M1009 Transmission Barfed from Dipstick

[Rustyshackelford]

I went on a nice little 4x4 trip yesterday and while I was on a semi steep incline in a pretty precarious position about .5-1 quart of trans fluid barfed out of the dipstick tube. Please weigh in on this and let me know what you think would cause this.

 

[Tinstar]

Sounds like either transmission was either too full or too hot.

If it was the latter, then the rest of the fluid is toast and needs changed asap.

Time for a transmission cooler.

 

[The FLU farm]

TH-400s are infamous for spitting out excess fluid. As Tinstar pointed out, check that what's left of the ATF is good.
If it is, and the level is still above "Min" on the dipstick, I wouldn't worry about it.
You may want to start carrying a fire extinguisher if it happens again, though.

 

[Rustyshackelford]

TH-400s are infamous for spitting out excess fluid. As Tinstar pointed out, check that what's left of the ATF is good.
If it is, and the level is still above "Min" on the dipstick, I wouldn't worry about it.
You may want to start carrying a fire extinguisher if it happens again, though.

Yikes that sounds scary. How do I tell if the remaining fluid is good? Just the smell?

 

[The FLU farm]

It should look and smell much like new ATF. If it looks brownish or smells somewhat burnt, it's toast.
I had a TH-350 spit ATF out once, and it caught fire. After discharging a fire extinguisher in the engine compartment I learned two things.
One, use Halon (or modern substitutes) not powder extinguishers. It was a mess to clean up. Two, to the point that part of me thought it'd been better to let it burn.
Also had a fresh (factory filled) 4LE80E puke some ATF out, but that was my own fault. I forgot to put in OD, so it (basically a TH-400 with OD) was turning pretty fast.
Just an oily mess underneath a nearly new vehicle resulted from that one, thankfully.

 

[Tinstar]

Do you have a trans temp gauge installed?
Very easy to do.

If you do a lot of 4 wheeling or pull trailers a lot I recommend installing one.
Along with a cooler.

 

[Ordak]

Installing a Transmission cooler is pretty easy, I used a B&M cooler (cannot remember Part #) like this on https://www.amazon.com/70264-SuperC...12825&sr=8-2&keywords=b&M+transmission+cooler and it works very well. Pulling my m101a1 up a steep hill my transmission never went over 195 (about 80 or 85F outside). You will need to grab 3 feet or so of extra transmission cooling lines because the kit did not come with enough. I have mine going from the transmission to the stock cooler to the extra transmission cooler and back to the transmission.

 

[Rustyshackelford]

Seems like a good idea. Can you tell me how to plumb it?maybe post some pics? That would be a great help thanks

 

[cucvrus]

I have a brand new Chevy with a towing package and the transmission goes up to 225-230 on hard hills and pulls. I quickly goes back down and like I said it has a towing package and an auxiliary engine oil and transmission cooler. I have an M1009 that used to spit transmission fluid out the plastic vent tube. I removed the transmission and had the transmission gone over and it stopped. Been quite a few years and I don't remember what was causing it but it was something inside the transmission. Maybe Rustystud can chime in with his input into the problem. First I tried to just add a length of rubber hose and vent it up under the hood beside the fuel filter. That did not help it still pushed it out and I always had spots on the tailgate. The R & R made the difference. Also the transfer case was always over full from the pressure in the transmission. Good Luck. I pull heavy with my M1009 and have no gauge or auxiliary cooler on the transmission. But I figured the military used it hard. It seems to have held up for 20+ years in my ownership. IMHO. Check out the root of the problem before redesigning the system. Something is making it do that. And I don't think it is off roading or mine would drain it self in 10 minutes.

 

[Chaski]

If it is heating because of slipping clutches and wear a cooler won't fix it... but I have one on my 9,000 mile old 700R4 just in case.

2nd on the fire extinguisher. I had an F-350 on fire one time when it barfed onto the hot catalytic converter when running it really hard. Looked like a drip torch, luckily I was on top of gravel and had a fire extinguisher. Probably would have lost the truck without one.


Most of the time people plumb the cooler between the outgoing line on the transmission and the incoming port on the cooler that is in the radiator tank. I guess the idea is that you want the transmission fluid not hot but warm, it does have to be at operating temp just like an engine. That being said they get plumbed both ways with arguments for and against (hot climate, cold climate...etc). I don't know which port is which on a TH400 since I have a 700R4, but it should be pretty easy to research. I plumbed mine with -an fittings and braided hose. Wasn't too hard, the worst part was trying to figure out a good way to mount it in front of the radiator. A lot of the kits have a cheesy zip tie like connector that you press through the fins on your radiator and secure the other one on top of it. I just ended up welding a bracket on the core support. The braided hose required some tape and a cutoff wheel to cut cleanly, and debris cleanup before install.

 

[cucvrus]

I dug thru my emails and I came acroos this form letter that GM sent out to the question on normal transmission operating temperatures. This is a copy of the email.

Thank you for giving me the time to do some research on your concern with the transmission temperature. I have consulted one of our engineers and am happy to inform you that I have the information you’ve requested. The normal operating temperature is between 160°F to 200°F (71°C to 93°C). For towing, the normal operating temperature is between 235°F (113°C) to 260°F (127°C).

I seldom seen it go over 225 but I did have it climb rapidly on hard pulls and it would go down fast after the climb was complete. That told me everything was working as designed. Also I use the tow haul mode and that helps a great deal and reprograms the shift cycles. Also grade braking and hill assist are a great help to relieve some of the pressure and strain on the automatic transmission. I think the TH 400 is a great transmission and it may require a bit of refreshing of seals and gaskets to operate at peak temperature and efficiency. Same as everything time and mileage take an equal toll on the performance and operation.

 

[Drock]

What about a dipstick that latches and seals tight? Most every modern car I can think of, has one of those dipsticks with the rubber plug & yellow latch.

 

[cucvrus]

All my CUCV's have them as original equipment. That just makes it push out somewhere else. Like the vent tube on top of the transmission.See the red transmission dipstick?

 

[Rustyshackelford]

Dang. I'd be happy to add a cooler but I'd really like to know if this is a symptom of a larger issue.

 

[doghead]

Were you driving in high range or low range when this happened

 

[cucvrus]

Dang. I'd be happy to add a cooler but I'd really like to know if this is a symptom of a larger issue.

I am sure Rustystud will have an explanation for the symptoms you have described. I don't remember what was doing it when my transmission did the same thing. good luck. And what would it be if he was in low range. Just as an example? Just saying do you have an answer?

 

[Rustyshackelford]

I was driving in low range

 

[cucvrus]

I was just using that as an example. I drive mine for a whole day in low range and it does not leak any fluid. That is pulling wood and a wood trailer in mud and up and down a few steep muddy hills. But I would also make sure the correct dipstick is in place. i had a vehicle that had a short dipstick in it and I needed to over fill it to show full on the dipstick. Compare it to another one that don't puke fluid to be sure. Good Luck. I hope you get it resolved.

 

[86m1028]

If your vent tube is clogged up, the trans will build pressure from heat & fluid come out the dipstick tube.
That is why gm went to the newer dipsticks (rubber seal with flip over lever).
My dad sat & watched his new truck (84-85) burn when trans got hot & puked fluid all over the converter.
Surprisingly gm did replace the truck.

 

[doghead]

Well, I asked because in general, it's easier to overheat the transmission in high range if you are driving slow or wheeling under high power without moving much.