Trans build IMO getting hot.

maccwall

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Nov 22, 2013
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I do not pretend to know much about mechanical things. I understand them when explained to me but I can't get my head wrapped around this new build. I recently had my trans rebuilt and upgraded with upgraded clutches, valve body and billet torque converter and what ever other parts they upgrade. I do not believe my temps are normal and are a bit, may I say, discerning, as before the build I did not have this issue. I elected to have the trans rebuild and updated after a number of instances of it going out of lock up and not going back in while towing. I tow a 31', 3 horse horse trailer all over the country. Total rig weight when loaded with 2 horses and all the creature comforts is right at 23,000#. Before, I was seeing trans temps maybe peak at 210ºF running 68-70mph with ECT around 190ºF, a little hotter when in the mountains of Wyoming last summer but nothing worrisome. The valve body was replaced hoping that would eliminate the lock up issue. It did not, so I opted to have the build done. Now, my temps are pushing 228ºF on flat ground running 68-70mph with the ambient temp being only 74-79ºF, ECT's are still averaging 190ºF. I have gone ahead and upgraded the cooler with a PPE cooler and upgraded transmission lines. Fan clutch has been replaced and the stack is clean but the trans temp has not changed. Mind you it doesn't get hot right away, it takes about 40 miles to get there but it just doesn't decrease. I know these transmissions can handle the high temp but this just seems excessive to me. I had it back at the shop that did the rebuild, a very reputable shop I might add here in Texas, and he did a number of diagnostics on it but could not find any issues. I am planning on a trip to California, crossing the Mojave and up into the Sierra Nevadas in mid July and am concerned about these temps. Guess what I just want to know are these temps acceptable? Thank in advance.

Todd
 
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Chevy1925

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We dont know what he did internally so this is all a stab in the dark.

you can pull the lower trans line off the radiator and look inside at the heat exchanger. if the fins are packed full of debris, thats a problem.
 

maccwall

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Nov 22, 2013
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We dont know what he did internally so this is all a stab in the dark.

you can pull the lower trans line off the radiator and look inside at the heat exchanger. if the fins are packed full of debris, thats a problem.
Thank you James. So the temps I am getting in your opinon, would not be considered normal then by what you are saying. If so then back it will go. I need this right.
 

maccwall

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Nov 22, 2013
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We dont know what he did internally so this is all a stab in the dark.

you can pull the lower trans line off the radiator and look inside at the heat exchanger. if the fins are packed full of debris, thats a problem.
I did find out that he did hot flush the heat exchanger.
 

Mike L.

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228 is too hot. Duplicate your 228 temp when you get a chance and then pull over and touch each cooler line at the cooler and see if the out line ( driver side ) is slightly cooler than the in line ( passenger side ). This should give you and idea if the cooler is flowing.
 
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Bdsankey

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IMO those temps are not acceptable, especially at only 74f ambient. A very good rule of thumb is 100-120f over ambient conditions is acceptable. Like Mike stated, I would check to see that both lines are similar in temperature at the transmission with the return being slightly cooler. If there is a big difference in temperature that lets you know that either the rad cooler or the front air to air cooler is not moving enough volume and has a restriction.
 
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JoshH

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I can tell you for sure that Jim has a hot flush machine to flush the coolers, and as far as I know, he uses it on every truck when he builds a transmission. When you would see 210 degree temps before the build, was that under the same conditions you were seeing 210 with the stock transmission? By any chance, do you have an aftermarket bumper on your truck or anything on the front of the truck that blocks airflow through the trans cooler? Have you discussed your concerns with Jim?
 
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maccwall

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Nov 22, 2013
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I can tell you for sure that Jim has a hot flush machine to flush the coolers, and as far as I know, he uses it on every truck when he builds a transmission. When you would see 210 degree temps before the build, was that under the same conditions you were seeing 210 with the stock transmission? By any chance, do you have an aftermarket bumper on your truck or anything on the front of the truck that blocks airflow through the trans cooler? Have you discussed your concerns with Jim?
Hey Josh,

Yes, I have discussed this with Jim. The times I was seeing 210° before the build was when I was climbing in the mountains of Wyoming. For the most part, it was running170-190° average dependent on the ambient temp. The higher (228°) temps started after the build and yes, he did flush the heat exchanger as I asked him last time we talked. As of the last week or two, I have replaced the water pump, upgraded the cooler lines, have an upgraded cooler, had the cooling stack cleaned, replaced the fan clutch and I am still having the same the issues unfortunately. Jim is top notch, just need to figure out what is going on. I have a friend who does work on my truck other than transmissions and had Jim rebuild his tranny and his truck is almost identical to mine. Same year, same trans, and he pulls a larger trailer than mine and his temps run from 190° to 210°. My truck has a stock bumper with stock grill and it is not lifted. I will be taking it back to Jim this Friday with trailer in tow so it is under load and he will run more diagnostics on it then. I have no doubt he will make it right. Like I said, he is top notch and a very nice guy to boot! Other than the temp issue, the truck runs and pulls fantastic!!
 

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maccwall

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Nov 22, 2013
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And a big thank you to everyone for your opinions. I will keep you up to date as t what we find out Friday.
 

Bdsankey

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Any chance you've got a pinched cooler line? Friend of mine with an L5P was chasing his tail and ended up having a pinched cooler line from the factory which caused the previous owner to sell it cheap.
 

juddski88

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Which converter is in it?

IMHO, depending on the converter efficiency, your temps while towing loaded in the mtns is not really abnormal with higher line pressures. The 6sp cooler placement behind the bumper, regardless of which generation factory bumper is in front of it, flows air terribly. Mounting some fans behind the cooler dropped full load temps towing over 16,000lbs (factory temp sensor @ 225deg/ 90 deg ambient at 35% humidity) 35 deg on my truck which I have a XDP trans cooler on in factory location. I flipped the cooler over so it mounted higher to recieve more airflow, and peak temps dropped an additional 15 degrees to 175 on a similar day and took longer to get to peak. This trans has a pretty inefficient rebuilt 1058 converter in it too and 295psi main line psi.
 
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maccwall

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Nov 22, 2013
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Okie dokie. Here is an update. I took the truck, with trailer in tow back to Jim Friday and he did some thermal tests and a few others. He said that when he flushed the heat exchanger in the radiator initially, he got some some strange debris from it what he put akin to the insides of a ball point pen cut up. He had never seen anything like that and sent images to a number of people, including Mike L. We have also discovered that the radiator in the truck is an aftermarket radiator, not an OEM so at some point before I got the truck the radiator had been replaced. It has also been spectacled that I may have been seeing some abnormal temps prior to the build and and now that the build was done, radiator cleaned, cooling system parts replaced, that the build has allowed those temps to rear their ugly head to be worse. We are thinking that theses is some sort if restriction. The temps at the pan and the lines match to the temps in both my DIC and my Edge monitor and we are getting a 20ºF drop of temp across the new trans cooler at idleI So, since the only thing left in the cooling chain that has not been replaced is the radiator, I have ordered a new A/C Delco rad and will have that replaced and see. If the temps continue with the new rad, then it has to be something in the trans build but at this point, everything is pointing to the radiator. There is no slippage and the truck runs, pulls and shifts great! I drove truck and trailer, Saturday, 20 miles to get new tires put on both and on the way back home, tranny temps reached 237º before I could pull over and let it cool down. ECT was upwards of 215º. Ambient temp was 88º. This was on a relatively flat Hwy.
 
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juddski88

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Your first post, you said that your ECT was around 190 running a longer distance (40 miles) than this last test (20 miles) which got you roughly 215 ECT and it was only 10deg warmer ambient temp. Something isn't adding up to me. In that short of a drive on flat ground, the TFT will not be getting hot enough to warm ECT that much with its tiny little heat exchanger, and that is if the exchanger is totally clean (most efficient). When the exchanger is plugged up, there is obviously less surface area for the trans fluid to exchange its heat with the coolant and therefore the coolant will not pick up its heat there. This can be verified with a temp gun, flir camera, or independent transducers, but your primary source of the heat problem seems to be your coolant. There certainly may still be something up with the trans or more likely the converter, but it will not drive fine on flat ground and create THAT much heat, then affect coolant temp that much, in my experiences...
 

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