Engine/Transmission (1994 - 1998) transmission cooler/coolant exchange unit nessary or not ?

[Gray 5.9]

Is it a must to have a coolant/exchange unit? Because I just had my transmission overhauled, and the shop that I took it too said that they would bypass the old system in order make transmission run cooler and last longer.



I got home with the truck and noticed that my temps were above the normal 180* and pushing towards the 200*mark. So I

looked under it to see what all they had done. And to my supprise, they had cut all the 1/2 inch lines out going too the coolant/exchange unit, and ran two 5/16 lines straight from the transmission too an aftermarket transmission cooler up front, in front of my AC condenser, completley eliminating my old cooler









Man I don't know what to think of this. The trans hooks up a hole lot better than it did thats for shure, gets up to speed much quicker than it did.



Guys, tell me what you think of this Thanks

 

[cerberusiam]

Take it back and make them hook it up the way it was IMMEDIATELY. While you can run without the coolant cooler you are already seeing temps climbing. I assume you weren't towing with it and just driving home thru traffic and thats the problem with the trans cooler up front, not enough air flow at low speeds to cool the trans. If you ever tow at low speeds with the converter unlocked it will cook the trans in short order. You can bypass the coolant cooler but you need to route thru a cooler with a thermo controlled fan on it and that will need to be sized correctly if it is the only cooling component. The fluid to fluid cooler is the best choice so if you don't have problems with it, use it. If you need extra cooler an additional fluid to air cooler with a fan mounted under the box is still the best option. The 5/16 lines would also cause me concern. The 1/2 lines are there for a reason.



Just my . 02 but I would be on their door step the first thing demanding the cooling system be put back the way it was and the additional cooler with correct line size plumbed in. Good luck.

 

[Howard Durand]

If I am not mistaken, the engine coolant/transmission fluid heat exchanger is the first level of cooling after the hot fluid leaves the TC. I can't see how by-passing that and replacing it with another air cooled radiator would improve cooling.



By the way, do you still have the original aluminim lines that came with the 94 or have they been upgraded to the steel ones?

 

[csutton7]

the oem cooler is a two fold animal --it cools the transmission fluid and helps to warm up the coolant-----I don't think reducing the line size was smart, so at least have them increase the line size and make the cooler has 1/2" ports and is large enuff to do the job--if they won't/can't have them remove it and reconnect the oem cooler--I have used an aftermarket cooler for two years now vs the oem one with few probs(small leak and fan tstat getting stuck letting the fan motor run)... ... ... ..... chris

 

[fortunate1]

OEM fluid-to-fluid cooler not needed...

It's been my experience for the last 100K miles that the OEM cooler does warm up the ATF faster in the winter (but so does driving), but also heats the ATF up more than it should with the 190* F engine coolant (especially in summer). When mine developed a small leak, I bypassed it completely and replaced it with a fairly large air cooler. I also placed a fan on the cooler to switch on when the temps rise to 150* (usually slow running in a traffic jam, etc. )



The ATF temps run around 55* F above ambient air temp, but usually never below 100* F (cold weather) nor above 150* (100*+ F hot days).



I'd change out those lines though. Try to keep them as large as possible to maintain ATF flow volume through the transmission system.



I last put in 150K mile coolant, and when the time is up for that to be changed I'm going to completely remove the OEM cooler to get it out of the way. Anyone want to buy a used cooler??

 

[Extreme1]

The hose size is a big problem with what they did. The difference in flow is most likely what is causing the problem.



Also look at the cooler they used. The round tube with fin type coolers are nowhere as efficient as a plate/fin (stock) type of cooler, they are cheaper though.



Is the place you took it to familiar with diesel transmission rebuilding and modification? I agree you could probably get by without the stock fluid/fluid cooler in Flordia as long as you didn't tow heavy (or if you added a fan to a air/fluid cooler). But 190 degrees is a lot cooler that the fluid coming out of the converter, it normally runs over 200 in traffic when warm out empty.



Where is your temp sender located? If it's not in the line out of the transmission, put it there now. Normally that is much higher than the pan but with reduced heat exchangers, the pan reading will go up.

 

[Gray 5.9]

Well... friday morning told me a different story. I left the house going to work and noticed that my TC wasn't locking up, when I got up too hwy speed. The engine temps were up above 140*. So i know for shure that either my trans temp sending unit was unplugged or elimanated. The more it warmed up the more it would serch bak and forth through the gears in heavier traffic. by the time I got to work (32 miles of driving) my gauge said between 180* and 200*.



I called the place that rebuilt my transmission and talked too the owner and told him what it was doin, and that I was very unhappy with was it was performing. He told me that the PCM had to be reset, that I needed to disconnect my Batterys for and hour.



I guess I'll just burn it up within a year.

Oo. and let the warranty do the rest

 

[Howard Durand]

If you are still running with the original aluminum coolant lines in that truck, it wouldn't be a bad idea to completely replace them with the new steel lines.

Remove their add-on cooler and the smaller lines they used and re-connect the heat exchanger.

If the temperature sender has been disconnected or removed, re-install it. (They probably removed the mounting for it when they replaced the heat exchanger and added their new lines) If that is the case, you will need the new lines or, at least that part of them.



They are probably right about the PCM needing reset. Disconnecting and re-connecting the batteries will sometimes do that.

Check the throttle cable adjustment too, it can cause improper shifting if it is not set right.

 

[Cooker]

As you already noticed there are alot of guy running w/o the OEM heat exchanger. If I end up with twins, I'm pretty sure I will have to dump it as well. My concern though is how the coolant and transmission will respond without it in the cool Michigan winters. In Florida with a proper sized additional cooler up front I would not worry about it missing, IMHO. You still have the issue with the line size you need to get resolved though.

 

[BPonci]

If im not mistaken,doesn't the stock cooler have a anti-backflow valve?

 

[csutton7]

there is a check valve at the cooler that's on the engine(the water to transmission fluid cooler), so if that's been bypassed I don't believe there's another checkvalve in the system, but I could be wrong---I've been running without that cooler and checkvalve for 2 years with no ill effects--chris

 

[KBalzuweit]

Well I hate to beat a dead horse, but most trans shops can not do a diesel trans. Mine was done by a shop that has a very good rep. 60,000 miles and the problems have began. My truck is going to DTT the first week of March for a total uprade. It will be by far worth the travel and extra cost to have it done correct.



Karl

 

[HoleshotHolset]

All of the OEM heat exchangers I have messed with had a check ball integrated into the JIC-pipe thread adapter that screws into the heat exchanger itself.



BTW: There's only one of 'em...



Matt

 

[Gray 5.9]

I just got the new Jeg's Highperformance mag yesterday. They ofer a TCI 13'' low stall convertor for $367. 99. , and a TCI 2. 5 extra quart aluminum pan that has cooling fins, and a dran plug. for $127. 99. Sounds awlful tempting, being that I'm tired of a stock convertor and getting nowhere like I want to when I hit the pedal.



What I might do is try hooking up the old trans cooler in with the aftermarket cooler and see If that makes a diffrence before I try going back with all the oringinal lines, and just pulling out my checkbook for now.



If I could afford it, I'd try to go with one of the trannys Thats always being metioned on this sight. Right now I'm trying to get started building a house, and I have to be on a bugget. This stuff is killing me

 

[KBalzuweit]

Just put in the TCI converter. It is an improvement. I just needed a fix for a bad conertor til I could afford the FULL upgrade.

 

[Howard Durand]

You say the rebuild did improve the transmission performance and that it is acceptable except for the change they made in the cooling system.

If the transmission fluid temperature sender has been removed, it should be reinstalled.

An improperly adjusted throttle cable and/or a problem with the TPS can cause erratic shifting.



You say you are building a house. What will you be using the truck for during the housebuilding time?

If you are not going to be hauling or towing real heavy loads, what you have should get you by until that is over.



THEN research the pros and cons of the different transmission upgrades, make a decision and do it right. That way you will only have to do it once.

 

[Gray 5.9]

Hello KBaltzuweit

How does the TCI convertor perform?

 

[KBalzuweit]

Works pretty good. It is better than stock. Drops the rpm more at the shifts too. Karl

 

[jelag]

I run a business in the trucking industry and have a great friend that does transmissions in another state.....



His advice has always been to add an aditional cooler on any automatic transmission where it will be doing some work... .



He overhauled a Ford E4D(I think) for me... . and wouldn't do it unless he could install another cooler... . but he runs the oil from the transmission through the new cooler... . this one was rated at 20K lbs... . and than back through the stock cooler in the rad.



He said that the cooler in the air stream on a cold winter day... could take the temperature of the tanny fluid to low... . and running it back through the rad... would bring the temp back up to a suitable temp for return back to the transmission... .



I don't have a flow chart in front of me for 5/16" hose and 1/2" hose but I'm guessing that 5/16" hose flows maybe 60% or less of 1/2"... . I'd be going back to seeing the shop... . and solving the problem... I'm guessing that the cooler they installed is designed for low volumn based on a cars transmission and has 5/16" fittings... .



You need to get this taken care of now... . one last thing... most good transmission shops belong to a national group of builders that take care of transmission warranty when your on the road and belong to this group to share information on transmissions... most of the tricks to reliable repairs come from the aftermarket as the guys in the dealership mostly replace the transmission... .



I own a half dozen 3/4 and 1 ton trucks, all diesels... and only one automatic... . even with the cooler... we don't get the life from the automatic that we get from the manual transmissions. .



We pull behind a 04 4X4 3500 Cummins 6 speed a trailer that has been up to 24K with great results... . and we'd never expect an automatice to handle those loads... .



Jim

 

[Extreme1]

The trans temp sensor on the '94-'95 trucks is in the line from the trans to the block mounted cooler. The truck won't upshift to O/D or lock up the TC unless the trans temp is high enough. If the sensor is still connected to the harness and just tied off to the side, it will probabaly still shift normally on a warm day (in Florida). I'd take a peek underneath it and see exactly what they did.



If they removed the lines, they messed up and should replace them. Be sure they get the correct parts if they wrecked the originals. The original lines are steel but the connections on the ends leak, the trans connections are the worst, probably because of the vibration.



I would also check the TV cable adjustment, it's probably wrong from the trans R & R. With the throttle wide open (pedal to the floor-NOT linkage at full travel under the hood) there should be ablut 1/8" of play in the TV cable. Before you set that, make sure the pedal is moving the pump lever all the way. look close, there is an "overcenter" mechanism involved.



If you noticed an improvement in acelleration, you probably already have an improved converter. Get the trans to work properly with the rebuild and drive it. You have a house to build!