Another overheating situation 63 Slant six

-

Hideogumperjr

Well-Known Member
Joined
Oct 21, 2011
Messages
278
Reaction score
12
Location
Bothell, Wa
Hi Guys, its been a long time since Ive been on here, been trying to get stuff done but my old body is just giving me fits and its getting harder and harder to do anything on the girl now a days. Heck, harder to get anything done now, hands arthritic.

So here is my problem, I am overheating at just getting around, I cant drive two miles here in Seattle, read that cool, and it will overheat.

A little history, engine was rebuilt completely a few years ago, block was tanked and cleaned, head rebuilt and all. I had the original radiator checked and it was toast so I bought one off of CL for a later model Dart.

The problem I found though is that the core is biased towards the engine compartment while the original was biased away from the compartment, end result, the radiator is too close to the fan so I removed the stock fan and am using a 16" electric fan in front of the radiator pushing air through. Ive had it there since 2017.

Ive lost coolant so replaced with only water and it overheated, last fall I did 50/50 new antifreeze, lost it this week.

The electric fan is here:
https://www.amazon.com/gp/product/B00VVWTAA2/?tag=fabo03-20

Upgr8 Universal High Performance 12V Slim Electric Cooling Radiator Fan With Fan Mounting Kit (16 Inch, Black) Comes with mount brackets , and tie straps kit
Maximum Fan CFM=3000 CFM, Maximum Fan RPM=2250 RPM
Size: 16 Inch, Thickness: 3.25 Inch
10 Blades, 12 Volts, 120W
OE Fitment or Replacement, Push or Pull Type

The radiator has a place for a sensor so I installed a thermostatic switch at 185︒F to turn on the fan. There is no fan shroud now nor never as far as I know.

I installed relays for all electronics per FABO and SSO suggestions. The fan circuit has a relay.

Since the radiator change the heating cooling has been topsy. I have put a new radiator cap on it, I have tried different thermostats at different temps, 160-185 I believe it is. I have an electronic temperature gauge inside the passenger compartment so I can see what the temp is and it certainly goes to overheating, 225︒F+, and only on a short two mile ride here is Seattle air temp was 60︒F.

I tried to run it while it was cooler here and it overheated so I drained antifreeze and removed the thermostat. It still overheated. Im pretty much at my wits end here and Ive been reading many of the posts here for overheating, Ive tried to make sure Ive covered all the suggestions so I guess my question is would the radiator the problem and should I just replace the damn thing with an aluminum 2 row? I wanted to try to get the original fixed so it would be the correct one but here in my area north of Seattle there is mostly no radiator shops. The man who did my previous radiator work died, I recently found out, a couple of years ago. Was going to take the car there to be fixed, I'm at that point.

Afraid to drive ANYWHERE!

Anyway, glad to be back online and want to get this fixed so I can drive her and I'm at the point of just selling her because of this dang overheating.

Any thoughts, new cuss words and such would be appreciated.

Thanks yall.
 
We need some more info.

What car
what year
What modifications

Sounds like you have a circulation issue. With no t stat the coolant should be circulating no matter what.

The cfm of your fan is good, pushing is not as efficient as pulling.

There are a number of things to check.

The water pump pulley diameter to crank diameter, find out what oem is.

I'm not familiar with slant 6s but on v8s you can pull off the lower hose and see into the water pump. If you can, see if the impellers are there. With the fan belt off see if the impellers turn with the pulley, maybe even insert a dowel to prevent the impeller from turning and see if the water pump pulley can be turned.

I think it was 67dart273 that has suggested take the lower hose off the radiator and put the garden hose onto the filler. With the hose on, the water should run out as fast as you can put it on ( maybe not on full blast)

If you drive the car at 40mph does the temp go down?

If you can get the oem rad fixed you will be in better shape than all other option, it fits, you can use the mechanical fan, an oem shroud might be available.

Get the correct thermostat for the engine and year.

Get the correct rad cap.

50/50 coolant
 
WHEN does it over heat? Sitting at a stop or running down the road? Does it ever cool back off?
 
Rats thought Id gotten all my data down. Sigh.
The car is a 63 Dart convertible with a 225 SS. It has a mild cam installed, it was bored .060 and the head milled .0100 or so. The cam was degreed in ok. It has the Super six dual barrel carb added.
The water pump was replaced last fall as the old one was squealing like a stuck pig.
The car will overheat when I run it up to speed and climb as I get up to speed. As I said in the post it heats up so quickly I cant really get going too long. I live in a subdivision and there is a stretch of road behind the high school where I can get up to 40 or so and by the time I go the less than two miles, it is going up and up. It seemed to run about 180 for a while at the beginning, about 30 mph. As I hit the back road and punched it to put a load on the motor it began to climb up to 200 the 220 and Im easing back home limping slowly.
I will take it out tomorrow, to see if I can better get a handle on the speed and how it heats up.
As far as the original radiator, I dont really have a place I have found in my area to get the original radiator recored and renewed.
Water pump pulley is stock, new belt, tight. At idle with the radiator cap off there is a ton of flow visible.
Thanks for the help yall.
 
WHERE is the timing set? What radiator? Number of rows? Aluminum or brass/copper?
 
Timing has been set at 8BTDC to 0TDC to retarded so much it lacks any power at all and still overheats.
The radiator is supposed to be a stock brass/copper I assume, not aluminum, radiator from a newer dart between 67-72 as I remember, it has been a few years since I bought it. Overall it fits the opening but is thinner than the original one.
I bought the radiator off craigslist still boxed but it was rebuild for sure. Ill check the row count and fire her up today to see if I can better document the heating situation.
Cheers and happy spring.
 
Timing has been set at 8BTDC to 0TDC to retarded so much it lacks any power at all and still overheats.
The radiator is supposed to be a stock brass/copper I assume, not aluminum, radiator from a newer dart between 67-72 as I remember, it has been a few years since I bought it. Overall it fits the opening but is thinner than the original one.
I bought the radiator off craigslist still boxed but it was rebuild for sure. Ill check the row count and fire her up today to see if I can better document the heating situation.
Cheers and happy spring.

Why would you retard timing trying to make it run cool? Here's how that works. When timing is retarded, the engine runs hotter. That's perhaps the number ONE first time engine start mistake in the WORLD.

With timing retarded, the mixture is ignited late and STILL burning coming out of the exhaust. The result is an over heated engine. I remember you said somewhere your engine has a mild cam, and the head is milled .100". I just put a modified 225 in my 64 Valiant. My build is similar, but my head was milled .155" (don't ask) and my cam is 250@ .050 duration ground on a 108 lobe separation. I have my timing on about 16-17 BTDC. 15 degrees is the last mark on the scale and the timing mark is just a "tic" before the scale. Total is about 35 degrees and it's all in by 3000 RPM. More timing will likely help your situation.....possibly......but retarded will 100% make it worse.

Here's a good method I learned years ago an older gentleman taught me. Before you make your timing adjustment, put your hand on the valve cover. Get a "feel" for the engine's vibration. I know....this sounds stupid but bear with me. Now, loosen the distributor and start advancing the timing until you feel a hard "rumble" through the valve cover, then back off until that "extra" rumble stops and go drive it. I know. It sounds like some stupid voodoo, but 9 times out of 10 it works very well.

But trust me when I tell you, retarding timing is the WRONG way to go. It might not be your issue, but it sure won't help.
 
Timing has been set at 8BTDC to 0TDC to retarded so much it lacks any power at all and still overheats.
The radiator is supposed to be a stock brass/copper I assume, not aluminum, radiator from a newer dart between 67-72 as I remember, it has been a few years since I bought it. Overall it fits the opening but is thinner than the original one.
I bought the radiator off craigslist still boxed but it was rebuild for sure. Ill check the row count and fire her up today to see if I can better document the heating situation.
Cheers and happy spring.
When the engine is cold, take the radiator cap off and start the engine. As the engine thermostat opens, do you see a rush of water into the radiator? After the rush, do you see good movement in the radiator, or is it almost imperceptible?
 
Well, the thought was to try timing early, on-time, and retarded to see if there were any difference, there was not.
Ill try the rumble, rumble (Im a tank!) suggestion.
As far as the coolant flow, I currently have the thermostat out, as another test for the problem. There is a ton of movement.
Now this am I went out and with air temp of about 60-65, I started the car in the driveway and let it warm up at idle, after 8 minutes the temp was up to 220 so I shut it down. The fan had come on around 200.
I waited till the fan stopped and popped the cap, still mostly the same amount of coolant as I started with as I didnt let it blow off any. I decided I would drain the radiator and pull the bottom hose and run water through as suggested earlier.
When I removed the drain petcock at the bottom of the radiator and catch the coolant I was pretty stunned to feel very cold water coming out of the petcock. I checked the water at the top with my finger and it was still hot but the bottom water was cold, seemed like a huge difference. So it sounds like the radiator is hosed but I asked for advice, what you think?.


Thanks
John
 
Well, the thought was to try timing early, on-time, and retarded to see if there were any difference, there was not.
Ill try the rumble, rumble (Im a tank!) suggestion.
As far as the coolant flow, I currently have the thermostat out, as another test for the problem. There is a ton of movement.
Now this am I went out and with air temp of about 60-65, I started the car in the driveway and let it warm up at idle, after 8 minutes the temp was up to 220 so I shut it down. The fan had come on around 200.
I waited till the fan stopped and popped the cap, still mostly the same amount of coolant as I started with as I didnt let it blow off any. I decided I would drain the radiator and pull the bottom hose and run water through as suggested earlier.
When I removed the drain petcock at the bottom of the radiator and catch the coolant I was pretty stunned to feel very cold water coming out of the petcock. I checked the water at the top with my finger and it was still hot but the bottom water was cold, seemed like a huge difference. So it sounds like the radiator is hosed but I asked for advice, what you think?.


Thanks
John
Sure sounds like there is a blockage in that radiator. If you squeeze the bottom hose, do you see movement in the water at the top? After running the engine, is the bottom hose hot?
 
Well, the thought was to try timing early, on-time, and retarded to see if there were any difference, there was not.
Ill try the rumble, rumble (Im a tank!) suggestion.
As far as the coolant flow, I currently have the thermostat out, as another test for the problem. There is a ton of movement.
Now this am I went out and with air temp of about 60-65, I started the car in the driveway and let it warm up at idle, after 8 minutes the temp was up to 220 so I shut it down. The fan had come on around 200.
I waited till the fan stopped and popped the cap, still mostly the same amount of coolant as I started with as I didnt let it blow off any. I decided I would drain the radiator and pull the bottom hose and run water through as suggested earlier.
When I removed the drain petcock at the bottom of the radiator and catch the coolant I was pretty stunned to feel very cold water coming out of the petcock. I checked the water at the top with my finger and it was still hot but the bottom water was cold, seemed like a huge difference. So it sounds like the radiator is hosed but I asked for advice, what you think?.


Thanks
John
The other thing I thought of is this: in a very hot engine, the heat will cause water to flow into the top of the radiator. If the water pump is not working properly, it cannot move the water through the radiator. That can give you the symptom of cold water at the bottom you are seeing. See if squeezing the bottom hose causes water to be disturbed at the top. That will help tell if the radiator is clogged. If water moves, then you should investigate the water pump function next.
 
Had a very similar problem years back. Pulling the cap off the flow looked good no real calcium build up. It drove me crazy. I finally took the rad to a shop. Down below where I couldn’t see was major league clogged. When he rodded it out the rad crumbled in his hands.
As already said check the pump, also could be a hose collapsing , and if you’re losing water Before it overheats could be a blown head gasket. Check to see if the oil appears milk looking.
 
Last edited:
The oil is fine, no foaming and minor discoloration, time for an oil change soon. I topped the radiator back with fluid and squeezed the bottom hose and yes there is movement and bubbles there but how accurate is that of a test?
The water at the bottom when I drained it was really cool, now warmth and the upper was quite hot.
Any more suggestions bar just replacing the radiator? So close to wits end!
 
The oil is fine, no foaming and minor discoloration, time for an oil change soon. I topped the radiator back with fluid and squeezed the bottom hose and yes there is movement and bubbles there but how accurate is that of a test?
The water at the bottom when I drained it was really cool, now warmth and the upper was quite hot.
Any more suggestions bar just replacing the radiator? So close to wits end!
Water pump? If all was working well until recently, I would discount the radiator being a problem. Though possible, they normally don't fail on a daily driver. Without a thermostat the flow ought to be very fast in the radiator and the bottom hose should be quite warm. If not, the water pump is the next stop I would make.
 
I just rechecked and let it run up to 215, bottom hose is hot, bottom of radiator is hot, and coolant from the pitcock is hot. So different than what I found this morning, at least as far as coolant temp goes after it had cooled down a bit.
 
Get an infra red heat gun. The coolant coming out in the bottom hose should be a good bit cooler than what's going in at the top. You can also check the temp at the thermostat housing and confirm what your gauge says.
 
Took it for another drive after I checked the heating this morning. It seemed to be fine, running at about 180 for the first part of the drive going about 35. I turned around and it was stil fine, distance was about a mile. I had to stop for a couple of minutes and the temp started rising nearly immediately and I headed back home temp got to about 215 or so.
 
So what will the IR reader determine? If the radiator is working?

Everything. It will confirm if it's really running hot. It will show what the water temp is going into and coming out of the radiator. You can see a lot of things with it. Under 20 bucks it's a fantastic diagnostic tool.
 
slant 6's NEED NEED NEED the thermostat to be IN PLACE. get a thermostat, test it on the stove in boiling water (make sure it opens) and install it. not having one in will cause more issues or may even be your cause.

went through literally everything that's been explained above. new water pump, new radiator, head gasket, checked timing.. everything. It was not having a thermostat that ended up being the issue.
 
I put the thermostat in backwards one time and that threw me for a loop!! Temp gun found the problem.
 
-
Back
Top