Leaking red fluid while running

[troverman]

2005 GMC 3500 with gas V8 and 4L80E trans. Truck seemed to be running/ driving fine...but suddenly smoke is pouring out. Smells like ATF. Seems to be originating right about mount that supports transfer case and transmission. Ran down all over exhaust and smoked. Fluid is red. Odometer is 128k miles. Is it the transfer case or transmission? Do the torsion bars have to be removed to get the transfer case / transmission out?

 

Thanks 

[CamGTP]

We are only but people on a computer screen and a keyboard. Telling you exactly what fluid it leaking is not possible for us.

 

You need to get another person and have them start the truck with you laying on the ground under it. Check to see where the leak is coming from. If it's all over the exhaust in that general area it could be a blown cooler line, rear gasket at the transmission to transfer case or the transfer case housing someone got a huge leak in it.

 

The normal pump rub issue on the transfer cases normally just leak at the bottom and drip on the ground, not spraying on the exhaust.

[HawkScot]

Might be the pump rub problem in the transfer case...

[troverman]

It definitely sprayed all over the exhaust. I checked the trans fluid and it appears to be fine on the stick. It’s all wet where the transfer case and transmission meet up. I don’t have another person to help me right now. 

[Formulabruce]

Most likely Transmission fluid, so get under there and find the wettest spot, and fix the transmission line. Could be running from further up towards the transmission cooler.

[troverman]

I’ll take a look again soon and check the cooler lines. Thanks. 

[diyer2]

 

Transfer case takes trans fluid.

Check it out.

[troverman]

Would the transfer case leak only when the engine was running? Once I shut the truck off, the leaking stopped pretty quick. I thought the pump rub problem was visible at the back of the transfer case housing. This leak is at the very front, at the transmission connection. 

[diyer2]

I can't diagnose this problem for you like mentioned in the first response by CamGTP.

Just trying to help.

Put a pan under it.

Start it.

Let it run for a while.

Monitor the amount of fluid in the pan.

Check trans fluid level.

 

[davester]

Yes, the pump rub problem generally only leaks while the truck is in motion (the hole is above the resting fluid level, so the fluid only comes out as it splashes up and through the hole), which is what makes the problem that much more annoying.

 

I would suggest getting some brake cleaner and, when the truck is cold, cleaning the the transmission of the transmission fluid, start up the truck, and then crawl under it and see where fluid starts coming out.

 

Since you say it seems to stop soon after you turn off the engine and is towards the rear of the transmission, I'll guess the rear transmission cooler line/port has a problem (line has rusted through, or has partially come out of the fitting in the transmission).

[troverman]

Thanks Davester. I'll be checking the lines as soon as the weather improves.

[troverman]

UPDATE** - it is the rear cooler line. I laid underneath with it jacked up and running, and fluid is coming out of that line.

 

I didn't realize GM uses "line connectors" on their cooler lines. It's leaking right out of the fitting; apparently there is an o-ring inside.

 

My question is...what size line connector is used on this transmission? Autozone shows there are a couple.

 

Thanks!

[David89GMC]

Search acdelco.com for the correct Delco part number. The 4L60 and 4L80 use the same o-rings. You can get them from globaltransmissionparts.com. Great company to work with.

[troverman]

Thanks David89GMC.

 

Update - fixed this a couple weeks ago. When I removed the fitting, the line snapped off inside. Ended up replacing the fitting with a Dorman and changed the whole line out. All set now.