I recently removed the engine and transmission so I could replace the gaskets and basically clean it up. I purchased new transmission cooling lines and I can't get the to stop leaking. I added sealant to the threads, removed and tightened everything up a few times and it still leaks. I found it leaking between the pipe and the nut that gets screwed into the housing. It's my sole frustration as everything else seems to be working well. If you look at the picture you'll see a small red drop where the nut and pipe are for both lines. I've observed it coming from this area. It leaks so fast that when I tried to just drive up the driveway it left a nice streak of oil.

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Are your lines stainless steel?

 

I'm not sure but I think they are not.

 

Those pipe threaded nuts are steel; the tranny housing is aluminum. If you overtorqued those nuts to attempt to get them to seal, the alum threads in the housing may have been compromised.

I don't know who made the 'new' lines, but I suspect therein lies the problem. IIWY, I would call the vendor and ask how many other folks had problems getting those lines to seal.

 

Apply teflon tape to the threads.Did you tighten them with a flare wrench or crow's foot?

 

I used a regular open ended wrench to get at them, you don't have a lot of room and I found the shorter tool worked best. As far as the threads, I added sealant to them. With the motor running the fluid is coming out from between the nut and the pipe for the cooling line. You can actually see it streaming out.

 

Those fittings seal via the flare joint. If you put [slippery] teflon tape on pipe threads and tighten them up, most likely the threads will completely strip out.

You are in a tough situation. If those threads can't take enough load to get the joints sealed, it's "drop the trans and fix the threads" time. Does it feel like those nuts are tightening properly...or are they "spongy"?

You might want to remove those nuts/tubes from the trans and inspect the flares in the trans and the flare ends of the tubes to see if there is some manufacturing or wear problem on them. Or, the flares on the tubes might just be "lousy".

 

I've seen the flare crack where the nut seats on top of it. Over torque will increase that possibility.

 

 

I took on a similar task as slopoke on my 78 that is an automatic transmission. The former owner had bubba upped up the connections to the radiator so I got new lines that were not the correct length. Purchased a second set that were to long and finally working through a forum vendor supporter, went directly to the tube vendor, sent them my originals and they made a set identical to the original.

Now, I could tell the flare nut was not aligning correctly into the tranny housing and did not force it. They were not aligning due to an incorrect length...the first time too short...second time to long. The third set finally got it right and its held up well. However, to get them installed and seated correctly, I removed the mount and dropped the tranny enough (a few inches) that I could get my hand and the flare wrench up there and be able to see to work on the flare nut without screwing up the threads...but it was a bear and took several six packs.

I think some of these vendors are selling M40 tranny lines to all and if you have an M38...you're screwed. Conversely, if you get M38 lines for an M40...you're screwed.

My suggestions...

1. Use only a flare nut wrench
2. Drop the tranny so you can see what you're doing...enough you can see.
3. Take the new lines and compare to the old...are they the correct length
4. With a high illuminating light source, inspect those threads in the housing. Get a mirror if you must.
5. You're at a point where you really need to assess the situation before going any further.

 

Thanks for all the information. I'm going to hit sears and get a flare wrench. I'm just going to take everything off and just make we have have no cracks. I'm thinking the flared end isn't large enough to seal as everything tightens up really well.

 

My vote is for an improperly flared line. It sounds like you did everything properly, maybe bubba got a job at the line company. Good Luck ,,,
Peace,,, moosie

 

Look into getting a flared crows foot also it fits into tighter spots better.

 

how far {how many turns } do the new flare nuts go in before getting tight? if you still have the old lines compare the nuts .possibly have a metric versus america thread issue .just because the wrench size is the same the threads may not be .most parts stores have a brass adaptor male/female . metric/american or vice versus that could be your fix. cood luck with the fix

 

I think his brother Hubba did the quality control as well.

 

That sux...if the fluid is coming out between line and nut. Like you stated ie its coming out the middle your flares are not seated. either wrong angle, cracked who knows. since it leaks on both my guess is you have the wrong lines.

I would stop. pull the lines compare them to the old ones and call the vender before you make a giant doo doo out of transmission

 

Replace the lines, trying hopefully a different vender. You should not have to put any teflon tape or sealant on the threads. Also if the bend is not enough or too much in the close area of the flare, it will not seat properly.

 

Found out what my problem was. When removing the lines for the third time I realized the pipe floats in and out of the fitting even though it was fully tightened. The length of the end fitting that came with the lines was not long enough to thread all the way into the casing and press against the flared end to make sure it sealed against the opening. I have to return the lines for a credit and will go to JEGS for the right size fittings. I told Corvette America about this and they will let their supplier know, doesn't help me much but hopefully it will be corrected in the future.

The photo shows the two different sized end fittings, the TH350 auto transmission requires the longer fitting.

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This is a good reason to compare the old parts with the new parts(if you have the old part). It saves a little time and grief.

 

Just another perfect example of how these aftermarket parts vendors are using the vehicle owners as their "Quality Control" system. We spend good money for their parts; and WE suffer the losses of time, money and grief when these parts are not adequate. Some of them even have the audacity to ask the purchaser to pay the return shipping for their JUNK!!

And what changes? Nothing.

Some vendors are "honorable"....many are not.