Plumbing in a tranny cooler

[SUX2BU99]

I already installed a B&M Supercooler in my truck to replace the leaking one it had, but the factory radiator cooler was bypassed completely. I know that isn't how it's supposed to be, so I want to rectify that. The hard lines are there and the rubber hoses to the B&M are simply clamped over the hard lines. To get the rad cooler back in the loop, I'd have to cut one of the hard lines to splice in the B&M cooler. Is that how it's usually done? I'd rather not cut hard lines, but is there an alternative way to do it? I picked up some tranny cooler-specific hose so now I won't have leaks again. It seems the fuel line I unwittingly used is being eaten by the tranny fluid as evidenced by the leaks right where it connectes to the B&M on both inlet and outlet fittings.

If a person can simply buy one hardline, than I don't mind cutting it just for the threaded fitting to go into the rad cooler.

[76_Scottsdale]

What tranny do you have? You want to run th "Out" or pressure line from the transmission to the stock cooler in. Then run line from the stock cooler out to the B&M cooler in, and run the out line of the B&M cooler to the "IN" line on your transmission. This way the fluid is warmed enough in the winter, but cooled enough for hard driving/towing.

[HAULIN IT]

Sux, You will most likely get varying opinions on this topic. Are you using this vehicle in cold climate for daily use? If not, I would not run through the rad. I was allways on the fence on this until a couple of years ago. I had the cooler in my rad. (a 2 year old GM copper/brass unit) split open & put coolant in the tranny, thus needing to pull it out & do new clutches & converter. So now that convinced me that I would rather pull the tranny from a heat problem that likely won't happen than deal with the coolant issue & try to get the gaskets off after the coolant gets to them. I had heard of this happening, but it seems that it is more common in the last few years.  I feel you should try to eliminate as many slip-on hose connections as possible. There are some fittings from good supply stores that should be able to  help you. Good Luck, Lorne     

[SUX2BU99]

TH350 with shift kit behind a mild 350. Is there clear markings on the transmission and rad to know what in and out is?  As an HVAC designer, I like to run hot fluids through coolers from the bottom to top, but with the relative height of the rad cooler being quite short, I'm not sure it really matters which way it goes in top or bottom, but the series in which the rad cooler and the tranny cooler is important, as you had said. So the important part there is knowing which of the hard lines is the pressure line.

[SUX2BU99]

I may have answered my own question. I did a search for tranny cooler installs and found one for a late 90's Mustang.  They said to perform the splice on the lower tranny line. I don't know if the pressure line is the same as on the TH350, but if the rad cooler has "IN" on it, that'll be the pressure line. Only thing is I don't know which hard lines is my pressure line since they are not connected to the rad cooler anymore. They also said to use a brass fitting from the kit. I remember getting some of those and that could be my answer for what to connect to the rad cooler. I'll have to dig out my parts bag if I can find it as I know it came with some stuff. I just don't remember keeping the instructions.

[76_Scottsdale]

On a TH350 the top fitting is the "Out" fitting. I'm not sure but the stock rad cooler may have a specific flow pattern like the B&M cooler, so you may need to make sure which fitting is the "IN" one.

[VileZambonie]

Keeping the fluid cool is important but maintaining consistent temps is also important and is one of the main functions of the radiator cooler. I would run them both, here's a diagram...

http://www.bmtrans.ca/FAQ's.htm

[SUX2BU99]

Awesome info, guys. Thanks alot. That diagram too is great. I saw the link on the B&M FAQ page but didn't go to it, not thinking there would be a diagram.

[Captkaos]

Ditto on what Vile said, I would always run both.

[SUX2BU99]

For sure. I feel like a goof for only running one, and that's the way the previous one was installed. Not sure why. If there was a leak, there would be coolant running out of the ports, but there isn't. Maybe the previous owner figured when you put in an outboard cooler, you can bypass the stocker. Or, the tranny fluid was causing the rad to heat up too much. Dunno.  What I do know is that I cannot find my installation kit from the B&M and I always keep everything  This might have been the first time I ever threw away spare parts and now I need them. DOH!

Anybody know what thread those fittings are? I went tothe local parts store and they didn't have female and male inverted seat (that's what they said tranny lines were: inverted seat) to hose barb fittings. Crap. Might have to phone a specialty supply house.

[SUX2BU99]

So I found these at Jegs. None of the kits I looked at (B&M or PermaCool) mentioned anything about inverted flares or seats so there is this regular 3/8" NPT x 3/8" hose barb that could fit in the rad:


But then there is this inverted flare fitting too. It's 5/16" though and for some reason I thought maybe the stock fittings were 3/8". Could be wrong though:


That one mentions fitting for rads, and the other ones talk about fuel line fittings and such. The female version I probably don't need as the hose clamps down on the hard line just fine after sliding the female nut back. I appreciate everyone's help with this.

[HAULIN IT]

Sux, The coolers can split open INSIDE the radiator tank. No coolant will leak out. Sometimes tranns. fluid will go into the coolant system & ruins the rad & heater hoses, but sometimes the coolant gets into the transmission & hurt it, or sometimes BOTH will happen. I would check it (pressure test) before you hook it up, it may be defective. You never answered my original question about how you are going to use this vehicle. I knew you would get both opinions on this & I realize in the cold climate it is plumbed this way to "maintain" the temperature. If it is a summer cruiser,ect. my original responce still stands. I have in the past used a NEW A/C condenser for a tranny cooler, you just have to be sure it does not have an orifice tube inserted the the end (or remove it). On the ones with steel lines you can solder/braze a fitting to adapt to hook up the hoses or some type of flare/adapter on aluminum ones. This gives you plenty of cooling area,original mounting provision & extra fluid capacity. Lorne 

[SUX2BU99]

Hi Lorne. My truck is off the road most of the year. I take it out on nice days and such. I don't get how the trans cooler can split open inside the rad end tank and not leak coolant out. From what I understand, the tranny fluid enters the cooler which is installed inside the passenger rad end tank, flows up it, and then out. If there was a split in the cooler, it would let rad coolant leak into it, which would then leak out the trans line ports, no? There is nothing connected to my trans cooler ports, so if no coolant is leaking out, can it still be split?

Did some more net searching and it appears inverted flares were used on Ford vehicles only. Still have to find out if the fitting is 5/16" or 3/8" though.

[HAULIN IT]

Sux, Ok, Now I understand what your saying, I didn't realize (read correctly) that  you were using this vehicle with fluid in it allready. I thought you were saying that "the leak" I was referring to would be coming out around the fittings at the tank also. My mistake on that. I understand from talking to mechanic's & my tranny friend some of these only show up once the vehicle is warm. I also don't really understand how a cooling system on one vehicle only lets tranny fluid in,but the next one lets coolant in the tranny. Anyone?  Years ago my brother's company car split open & tranny fluid ruined all of the hoses on the cooling system, they got the tranny fluid & filter changed & he drove it for years. When mine went, no sign in the rad, but the tranny fluid was Strawberry milkshake, hmmm. Sorry for the misunderstanding, Lorne

[SUX2BU99]

No worries. If the tranny lines were connected to the rad, yeah it would be difficult to tell what was leaking. Trans cooler to rad, or vice versa. Whichever one has the higher pressure will flow to the lower pressure one and I imagine tranny lines operate at different pressures than a coolant radiator. Which is higher, I really don't know. But, since I have no coolant leaking out of the empty stock tranny cooler, I'm not worried about it leaking.

Called another parts store with a guy there I am getting to know and he too mentioned the inverted flare. So I'll just go down there and see what they have, as that's what he suggested. Will probably have to take home a few fittings to see what works.