3.9 Throttle Body Hose Swap to Hardlines

Pyts

New LVC Member
Joined
Mar 15, 2026
Messages
9
Reaction score
3
Location
ATL, GA
Hang on - just inhaled some of my lunch.

Okay, cool. First, I'll lure you in with pics

PXL_20260328_181637322.jpg


PXL_20260328_181649167.jpg


PXL_20260328_191605650.jpg


PXL_20260328_200508297.jpg


PXL_20260328_201359016.jpg


PXL_20260328_201401496.jpg


PXL_20260328_201654556.jpg


So, I'm doing the cooling system overhaul (because I have to). Metal thermostat body, metal degas bottle, metal upper radiator hose fitting, intake manifold removed, and it occurred to me: what about these throttle body coolant hoses?

I'll get right to the point. The formed hoses are discontinued, the boiling method for forming hoses isn't good for 180° bends (and I just plain don't like it. Coolant runs near boiling temp in normal operation, so how's that supposed to hold up, huh?)

I still have good hoses, but I don't wanna rely on 'em. Removing the intake manifold was annoying. So after reading and head-scratching for a few days, I'm doing hand-formed aluminum hardline with double-flared ends.

No wait. I did hand-formed aluminum hardlines with double-flared ends.
It'll hook up via some little snips of fresh 3/8 heater hose, serving as Fernco-style couplings (if you're familiar with residential plumbing drains).

I don't foresee any issues, since the cooling system really isn't that high pressure. 16 psi according to the degas bottle cap. This aluminum tubing is sold for fuel lines, which per my googling, operate at 30-60 psi

I went with aluminum because copper and aluminum don't like each other, and cylinder heads are aluminum. Stainless would have likely required annealing. Since I've only just read about annealing stainless tubing for the first time, aluminum that I can hand-bend cold is pretty sweet.

Here's pics. Parts/tools used are:

3/8 aluminum fuel line tubing from "A-Team Performance" on amazon. 25ft. coiled for $19.

There's tons of other brands, but I didn't want thin-wall stuff. This is 0.035" thick, and folks say it'll do.

Up next, a tubing straightener.

YHDD branded knock-off of Altitude Craft "Tubing Straightener for 3/16"-1.0" Diameters". I wanted something I could use more than once. - also amazon. $65

The big purchase:

OTC 6502 - Master Brake Flaring Tool Kit
There are other options. Bubble flare or double flare don't matter. Bubble seems harder to find, and it's what I originally thought I needed. But even my master kit didn't cover it for 3/8. The flared ends you see on my pipes are "double-flared". Amazon $130

The unsung, tumultuous hero:

THOBEYA 3-in-1 Copper Tube Bender, 1/4″, 5/16″ and 3/8″ Copper Pipe Bender, Bend Copper Pipe to Any Angle Manual Kink-Free Bending Tool for Plumbing, HVAC & DIY. Amazon "pocket size" kit: $22.

I went with these because the proper tubing benders required inches of straight tubing between every bend (besides the plier type tools, which have no protection against collapse in tighter bends). That's like using a chop saw when what we need is a miter saw.

You spit on and shove the spring *inside*, and do A SINGLE bend. Then you back (fight) the spring out, and stick it back in for the NEXT bend. If you try doing multiple bends with the spring running the full internal length of the tubing, it'll get stuck.


Okie dokie, that's all I got. Now I gotta go get some 3/8 heater hose.
By the way. Don't use fuel hose. It works for a few years, and then it leaks without ever cracking. There's a reason companies like Gates and Continental go to the trouble of making coolant hose.

There. That's *really* all I got
 
Last edited:
Oh. If you're wondering: Why 25' of coiled tubing, thus necessitating a tubing straightener? My answer is shipping speed, material availability, reuse value of an adjustable tubing straightener, and humility.

I messed up several times, and had to get a feel for the material. When I got the spring stuck inside, I had to unbend pipe, and I'm not reusing pipe that's already been manipulated, as that would compromise strength to some unknown degree (I'm not an engineer).

I had to learn how to use the tubing flarer (low-risk/pretty easy, but I still tried the 10mm bubble flare on the 3/8 tube and it didn't work.
If the tube is slightly crooked, you don't get a straight cut, and it may affect your flare.

Hell, you don't even have to flare the tubing if you want to be cheap! Just use 5/16 heater hose instead of 3/8. But you'll have to fight it onto the throttle body..

With how much Aspergers level fixation I put into this, I wanted redundancy.

You wanna be cheap A.F., just get the tubing, spring benders, and a pipe cutter, and let me know how it goes!

I'll be doing a test fit once I got 3/8 hose and appropriate hose clamps
 

Members online

No members online now.
Back
Top