Transmission lines leak at the fittings - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crm318 · 10-25-2009, 09:32 PM

I was replacing a bad freeze plug on my truck the other day and i had to remove the transmission cooling lines for access. The lines come about 8 in out of the transmission and thengo to these brass fittings. The fittings have the little ferrel and they thread into each each other (kind of like an oil pressure line. When the truck is running, transmission fluid drips out of the back of the threaded part where the transmission line comes out of it. I even used teflon tape. How can i get it to stop.

Longhorn Man · 10-25-2009, 09:38 PM

remove the tape. the threads aren't what holds the fluid in, it's the tight fitting from the pieces threaded together. With the tape in there, you can't tighten it up all the way.

mclairmo · 10-25-2009, 10:43 PM

New hard lines are cheap. I have had trouble in the past getting them to re-seal after removing them. I would buy new ones if the old ones won't stop leaking.

crm318 · 10-26-2009, 06:24 AM

good call guys. Ill try it with the tape off.

cdowns · 10-26-2009, 07:25 AM

no tape// and b4 putting back together use very fine steel wool to clean up and burrs on the fittings

big_al_71 · 10-26-2009, 07:40 AM

definetly the tape has to come off, like cdowns said clean out the threads then tighten it all up. If not replace them and no tape.

geezer#99 · 10-26-2009, 10:43 AM

If the connector has a little ferul inside it seems to me the po used a tubing union to join the lines. There are 2 feruls per side. These are compression type fittings. One ferrul is compressed onto the tube and the other one acts as a seal between the tube and the fitting. This one looks like a small o-ring. You might have lost this one. No matter how tight you try it will still leak. You might need to buy another tube union to get another ferrul.

71tahoe · 10-26-2009, 12:27 PM

Is the end of the tube straight or does it have a double flare?

straight:
===

double flare:
==<<

Straight would have the ferrules and I've never been able to get one off intact after one use.

Double flare requires a inverted flare union. Brass is softer than steel and I've seen these leak because they get dimpled and when reused they don't have a regular surface to seal. If you have double flare, try new 5/16 unions and see if it stops leaking.

crm318 · 10-26-2009, 12:45 PM

The tube is straight (not flared) and there are two feruls on each line (one on either sides of the double eneded threded piece). When this rain lets up, ill let you guys know how it goes.

mclairmo · 10-26-2009, 01:29 PM

I would use new ferrules. Once they are compressed, they may not seal again correctly.

crm318 · 10-29-2009, 08:56 PM

Well guys, I tool the tape off and tightened the hell out of them. No more leaks. Problem soleved. Thanks for everything.

10-25-2009, 09:32 PM	#1
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Transmission lines leak at the fittings I was replacing a bad freeze plug on my truck the other day and i had to remove the transmission cooling lines for access. The lines come about 8 in out of the transmission and thengo to these brass fittings. The fittings have the little ferrel and they thread into each each other (kind of like an oil pressure line. When the truck is running, transmission fluid drips out of the back of the threaded part where the transmission line comes out of it. I even used teflon tape. How can i get it to stop. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

10-25-2009, 09:38 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Transmission lines leak at the fittings remove the tape. the threads aren't what holds the fluid in, it's the tight fitting from the pieces threaded together. With the tape in there, you can't tighten it up all the way.

10-25-2009, 10:43 PM	#3
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Transmission lines leak at the fittings New hard lines are cheap. I have had trouble in the past getting them to re-seal after removing them. I would buy new ones if the old ones won't stop leaking.

10-26-2009, 06:24 AM	#4
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: Transmission lines leak at the fittings good call guys. Ill try it with the tape off. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

10-26-2009, 07:25 AM	#5
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Transmission lines leak at the fittings no tape// and b4 putting back together use very fine steel wool to clean up and burrs on the fittings __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

10-26-2009, 07:40 AM	#6
big_al_71 Registered User Join Date: Jun 2008 Location: South Florida Posts: 11,375	Re: Transmission lines leak at the fittings definetly the tape has to come off, like cdowns said clean out the threads then tighten it all up. If not replace them and no tape. __________________ Get your facts first, and then you can distort them as much as you please!!!!!. Sylvester's build thread >>>http://67-72chevytrucks.com/vboard/s...ht=big+rebuild

10-26-2009, 10:43 AM	#7
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,736	Re: Transmission lines leak at the fittings If the connector has a little ferul inside it seems to me the po used a tubing union to join the lines. There are 2 feruls per side. These are compression type fittings. One ferrul is compressed onto the tube and the other one acts as a seal between the tube and the fitting. This one looks like a small o-ring. You might have lost this one. No matter how tight you try it will still leak. You might need to buy another tube union to get another ferrul.

10-26-2009, 12:27 PM	#8
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Transmission lines leak at the fittings Is the end of the tube straight or does it have a double flare? straight: === double flare: ==<< Straight would have the ferrules and I've never been able to get one off intact after one use. Double flare requires a inverted flare union. Brass is softer than steel and I've seen these leak because they get dimpled and when reused they don't have a regular surface to seal. If you have double flare, try new 5/16 unions and see if it stops leaking.

10-26-2009, 12:45 PM	#9
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: Transmission lines leak at the fittings The tube is straight (not flared) and there are two feruls on each line (one on either sides of the double eneded threded piece). When this rain lets up, ill let you guys know how it goes. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

10-26-2009, 01:29 PM	#10
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Transmission lines leak at the fittings I would use new ferrules. Once they are compressed, they may not seal again correctly.

10-29-2009, 08:56 PM	#11
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: Transmission lines leak at the fittings Well guys, I tool the tape off and tightened the hell out of them. No more leaks. Problem soleved. Thanks for everything. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies



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