Failure of ATF cooling lines at 135,000 miles?

[2.5_IMP]

I have a 2002 Impreza with a 4EAT that's just about to hit 135,000 miles. When I was driving it this afternoon, I noticed smoke coming from underneath the car. To make a long story short, one of the lines that sends the ATF to the cooler had developed a sudden and severe leak, and was coating the exhaust with ATF. Fortunately, there was enough left in the trans. to limp it home.

 

Is this a common failure? I searched and couldn't seem to find much.

[MilesFox]

The hoses could fail prematurely if there is constant oil leaks on them and the rubber breaks down.

 

The other possibility is rust, caused by winter road salts, that could have caused a pinhole leak in the metal portion of the line. this is especially possoble whre the metal line has a fastener or clip that would hold dirt and moisture causing the rust-through.

 

Another possibility would be if the trans was serviced or flushed, and one of the hoses could have been stretched or torn, or a bad clamp installed

[nipper]

135,000 miles is not premature by any standard for rubber hoses, especially hoses athat are in less then an idea location.

 

Metal lines do fail, again because of enviormental conditions.

 

And there is always, stuff breaks.

[2.5_IMP]

The hoses could fail prematurely if there is constant oil leaks on them and the rubber breaks down.

 

The other possibility is rust, caused by winter road salts, that could have caused a pinhole leak in the metal portion of the line. this is especially possoble whre the metal line has a fastener or clip that would hold dirt and moisture causing the rust-through.

 

Another possibility would be if the trans was serviced or flushed, and one of the hoses could have been stretched or torn, or a bad clamp installed

 

There was definitely no oil leaking onto the hoses. I try to keep things clean and dry under the hood. Well, until today at least.

 

I bought the car when I lived in Oregon, so it has only been through one salty winter since moving back east.

 

135,000 miles is not premature by any standard for rubber hoses, especially hoses athat are in less then an idea location.

 

Metal lines do fail, again because of enviormental conditions.

 

And there is always, stuff breaks.

 

The lines aren't in the best location. There isn't much room between the lines and the steering shaft, and it looks like there may have been some rubbing.

 

Thank you both for the suggestions. I'm going to be replacing the line that failed, as well as all the rest of the lines and fittings as a precaution.

[nipper]

The one truly nice thing about tranny lines is that they are are easy to repair. They are one of the few things that are still fixable with duct tape and bubblegum (some hose and clamps).

[idosubaru]

take note of how it failed when you remove it, i'd be interested to see if it was hose degradation, clamp induced, or clamp too loose or rusty.

 

they have some tight bends in them but they can be replaced with non-formed generic transmission fluid hose. just make it a bit longer than the original so you can make wider bends.

[GeneralDisorder]

On the Imp the lines run under the head (actually attached to the head on the hard-lines) and thus seem to get hard and crack sooner than the Legacy lines. 135k is about right for that failure on the Imp.

 

GD

[2.5_IMP]

take note of how it failed when you remove it, i'd be interested to see if it was hose degradation, clamp induced, or clamp too loose or rusty.

 

they have some tight bends in them but they can be replaced with non-formed generic transmission fluid hose. just make it a bit longer than the original so you can make wider bends.

 

I ended up ordering the OEM formed hoses, but I'm going to buy some generic high pressure hose for the next time something like this happens.

 

On the Imp the lines run under the head (actually attached to the head on the hard-lines) and thus seem to get hard and crack sooner than the Legacy lines. 135k is about right for that failure on the Imp. GD

 

I was waiting for you to chime in. Yes, the lines do run under the head on Imprezas. I removed the hoses this morning, and this is what I found:

 

• All clamps were tight, and not rusty.
  
• Both hoses showed no signs of damage from heat, and were suprisingly soft and pliable.
  
• BUT - one of the lines had a giant hole rubbed in it by the steering shaft. The hard line closest to the head had been bent, causing the hose to rub against the steering shaft.
  

 

So, how did this happen? Before I left Portland, I had the head gaskets done at an independent Subaru shop. This the only time the engine has been out of the car, and I suspect that this is when the hard line was bent. Can I prove it? Of course not, and so I won't name names.