Sealing up coolant tubes?

[chazz79]

I'm in the middle of a conversion on a 73 bus to watercooled. I've made up some nice tubes with mandrel bends and the whole works but I'd like to do some sort of liner inside the pipe before running coolant through them. Is there any product that will withstand 250+ degrees and bond to steel to prevent corrosion? I was thinking some sort of epoxy but I'm also looking for something that won't delaminate and end up in my coolant system. The tubing I used is 2"od 1/4 wall so it's pretty stout stuff that'd take some time to rot through but some of it is a structural member that supports the engine and I'd rather not be replacing that soon. I have some pics from my rough out stage that I can upload if it gives a better idea of what I'm doing here.
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[Wellington]

1/4 inch wall!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I think you will go through 20 heater cores and a dozen radiators before your pipes.

[wcdennis]

No need to seal the inside if you run good coolant. The outside is where the rust will form.

[Wildthings]

You are supporting your engine off your coolant pipes? Pics please.

[foodeater]

Yeah, I need to see pics also.

But I agree that rust on the outside will be more troublesome than rust inside. What material are your pipes? CroMoly? Mild steel?...etc?
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[Famous 01]

Maybe he means .025" wall. A .25" wall mandrel bender, now that would be a manly bender!
-Kent

[chazz79]

I'm more worried about the areas where the bends are welded to the straight sections. There's only @3/16 penetration there so it left a pretty clear line inside for corrosion to start. The thing looks pretty but I'm afraid the inside is something I can't fix at this point. I'm putting a ford 2.3l in my bus and this crossmember routes coolant from the rearmost drivers side towards the front two frame rails (right and left). I'm aiming to keep the rubber hose sections to a minimum in length even though I'm still stuck using 6 hose sections to couple my system.

this is 1/4 wall boiler pipe. They make 90 degree mandrel bends that I've welded to straight sections, the same way custom fabricated exhaust are made.
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[tencentlife]

1/4 wall, as in .250"? That's some heavy stuff, like more than Sched.80 for 2" (whereas .025" is like 24ga., way too thin and would dent and collapse just by looking at it).

Anyway, as stated already, the worries about corrosion are from the outside, the inside will be well-protected by the antifreeze's protective agents and the general paucity of free O2 in there. Look up corrosion effects, galvanic and otherwise, and you'll see that there's little need to worry about the pipes' interior. To remove potentially acidic residue from your welding process you would do well to run a small wirewheel inside at the joints, if they can be reached, but I wouldn't worry about it much. Treat the outside well, though, as that is where the rust will do its thing.
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[chazz79]

here's some pics to give you an idea of what I'm doing.

This is the beginnings of my "water cradle"
The design is simple enough- just route the water forward in a fashion to clear all moving parts, hot parts and use as little rubber hose as possible. The chalk lines are where the 2x3 rectangular tubing comes up to catch the motor mounts and reach over towards the frame rails. Inside the square is where the oil pan drops through.

every place you see a bend is a 90 degree elbow welded to straight pipes. These welded areas are where I'm concerned with sealing to insure no leaks happen. My best guess so far is to fill it with POR 15 and roll the thing around to insure good coating. I'm a decent welder but it's a pain to find a leak after water's been run through it.

The area where the pan drops through will have a small skid plate made to fit as protection for the pan.
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One day as a lion, or a lifetime as lamb

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[newt909]

You might be able to annodize the steel pipes. It would require talking to someone very knowledgeable in the field. That is some stout pipewerk...
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