What 1st gens have what automatic transmissions?
89-90 different than 91-93?
727 and 518? Whats the difference?
How much power can they handle stock?
What are common transmission upgrades for mildly BOMBed trucks?
What are common and extreme trans temperatures?
What vendors supply the best parts?

 

Only real difference between the 727 and the 518 is an added overdrive unit.
You are pretty much right on the years, its 91.5 though
They can handle descent power stock, they are a stout tranny, but the best upgrades that you can do for them would be a shiftkit/valve body, and a good torque conveter. Also upgrade to a second gen. fly wheel.
As far as temperatures, I usually see around 190-195 in my truck, and they get has hight as 125, but thats the highest i've ever seen it, I haven't pulled a trailer since I had the tranny rebuilt and installed a temp gauge though.
As far as vendors, theres a plethora out there for actually tranny parts and valve bodies or shift kits. There are also lots of suppliers for torque converters, however; most will tell you that you definately get the most bang for your buck from Hughes.

 

Check my sig. I hit 240*F pulling 7000# easy.

 

As far as temps go, I just installed my temp guage. (My sig is accurate)

When pulling my rockcrawler down to the Rubicon last week (prob about 7000# total load) my tranny would easily climb to 250 degrees if the truck was hot and I started out from a stop in OD with my TPS mod. The tranny gets hot REALLY quick while towing if I don't turn off the OD below about 60 or 65. I could tow up some pretty big hills in 3rd at 55 and it didn't get too hot although the air temp seemed to affect my trans temp a lot and a few times I had to back out of it because it went up to 250 even in 3rd on a small hill if I had the peddle to the floor when the sun was blazing and the air was hot.

My flat ground towing temp seemed to be about 230 in OD at 70 and 190 at 60 in 3rd. Those numbersseemed high to me though.

So my problem is that my tranny temp is by far the weak link in my system. My exhaust temp doesn't get higher than 1300 and thats on super steep slopes where my tranny is in 2nd and the engine is laboring hard. The engine temp never made it past the second factory mark. I'm cooling just fine but I felt like I was on the edge of my seat just trying to keep the tranny from blowing.

What about putting another tranny cooler in it in addition to the factory unit?

Chass
ct

 

I'm having tranny temp issues too, even with the factory under-bed cooler. It will be interesting to see how the new Hughes torque converter will improve things - it's supposed to flow something like 7 gallons per minute more than the original OEM T/C.

 

Pulling 12K with the Hughes TC and an add on trans.cooler mine will go from 150* down hill to about 240* up hill in 3rd.If I put it in OD.the trans.would spike the guage at 250* and the motor would hit 230*like nothing.The next thing will be a DEEP trans.pan and an add on filter and try to get an extra 3 quarts of fluid to see if that will cool it down.

 

Ah the old heat issue, well loch to the rescue. A friends 91 would fry an egg but since he was unable to afford an underbed cooler, he inlisted my help, since i'm known for uhm being creative. After much consideration i fell upon an idea, i recently changed my A/C evaperater, so after cutting the two fittings off, i attached a small fan off of a ford tempo and plumbed it in. He pulled his belshie trailer and a john deere 450 dozer today with it, it got to 190 and never moved past that. So if you need a nice cooler and the funds are short try an a/c coil out of our trucks , thier plentiful and cheap and more than enough to cool our trannys off with no worries.

 

Grate idea loch just didn't think that thay would have been that efficent.
loch you

 

Folks, I gotta ask you to say WHERE you measured the temp as well as what temp you got. 250* at the output of the trans is vastly different from 250* in the pan.

Tx, DBF

 

Lemme add an observation here. Only one person above mentioned engine coolant temp, but that's directly linked to trans fluid temp.

The heat exchanger on the passenger side of the engine passes heat back and forth between the trans fluid and the engine coolant. Whichever is hotter transfers some of its heat to the the other.

The engine coolant is regulated to 170* by the thermostat and fan if working correctly.

This system works in very cold locations when the engine helps the trans fluid get up into operating range (~170*) sooner.

In these hot summer days, it works both ways:

1. If you're towing and lugging along in OD (where there is less trans fluid flow to the coolers), the trans heats up. Some of the heat is passed to engine coolant. Normally, the engine will heat up a little, the fan will engage, and that heat will pass to the environment. However, a partly clogged radiator or partly-closed thermostat or a poorly working fan clutch will not get rid of the heat via the radiator and engine temperature will rise to some point (probably to equal trans temp), after which both temperatures increase together.

2. If you're banging along and not towing, but your engine coolant system isn't up to snuff, you can be misled. The engine temp goes up, and some of its heat goes to the trans fluid where it is cooled by trans fluid coolers, bringing the engine temp back down. You might not notice this happening, but it will work this way.

In summer, it's obvious that the ability of the system to pass heat back to the air is decreased. It's a lot easier to push heat out when the air is 50* than when it's 100*. Only way to push out more heat is by more heat exchangers (radiators/coolers) and having the ones in the truck doing their best work.

If you have an auto, you have to watch both cooling systems (engine and trans) to get the best.

I had a problem where the *@#*&^ heat exchanger started leaking (I thought). So I re-plumbed the mess and removed the heat exchanger. Then I added a second under-the-bed trans cooler with fan. Works fine with truck only. In a couple of days, I'll take off with the trailer and see what happens.

I'll update my gallery to reflect the new piping and report on the results when I return.

Regards, DBF

 

The most I see with a deep trans pan and aux trans cooler mounted in the grill is 210* when pulling a load in the hot summer heat. Driving around empty I see 150* - 180*. This is also with the stock trans air cooler disconnected. My temp sensor is in the pan.

 

Good discussion here! I am getting ready to install the mopar performance deep alluminum tranny pan that is in my gallery, on my 92' D250 that is also in my gallery. This truck is 100% stock, and will remain that way other than maybe a partial 4" exhaust. My trans pan has a port for a temp sensor in the bottom which I plan on installing. I pull that white 24' Circle D stock trailer that is also in my gallery with the D250 occasionally, maybe once a month. Max total weight of trailer no more than 12k, but usually only about 8-9k. The truck has the factory underbed cooler. I NEVER, and I mean NEVER, pull anywhere in OD. If it is hooked to anything we run in third, and keep the speed around 60-65. What would you guys say would be an "acceptable" temp to see in the bottom of of my new pan? I plan on having Dave Goerand completely going through this tranny when it starts giving me trouble some day, but as this truck had never had a trailer hooked to it in its life untill we got it a couple months ago the tranny from what I can tell is in pretty good shape, and I don't want to spend the money to fix something that is not broken and woking perfect. So how bout it? What's an acceptable temp in the bottom of the pan?

 

That's a nice pan!! How deep is it? 4-4.5"?? Heat is one of the reasons I am going to replace my old non lockup trans with the newer lockup versions. I will bet pulling hard with the truck of yours you will see 225+ and as high as 260.

 

Here's a link to a discussion on trans fluid temperatures and fluid breakdown:

http://www.findarticles.com/p/articl...23/ai_n8688053

...and another:

http://ca.autos.yahoo.com/maintain/a...smission1.html

Note that the discussion focuses on cars, but the same breakdown happens in trucks. The discussion also notes that Dexron is ok in Chrysler transmissions - wrong - use ATF+3 or ATF+4 for our Dodge trucks.

Keep it cool, folks!!

Regards, DBF

 

Would you please share the Mopar part number for that pan. Looks really nice.

Do you know offhand the size of the sensor hole?

Regards, DBF