th350 to 700r4 cooling lines
Thread Starter
Racer
Joined: Sep 2005
Posts: 453
Likes: 1
From: Austin TX
th350 to 700r4 cooling lines
Back when I swapped my th350 for a 700r4 in the 78, I had to manually bend my factory hard lines to make them line up with the 700r4 fittings at the transmission. This has worked for some time now but I have a strange leak that usually only happens when the car sits for a while. I took it back to the shop that built the tranny (I installed it) and they confirmed it to be leaking from one of the coolant hard line fittings at the transmission. So I'm in the market for new hard lines if some additional torque doesn't stop the leak.
BTO has "700r4" hardline kits on their site. Does anyone know if these fit correctly on our cars? If not where can I get the lines with correct geometry at the end to screw into the 700r4? I don't really want to struggle with the factory replacement th350 lines again.
BTO has "700r4" hardline kits on their site. Does anyone know if these fit correctly on our cars? If not where can I get the lines with correct geometry at the end to screw into the 700r4? I don't really want to struggle with the factory replacement th350 lines again.
Le Mans Master
Joined: Mar 2001
Posts: 6,640
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From: Ann Arbor Michigan
You can try these guys. They claim they can make any tube if you supply dimensions.
http://www.inlinetube.com/
http://www.inlinetube.com/
Safety Car
Joined: Nov 1999
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From: Paducah KY
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St. Jude Donor '03
Don't know how much difference there is between the TH350 and the TH400, but BTO supplied the lines for my TH400 to 700R4 swap. Great fit, no problems.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
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From: Orange Park Fl
I used my stock lines like you and had a leak at a tranny fitting. It was hard to get at it to tighten it enough. I gave up and took it to a mechanic friend's shop. I think he bent an extension and put a crow's foot on it and finally got it tight enough not to leak.
God bless, Sensei
God bless, Sensei
Thread Starter
Racer
Joined: Sep 2005
Posts: 453
Likes: 1
From: Austin TX
Well, I sorta feel dumb now. I've been going on the tranny shop's word of the the leak being at the lines, but today when I crawled underneath I found there is no leak at the fittings. In fact, I saw where they sprayed silver paint on my lines/unused fittings at the connection to determine where the leak was coming from previously.
So perhaps it was leaking at the lines and they were able to fix it with some more torque. However, after seeing this, I've come to the conclusion that it is not leaking at the fittings and appears to be coming from around the pan gasket. This is the second pan they gave me (as I've been back previously for a leak that I thought was coming from the pan) so I was given a different one since the old one looked warped. Tomorrow I plan to pull the pan, check for small hairline cracks around the pain gasket surface and install and new gasket then see what happpens.
I'll let you know what I find. Honestly, it'd be easier to replace a pan gasket than a set of lines, so I'm keeping my head up.
So perhaps it was leaking at the lines and they were able to fix it with some more torque. However, after seeing this, I've come to the conclusion that it is not leaking at the fittings and appears to be coming from around the pan gasket. This is the second pan they gave me (as I've been back previously for a leak that I thought was coming from the pan) so I was given a different one since the old one looked warped. Tomorrow I plan to pull the pan, check for small hairline cracks around the pain gasket surface and install and new gasket then see what happpens.
I'll let you know what I find. Honestly, it'd be easier to replace a pan gasket than a set of lines, so I'm keeping my head up.
Drifting
Joined: Oct 2004
Posts: 1,496
Likes: 1
From: Lafayette Louisiana
Be sure and look at the tv cable where it enters the trans. Mine would leak from there after it sat for a few days. There is one bolt that holds it in place and sometimes it will torque to one side and leak. I had to pack sealant around the top of mine to stop the leak. Btw, this was an after market cable, the base on the gm version may be strong enough that it will not torque.
