Dart over heating???

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604

604

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A month ago I got a nice 1973 dart sport. Well now that it is 95 in the shade it is over heating. It is a non AC car, so it still had the little 19in core skinny radiator, with no fan shroud. Witch I found out was correct for the car. So I went and bought one of the big 25in core radiators, and a 180 Milodon T-stat. Still over heats. The only thing I can think of it how far the fan is from the radiator. It is about 3.25in away from it. I can feel it pulling air threw, but could be stronger. It only has a 1in fan spacer on it now, and am thinking of trying a 2in to get it closer???? Have tried to find a fan shroud from a AC car but have not had any luck. Any one have any other ideas???

Thanks!
 
FIRST question "how do you know" it is overheating, and please don't say "because the factory dash gauge says so."

Aftermarket thermometers are not that expensive, you can get a meat/ heating/ ac type with a probe and just tape it to the under 3/4 of the top hose, then wrap and tape some insulation or a rag over it to insulate it, then see what it is actually running for temp

Is it puking out the overflow? You know you have a good cap?

Wind up the engine and see if the bottom hose tries to suck shut. This is a sure sign of a restriction in the system

Do you have a feel for how dirty/ clean the block is?


I would agree that WITHOUT a shroud, the fan needs to be closer to the rad.

DOES IT OVERHEAT at speed/ cruise? If so, the fan is not the problem, for now.

WHERE IS the timing? Retarded timing will cause overheating.

What engine combo, etc do you have?
 
Gage is saying it is overheating, and it is puking out the over flow. Only overheats at idle. Or pulling a steep hill at a slow rate of speed. I can look in the new radiator and it has great flow. Timing is at 5 before. It is a 318 auto. I did just find a fan shroud from a big mopar junk yard. So hopefully that should fix the problem. I am going to pick up a new cap just in case. It may be iffy. Thanks!
 
Yup. sounds to me like you are on the right track. A fan spacer may help some if you can round one up.

You might consider having a shroud mocked up in sheet metal, not all that hard. Have a sheet metal guy bend up a pan the right size for the rad, but don't cut it out. Have him give you a strip that's "tabbed" along one edge wide enough to extend out over the fan, and long enough to "go round."

You can do a lot of the work yourself just having the pan roughed out, drilling the mount holes, etc, and trimming to fit. A pair of red/ green snips at Lowe's are only about 15 bucks last time I looked.

Then put it in the car and "figgger" where the outside of the fan needs to be, add 3/4 or so for clearance and cut the hole. then install the tabbed strip around the hold to form the cylinder for the fan. You can tack weld the tabs to the shroud, or just put a few sheet metal screws or pop rivets in 'em.
 
If that doesn't work you might want to get dual fans. I got them on my and it doesn't get over 190 driving and 175 at idle.
 
When you get your shroud on, make sure you space your fan so that the blades are just about 1/2 way inside the shroud...1/2 way outside. I expect this will help as mentioned. A new cap never hurts either if they old one looks suspect and you dont know when it was last replaced. 16lb I believe is std for our cars...
 
Take the fan spacers and throw 'em into the trash , then go buy a real fan ( more than 4 blades ! ) and get a fan clutch .
Direct-drive fans are worthless ; they suck power from the motor , whereas a fan which declutches is much less of a drag .

IF you end up replacing the radiator , go wide with the core . Too many rows can makes it run hotter than :twisted: .

Here's my suggestion :
-26" wide radiator
- 3 row core
- Factory fan shroud
- 5-7 paddle fan
- Fan clutch
- Overflow tank
- Distilled water ( unless your locality has good tap water )
- 185-195 degree thermostat

Best of luck :mrgreen:
 
I think it would be more prudent to determine why it is over heating than to try to add more and more cooling.

Check for flow, you may have a bad waterpump.
check your spark plugs to see if you are getting the correct fuel mixture.
backflush the block
check to see if your exhaust is flowing freely.
 
trapster said:
I think it would be more prudent to determine why it is over heating than to try to add more and more cooling.

Check for flow, you may have a bad waterpump.
Click to expand...

Without the shroud it would be hard to determine because the cooling system is not complete, the shroud plays a significant role at keeping the engine cool at idle or slow speed, which is where he is experiencing the problem. He also stated that he does have good flow.

I run a 26" rad with a fixed flex fan and shroud on my Dart Sport with the 318. 180* stat and the fan is half in/half out of the shroud. The fan is also closer to the rad, about 2", I can run in 90* temps and it "might" eek up to 185* when cruising at 60mph. At idle and slow speeds it sits right on 180*. You may also want to consider a mechanical temp gauge as well.

Also don't overfill the rad, I fill mine to just cover the cores, not to the neck.
 
Thanks for all the input.
I am looking forward to getting the shroud and getting it on there. I looked at my original sales brochure, ad sure enough a fan shroud was an option! Hard to believe that in 1973 they were still putting out cars with out them. Explains why it was so hard to find one. I hate to add any gages as I am trying to keep this car looking stock for now. I think the shroud will fix it. As I put a big fan in front of the radiator in the garage and it runs nice and cool with it.
 
I had to replace a distributor in my 66 and it never got hot till I did, I moved the timing down a few degree's and it runs cool, you may want to look at that also, a lean mixture on the carb will make your engine run hot also but I am sure you know this already.
Have you tried backing off your timing a couple degree's ? it could help and not effect your daily driving. Just a thought.
 
LH23H2R said:
Take the fan spacers and throw 'em into the trash , then go buy a real fan ( more than 4 blades ! ) and get a fan clutch .
Direct-drive fans are worthless ; they suck power from the motor , whereas a fan which declutches is much less of a drag .

IF you end up replacing the radiator , go wide with the core . Too many rows can makes it run hotter than :twisted: .

Here's my suggestion :
-26" wide radiator
- 3 row core
- Factory fan shroud
- 5-7 paddle fan
- Fan clutch
- Overflow tank
- Distilled water ( unless your locality has good tap water )
- 185-195 degree thermostat

Best of luck :mrgreen:
Click to expand...

x2. Add the proper shroud and all of the above.
 
If you are over heating at idle and low speed, your fan isn't pulling enough air.

Like mentioned above.......

Get a real fan.

Get a shroud if you can.

Tape up any holes in your core support other than the radiator opening.

Make sure you don't have an open gap around the radiator where it meets the core support, you can get thick foam tape to fill these gaps at a hardware store.

Make sure you have the rubber seal on the underside of the front of the hood, this should seal the hood to the core support when closed.


You want as much air as you can going through the radiator.
 
I would also try running a 160° thermostat. You don't need the heat in the summer.

I also agree on getting a good shroud.

You need to concentrate on the airflow at idle/standing still. If you run ok when moving, your system has the capacity to cool, it is then getting restricted when standing still due to low airflow through the radiator. From what I'm reading here, you are not getting enough airflow through the radiator at idle/standing still. Get a good fan 5 - 7 blades and shoot for half of it to be covered in the shroud and half out.
 
Oh boy here we go again.

Don't change the thermostat temperature, The only thing a thermostat does is keep your car from running too cold. Lowering it does not increase your systems cooling capacity one bit.

There are higher flow thermostats that may help, but I would not change the recommended temperature.
 
trapster said:
Oh boy here we go again.

Don't change the thermostat temperature, The only thing a thermostat does is keep your car from running too cold. Lowering it does not increase your systems cooling capacity one bit.

There are higher flow thermostats that may help, but I would not change the recommended temperature.
Click to expand...

Bingo , you need a shroud , a good fan and the other parts mentioned . My Dart has factory cooling 180 thermostat and it runs cool , it's over 95 and have no trouble sitting in traffic or on the highway . Think clutch fan is best , cuts out when not needed , pulls lots of air when in combo with shroud . Rubber seal under hood helps as well .
Never had great luck with those aftermarket flex fans , look good , that's about it
 
Wighting on my shroud. I am sure it will do the trick.

It already has the factory 7 blade fan.

I put in a 180 Milodon T-stat

Timing is not the issue, as It over heated when I first got it, and the timing was at 5 deg after top center. Now it is at 5 deg before top and still doing the same thing.

The car dose still have the rubber hood seal.

I think it is just a mater of the fan to far from the radiator.

Still has the factory carter 2bbl carb. I do not think it is to Lean. Starts right up when cold with a single pump of the peddle, and runs great down the road. But it is a mother#$%$ to start when warm. But that is another problem.

Thanks for all the help!
 
160* stat = increased engine wear. A 180* stat will put you in the optimal range. The biggest part of the equation is the shroud IMO, without it you are pulling air around the rad instead of through it.

I run a 180* stat with 4 holes drilled around the flat plate, shroud and flex fan. This combo works great for my needs.

I can idle in 90* temps with absolutely no issues. Cruise at 60 with 2800 rpm becuase of my gearing with no issues as well.

After the shroud is on you may or may not need a spacer to achieve the 1/2 in 1/2 out of the shroud for optimal performance. The fan is about 2 inches from the rad surface.
 

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Something not mentioned. The bottom radiator hose does it have the spring in it? I see people on here with same problems and its because the lower hose is collapsing not allowing proper flow?
 
If the bottom hose is collapsing it is because you have problems elsewhere in the system , not because of no spring in hose . Forget why spring is there from factory , but none in mine and no problem .
 
72ScampTramp said:
Something not mentioned. The bottom radiator hose does it have the spring in it? I see people on here with same problems and its because the lower hose is collapsing not allowing proper flow?
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No spring. There was not one in the new hose. But it is a really thick hose, and is not collapsing. But good to know. I will keep an eye on it. Were can you get one with the spring??
 
604 said:
No spring. There was not one in the new hose. But it is a really thick hose, and is not collapsing. But good to know. I will keep an eye on it. Were can you get one with the spring??
Click to expand...


It may not be collapsing but under heavy loads while driving. I would trying it and see. auto parts store should have it.
 
I've seen people argue the spring thing back and forth...but I think it has merit. The bottom hose is on the suction side. I can certainly see where it might cause a problem. I'm no cooling engineer so I cannot argue any technical data, but lookin at it, it just makes sense. That and the fact that I have seen people fix their overheating problem by putting a spring in the bottom hose. lol
 
604 said:
No spring. There was not one in the new hose. But it is a really thick hose, and is not collapsing. But good to know. I will keep an eye on it. Were can you get one with the spring??
Click to expand...

Bring your engine to temp, and blurp the throttle from under the hood while watching the hose, probably not the issue in your case though.

Collapsing hose usually suggests a blockage in the radiator. The springs where installed to make filling of the cooling system faster on the production line (or so I've been told). I have not seen a hose with a spring in it for years from the parts store.

If you want/need a spring just get a wire coat hanger and coil it around something and install it in the hose, a piece of stainless wire would be better yet. I had to do that on my kid's car a while back.
 
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