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Dynaflow cooler for a 1956 (or other)


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I'm to the point where I need to hook the Dynaflow cooler lines up, but I don't want to run them to the radiator as I've heard that's really an inefficient way to cool the Dynaflow. I'm curious as to what type of transmission coolers others have used, what type of fittings/tubing was used and placement? I'm sure it's not too hard to reroute to the front of the radiator.

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Beemon,just wonder how many people have sad it is inefficient way to cool the 1956 Dynaflow?   I think most of us who are using the 1956 radiators lower part for cooling are very satiesfied with that system,I have never heard any negativ talk about that.But of course it meens that the  water part of the radiator is in good condition too.If you have restored your engine I would suggested you to put a new "water cooler"too,and that will cost a lot less than the engine restoring,and you can use your car on "crusing" too without problem.

Leif in Sweden.

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I might have mixed up my information with 1955... I have had the Dynaflow, Nailhead and Radiator rebuilt. So you are saying the 1956 radiator will be sufficient? I'm just concerned with fluid getting into the transmission and if it would just be better to mount a remote transmission cooler to the front on the radiator and plug the transmission cooler holes on the radiator.

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The radiator "oil cooling" works great on my 1956 since 1999 when the car was restored,but of course you can use a remote transmission cooler to the front if you think that`s safer or better.But I hope anyone else will answer your question as well,and give there opinions too.

Leif in Sweden.

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I agree with Leif.  There is little concern with the factory 1956 transmission cooling system.  However, if you are planning long distance driving, for example : to National Meets , then employing an additional trans cooler may be effective.  The question would be which way to route it.  Through the radiator first then the aux cooler, or the opposite.

 

Personally I would vote for Aux cooler first, then the radiator.  My theory would be that the aux cooler under some conditions may cool the trans fluid too much and in those cases, running the fluid through the radiator would then re heat the fluid back to the thermostat setting before reentering the trans.  Also in extreme heat conditions the aux cooler would dispose of some excess heat before the radiator absorbed the rest, making for a cooler running engine. 

 

But I would suggest the best approach to cooling both the engine and trans is to do what you can to seal the small gap between the fan shroud and the radiator.  Last year I saw the benefit of that when driving across country  to the National Meet.  The car that went both ways has an external temp gauge.  Based on that gauge I know that car would run 205- 215 at sustained highway speeds.  For the X country run we sealed the shroud gap using foam pipe insulation.  It was not pretty but it was pretty effective.  Sustained highway speeds resulted in 180- 195 readings and the car would climb on some of the 7-9K mountains to 210. 

 

Using the foam pipe insulation allowed the materials to be removed for the actual show at the meet and easily reinstalled for the trip home.

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I got rid of the 4 blade stock fan and used a 6 blade flex fan with a longer extension to move the fan closer to the radiator and that helped cool down the engine.  I did this to all of my Buicks.

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  • 1 year later...

This is how I attached my cooler, it's approximately 1 inch from the radiator. It's a Hayden 678 I believe. It was suggested by the transmission shop that the cooler the fluid the longer it lasts and that ribbing it through the radiator will raise ambient engine temperature and only cool the transmission to the hottest engine temperature. This type of thing isn't for everyone but I thought it was worth the mod. 

20160623_215245.jpg

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I have found that 6 blade fans from Buicks or other GM cars with Air Conditioning from the 1950's will fit the water pump and pulley.  Before you buy one, check the bolt pattern.   As for flexible aftermarket fans, the sellers usually give you the bolt hole pattern.  The old OEM 6 blade fans just look better and are not easily detected as being not original, that is having 4 blades.

Joe

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2 hours ago, Airy Cat said:

I got the 6 blade fan from Summit.

Do you remember the extension length and what size of fan? The stock fan is 18" wide but has a 1" air gap on both sides in the shroud so I'm thinking a 19" fan would fit comfortably in there. If I recall correctly, the stock fan spacer is 1 5/8" long and the pulley has a 1" recess.

 

I only ask because recently, I've been running a little hot. I've also had some ignition issues so maybe the issue will go away, but I like to keep my options open on the table.

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 ATF is generally fine as long as the trans fluid temp is below about 270 degrees F (for normal "dino" atf).  In the 2014 GMC 1/2 ton I have at work, I found the DIC readout for ATF temperature and watched that for a few days this summer.  Engine coolant temp is normally 210 degrees F.  In normal "drive around" use, with the engine temp at 210, trans temp was usually about 195 degrees F.  Dexron VI is a semi-syn fluid and there's supposed to be a "full-syn" fluid for newer GM automatics (due to converter clutch partial-engagement duty cycles and the need for additional, related, heat resistance).

 

Like engine oil, trans temp will come up slower and later than engine coolant temp, by observation.  I found out about the motor oil temp increase "rate" on '84 Corvettes, which had an engine oil temp readout on the factory cluster.

 

It would appear that an air-to-oil auxiliary atf cooler would be more effective than an oil-to-coolant "cooler", which can be true as on GM pickups, the auxiliary atf cooler is mounted in series with the radiator cooler.  In some years, the radiator cooler size was upsized such that an external cooler was not needed on some HD applications.

 

In many climates, the oil-to-coolant cooler will be plenty, plus it might help with getting the trans "up to temp" quicker in cooler weather, too.

 

Years ago, our then-service manager was test driving a customer's pickup after a repair.  He noticed a trans temp gauge, so he did a few things.  He got the powertrain up to a stabilized operating temperature.  He pulled to the side of the road, stopped, torqued the engine against the foot brake, held it for a short time, then took off under heavy throttle . . . both things "thought" to increase transmission fluid temp.  Only thing was that the trans temp didn't increase by very much.  After things got back down to normal, he did a manual downshift and used "engine braking" to slow the vehicle.  THAT increased fluid temp MORE than the "under load" situation did.  Why?  With the torque converter in "over-run", it was using "fluid running into fluid" inside of the torque converter to slow the vehicle.  THAT was building heat.

 

His little brother was a parts guy for a large construction company.  He noted that they had one job where the dump trucks had to back down a long hill to get to the dump site.  That cooked the transmissions on many of the trucks on that job as they needed the engine braking to assist their service brakes in that loaded descent.

 

Just ensure the radiator innards are clean AND the radiator gets a "clean" air supply (no "recycles" from under the car in traffic).  Also ensure the innards of the trans cooler are similarly clean for the best heat transfer, too.  For data acquisition, you can probably find a magnetic-mount heat sensor for the trans oil pan (possibly in some of the trailering magazines).

 

Enjoy!

NTX5467

Edited by NTX5467 (see edit history)
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I was told the opposite. That water to ATF cooler is more efficient than air to ATF. I am supposed to have lines from the water pump running to an ATF cooler but I am running air to ATF cooler in front of my rad. Seems ok. 

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