Overheating/Fan clutch options

[Gross Polluter]

I'm having overheating problems in my 383 with 22" radiator.  It's definitely worse on warm days, but the temp eventually creeps up on cooler days when driving at low speeds.  The thermostat and water pump are several years old but have very few miles on them.  The fan clutch doesn't spin a lot by hand, but it looks like it has leaked so that seems like an obvious place to start. 

Hayden clutches makes a heavy duty 2747, heavy duty low profile 2947, and severe duty 2797.  Any suggestions on which would be best?  One other factor is I'm using a flex a lite #5718, 6 blade fan.  The info for the clutches mention the fan blades should have a 2.5" pitch and I can't find any info of the sort for the the flex a lite.  Any thoughts on that as well? 

Thanks!

[Dakota]

Do you have a shroud around the fan?   Past posts here indicate that can have a big impact on cooling efficiency.

A fan clutch rebuild service is included in this recent thread:
https://www.forbbodiesonly.com/moparforum/threads/clutch-fan.268087/

One of the posts on the thread was from @Floyd who I believe is a member here as well, so maybe he can comment further.

[mopar jack]

 A complete 22" radiator system can run cool with the right components. I run a 3 core radiator, hayden fan clutch, the 216 fan, and factory shroud. The fan clutch and fan cost around $200. and the shroud around $200. see attached for parts availability: themoparshop.com/product-category/cooling/fan-blade-fan-clutch/

[Cuda Cody]

Timing can have a big effect on temps too.  Has the 383 been rebuilt?  What kind of power is it making and do you know where you set the timing?

[MoparLeo]

Can you please define what overheating means to you ?
Has anything recently been done to your car tht resulted in the " overheating issue?"
I have seen many posts over the years where some people think that 200-210° is overheating.
The Factory thermostat back then was 195 °.
That doesn't mean that the engine temp is supposed to be 195 °. That is just the temperature that the thermosat is designed to open so the coolant will flow through the radiator. Many things can affect temperatures. The more info you can give, the better diagnosis you will get.
Pictures help immensely.

[Gross Polluter]

Thanks for all the info! I'll try to take the questions in order.

I have a shroud. 

The clutch is a flex a lite standard duty and given the leak it seems more like a replace candidate rather than rebuild, to me. 

I've considered getting a more robust radiator but for this problem wanted to try to narrow down the causes a little more. 

I can't remember exactly where the timing is set but its advanced, somewhere in the teens.

The 383 was rebuilt by a previous owner, he said it was bored .030 over with a mild "torquer" cam.  Wish I knew more about it.  It was rebuilt about 20 years ago but only about 10k mi since. 

The power doesn't seem great, but aside from timing, I know the plugs, plug wires, coil, carb could probably all use some attention. 

I've seen the temp gauge approach 230* before I shut it down.  On a cool day or in the evening it runs more in the 180 to 190 range but will still creep up the more low speed driving I do. 

The water pump is a mopar 8 blade pump. Thermostat is 180*

Let me know what sort of pics will help and I will provide them

Thanks again!

[Cuda Cody]

If you want to test and see what happens, I've ran my engines without a thermostat before.  Not something you want to do on a daily driver, but I only use my cars in summer and that keeps them the coolest.  Might not be the final solution, but you will know there's nothing stopping the flow of coolant and if you still have issues you will need to address the size of the cooling system or the timing.  Most likely not a timing issue if you don't have a hard time starting it when it's already ran and the engine is warm. 

[Gross Polluter]

If you want to test and see what happens, I've ran my engines without a thermostat before.  Not something you want to do on a daily driver, but I only use my cars in summer and that keeps them the coolest.  Might not be the final solution, but you will know there's nothing stopping the flow of coolant and if you still have issues you will need to address the size of the cooling system or the timing.  Most likely not a timing issue if you don't have a hard time starting it when it's already ran and the engine is warm. 

Thanks.  I bench tested the thermostat before installing.  That was after I first noticed the problem of running hot so I guess I don't expect it's malfunctioning. 

Starting when the engine is warm has been an issue depending on how warm the engine is/was.  But I think it's complicated by gas boiling over from the carb into the engine if it's gotten hot enough.  Not sure if timing might be another factor.  If so, would you think it's not advanced enough?

[MoparLeo]

OK. You still haven't said wht hot is.Remeber that a fans only job is to supply enough airflow through the radiator at speeds below 45 mph. After that speed the natural force of air is more than the fan can provide. So It is natural forr the temps to be a little higher at idle and low speeds than at higher speeds. there are a few things that also control temps. The most overlooked is the radiator cap. The standard cap pressure was 16 lbs. It needs to be tested. Even new caps fail the pressure test a lot of times, so don't trust new as meaning it works.
approximately 3°F.
With every pound per square inch (PSI) placed on the cooling system, the coolant's boiling point raises approximately 3°F. A 15 PSI pressure cap twisted onto the radiator will result in a 45°F boiling point increase over the 220°F for a 265°F boiling point.
A proper 50/50 mix of distilled water to the proper type coolant also raises the boiling point.
Refer to the Cooling section (Group 7 ) of your factory service Manual for the proper cooling system specifications for your car. Downloads are available in our Resource Section.

[Gross Polluter]

OK. You still haven't said wht hot is.Remeber that a fans only job is to supply enough airflow through the radiator at speeds below 45 mph. After that speed the natural force of air is more than the fan can provide. So It is natural forr the temps to be a little higher at idle and low speeds than at higher speeds. there are a few things that also control temps. The most overlooked is the radiator cap. The standard cap pressure was 16 lbs. It needs to be tested. Even new caps fail the pressure test a lot of times, so don't trust new as meaning it works.
approximately 3°F.
With every pound per square inch (PSI) placed on the cooling system, the coolant's boiling point raises approximately 3°F. A 15 PSI pressure cap twisted onto the radiator will result in a 45°F boiling point increase over the 220°F for a 265°F boiling point.
A proper 50/50 mix of distilled water to the proper type coolant also raises the boiling point.
Refer to the Cooling section (Group 7 ) of your factory service Manual for the proper cooling system specifications for your car. Downloads are available in our Resource Section.

Thanks, appreciate the info.  I mentioned earlier that I've seen the temp reach nearly 230* before I thought it best to shut down.  Seems too hot, but what do you think? 

I understand it's normal for temps to run "a little" higher at low speeds, but how much is a little?  And once it reaches that point I find it difficult to restore to a lower temp. 

I have a roughly 50/50 coolant mix and a 16 lb cap (untested). 

[Strawdawg]

Looks to me as if the clutch is the main problem.  I would get a hd factory style fan and a good clutch.  In your current state, a clutch will probably fix it.  I live in a hot area and have learned not to like flex a lite type fans

Low speed problems are usually due to a lack of air flow thru the radiator.  I would use the factory fan not withstanding my comment above and a fan clutch that slips less.  I forget the Hayden number for the lower slip fan but it should be listed somewhere in comments on the site or on Hayden's page.  For some reason in the foggy banks of my mind is "Jaguar clutch" LOL, but you want the lower slip fan.  Makes a world of difference in traffic.

Looked it up.  Hayden 2765 appears to be the correct number.  Believe Chryco sent me that way many years ago.

[blown motor]

What do you mean "the fan clutch leaks? There is no coolant at or around the clutch. Is the water pump shaft leaking?

[Strawdawg]

What do you mean "the fan clutch leaks? There is no coolant at or around the clutch. Is the water pump shaft leaking?

Clutch fans have silicone fluid in them as I recall.  They definitely can leak and when they do, they don't work right.  Seems like they are supposed to be stored in a vertical position to minimize the chances of leakage.

If you can reach under the hood and try to spin the fan by hand (engine off, of course)  on a warm engine, and it spins much more than a full turn, the clutch is shot!

When turning a warm engine off, the fan should stop spinning almost immediately....

[blown motor]

What do you mean "the fan clutch leaks? There is no coolant at or around the clutch. Is the water pump shaft leaking?

Clutch fans have silicone fluid in them as I recall.  They definitely can leak and when they do, they don't work right.  Seems like they are supposed to be stored in a vertical position to minimize the chances of leakage.

If you can reach under the hood and try to spin the fan by hand (engine off, of course)  on a warm engine, and it spins much more than a full turn, the clutch is shot!

When turning a warm engine off, the fan should stop spinning almost immediately....

I never knew that. Learned something today.

[Jay Bee]

For future reference RE: fan clutch
https://www.onallcylinders.com/2016/11/10/understanding-fan-clutches-time-replace/