Cooling my 360 in my 1970 Duster

[crackedback]

Put the box fan in front with the hood down. Simulate sitting in traffic.

Hood up may not make much difference with the shroud. Good luck with it and hope you narrow down the base issue.

 

[nm9stheham]

Just some observations: That fan shroud is not all that good. Not surprised that sealing it helped. Post 33 shows a setup that is about as good as you can get with the limited space. And the observations by Crackedback about aluminum flex fan blades cracking eventually is correct; they are going to eventually break. (Aluminum fatigues every time it is bent; that is why aircraft airframes have limited life.)

BTW, coolant going up to the 195F range should not be a big concern, but 210 F is certainly quite a rise in temps. Your cooling system is basically sound, since temps go back to 180 with just a small amount of extra airflow.

May I ask what part of Sweden you are in? I have a snowmobile friend up near Boden.

 

[MopaR&D]

I agree on getting a bigger fan and/or changing pulley ratio to speed up water pump and fan, sounds like everything else you have is working like it should. I lean more towards the fan as my Duster has a similar setup to yours in terms of aluminum rad, pulleys etc but with a factory-style 18" fan and viscous clutch and it has zero issues with rising temps. I can idle endlessly in traffic in summer heat and it never gets much over 190°F, I'm ready to quit before the car is lol. IIRC I've run it temporarily without a shroud and it didn't affect coolant temps much when stopped or at low speeds.

 

[RustyRatRod]

The boiling point is raised 3 degrees for every pound of pressure the system is under. If you have a 16 pound cap, that means your boiling point now becomes 260 degrees. ...and that's just using water in the formula. Coolant has a higher boiling point yet. The issue becomes when temperatures increase past about 230 in these old V8s, the temperature often keeps climbing. That's when you can get in trouble.

 

[trebor75]

Just some observations: That fan shroud is not all that good. Not surprised that sealing it helped. Post 33 shows a setup that is about as good as you can get with the limited space. And the observations by Crackedback about aluminum flex fan blades cracking eventually is correct; they are going to eventually break. (Aluminum fatigues every time it is bent; that is why aircraft airframes have limited life.)

BTW, coolant going up to the 195F range should not be a big concern, but 210 F is certainly quite a rise in temps. Your cooling system is basically sound, since temps go back to 180 with just a small amount of extra airflow.

May I ask what part of Sweden you are in? I have a snowmobile friend up near Boden.

Thanks. I'm not that far north as your friend. I'm located in Stockholm.

 

[trebor75]

It was suggested to try and move the fan a little bit more out of the shroud. Thats inexpensive and easy so I'm doing that first. Also plugging the passages where I had looped the heater core hoses. And lastly changing my lower radiator hose to a molded one. I'm aslo gonna order a quality high flow thermostat.

Have a look at the pictures (only test fitting here). This spacer is the best one I could find. I'm concerned I'm moving it to far out of the shroud with this one. This spacer is a 1". It's about 1/2 inch (13 mm) shorter than the previous one.

 

[nm9stheham]

Here is an observation from the pictures. The belt on the alternator and water pump is what is called a 'top cog' belt in North America; I think this term is a trademark of Dayco, so it may be called by other names if these are made by other belt manufacturers. I have had trouble more than once with these slipping without making any squealing noise, and so quit using them many years ago. The ones that slipped were made by Dayco and I could tighten them to an extreme degree and they would still slip.

So I would suggest a different belt be one of the changes that you try here. With so many rubber parts in the world becoming more questionable as to rubber characteristics, this might be one problem.

Also, that belt looks loose in one picture but that may be just for test fitting. But make sure that the belt tension is correct.

 

[trebor75]

Here is an observation from the pictures. The belt on the alternator and water pump is what is called a 'top cog' belt in North America; I think this term is a trademark of Dayco, so it may be called by other names if these are made by other belt manufacturers. I have had trouble more than once with these slipping without making any squealing noise, and so quit using them many years ago. The ones that slipped were made by Dayco and I could tighten them to an extreme degree and they would still slip.

So I would suggest a different belt be one of the changes that you try here. With so many rubber parts in the world becoming more questionable as to rubber characteristics, this might be one problem.

Also, that belt looks loose in one picture but that may be just for test fitting. But make sure that the belt tension is correct.

Thanks. I was not aware. Also a cheap easy thing to change. Just like you said, it's loose because of test fitting. I'm putting it back together tomorrow.

 

[Bewy]

Easy to change but do not think it will fix the problem.....
Hard to judge from the pics, but the fan looks too small for the shroud. Obviously, if the fan becomes too small, the fan will do nothing irrespective of how far the fan is in/out of the shroud.

 

[trebor75]

Easy to change but do not think it will fix the problem.....
Hard to judge from the pics, but the fan looks too small for the shroud. Obviously, if the fan becomes too small, the fan will do nothing irrespective of how far the fan is in/out of the shroud.

It's an 18" fan. I can get about a finger in between the fan blade and the shroud.

 

[Bewy]

That sounds good...

 

[nm9stheham]

Since the topic of belts has come up, you might want to view this thread, and post #4 specifically. It gives a good explanation on the changes in widths of belt widths over the decades and the fact that these older pulleys were designed for a 1/2" belt width, which is not common anymore.

Thread 'Belt Squeal'

Aug 7, 2026

I installed a VintageAir system on an 1986 318 engine and also installed the Compressor bracket they sell (162774-SDA).
I even bought their Crank and Water pump pulleys. I'm using Gates v-belts not flat belts.
The belt squeals a lot when the AC is ON. I will insert an image of their recommended arrangement.

Notice how the water pump pully does not have very much surface area, I feel that is the Squeal source.
I tried cleaning the pulleys very good, replaced the belts, still squeals occasionally.
I tightend the belt very tight, too much in my opinion, and the squeal only...

• dkamp
• Replies: 31
• Forum: Heating / Cooling / AC

 

[trebor75]

It's back together. I held a sheet of paper infront of the radiator core, I've done this before, and I can tell it is actually moving more air now with the fan moved a little bit more out of the shroud. The paper will also stick to the outside of the grill. I plugged the heater core loop I had and also switched to a molded lower radiator hose. I took it out driving yesterday in city traffic. It was a pretty hot day and it saw 194F when I was creeping around and in heavy traffic and lots of stop lights, and corrected back to 180F when driving. Will be test driving more today.