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Trans Cooler disk?

May 09, 2016, 10:22:31 pm

Changing antifreeze-hoses-thermostat, flushing old green antifreeze out to go to Red antifreeze so I decided to remove T-stat to make flushing easier and found a thick washer with a small hole 1/8 to 3/16 in bypass hose between water pump and t-stat housing,wasn't sure what it was then I found in the book that it had to do with trans cooler. Could anyone explain how it works, and if anything has changed with application of disk?  1996 U320 Cummings M11 400 HP Serial# 34775925

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Re: Trans Cooler disk?

Reply #1 – May 10, 2016, 06:24:19 pm

Foretravel could not answer question so I dug a little bit more and found the disk is a re stricter ,it forces water to transmission cooler, Cummings had to think about it before we came up with answer , so metal disk with an 1/8 inch hole in it has to be there.

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Reply #2 – May 10, 2016, 06:28:21 pm

Art,

Yes, no question the washer with small hole in it IS a restrictor.  A bit surprised that James was not familiar with it. 

One would have to be very familiar with both the water flow through the engine, radiator, transmission cooler, dash heater, water heater..... to be conversant on this. 

Said another way, you are into system design!

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Reply #3 – May 10, 2016, 06:31:44 pm

We do the same as that disc in race car engine to slow the water down going through the system to give coolant time to transfer heat and also to stop aeration. That's what we use in place of the thermostat but for us the water pump only turns the ideal speed twice a lap.

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Reply #4 – May 10, 2016, 07:27:25 pm

Yes, a common practice on some engines and some applications to slow the water flow to allow a better heat transfer than high speed water flow that  does not capture heat.  Fixed lots of issues  with a hand full of washers of varying sizes until you get the correct  flow.
Also for water flow to a heater for better heating, example.
Learned this trick about 1968 from a Mercruiser factory rep named Rocky DeCarlo out of Wis factory.

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Reply #5 – May 10, 2016, 07:57:52 pm

Yes James is amazing, But he was not there today it was a different guy

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Reply #6 – November 14, 2016, 08:18:25 am

The shop manual indicates that if there is a torque converter cooler there should be a disc in the bypass hose. I recently replaced my thermostat and did not find a disc. Is the transmission fluid cooler the same as a torque convertor cooler?

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Reply #7 – November 14, 2016, 01:29:24 pm

Interesting thread.  My cooling fan was seemingly set too high.  This is trickier.  Will be interested in the use or need of the washer.

More flow to radiator?  Needed or not?  The devil is in the details sometimes.

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Reply #8 – November 14, 2016, 02:10:01 pm

I would sure ask Jame Triana the question.

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Reply #9 – November 14, 2016, 03:54:35 pm

I spoke to James this morning. He had no idea that the disc even existed. After checking with the engineering dept they confirmed that the disc was ordered/installed by Cummins when a retarder was utilized. A Cummins tech in Fresno identified the part after I sent Art's picture to the parts dept.

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Reply #10 – November 14, 2016, 04:11:22 pm

Thanks, Bob.

Another very unusual fact run to ground. Those with the same drivetrain, take note.

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Reply #11 – November 14, 2016, 07:21:02 pm

So we have a 96 with a restrictor and a 97 without.  Anyone else?

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Reply #12 – November 14, 2016, 08:21:22 pm

Knowing a little bit about fluids, my educated guess is that the reason for the restrictor is to "encourage" coolant flow through the transmission cooler. Flow will go the path of least resistance. The flow can go through the bypass (easy) or it can go through the cooler (pressure drop due to longer/more curves). Without the orifice, the coolant would just sneak right by the transmission cooler.

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Reply #13 – November 15, 2016, 06:06:33 am

This is from the maintenance manual.

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