Aluminum Water Lines FAQ
 

Just finished this on my car and I kept close track of what I did and spent to make it happen.

Question: What are they?
Answer:
Attachment 207540

Instead of using rubber for your coolant lines, you use 3/8" aluminum line and -6AN fittings. This is the same stuff FM sells for nearly $200; make it yourself for half that.

Question: Why are they better:
Answer: They will last, literally, forever. Rubber wears out and becomes hard. Even SS line has a life expectancy; it's still rubber or teflon on the inside. Hard lines have no rubber, so they last a LOT longer. You don't have to replace them, since they essentially don't wear.

PARTS LIST:
You need to have a fabrication shop or a friend with a TIG welder put a -6AN bung in place of the steel fitting pressed into the stock water neck. You can have another -6AN bung welded to the front water neck, or you can use the M12 port on the side of your block (pre-96 guys).

I ordered a few items from AN Plumbing that could be gotten cheaper on Summit, but Summit was out of stock. AN was also cheaper than Summit on some items. Cross-check yourself before ordering to get the best price.

(1) or (2) -6AN male weld bungs (Summit Racing PRM-15669, $4.25 each)
(1) M12x1.25 to -6AN male adapter (AN Plumbing 991945, $6.79 each)
(2) -6AN tube nuts - pair (Summit Racing SUM-220633-2B, $1.25 each)
(2) -6AN tube sleeves - pair (Summit Racing SUM-220634-2B, $1.25 each)
(2) M14x1.5 to -6AN male adapter (Summit Racing RUS-670520, $4.95 each)
(4) -6AN male to -6AN female 90 ell (AN Plumbing 966306, $4.95 each) [Note: You might be able to get away with only a couple of these, one at the motor and one at the inner turbo. I bought 4 just to make the bends a little cleaner]
(1) 25ft spool of 3/8" hardline (Summit Racing SUM-G2538, $16.95) [you can get a 10ft spool for like $10, I decided to buy extra and maybe produce a kit?]
(1) Summit Racing 37deg flare tool (Summit Racing SUM-900311, $26.95) [Note: You may not need this, but nobody I knew owned a 37 degree flaring tool. 45 degree WILL NOT WORK.]

Fittings cost is $64.33, total including tool and $20 in welding for me was $111.28 plus shipping plus tax on the AN Plumbing items.

mor photoz plez

I was just contemplating how to do this sort of thing but on a smaller scale - to replace the rubber heater line that is so close to the downpipe with all aluminum tubing. Very cool what you've done.
How would one connect the new aluminum tube like you've used to the aluminum tubes coming out of the firewall which normally one would slide the rubber hose over?

A pic of the other end of this line would be great.

You would have to braze a -10AN weld bung to the copper heater core and it would make it irremovable from the car. Easier to just use short rubber bits there and hardline the majority of it.

There is no rubber anywhere in your setup? You don't normally see hard lines that don't have some sort of flex section (like OE DSM oil drains). Not sure if this is a real concern or not.

FM lines attach using short rubber pieces.

http://www.flyinmiata.com/Store/images/22-80012a.jpg

right that's the problem there.. the part which the downpipe practically hits the heater line is the point where the rubber hose slips over the aluminum pipe that runs under the manifold.. so doing a hard line connected by rubber lines would leave rubber in that same place.

great writeup. Already did mine like this:)

Great idea
 

Nice job on those hardlines! Yeah, you wouldn't need any rubber sections if you are sure to have a couple of bends or a partial loop to allow for expansion and contraction. We do it all the time for instrumentation lines at the power plant.
I believe that the only reason that FM would have for short rubber sections is to attach the lines to an existing nipple.

The line is more than flexible enough to deal with a serious amount of contraction/expansion. FM uses rubber to attach to existing nipples; I had a -6AN bung welded up. :)

Very nice work! That is the right way to do it!