Terminating Cooling Lines (Thru Hull and how to hook up)

[smokeysevin]

I am planning to update my js550/750 swap to a new dual cooling setup and have been trying to figure out the best way to run the lines and connect them to the hull so they are secure and easy to connect.

I have been considering running pex or stainless steel lines. I am leaning towards the pex setup because I want to minimize anything that can corrode.

Typically I have seen any hull line (steering, exhaust, cooling) just run through the bulkhead and bonded to the hull with something like cabosil thickened epoxy or 4200/5200 depending on the material. If I run pex, I would like to have the brass fitting just stick out enough to slip the hose on the barbed end and clamp it, with stainless I would flare the end.

With all that said, if you have run pex, how do you secure it? do you clamp the line to the fitting and just glue the fitting in place? I would love to run a bulkhead style fitting but I have not found any that are flanged.

I also considered running an AN style bulkhead but I am not set on that. I did run those fittings on the original build of my 15f when I was setting it up to log pump pressure, nozzle pressure, and tunnel pressure. If I went that route, I would use hard tubing adapters on the bulkhead fittings.

Sean

 

[mikidymac]

What engine mods are you planning. If it’s stock then you don’t need to do anything.

Back in the day we used to just remove the stock line and replace it with a true 3/8” stainless tube and seal with 5200 and it flows way more water than the stock ones instead of messing with dual cooling. This was with 550’s and 650’s with pipes, porting and heads.


Sent from my iPhone using Tapatalk

 

[Carrera911]

I haven’t worked with pex much, but I think the wall thickness would probably be a lot more than stainless tube. 3/8 ID hose is standard, so a 3/8 OD pex tube might only be a bit over 1/8 ID. I’m not sure how well 5200 will bond to slick plastic, even if it’s scuffed. The flexibility of it might cause it to pull away from the 5200 as well. It seems like it always takes a lot of force installing / removing the cooling lines in that cramped space. 316 stainless is supposed to hold up to salt pretty good. Mine came from onlinemetals.com


1 piece @ $15.28/piece

Stainless T-316/316L

Seamless Tube

0.375" x 0.035" x 0.305"

48” long


Sent from my iPhone using Tapatalk

 

[smokeysevin]

Big Pin 750, may do carbs and a head. When it comes time to rebuild I may try the 800 cylinder and pistons but hopefully that is a way off.

I was thinking I would bond the hull to the pex fitting which is brass and use a 3/8" ID tube.

(https://www.pexuniverse.com/pex-tubing-technical-specs) Pex Specs

The price on that stainless is less than I would have guessed.

The big thing for me is to get away from the crap flex lines that are in there, I just want to make sure and do it right in the process.

Sean

 

[mikidymac]

The Pex is also going to be hard to push through the hull.
You will have no issues with the stainless rusting. The stainless is really the way to go and I wouldn't mess with the PEX.

The stock 750's ran an aluminum hose that was crimped way down to flair for the hose so a true 3/8 will flow plenty of water for your setup.

 

[smokeysevin]

The Pex is also going to be hard to push through the hull.
You will have no issues with the stainless rusting. The stainless is really the way to go and I wouldn't mess with the PEX.

The stock 750's ran an aluminum hose that was crimped way down to flair for the hose so a true 3/8 will flow plenty of water for your setup.

As far as the install goes I am 50/50 on widening the tray and doing a rear exhaust so its less of an issue but I am good with simple.

Sean

Sent from my LM-G710 using Tapatalk

 

[G-Body]

McMaster carr 5779k679 I wouldn't use it with pex, but mc master also has the correct flexible plastic tubing to go with it.

 

[smokeysevin]

McMaster carr 5779k679 I wouldn't use it with pex, but mc master also has the correct flexible plastic tubing to go with it.

Those are interesting and I would have never considered them until you mentioned it. I have used similar fittings on airbags and the trim tabs on my old 15f build.

Sean