Transmission line uncoupled

coolride

Well-Known Member
Was doing 70mph on the interstate. A moment later the tach went to 3500 and the Trailblazer was in neutral and coasting.

Nothing but neutral; stopped and called AAA. Got out and walked around the vehicle and found a puddle of transmission fluid ahead of the front passenger side wheel.

The truck driver put the TB in my garage, and this morning I found a failed line coupler.

The top left coupling looks good, the bottom right coupling is blown apart. Did I destroy anything?
 

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christo829

Well-Known Member
Hard to say if anything has been destroyed beyond the pipe/coupling. From the sound of it, it happened quite suddenly, and you shut it off after you got it to the side of the road. so while it might have gotten a bit hot, it may not have run starved long enough to kill anything. No matter what, you won't be able to tell until you replace that cooling pipe, refill the trans, and try it. Looks like there's enough rust on that blown pipe to just replace it instead of patching it.

Do you show any fluid on the trans dip stick at all? I'm betting it mostly got blown out, but if you can still see any, that might also indicate that enough stayed in the system to keep the trans from eating itself.

Good Luck!

Chris
 
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coolride

coolride

Well-Known Member
Is there a special bleeding procedure? So replace the pipe, fill with fluid, and then it's good to go?
 

DocBrown

Well-Known Member
If that hadn't failed you would have had a leak soon anyway. That rust is about as bad as I've seen it on transmission lines. And it's not just TBs. I just had the lines on my Sierra replaced in March because of a leak due to rust.
 
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coolride

coolride

Well-Known Member
I want to thank everyone for the info. Thank you.

I just put the front corner on a jack stand and removed the wheel. Cleaning up the spills and then will get a better look around.
 

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coolride

coolride

Well-Known Member
If that hadn't failed you would have had a leak soon anyway. That rust is about as bad as I've seen it on transmission lines. And it's not just TBs. I just had the lines on my Sierra replaced in March because of a leak due to rust.

The picture might make it look worse than it is. But yeah, it's rusty.

This coupling blew out. It looks like a metal collar, on the female side, corroded into dust. Inside the black plastic ring is a bunch of metal corrosion. (The o-ring is still hanging out the bottom.)
 

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MRRSM

Lifetime VIP Supporter
I know its a lot more work ...but since the escaping Pressurized Transmission Fluid managed to thoroughly decorate and soak down almost everything in the adjacent areas of your Front Suspension... it might require a very good clean up.

Your Excellent Photos amplify the proof that the Dexron managed to make it all the way out and onto your Brakes Calipers and this Fluid can act with a strong solvent action that might allow your Brake Pads to separate from their Steel Backing Plates.

So the suggestion is that after you finish your Transmission Cooler Lines Replacement Job, while wearing a decent pair of Clear Acrylic Lens Work Glasses to protect your eyes, use a few cans of Brake Kleen outside in the open air and thoroughly spray down the underside suspension areas presently coated with that stuff.

The Transmission Fluid has a mind of its own and it will continue its migration outwards and can make its way inside of your Brake Hardware unless otherwise removed. If you have the same concerns that I have... after the Spray Down of those locations... it might do to remove the Brake Calipers as well and examine the condition of all your Brake Pads... just to be sure nothing has gone 'sideways' hidden beneath the Calipers.
 
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coolride

coolride

Well-Known Member
I'm certain that a small amount of water is dripping on the floor from the radiator, from the port where I removed the transmission pipe (shown below.) The ATF wasn't "milky;" also, I was almost sure a saw a few drops of water on the bottom of the drain pan (maybe sweat from my face.)

Can anyone point me toward a good dedicated transmission fluid cooler?

I guess I'll loop together the fluid pipes just long enough for a short test drive, then block off the radiator ports and install an external trans cooler. (Or maybe a new radiator.)

tb7.JPG
 
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coolride

coolride

Well-Known Member
Is this normal?

Coolant is leaking from around the outside edge of the pipe fitting (on the bottom of the radiator.) At first I thought the coolant was leaking from inside the fitting, but then took a closer look.

Leak is from the outside edge.
tb10.jpg


I reinstalled the old pipe and the big dish shaped washer pulls the fitting tight and stops the leak. Is this the way it's designed to seal?
tb9.jpg
 

MRRSM

Lifetime VIP Supporter
Using your own image...you can see within the Red Circle Highlighted area... the Original Seal around the Aluminum Port entry into the Transmission Fluid Heat Exchanger is completely compromised... split and bulging out ...essentially irreparable and now... wanting for a New Radiator. Repairing that location using JB-Weld or other similar Bonding Agents with such dissimilar materials as Poly-Carbonate Plastic and Aluminum fighting with so many Thermal Heating and Cooling Cycles... will be well nigh impossible:

CRACKEDSEAL.jpg
 

christo829

Well-Known Member
When I replaced my rusted out cooler lines, I did not see any coolant leaking from the radiator connection, and I don't recall seeing the seal around the port at all. You might be able to get away with putting the line back in for now, but I suspect you'll be replacing the radiator at some point, thanks to those heating/cooling cycles MRRSM points out. Between those, internal pressure and the inevitable vibrations of a moving vehicle, that seal will most likely give up again. Then again, it might last for the rest of the time you have the truck. Murphy loves automobiles and people who work on them. :wink: But not sure you want to rely on it holding up next time you're doing 70 down the interstate!
 

Maverick6587

Well-Known Member
You might also think about replacing the other three lines. They all look pretty rusted. I had one of the lines crack from rust back near the transmission and I just replaced them all because they were about as bad as yours.

Since you already have the one unplugged and you lost so much on the highway you won't have to worry about losing much more transmission fluid. I think amazon sells them in pairs for pretty cheap. I think I paid $40 or so for each pair. Or you could just buy the straight lines and bend them, matching the bends of the originals.

Your local parts store should have a bending tool and flaring tool that would make the job a lot cheaper.

Since you lost most of your fluid and there is a possibility of some burning/grinding that happened. You might also want to change the transmission filter and clean the pan.
 

Mooseman

Moderator
Did you unscrew the fitting from the radiator? If so, that is not the proper procedure to remove the line unless it's so rusted in there that it won't come out of the fitting after removing the clip. It's probably leaking because you are removing the pressure that holds the seal inside the radiator tank. And this was proven when you reinstalled the fitting and it stopped leaking. The two fittings basically hold the cooler inside the radiator tank.

If your line is stuck in the fitting, you might have to find a replacement.
 
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coolride

coolride

Well-Known Member
Yes, I had to unscrew the fitting to remove the line. It was stuck. I have the new pipe, that's the segment that failed. I'm happy to replace the other three lines, but after I know that the transmission still works.
tb7.JPG
 
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coolride

coolride

Well-Known Member
Low voltage.

On the side of the highway, I let the engine idle for awhile. The voltage needle dropped and was erratic. Maybe tranny fluid was sucked into the alternator?

I could douse it with electrical cleaner...
 

Mooseman

Moderator
I don't think it's related. Please start a new thread on this separate problem.
 
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coolride

coolride

Well-Known Member
Torque for pan bolts "wet."

The torque spec. is 109 inch pounds, and I guess that's the dry spec. These bolts soaked in a bowl of ATF and I set them at 60in-lbs. Is that way off?
tb11.jpg

Sanding and grinding to clean up the pan (far from perfect though.) Covered it with brake caliper paint. The heat shield too..
tb12.JPG
 
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Mooseman

Moderator
I'd still torque them to 109. Hopefully the sealing surface wasn't gouged.
 
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coolride

coolride

Well-Known Member
You might also think about replacing the other three lines. They all look pretty rusted. I had one of the lines crack from rust back near the transmission and I just replaced them all because they were about as bad as yours.

Since you already have the one unplugged and you lost so much on the highway you won't have to worry about losing much more transmission fluid. I think amazon sells them in pairs for pretty cheap. I think I paid $40 or so for each pair. Or you could just buy the straight lines and bend them, matching the bends of the originals.

Your local parts store should have a bending tool and flaring tool that would make the job a lot cheaper.

Since you lost most of your fluid and there is a possibility of some burning/grinding that happened. You might also want to change the transmission filter and clean the pan.
I just installed a new filter and gasket today. Picked up 5 quarts of fluid retail, and have another 4 on the way from amazon. I own some bending and flaring tools. Yeah, I'll think about maybe making a few lines. Thanks for the reminder.
 
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coolride

coolride

Well-Known Member
Using your own image...you can see within the Red Circle Highlighted area... the Original Seal around the Aluminum Port entry into the Transmission Fluid Heat Exchanger is completely compromised... split and bulging out ...essentially irreparable and now... wanting for a New Radiator. Repairing that location using JB-Weld or other similar Bonding Agents with such dissimilar materials as Poly-Carbonate Plastic and Aluminum fighting with so many Thermal Heating and Cooling Cycles... will be well nigh impossible:

View attachment 90753
I'm pretty sure that whatever looks like damage is caused by light reflecting off the coolant droplets. That plastic bore might be wallowed out by a few thou. but I didn't notice cracks or other obvious damage when I had my eyeball up there close. Or maybe it's toast...Hard to know for sure. It did stop leaking after the coolant line fitting was replaced.
 
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MRRSM

Lifetime VIP Supporter
Not to *Jinx* your present successful repair efforts ... Looking over ALL of your Brake Lines for signs of similar excessive Rust and Corrosion with "..a Very Jaundiced Eye..." would not hurt a bit. Having Hard Brake Lines Rust through on Vehicles dealing with Mountainous or Hilly Terrain is the very Stuff of Nightmares, let alone losing Brake Pedal on Flat Ground. It strikes me that their Rate of Decay from Salted Roads and Impacted Snow Slush might be similar... and very worthy of inspection for that reason alone.
 
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coolride

coolride

Well-Known Member
Last month I borrowed my father's 2003 Silverado and blew a brake line. It's a regular occurrence around here, that's a fact. I spent a fair amount of time under the TrailBlazer and always looking for bad brake lines. I'll trace everything from the master to the wheels.
 
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coolride

coolride

Well-Known Member
Not to *Jinx* your present successful repair efforts ... Looking over ALL of your Brake Lines for signs of similar excessive Rust and Corrosion with "..a Very Jaundiced Eye..." would not hurt a bit. Having Hard Brake Lines Rust through on Vehicles dealing with Mountainous or Hilly Terrain is the very Stuff of Nightmares, let alone losing Brake Pedal on Flat Ground. It strikes me that their Rate of Decay from Salted Roads and Impacted Snow Slush might be similar... and very worthy of inspection for that reason alone.
I went out to the garage and had a look. All the brake lines are coated with black paint or plastic. I don't see corrosion on a single line. Here's the master; coated lines (right) loop under and then feed into the stainless steel braid (left.) And then everywhere else are the black coated brake lines.
tb13.JPG
 
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coolride

coolride

Well-Known Member
Added 5 quarts and then pumped fluid into a drain pan until the flow started to cough. Then I added 4 more quarts. If I was smart (yesterday was a bad day for smarts,) I'd of checked the fluid level once or twice while adding the second gallon of fluid.

This morning the dip stick level was super high (dumped a gallon in last night and hit the hay.) For 20 seconds I ran the engine and pumped 1 and 1/4 quarts into this empty container. The jug has a "window" along the side for measuring volume. Now the dip stick reads nothing... I'm guessing it was all sucked into the pump?

Dip stick readings go from way too high, to nothing, after pumping out 1 1/4 quarts.
tb14.JPG
 

Blckshdw

Moderator
Dip stick readings go from way too high, to nothing, after pumping out 1 1/4 quarts.
I seem to have the opposite problem on mine. Seems to always read in the right level on the stick. Last weekend, turned out to be low, and during a test drive the transmission started slipping. Had to pull over and add half a quart, fluid level didn't move on the stick. :hopeless: Hopefully yours gets dialed in without much more effort
 
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coolride

coolride

Well-Known Member
I learned that all levels are measured when the engine is running. So there's no such thing as checking the level when the engine is cold and not running.
 
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coolride

coolride

Well-Known Member
Best I can figure, the dip stick tube gets coated with fluid and it's impossible to get a good reading soon after filling.

I checked the temp of the pan with the IR (I'm not sure why now.)
tb16.JPG

And checked the level; it's that shiny zig zag just above the loop. I ran the engine in park and added another 3rd of a quart. Will let the tube drain down for 20 minutes and check level again.
tb15.JPG
 

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Blckshdw

Moderator
I think the only time you check it cold and shut off, is after an initial fill.

Best I can figure, the dip stick tube gets coated with fluid and it's impossible to get a good reading soon after filling.
To me it seems this also applies when the engine is running. Mine, always has a little bit of fluid in the first (and sometimes second) hole on the stick, even the time it was low. I'll wipe the stick clean and recheck, but it always looks the same. So I'm always a little unsure of how accurate that reading really is.
 
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coolride

coolride

Well-Known Member
I think the only time you check it cold and shut off, is after an initial fill.



To me it seems this also applies when the engine is running. Mine, always has a little bit of fluid in the first (and sometimes second) hole on the stick, even the time it was low. I'll wipe the stick clean and recheck, but it always looks the same. So I'm always a little unsure of how accurate that reading really is.
You are in Florida right? I lived there for 14 years and not only were the roads hot enough to cook dinner on, but my garage was always like an oven. This might have something to do with your fluid readings. There is no such thing as a "cold" reading during the summer in Florida.
 

Mooseman

Moderator
On both oil and tranny fluid, I check both sides of the dipstick. If one side got some from contact on the tube, the other side is usually good and will show the true level. Keep the stick pointed down.
 

Blckshdw

Moderator
You are in Florida right? ...my garage was always like an oven.
I am, and my garage does too. If I'm gonna be out there for more than a few minutes, the big fan gets turned on so my shirt doesn't get soaked.

On both oil and tranny fluid, I check both sides of the dipstick. If one side got some from contact on the tube, the other side is usually good and will show the true level. Keep the stick pointed down.
I do both of these. :thumbsup:
 
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coolride

coolride

Well-Known Member
I repeated the process of checking the cold idle level, adding a 3rd of a quart, shuting it down and letting everything settle for about 40 minutes, then checking the cold idle mark again.

After about 5 cycles of adding fluid and waiting, It reached a cold idle level of just slightly above the top cold mark. I re-installed the front passenger wheel (after spraying down the brakes with a full can of brake cleaner,) and I lowered the TrailBlazer down from the jack stand.

Opened the garage door and went for a ride: Seemed to have no trouble shifting through all the gears. I dare say the shifts were smoother and more consistent than before I blew the coupling.

Thank you everyone!!!!! I'll add to this thread if something changes.
 
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