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Discussion Starter · #1 ·
A couple of year ago I installed a set of Red's Auto Rehab 1/2" transmission lines in my 2006 2500HD. It worked fine for a while and then started leaking at the connection at the lower radiator. I took it apart today and it was very loose where the 45 degree "adapter" screws into the cooler inside the radiator. Assuming that was the problem I tightened it up as much as I dared (I can't get a torque wrench on it), then reassembled and took it for a drive. It's still leaking just as bad as it was before. Below is what the set looks like along with a close-up of the offending connection (this is from their website, mine is still on the truck).

The O-rings do not appear damaged. It's really hard to see down there but I'm assuming the connection pushed into the cooler and the O-rings seal between the line and the cooler and that the face of the cooler is compressed against and seals on the inside of the radiator. Is this correct?

So what could cause this to leak if the O-rings aren't damaged? It is not leaking water, just transmission fluid. I can replace the O-rings if that's the problem but it's a fairly long operation so I want to be reasonably sure that will work before I start (just letting the truck idle won't cause it to leak, I have to re-assemble everything and drive it a bit).

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Discussion Starter · #9 ·
Thank you mp06011999. My kit did come with two O-rings per fitting which isn't obvious in the pictures. Maybe they just shrunk or something? I do know it's not very tight. It came off and went back in very easily. One thing that bothers me is that you can't really tighten the fitting by screwing it in since it won't line up with the hose the way you need. I then have to "back it up" 1/4 turn or so to line up with the hose. I'm sure that is why it has the nut to tighten things up but it still makes me nervous. It's the only fitting I have to do that with and it's the only one leaking.

I was going to write the manufacturer today if I hand't had any comments here yet so I guess I'll do that and hopefully can get some new O-rings from him. I wish I could get my head in there and inspect things a bit closer to see if there are any cracks but damn there's a lot of stuff in there.
 

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Discussion Starter · #12 ·
There is no question it is transmission fluid or which fitting it's coming from. Definitely not from the hose but from the fitting-to-radiator. There is no water in the transmission fluid or vice-versa so I assume that seal is working ok. I'm assuming it has to be the o-rings even though they look fine. It seems a bit loose so maybe they shrunk?

I wrote the manufacturer and he replied quickly with the size. For those wanting to know, #910. So I'll bet getting some viton o-rings and give it another go I guess.

When I first installed them I removed the wheel liner. This is the only fitting that seemed to require that and I guess it did make things easier to install the lines, but if I did it again I would not remove the liner. I removed only the air box this time and dealing with the liner in place wasn't nearly as bad as taking it out and putting it back in, not to mention the fasteners lost or destroyed. Live and learn.

Thank you for all your help.
 

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Discussion Starter · #16 ·
Thanks for o-ring size info. I'd say new o-rings will prolly be the issue. Fingers crossed and make sure they're sitting perfectly within the washer. Good luck with it and let us know. I never had tranny fluid, coolant cross contamination either.

I've had my passenger wheel liner out so much that the aftermarket access door you cut into the liner for fuel filter replacements has never been used. I bought one of these and a bag of GM pushpins years ago.

View attachment 646562
I couldn't find the o-rings locally and had to order from Amazon. They are here now so I know what I'm doing this weekend.

What do you mean by "sitting perfectly within the washer"? I don't have them out yet again but I recall the washer basically sat on top of the o-rings but not really snugly. You just sort of pushed it on and then screwed the fitting in.
 

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Discussion Starter · #18 ·
See how in your pic you can only see one o-ring sticking out beyond the washers?
View attachment 646725


From memory... I believe the o-rings are small enough to sit inside the ID of the washer. And not big enough not to. But to make sure they are not part in the ID and part out, like pinched. The first o-ring sits entirely inside the washer ID and not against the face of the washer. The second o-ring then sits against the first one that is completely captured within the washer. The first one providing the backstop for the second. The second one actually doing the sealing. The first one is just a spacer, of sorts.

Make sense? It should when you have it apart. And if I'm misremembering, let me know. But I believe THAT was my seeping issue. I did not know to make sure the first o-ring sits inside the washer rather than against the face of it.
The o-rings do sit inside the washer, that all looks as you describe.. If there was a difference in size between the old ones and the new ones I put on today I couldn't tell. But at least I feel confident that I do not have an o-ring problem.

I do appear to have a not-tight-enough problem. The 45-degree fitting was pointed somewhat down and left. If you were looking at it face-on it would be facing about 5 o'clock. The problem is it's not tight like that so you have to use the lock washer (don't know if that's the actual name) to snug it all down. I'm assuming that's how it's supposed to work. What apparently happened is the weight of the hose pulled it down some more which loosened it and it leaked. It did it again the second time. Today when I replaced the o-rings I turned it to about 11 o'clock and re-routed the hose to come from slightly above. It was a tight fit with the air intake for the inter-cooler there but we got it done, plus I got it a good bit tighter. Unfortunately it's still leaking. A whole lot less this time, just a drop or two after 15 minutes or so of driving, and the hose won't pull down on it again, but I don't feel like it's done.

I'm looking for a set of crows-foot wrenches so I can put a torque wrench on it. If I can't fit that in there then I'll find me a shorter, thinner wrench. Right now the only 1" wrench I have is a good 18" long and really thick. The adjustable wrench isn't any better. I just can't get ahold of it to give it the 1/4 turn or so I think it needs. But I'm almost there.

Thank you again for your help.
 
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