Black iron pipe. Can it be used to run transmission fluid?

[Ed Hackenbruch]

Probably should mention that he mounted the coolers so that there is a 6" airspace between them and the radiators. Looks like he could have even a little more space between them if he had wanted to. I think that one of the key things is that he used 2 coolers instead of just one.

[luvrbus]

Better check the gauge Ed those transmissions need to run at 180 to 200 degrees running one cold does just as much damage as running one hot fwiw and barn Owl has a GM bus one radiator,rule of thumb is 90 to 100 degrees above the outside temp doesn't always work on a cold day but the engine cooler heats the transmission oil on a cold day   

good luck

[Lin]

Clifford,

The Allison manual says the sump fluid minimum continuous temperature is 100 degrees, 200 is typical and 250 is max.  The maximum converter out temp is 300 degrees.  I know that this is a little odd since it also says that any level reading below 120 degrees is considered a cold reading.  When you recommend a minimum of 180 degree operating temp, is that at the converter?  Apparently that would be higher than the sump.

[JohnEd]

What Clifford said.  I did it as the op suggested....put the cooler in front of the engine rad water to oil heat exchanger inside the rad.  That will reduce the heat load on the engine.  With the oil going to the trans coming from the rad you get preheating so in the winter your oil is thinner.

If you make the Black Iron pipes over sized then you will add volume to the circuit and the oil will hang around longer and get cooler.......just like enlarging the oil pan capacity will lower the oil temp.

To use the smallest diameter pipe possible and keep up the flo... do what Clifford said about using formed and long radiused bends tx tubing.  If you oversize the BI then you will  have flo to burn and not have to be concerned with restrictive bends.

I haven't looked into this subject since 1990.  Here is an approximation of what I was told as I recall and bear in mind that I have slept and eaten since I was given this information:  running the tx at 180 is advisable due to to efficiency considerations....thin oil is easier to move and at 180 it won't scorch and lubricates well.  220 was the MAX suggested allowable temp.  At 180 the tx was estimated to last 200+K miles with proper maint and fluid changes.  At 220 the life expectancy dropped to 150K.  At 300 you only got 8K miles or less.  Keeping it cool was of serious import.  But, that was a tx using ATF and ATF is used to carry away heat and be able to withstand 280 degrees at spots ??  I was surprised to learn that the bus transmissions used motor oil as it scorches at a lower temp than ATF and is more resistant to flo than ATF.

My oil always went thru the rad and it came up to temp as quickly as the engine temp.  But the TX temp went thru the roof on a hill and my engine temp never flinched.  My conclusion was that the number of coils in the TX heat exchanging section of the rad was way to small.  The going into the TX needed to be lowered badly so I installed the Haden cooler in the return line to the TX like the install plans called for. My aux cooler was placed in front of the rad along with the AC condenser.  Oil doesn't give up itsd heat very quickly so you need to increase the volume in my opinion.

The TX I was working with was the storied Chrysler 727 three speed with locking TC and I am certain a lot of the data I was given was TX specific but this was the gist.

HTH,

John

[demodriver]

Why won't black pipe stand vibration ? every RV made uses black pipe on the propane lines what am I missing here

good luck

Every rv that I have ever saw has had copper, not black pipe. In my experiences the black pipe will crack when exposed to vibration over a period of time. Just my preference I guess, to each there own.

[luvrbus]

Make that 98 % I have 3 here now all 3 have black pipe with copper to appliances wit a loop lol the sch 40 is pretty tough FWIW I just read the RVIA book it call's for black pipe and the manufactures of rv's wrote the book

good luck

[rusty]

I used black pipe for my power steering system. I do not use ATF I use motor oil in the system. It has been working for 90,000 miles. We will see how long it lasts.

Good Luck Wayne

[oldmansax]

Make that 98 % I have 3 here now all 3 have black pipe with copper to appliances wit a loop lol the sch 40 is pretty tough FWIW I just read the RVIA book it call's for black pipe and the manufactures of rv's wrote the book

good luck

Make that 98.0000001%!! My bluebird has it! 

TOM

[Barn Owl]

I also thought that putting the cooler in front of the radiator would defeat the benefit I was looking for, but after talking with the Hayden Engineers that is the best place. The short of it is that the coolers need a tremendous amount of air flow to work effectively. It must be the inefficiencies of heat transfer that really makes it work this way. The air out of the transmission cooler does not absorb as much as we would like, but in fact still has the ability to remove heat, just not as much because it's temperature has risen. Also remember that the transmission oil would still have to go through the oil/water cooler, so cooled transmission oil would remove heat if it was cooler than the antifreeze. In the end the entire system has the ability to shed more heat and that is the goal. With a DIY oil change running over $130, it is less expensive to keep the oil cool than to change it more often, not to mention there is less stress on the engine and transmission itself. After pulling those 8 to 12 percent grades for mile after mile in the Rockies I agree that the oil/water cooler is too small to shed that type of continuos heat load. The 1290 Hayden cooler was a $110 Ebay find shipped to my door, might cost the same in hoses and fittings by the time I am done. I had my oil tested after getting back from my western trip and it came back OK, in-spite of looking very dark. I am hoping this will allow me a larger safety margin if I find myself pulling those type of grades again. I cut it close more than a few times.

Second question. I have been to two hose shops and the hose and fittings they say I need are expensive. I don't have a problem doing it right, but I am not sure if some of what they want to sell me is necessary. What type of oil line should I use? I don't know what pressure the transmission runs but it surly must be low. So I need a high temp/low pressure hose that can carry oil. Anyone with any experience with this? What type of fittings would you use? The cooler has standard 3/4 pipe thread but I have been told it would be easier to adapt it to hydraulic fittings to avoid the expensive swivels. The more I can do myself the better. I want to complete this project this week, so don't sit this one out if you have any ideas. Thanks

[JohnEd]

Have not a clue about your trans.  Sorry.  In my Jeep J10 I had a GM Turbo 400 trans.  I blew a hose.  I replaced the blown hose with a fuel line hose.  Like you, I assumed that the line carried low pressure but hot oil.  I was right about the hot.  The pressure was 60+psi if memory serves and the hose lasted a month and disgorged all the ATF on the street at an intersection and in front of a cop car with an unhappy cop in it.  Anybody ever seen one of those birds in a good mood?  The good news was that it was all bright cherry red and didn't smell burned in the least.  (find the joke).  Use high pressure hydraulic hose that is called for in the manual.

John

[luvrbus]

High temps oil and low pressure don't mix I don't know about the 730 but the 740 is over 100lbs on the return 

good luck

[Zeroclearance]

My 2 cents..    Growing up I would help thread and install gas piping.   I have seen over the years "imported" pipe come into the US.   The quality for gas at low PSI was okay.    The problem that I see is the quality of the interior of the pipe.   It will have slag and burrs that WILL dislodge with the high pressure.   It will be a gamble to your Allison and not worth the expense.    I would opt for hydraulic tubing.   

Put another way, it's not that the pipe will hold the fluid>> it's the damage the metal will due to your tranny.

[Ed Hackenbruch]

Clifford,  would running the bus for a couple of hours and then taking a temperature reading on the bottom of the tranny pan with an IR gun give a guy any good info? 

[luvrbus]

Checking it after about a hour drive Ed would be best 160 to 220 is the norm check it were the lines leave the tranny the pan won't tell you that much but check it anyway

good luck

[Barn Owl]

Final update: cooler installed, decided not to experiment and just used hose. Hayden 1290 cooler ~$120. Hoses to make it all work ~$160. And five additional quarts of fluid. Other than wanting a 6v92t transplant there is not much left for mechanical upgrades. Next future project: moving the A/C forward and adding a fan to fill in the hole. Then I might get to try my hand at outdoor painting. Progress made in terms of years.