451 overheating, even when moving

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canajien

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I brought my 71 Duster home yday, and had to stop 2x to let it cool down and puke :( what is normally a 30 min drive, using the highway, took almost 3 hours while avoiding the highway

it has a 400 bored out to 451, and would get up to 230f after to 12 minutes, and it wasn't even 30c (less than 90f?)

It was a drag car and the engine is very high compression which contributes to the problem

3 core champion rad, electric fans that are always on when running, using a manual switch

Everything was flushed so there is a possibility they put too much back in the rad, what's a good level? Touching the top hose? Above the top hose?

Any suggestions to help it keep cooler are appreciated

I don't know if they replaced the t-stat, so I've ordered a high flow Mr gasket, the milodon is sold out everywhere I looked

I'm going to grab some water wetter this morning, it can't hurt, and the car is no longer drag racing anyway.

My neighbour, a retired mechanical engineer who used build race engines as a hobby, has suggested adding a big remote oil cooler to the mix with a t-stat controller.

Thanks
 
Do you have a fan shroud to help direct air through the radiator and not let it go around it???

Post some pictures of your set-up so we can see what you have and make more suggestions...
 
If that engine was a race engine- 12minutes is about 11-1/2 minutes more than it was used to running. Water pump turning too slow? Radiator airflow proper? Block coolant passages filled? Timing to advanced/ engine working too hard? Rear gears too low for road use?
Just spit balling.
 
Atta Cruising speed that produces 2400 to 2800rpm, the ignition timing will want to be in the window of 46 to 56 degrees.
The trans should have it's own cooler.
Good luck with the electric fans. make sure they are rotating in the right direction.
BTW
the thermostat sets the minimum temperature; if you take it out for testing purposes, swap in a restrictor washer or a gutted old stat, to prevent erroneous temperature readings.
While in park and idling;
the rad needs to drop the temperature about 25/30*F from tank to tank. If she can't do it with the fans running top speed and the stat removed for testing, IMA suspecting the fans, or the fan-system.

Don't forget that water expands with increasing temperature. If the cooling system is NOT of the recirculating kind, and the rad is overfilled when cold, it WILL puke coolant until it finds it's natural level. After it is finished puking and has cooled off, pop the cap and witness the correct level. In my experience this will be above the cores and not much more than 1 inch below the top of the tank.
and
if the car still has a heater, you can set the blowerfan on high and in an emergency, extract quite a bit of heat this way.
and
Until you get this figured out, the water pump should be turning faster than the crank, which means the pump-pulley needs to be smaller than the crank.
EDIT
oh I see you know about liquid-expansion with heat.
BTW-2
The point in the cranks rotation at which optimum energy transfer of the expanding gasses should occur is in the window of 25>28 degrees AFTER TDC. All your timing systems are or should be, engineered to try and hit that mark as often as possible, under as many different rpm and load settings as is possible. Therefore;
1) if your timing is locked out at some racing number, that will be part of your problem, as retarded timing puts additional heat into the coolant,and
2) it is as good as impossible to give the engine the large amount of Idle-timing that it actually wants, with a distributor, and still be able to drive that engine at low rpm, without getting into detonation..... but that is somewhat combination dependent.
 
Last edited:
All good points

I forgot to mention, the guy I bought it from, got it 18 years ago and proceeded to make it street able again removed the roll cage, etc....

He would often take it out 20 to 30 mins from his place to various shows/meets and it never went past 210f on him.

But he's out in the country and it's pretty much non stop driving for him anywhere he went, whereas I brought it back to the city.

3:91 gears in the back could be a part of it, but I made sure to get that torque flight into 3rd as soon as possible after every stop and the rpms were always low.

I may get a pusher fan to add to the set up, the e-fans in there right now move plenty of air and the rad seems to be clear of any debris. Not enough room to use an engine driven fan so that's not an option :(

Timing is a good idea to add to the list, doesn't cost a thing, thanks!!!

Smaller water pump pulley and maybe a water pump when I do the t-stat.
 
Have you looked into the radiator fill neck to see if there is coolant movement?
 
Atta Cruising speed that produces 2400 to 2800rpm, the timing will want to be in the window of 46 to 56 degrees.
The trans should have it's own cooler.
Good luck with the electric fans.
BTW
the thermostat sets the minimum temperature; if you take it out for testing purposes, swap in a restrictor washer or a gutted old stat, to prevent erroneous temperature readings.
While in park and idling;
the rad needs to drop the temperature about 25/30*F from tank to tank. If she can't do it with the fans running top speed and the stat removed for testing, IMA suspecting the fans, or the fan-system.
Trans has its own cooler, in front of rad, couldn't hurt to throw a pusher fan in there as well.

Lotsa good ideas here... Thanks!!!
 
All good points

I forgot to mention, the guy I bought it from, got it 18 years ago and proceeded to make it street able again removed the roll cage, etc....

He would often take it out 20 to 30 mins from his place to various shows/meets and it never went past 210f on him.

But he's out in the country and it's pretty much non stop driving for him anywhere he went, whereas I brought it back to the city.

3:91 gears in the back could be a part of it, but I made sure to get that torque flight into 3rd as soon as possible after every stop and the rpms were always low.

I may get a pusher fan to add to the set up, the e-fans in there right now move plenty of air and the rad seems to be clear of any debris. Not enough room to use an engine driven fan so that's not an option :(

Timing is a good idea to add to the list, doesn't cost a thing, thanks!!!

Smaller water pump pulley and maybe a water pump when I do the t-stat.

I wouldn't add another obstruction in-front of the radiator until you 100% confirm you have an airflow problem.

Check to ensure fluid is circulating. Check timing. Check carb settings. Etc...

I've seen it where adding a pusher fan actually made the situation worse.
 
another thing you can do to see the effects of adding idle-timing is to, with an IR gun, watch the temp of the exhaust in the headers, of the warm and running engine.. Pick the hottest spots within a few inches of the heads, on various headers, and mentally mark those spots. Check and record with the current timing then advance the timing, in say 5*increments. This will cause the Idle rpm to increase. Keep adding, until additional timing produces no additional rpm, then back it up to the last increment. All the while you should be watching those hot spots.
However, for this to be accurate the engine temp has to remain reasonable stable. What I do is just grab the D and crank to whatever peaks the rpm, without regard to watching the actual timing. In this way it only takes seconds to see the results..... which should see the exhaust temp drop into the 375/450 zone.
Now;
The rpm goes up because by starting the fire earlier, MORE pressure is created earlier in the Piston's downstroke, which pushes harder on the piston, producing more Idle-Power. Don't be surprised to, when yur done testing, see timing in the amount of 30 degrees or more at Idle.
But if running the stock-type open-chamber iron heads, it's hardly likely that you could run it like that under load without detonation.
Furthermore,
it will clang the Neutral to in-gear shift pretty hard. And if you idle her down, you will upset the Transferslot operation, and this
will introduce tip-in woes, and possibly
to the point that she may stall when going into gear.
Therefore with an automatic trans, chose an idle-timing number in the 16 to 20 degree window, that does not manifest these kinds of issues. Just make sure the Power-Timing does not get you into detonation.
 
Have you confirmed the cooling system has been burped? Air in the system can the same problem you're having. Just thought I'd add to the list of things to check....
 
e-fans in there right now move plenty of air and the rad seems to be clear of any debris. Not enough room to use an engine driven fan so that's not an option.

This was the same senario with with electric fan and flat box shroud blocking airflow on this high performance 440, not enough room, and was overheating.

Made room for the 18" fan by modifying the upper serpentine water pump pully to fit the fan spacer, and losing the flat box shroud.

Keeping cool now, 2 years running.

Screenshot_20220621-205007_Gallery.jpg


18" Fan

Resized_20220627_134158(0)_6427.jpeg


Modified water pump serpentine pulley.

Resized_20220621_174251_9888.jpeg


Working good and runs quiet too. Simple, just works.

Your deep gears are not doing you any favors, as far as trying to keep things running cool.

☆☆☆☆☆
 
If wasn't burped before, it likely is now.

I opened the rad, and gently revved till it reached 180, then I got out and let it run in its own at about 950rpm for 10 mins while I mucked about.

The coolant was definitely moving around and the temp stayed at 180 the whole time, but it's also 7 or 10 degrees celsius cooler today.

There's a list of things everyone has given me to check, I'll compile it later. In the meantime here's the cooling set up.

IMG_20230708_123444647_HDR.jpg
 
Looks ^^^ like your 2 electric fans are mounted inside the flat box shroud, only allowing them to pull air from the 2 Bullseyes directly in front of them.

Would say this layout is better run without the shroud so that it is not blocking airflow from around the rest of the radiator core.

Screenshot_20230708-143902_Firefox.jpg


Now if you choose to run the flat box shroud, the fans should be mounted on the outside (engine side) of the shroud like Champion shows in their advertisement so it can pull air through the full radiator core.

Screenshot_20230708-144145_Firefox.jpg


Your coolant recovery add on bottle is a good idea so that you can run a 100% full cooling system.

20230708_144349.jpg


☆☆☆☆☆
 
Easy enough ^^^ to pull that flat shroud off of your existing setup, as it is certainly blocking air around the 2 electric fans.

☆☆☆☆☆
 
I brought my 71 Duster home yday, and had to stop 2x to let it cool down and puke :( what is normally a 30 min drive, using the highway, took almost 3 hours while avoiding the highway

it has a 400 bored out to 451, and would get up to 230f after to 12 minutes, and it wasn't even 30c (less than 90f?)

It was a drag car and the engine is very high compression which contributes to the problem

3 core champion rad, electric fans that are always on when running, using a manual switch

Everything was flushed so there is a possibility they put too much back in the rad, what's a good level? Touching the top hose? Above the top hose?

Any suggestions to help it keep cooler are appreciated

I don't know if they replaced the t-stat, so I've ordered a high flow Mr gasket, the milodon is sold out everywhere I looked

I'm going to grab some water wetter this morning, it can't hurt, and the car is no longer drag racing anyway.

My neighbour, a retired mechanical engineer who used build race engines as a hobby, has suggested adding a big remote oil cooler to the mix with a t-stat controller.

Thanks
Make sure its purged, make sure the timing is right, make sure the radiator cap is good and after all that pressure test system see if you got a head gasket leak... it from there you'll focus on the tune or more radiator capacity
 
All good points

I forgot to mention, the guy I bought it from, got it 18 years ago and proceeded to make it street able again removed the roll cage, etc....

He would often take it out 20 to 30 mins from his place to various shows/meets and it never went past 210f on him.

But he's out in the country and it's pretty much non stop driving for him anywhere he went, whereas I brought it back to the city.

3:91 gears in the back could be a part of it, but I made sure to get that torque flight into 3rd as soon as possible after every stop and the rpms were always low.

I may get a pusher fan to add to the set up, the e-fans in there right now move plenty of air and the rad seems to be clear of any debris. Not enough room to use an engine driven fan so that's not an option :(

Timing is a good idea to add to the list, doesn't cost a thing, thanks!!!

Smaller water pump pulley and maybe a water pump when I do the t-stat.
Timing is a good idea. Being 10 degrees off/retarded will make low speeds heat up
 
Atta Cruising speed that produces 2400 to 2800rpm, the ignition timing will want to be in the window of 46 to 56 degrees.
The trans should have it's own cooler.
Good luck with the electric fans. make sure they are rotating in the right direction.
BTW
the thermostat sets the minimum temperature; if you take it out for testing purposes, swap in a restrictor washer or a gutted old stat, to prevent erroneous temperature readings.
While in park and idling;
the rad needs to drop the temperature about 25/30*F from tank to tank. If she can't do it with the fans running top speed and the stat removed for testing, IMA suspecting the fans, or the fan-system.

Don't forget that water expands with increasing temperature. If the cooling system is NOT of the recirculating kind, and the rad is overfilled when cold, it WILL puke coolant until it finds it's natural level. After it is finished puking and has cooled off, pop the cap and witness the correct level. In my experience this will be above the cores and not much more than 1 inch below the top of the tank.
and
if the car still has a heater, you can set the blowerfan on high and in an emergency, extract quite a bit of heat this way.
and
Until you get this figured out, the water pump should be turning faster than the crank, which means the pump-pulley needs to be smaller than the crank.
EDIT
oh I see you know about liquid-expansion with heat.
BTW-2
The point in the cranks rotation at which optimum energy transfer of the expanding gasses should occur is in the window of 25>28 degrees AFTER TDC. All your timing systems are or should be, engineered to try and hit that mark as often as possible, under as many different rpm and load settings as is possible. Therefore;
1) if your timing is locked out at some racing number, that will be part of your problem, as retarded timing puts additional heat into the coolant,and
2) it is as good as impossible to give the engine the large amount of Idle-timing that it actually wants, with a distributor, and still be able to drive that engine at low rpm, without getting into detonation..... but that is somewhat combination dependent.
I'm gonna print this and keep it with the car, thanks!!!
 
Alrighty then, shroud off and we'll see what happens next
Unless the fans are mounted on the shroud. Seems to me they would work if mounted like pictured above in post #14. I would see if there is room to mount them like that. Then be sure the fans are blowing the correct direction.
 
One other thing I haven't seen mentioned yet is check to be sure the bottom radiator hose isn't sucking shut at speed. Some have a wire inside like a spring to prevent this but I have seen some that don't. Seems to me a properly pressurized system wouldn't allow it but I'm no expert.
 
Unless the fans are mounted on the shroud. Seems to me they would work if mounted like pictured above in post #14. I would see if there is room to mount them like that. Then be sure the fans are blowing the correct direction.
How they are mounted now i’d think they are only able to pull air from where they are mounted on the rad vs if they were mounted on the shroud they can pull from that whole air volume. So right now the shroud is more or less just acting like an insulation box forcing the area behind the rad, but in front of the shroud to become pressurized at speed. Plus side is if the fans are mounted to the rad then he can just remove the shroud box and give it a test run.
 
Alrighty then, shroud off and we'll see what happens next


When it starts to run hot when idling, try running the garden hose through the radiator to see if it cools down... If it does cool down, then the issue is you are not getting enough air flow through the radiator... Then you need to get more air to flow through the radiator...

I agree with the comment on how the shroud looks like a wall that blocks the air and only allows it to flow through the two fan 'targets'...
 
Last edited:
So quick update, the fans were modified to put them inside the shroud, notice the dried up JB Weld....

IMG_20230709_175148630.jpg


IMG_20230709_175152036.jpg


IMG_20230709_175158128_HDR.jpg
 
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