Transmission cooler line fitting for fluid exchange
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Senior Member
Joined: Nov 2019
Posts: 110
Transmission cooler line fitting for fluid exchange
Hey guys, will be fluid exchanging my 4l60 out in a couple days and wanted some input.
i was reading and other 4l60 chevy owners hook up a 3/8 brass transmission cooler fitting onto the rad? And then hook a line of tubing to pump the fluid out.i can’t seem to find the exact one there talking about but can I just buy any 3/8 fitting for like a pressure washer and just hose clamp a tube to the other end? If so, are the threads npt?
i read some people said the 3/8 doesn’t fit, and some use plastic fittin Bevause they could just bend the threads.
has anyone used a fitting if so which one works? Or what did you do otherwise?
thx
i was reading and other 4l60 chevy owners hook up a 3/8 brass transmission cooler fitting onto the rad? And then hook a line of tubing to pump the fluid out.i can’t seem to find the exact one there talking about but can I just buy any 3/8 fitting for like a pressure washer and just hose clamp a tube to the other end? If so, are the threads npt?
i read some people said the 3/8 doesn’t fit, and some use plastic fittin Bevause they could just bend the threads.
has anyone used a fitting if so which one works? Or what did you do otherwise?
thx
Senior Member
Joined: Apr 2010
Posts: 1,006
From: Deep South Louisiana
The only way to know for sure if the fitting will fit is to remove the upper cooler line and try it, Don't remove the line from the fitting just unscrew the fitting from the radiator then try the 3/8" fitting.
I have not done this on my H2 so cannot say for sure what fitting it will take.
Sorry i couldn't be more help,
Neal
I have not done this on my H2 so cannot say for sure what fitting it will take.
Sorry i couldn't be more help,
Neal
Senior Member
Joined: Jan 2017
Posts: 2,320
From: SC
Not sure if it is the same size line as on my GMC truck but I think they are (same transmission). I added a trans cooler to my truck and used a brass compression fitting no problem on the line (does not leak one bit). I'm almost certain it was a 3/8" one too.
You cannot remove a line and try it as the lines have ends attached to them already.
You cannot remove a line and try it as the lines have ends attached to them already.
Thread Starter
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Senior Member
Joined: Nov 2019
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thanks for the help! do you remember if the threads were NPT or NPTM or NPS?
im looking at one of these but will prob buy a bunch of them till one fits
https://www.princessauto.com/en/deta...rb/A-p0431668e
https://www.princessauto.com/en/deta...rb/A-p0431643e
https://www.princessauto.com/en/deta...ng/A-p0400077e
any of these look like they would work? i read someone say if the fitting doesnt seal against the rad properly then coolant begins to leak or something?
thx
im looking at one of these but will prob buy a bunch of them till one fits
https://www.princessauto.com/en/deta...rb/A-p0431668e
https://www.princessauto.com/en/deta...rb/A-p0431643e
https://www.princessauto.com/en/deta...ng/A-p0400077e
any of these look like they would work? i read someone say if the fitting doesnt seal against the rad properly then coolant begins to leak or something?
thx
Senior Member
Joined: Jan 2017
Posts: 2,320
From: SC
The 3/8" brass fittings I'm talking about can only be used on a smooth flat part of the metal lines (you have to cut them very clean with a tubing cutter). The first one you linked is a brass compression fitting like what I used but I was joining two pieces of the factory metal tubing. Where the cooler lines attach to the transmission, radiator, and trans cooler (factory cooler and radiator) are a specific fitting that is not a threaded fitting. I have no idea what those fittings are called.
That being said - on my truck anyways, there are also parts of the cooler lines where the hard tubing has a flexible tubing section. That seems like that would be the ideal place to cut into one of the lines because you could then just use run of the mill barb fittings for tubing. The ones you linked are also available at most any hardware store as well.
I'd strongly recommend reading more on some of the various GM truck forums out there. They have the same engine and trans and will have a ton more info since so many more of those are on the road. Probably search for trans cooler upgrade info since that is a popular modification and you will probably find a lot of info on tubing sizes, fittings, etc.
Last I remember when I flushed the trans on my truck though. I just took the line loose on the radiator, and stuck it in a bucket, started the truck till the trans pumped about 4 quarts out, shut it off, added 4 more quarts, and repeated this until the fluid being pumped out looked brand new. This also flushes any out of the torque converter as well... Might be other better methods though and probably just as many recommend NOT flushing as there are who do. I think just drop the pan, change the filter and gasket, refill and go is the most suggested thing these days.
That being said - on my truck anyways, there are also parts of the cooler lines where the hard tubing has a flexible tubing section. That seems like that would be the ideal place to cut into one of the lines because you could then just use run of the mill barb fittings for tubing. The ones you linked are also available at most any hardware store as well.
I'd strongly recommend reading more on some of the various GM truck forums out there. They have the same engine and trans and will have a ton more info since so many more of those are on the road. Probably search for trans cooler upgrade info since that is a popular modification and you will probably find a lot of info on tubing sizes, fittings, etc.
Last I remember when I flushed the trans on my truck though. I just took the line loose on the radiator, and stuck it in a bucket, started the truck till the trans pumped about 4 quarts out, shut it off, added 4 more quarts, and repeated this until the fluid being pumped out looked brand new. This also flushes any out of the torque converter as well... Might be other better methods though and probably just as many recommend NOT flushing as there are who do. I think just drop the pan, change the filter and gasket, refill and go is the most suggested thing these days.
Thread Starter
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Senior Member
Joined: Nov 2019
Posts: 110
The 3/8" brass fittings I'm talking about can only be used on a smooth flat part of the metal lines (you have to cut them very clean with a tubing cutter). The first one you linked is a brass compression fitting like what I used but I was joining two pieces of the factory metal tubing. Where the cooler lines attach to the transmission, radiator, and trans cooler (factory cooler and radiator) are a specific fitting that is not a threaded fitting. I have no idea what those fittings are called.
That being said - on my truck anyways, there are also parts of the cooler lines where the hard tubing has a flexible tubing section. That seems like that would be the ideal place to cut into one of the lines because you could then just use run of the mill barb fittings for tubing. The ones you linked are also available at most any hardware store as well.
I'd strongly recommend reading more on some of the various GM truck forums out there. They have the same engine and trans and will have a ton more info since so many more of those are on the road. Probably search for trans cooler upgrade info since that is a popular modification and you will probably find a lot of info on tubing sizes, fittings, etc.
Last I remember when I flushed the trans on my truck though. I just took the line loose on the radiator, and stuck it in a bucket, started the truck till the trans pumped about 4 quarts out, shut it off, added 4 more quarts, and repeated this until the fluid being pumped out looked brand new. This also flushes any out of the torque converter as well... Might be other better methods though and probably just as many recommend NOT flushing as there are who do. I think just drop the pan, change the filter and gasket, refill and go is the most suggested thing these days.
That being said - on my truck anyways, there are also parts of the cooler lines where the hard tubing has a flexible tubing section. That seems like that would be the ideal place to cut into one of the lines because you could then just use run of the mill barb fittings for tubing. The ones you linked are also available at most any hardware store as well.
I'd strongly recommend reading more on some of the various GM truck forums out there. They have the same engine and trans and will have a ton more info since so many more of those are on the road. Probably search for trans cooler upgrade info since that is a popular modification and you will probably find a lot of info on tubing sizes, fittings, etc.
Last I remember when I flushed the trans on my truck though. I just took the line loose on the radiator, and stuck it in a bucket, started the truck till the trans pumped about 4 quarts out, shut it off, added 4 more quarts, and repeated this until the fluid being pumped out looked brand new. This also flushes any out of the torque converter as well... Might be other better methods though and probably just as many recommend NOT flushing as there are who do. I think just drop the pan, change the filter and gasket, refill and go is the most suggested thing these days.
great thanks so much!! i think im just gonna follow your method rather then finding fittings!
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
If you have an external cooler, remove the hose connection, and adapt/add a hose to drain into a pan or bucket. Just make sure to leave in park when running, dump/refill until you see fresh clean fluid. Refill with Dex6.
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
When a customer would come to my shop requesting a transmission fluid flush, there was the important question: Why?
Regardless of answer, always check fluid condition and test drive first and note any transmission shifting issues, then notify the customer this service is not guaranteed to correct, transmission shifting issues. 99% of the time, trans flush improved transmission performance. On a side note, if the transmission fluid looks like molasses or a chocolate milkshake, I would refuse the service.
Regardless of answer, always check fluid condition and test drive first and note any transmission shifting issues, then notify the customer this service is not guaranteed to correct, transmission shifting issues. 99% of the time, trans flush improved transmission performance. On a side note, if the transmission fluid looks like molasses or a chocolate milkshake, I would refuse the service.