Jim Lane

My transmission has started slipping again but only when it is cold and only in first gear, after it drives for a few blocks if I am at a stop I can feel idle slow down as the transmission locks up, after that the transmission works fine either until the next day or if it is cold out until it cools down.

It was pretty much doing the same as it was back in June 2009

https://www.dieseltruckresource.com/...n-t246291.html

I stopped at the auto parts today and picked up a filter and then this afternoon I dropped the pan to see what was going on inside.

I hate dropping the pan on a transmission because I can never seem to hit my big 30" square drain pan and always wind up with a big mess so this time
I drained the pan through the dipstick tube and all that I had left was about 1 pint in the bottom of the pan and I didn't spill a drop.

Here I use an electric fuel pump with 3/8" PVC hose on both ends, I dropped the suction suction tube down the dipstick of the transmission about 30 minuets after I came home so the fluid was still nice and hot.
Reminds me of pumping ones stomach.



The discharge side I simply had fill a used 1 gallon plastic bottle for storage as I am going to reuse it.



Now I could remove the bolts and drop the pan without having it full of hot oil.
I also have a drain pan under the trans to catch the millions of drops of oil that will drip for the next hour.



And again the fluid is not nice and red the way I thought it should be, there is less than 50,000 miles on this fluid and filter.



Here is the fine metallic mud in the bottom of the pan, I would assume it is a combination of clutch friction surface, bronze from the bushings, ferrous metal from the drums and torque converter, the slivers of aluminum , that I am not sure but it does look kinda pretty, pretty expensive.



Here is the filter, there was a bit of metal on the bottom where it sits against the pan.



Here are the filings I found with my magnet, mysteriously the magnet in the bottom on the pan is missing.



This is sure not the color that I remember Dexron III to be it is NOT burned but it just looks well used.



I looked into the case as well as I could and I did not see anything broken where the shavings might have come from.



I replaced the filter and cleaned it up and then I replaced the pan.



After I got the pan on I pumped all of the fluid back into the trans that I had filtered through a paint strainer and went for a road test,

As I knew it would do, it still slipped when it was cold and then it started working fine after a few miles, at least I only wasted $5.00 on the filter.

My truck absolutely has to be dependable and be able to go at a seconds notice so It looks like I am going to have my transmission rebuilt, I have found a shop locally that I feel pretty comfortable with, I ask the tech a lot of questions and he got them right so I think he knows about transmissions behind diesels.

I got a price of $750.00 Bench or $1250.00 if he does the R&R includes flushing all of the cooler lines, fluids and adjustments.

I am having him check into the heavy duty torque converters for me because I sure cannot afford what I want right now.

So,
What do you think is happening, why is the fluid turning brown with so little miles, (50,000K) I do not abuse or tow anything.

If I am driving through my torque converter could I be generating enough heat break down the fluid without burning it?

Thinking they weren't related but when I drive above 70-MPH for any length of this my coolant temp will rise to the next mark but go back to normal after I slow down, the heat exchanger could be passing the excess heat into the coolant, makes sense to me now, possible?

Also my axillary trans cooler under the bed looks like it is starting to leak, who has replaced this with an aftermarket fan cooled unit, what did you use? hHw many BTU is your cooler.

Just thinking out loud, what do you think.

BTW my new Autometer transmission temp gauge is still sitting on the shelf in my garage, now I am really going to install it.

Jim

bobva

50,000 miles I"m it even moves.

24,000 is the recommended.

Rick 12v CTD

I know people who had driven their vehicles over 190k miles without ever having replaced the trans fluid. Now, in that instance I'm surprised it even moved lol

50k miles is a lot, but not overly excessive if it's driven kindly imo. The trans color is about right I'd think, for that many miles.

If you can afford, get a goerend converter, shift kit and upgrade the low/reverse band/apply lever when you rebuild it and call it a day, it'd be good to go for a long time I'd think. Of course upgrade the clutch count and that standard stuff as per David's build thread as well. Do it once, do it right.

lovin1stgens

This seems like a good place to ask as any, and Jim lane would probably be the one to know, I've been told that the auto tranny's have this sensor. and when the sensor says its too cold it doesnt really like the tranny going into the top gear. i was told by the same person that you can just completely bypass the sensor.

Do you know where its located? anyone?

Crossy's son

oh please, people drive these trucks 100,000+ miles without changing the fluid, simply because it works and they don't care.

BC847

Actually, it's not. Start a thread of your own for the best answers directly related to YOUR question.

gyman98

I think 50,000 miles is a lot too, when was the last time a band adjustment was done?

If the truck is strictly highway driven with no load its not so bad, if its a city driver with lots of stop and go then its bad.

sootnsmoke

As an FYI, the factory 91 owners manual specifies every 12k miles for a filter change and band adjustment. On my automatic trans vehicles, I have never gone past 25k miles for a fluid/filter with band adjustment servicing.

KRB

Derale offers a tranny cooler with the proper size lines. Thats what I've been running.

Trans fluid almost looks like its contaminated? Was there more than there should be? Sometimes that heat exchange heater thing along the right side of the block can leak and allow coolant/AT fluid to cross.

NJTman

Jim,

What temp does your trans run @ while driving, in traffic, etc ? Looks like overheated fluid to me.... or somehow moisture entered into the trans.... which is unlikely.... but that's what it looks like....

I put the Derale deep cooling pan on my truck, and it has never topped 160* since

https://www.dieseltruckresource.com/...n-t293575.html

With the quick drain in the pan, I get to dump the pan every year after plow seasons over. I guess that means not all of the fluid gets changed, but if it's only being dumped @ every 8k or so, it's better than not. Every couple of years, I'll drop the pan and change out the filter.

339K&Counting

Jim
FWIW
I know that you are meticulous so I wonder where is the pan magnet?Also, the color bothers me.
I change the autos (of family members) every 25K and have never seen that color. Is it possible that when you power wash that water is going down the dipstick tube. Take a sample to your tranny expert.
Did you check the level before you drained it?
I think it would be a good idea to get all the fluid out of the tranny and torque C. Refill with aynthetic and try again.
Cheers

jbawden

Did I read the post correctly, you put the nasty 50k mile old brown oil (mud) back in the tranny?

NJTman

Crazy, huh ?


I couldn't believe that either..


I've heard many times that if you flush the fluid, change the filter, sometimes that the trans comes back to life .... with no further complications.

Greed 93

That is how my fluid looked after 10 k of just driving back and forth to work. After i put that DTT converter in all was well again.

jimbo486

If coolant/water and transmission fluid act the same when mixed as coolant/water and engine oil do, I would venture a guess that there could be a pin-hole sized leak in the factory transmission cooler on the side of the block.

I've always heard the recommendation that if you're truck or car is a daily driver, service the transmission once every year. While that may sound like overkill to some people, at least you'd know of an sooner rather than later and before it gets out of hand.