surface of the radiator through the fan.
 
Midlife,

Yup a shroud will improve the efficiency of the fan and it's ability to draw air only through the radiator. Which is of course desirable.
 
here are some things i have done in the past...changed pulley diameters to speed up flow,purchased hi flow water pumps..and when i wasnt using a thermostat i made a plate to put in the water neck in place of thermostat with different hole diameters plus and minus 5/8 inch...i know they may sound odd, but it worked,and all the things listed above..timing can cause heating problems also...and the type of fan can make a difference like the number of blades and the pitch....make sure you have a good radiator,and you cant trust guages...maybe change your guage and see if it reads like the old one...one thing for sure boiling noises is bad.lol
 
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