Leaking 700r4

by rosco77 Fri Apr 21, 2017 8:02 pm

So here's the deal, got the car running good. Went for a test drive the other day, and it started smoking. Filling the cab smoking, but it smelled like some kind of oil burning off the exhaust. It didn't take me long to figure out it was tranny oil. I let it cool down before getting under there again next to the exhaust. Come to find out, it was leaking out of the cooler lines. You guys know the hard lines that run to the radiator. I used the same ones that were on the old th350 since they screwed right in. Looks like there was and adapter for it already in the transmission. They were tight, but I disconnected them and reconnected them. They stopped leaking for a bit, but started again after driving for a few minutes, although not as bad this time. It appears to be leaking from around the hard line, not the threads. My question, is there supposed to be an o-ring of some sort in there? There isn't now, and I'm thinking of adding one to see if it helps. I guess I just wanted a second opinion.

by clanceman427 Fri Apr 21, 2017 11:04 pm

Hi rosco no o rings. It's an inverted flare connection, so it seals in the mating flat angled surfaces inside. Same as brake lines.

by bigredlaguna Sat Apr 22, 2017 12:39 am

Next time you back loosen the lines, move the fitting away from the flare and check the natural alignment of the lines going into the fittings. They need to be as straight as possible without the threaded part being screwed in. Just muscle them into position before starting the threaded part.

Also make sure they are clear of debris on both mating surfaces.

by rosco77 Mon Apr 24, 2017 8:04 pm

I've checked that bigred, and I couldn't start threading them on unless they were almost perfect. This is what led me to start thinking there may be a missing o-ring. I was thinking about adding one in. Putting it on the hard line, behind the flare so when it's threaded in, the o-ring gets squished between the nut and the flare.

Anyhow, got other things going on with it now. This is gonna have to wait a bit. I'll update my build thread.

by Hs1973 Tue Apr 25, 2017 3:33 am

The oring deal wont work, there is so much pressure in the Lines that it will just leak even worse. I know that if you have original steel Lines they can be a pain to get sealed. Make sure the Flares are ok, and not in any Way distortet or have any nicks in them. The have to be tightent alot to be leak free. I have some times made new ones out of cobber hard Line. They seal alot easier and dont need to be tightent as hard. Oh and be careful that you have a tool on both fittings when tighten it up, so you dont crack the tranny housing. Hope you get it fixed.

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