Engine overheating

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wes beem

wes beem

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I have a 1970 dodge dart with a bone stock 318 magnum out of a 98 jeep, 727 transmission, No A/C. the car keeps overheating just sitting in the driveway idling, it gets so hot that you can see steam coming out of the valve covers and everything is HOT HOT HOT. Previously the thermostat was stuck so i removed it completely, it seemed like it helped at the time but that doesnt seem to be the case. Im thinking about completely gutting the radiator and getting a new one...Looking for recommendations in what the best radiator would be to keep this thing cool. I dont know much about fans, it has a fan blade connected to the motor that is belt driven, no shroud. I included under hood pics of what i currently have going on
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There is a chance that your radiator is badly clogged or has been repaired enough times that it just doesn't have much capacity. However, that looks like a 26" unit you have there. No reason you should be getting so hot at idle with a 318. If you have no thermostat, open up the filler and look inside there and make sure you see the fluid moving pretty good. If not, you have a water pump problem and can concentrate on that first.
 
Test your clutch fan, I bet it freewheels when hot, and that would be a bad thing. For a test you can sub in a direct-drive fan, the more blades the better, but a high pitch 5-blade trumps a 6-blade shallow angle. Run it as close to the rad as you dare with a 1-inch minimum.
 
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I see you have the PCV hooked up, but where is it drawing fresh air into the crankcase?
I also see you have looped the heater hose from inlet to outlet, and you said you took the stat out. In that case I would plug that loop, else the water will want to go round and round inside the engine,getting hotter and hotter with every trip.
And the missing shroud
And the fan is quite far from the rad. Without the shroud, this is a no-no, as the fan finds it far easier to draw air in from the sides,than thru the rad..The stock-cam 318 doesn't absolutely need the shroud, if the WORKING fan clutch/fan is snuggled up to the rad to within 1 inch of the fins. You can go closer with a low-rpm engine, but as the engine winds up, the blades will tend to bend forward into the rad, especially if the air passes freely thru the rad. WATCH-OUT, the fan does not usually sit parallel to the fan. Usually the bottom is closer to the blades than the top.

PUT the stat back in, it sets the minimum operating temperature. I like a 195 for performance and fuel economy and for a long engine life. The stat provides a bit of a restriction, to make sure the water goes all the way to the back before turning around and coming back. The bypass is just for a quick warm-up, allowing the cold fluid to circulate until it is hot enough to open the stat.
An overheat in the driveway at idle is 100% a failure of the rad to shed heat. Either the hot water is not getting into the rad, or thru the rad OR it's not getting cooled on the trip.
The temperature difference from top top bottom should be about 30*F
The fan should be able to suck an 8.5x11 sheet of paper up tight to the front of the rad.
The water should clearly be seen circulating under the cap and should speed up when the rpm is raised.
Steam coming from the valve covers better not be steam, but rather blow-by, AND at idle the PCV should be sucking that up like a big old vacuum-cleaner. If it doesn't seem to be doing that, either it is faulty,the hose is plugged, or the engine needs a rebuild. Put a vacuum/fuel-pump gauge on the dipstick, and measure the pressure. It should measure a slight vacuum when you plug the CC intake breather, but NOT pressure.
And finally check your timing. Idle-timing can be 8 to 12 degrees, while power-timing must be limited to about 34/36. You can run even more idle timing if your T-port exposure below the throttle valves doesn't fall below a square shape.
 
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71DodgeDemon340 said:
Does it overheat while driving? In not then its most likely a airflow problem
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That i dont know, it has a very bad fuel leak and i havent had a chance to drive it anywhere but from the garrage to the backyard
 
Gotcha. Also check timing too, may need to back it off a little. Radiator fins could be partially clogged reducing airflow as well
 
Timing should be good, had a mechanic do that a while back, it was overheating both before and after so i think that's ruled out.I have a strong feeling my radiator is junk.

So i should check in the following order?

Water pump
Clutch fan
Clutch Fan distance
Install a Fan Shroud
Buy New Radiator
 
As mentioned,engine cold, open rad cap and check for flow.
Engine hot,feel the air behind the fan,like above the intake,it should be hot from heat transfer.

Fix your fuel leak.....
 
This ^

I would also check the distance from the fan to the radiator. A good rule of thumb would be 3/4” to 1 1/2” away from the radiator. Any more distance and a shroud will be beneficial. Have you ever replaced the t stat with a new one?
 
71DodgeDemon340 said:
This ^

I would also check the distance from the fan to the radiator. A good rule of thumb would be 3/4” to 1 1/2” away from the radiator. Any more distance and a shroud will be beneficial. Have you ever replaced the t stat with a new one?
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Never replaced the thermostat, I was told its unnecessary since i dont have a working heater in the car, figured id install it when i install the heater stuff
 
So i should check in the following order?

1) test Clutch fan; When cold it should have minor resistance, when hot it should have major resistance.If NG,either replace it or go to #17.If good;
3) test rad air cross-flow with a sheet of paper; If NG,blow out the fins with compressed air and retest. If now good, go to #25. If the test is now good, but still overheats, then;
5) check/adjust ignition timing, and retest. If now good go to #25. If still NG,then;
7) restrict heater bypass, and retest. If good go to #25 If NG, then:
9) With the stat still out,Remove the cap when cold,then check water circulation in top of rad; if good go to #15 if NG then;
11) remove and check the Water pump impeller; if NG replace it, and retest.If now good go to #25. If NG then;
13) test rad water flow,from top to bottom.If good,go to #15 if flow NG then #23
15) install stat, and retest.If now good, go to 25. If still NG, then;
17) install a direct drive fan and retest. If still NG then go to #3 If already a direct-drive then;
19)Install a Fan Shroud or
21) move Fan closer to rad, and retest. If still NG go to #27/29
23)Buy New Radiator
25) Done!
27) I guess a compression test is in order by this time
29) I'm outta ideas

This is a summary. Many items have already been mentioned. I hope I didn't miss anything. Guys, feel free to add stuff in the appropriate places.
 
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Had a similar issue, jeep.
Replaced thermostat,fan clutch and water pump. It improved marginally. I never expected rad to be bad, but it was overheating,and air blowing through rad was ambient air temperature.
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wes beem said:
Never replaced the thermostat, I was told its unnecessary since i dont have a working heater in the car, figured id install it when i install the heater stuff
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Whoever told you that is wrong. The thermo provides a restriction in the water flow, even when open, to allow the water to remain in the rad long enough to be cooled properly, before returning to the engine.
 
wes beem said:
Never replaced the thermostat, I was told its unnecessary since i dont have a working heater in the car, figured id install it when i install the heater stuff
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The t stat isnt dependant on having a heater at all, the heater bypasses the thermostat anyway. Its in a seperate loop with one end on the water pump and other going to the intake.
 
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Thermostat should be considered engine temperature regulator. Is absolutely necessary.
 
This is my 2 cents worth. You have a good chance that the radiator has corrosion built up in it unless someone has cleaned it in the past. If it were my vehicle I would put a thermostat in it and get rid of the fan clutch and put a black injection molded fan on it . They cost about $50 plus spacers. Put the fan roughly 1" away from rad but no closer than 3/4" from rad. One of your problems is air flow. So start with the cheaper fix . You will have to change the fan eventually any way. If this doesn't solve the problem providing you haven't done engine damage from overheating then pull rad and bring it to a rad shop for them to look at it. Just my 2 cents worth
 
solarcabin1 said:
This is my 2 cents worth. You have a good chance that the radiator has corrosion built up in it unless someone has cleaned it in the past. If it were my vehicle I would put a thermostat in it and get rid of the fan clutch and put a black injection molded fan on it . They cost about $50 plus spacers. Put the fan roughly 1" away from rad but no closer than 3/4" from rad. One of your problems is air flow. So start with the cheaper fix . You will have to change the fan eventually any way. If this doesn't solve the problem providing you haven't done engine damage from overheating then pull rad and bring it to a rad shop for them to look at it. Just my 2 cents worth
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can you send me a link to the fans your talking about? Sorry this is all new to me.
 
I noticed in your pictures that you do not have a fan shroud. Without a shroud, air will not be forced through the radiator and it absolutely WILL overheat when standing still; even if the radiator is fine. A shroud will force the air to flow through the radiator; not around it. You also need a hood to radiator seal. The car came with one, and they also help force air through the radiator.
 
So how do you know it is over heating? Usually steam wont come from valve covers, it will usually boil out through the over flow tube
 
Possible you've done a head gasket and combustion gasses are heating your coolant.

Check the dipstick for white sludge...may or may not be there. You can also test your radiator for combustion gasses:

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I would advise going to the zone or oreillys and buying a set of mechanical oil press and water temp gauges. Without them its like trying to fly a plane without a altimeter
 
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