Homemade Heater Bypass Tube

My heater bypass tube was too corroded for me to use. I could order one, right? Sure, but then I wouldn’t need to make one. This is for an FE and could work for other engines or other applications. I dug up a brass bushing that was 1/2"NPT to 3/8"NPT. It really doesn't need to be a bushing if you’re willing to cut it. I also have a 1/2 NPT to barb I could easily have used. I cut a 4" length of 1/2" hard copper tubing, cleaned it up and deburred it. I used hard tubing because that is what I had. I wanted to use soft copper to have the bend like the original part. Don't bother trying to bent the hard copper, it'll just break. If I need a bend to clear anything like an air cleaner or just to have it route differently, I can remove it and put an elbow on it after I test fit it.


You can drill out the center of the bushing with a 3/8" drill or bore it out on a lathe. My 3/8" was MIA and I like using my micro lathe. I bored it out until the tubing just fit inside.






The next point is pretty important if you want the hose to stay on, the flare. I clamped a body hammer with a conical pick end in a vise and put the tubing over the end. Using another hammer, hammer the tube onto the body hammer. This will flare the end of the tube. There's no need to be brutal, just good solid hits. Test it on a scrap piece if you're uncomfortable.




I prepped the tube with tinning flux and assembled the tube and nut. Clamp the nut into the vise and position the tube so that at least 1-1/8" is below the nut. I don't know how critical this is. 1-1/8" puts the end just at the top of the thermostat were the original one would be.


I used a Map Gas torch and lead-free silver solder with a melting point of about 440F. It soldered just like copper pipe.


I used Scotch-Bright to clean up the heat discoloration and prep for paint.


I taped off and painted the parts that would be exposed and installed it in the manifold when it was dry.



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Nice job. I make alot of parts using the "sweat method" or soldering of parts together, like dipstick tubes, overflow canisters and fittings just like you did.

Originally Posted by F15Falcon

Nice job. I make alot of parts using the "sweat method" or soldering of parts together, like dipstick tubes, overflow canisters and fittings just like you did.

Thanks, I knew that anything to do with the coolant would stay cool enough to use solder.

I couldn't figure out how this engine's dipstick tube was secured the last time because it had been "modified" or "fixed" or something. I didn't know if the solder would hold up that close to the exhaust, so I just made a new tab and welded it on.

I loved the opening line.... "I could order one, right? Sure, but then I wouldn’t need to make one."

That could be a forums signature and even a creed to live by. Nice work.

Originally Posted by Mikelonis

I loved the opening line.... "I could order one, right? Sure, but then I wouldn’t need to make one."

That could be a forums signature and even a creed to live by. Nice work.

Sig updated.

LOL... Perfect!

There's no doubt this country would be in much better shape if more Americans lived by that sentiment...

Cool you made it a sig.

nicely done. It is very important that the end of the tube is rounded, like you have. Othervise it will eat the hose quite fast with vibration.

Originally Posted by Mosse

nicely done. It is very important that the end of the tube is rounded, like you have. Other vise it will eat the hose quite fast with vibration.

Good point. I didn't emphasize that, just mentioned deburring. Deburring rounded it over so that there is no sharp edge. A smooth file or sandpaper would work good.

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