RookieRick

Looking for guidance on how to properly install a replacement heater core pipe (N3H1-10-C71, the one that comes out of the rear iron). Old one got bent when removing from old housing, so I'm now trying to fit a new pipe in a new housing. It is a really tight fit (which makes sense I suppose as there's nothing else to hold it in place) - not sure if I should just be gently tapping it in with a mallet while doing my best to hold it straight (with it being angled the way it is, tapping it wants to force it to not be straight of course), or if I'm supposed to add anything to it to lube it for install and/or to hold it in place once it's there, and/or if there's some SST that is supposed to be used to keep it straight (seems like something similar to an O2 sensor wrench could be helpful)? Feels like a dumb question but I'm a software engineer by day, amateur rotary rebuilder by night, and farthest thing from a qualified pipefitter 24-7 :D

TeamRX8

iTrader: (25)

I believe it’s just a semi-tight press fit. I know mine rotates by hand with some pressure as I’ve had to slightly reposition it a few times after reinstalling the motor. Is it serious enough that it requires replacement?

In the Mazda engine rebuild manual they don’t list anything about it. It’s not installed in one view and the next it’s installed. You might just try seeing if you can push or pull on it while rotating it back and forth to get it either in or out. The problem with using something to seal or lube it is that getting into the coolant system. Based on my experience, which doesn’t include removing or installing it unfortunately, I’m inclined to believe that it’s a dry semi-tight fit only. Best wishes.

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TeamRX8

iTrader: (25)

So I sent an email to my builder asking the question, but I can barely get an update on the status of my engine with him. So I’m not sure if he’ll answer or not. I was thinking though, if you get a pair of regular or channel lock pliers that gave a circular grip rather than straight, take a piece of cloth or rag and fold it to be two or three layers thick, wrap that around the pipe where the stop bulge is and adjust the pliers to grab the pipe firmly there, but not too tightly and on the side opposite of the elbow, then try to use a mallet tapping against the pliers while holding it straight, and see if you tap it in like that

no idea, it’s just how I might try to tackle it. If the engine is installed in the chassis then getting at it within that limited space might be a bit tough. If all else fails I’d try to push it in while rotating it back and forth. It’d probably be better to tackle it with the engine assembled rather than try to put it in the loose iron just for the sake of stability. I’m pretty sure you can get it out that way at least. So it seems like it might go in the same way.

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RookieRick

Thanks! To your question of seriousness - absolutely required heh. When I rebuilt the engine and tried to re-use the pipe it was loose enough that it blew out on the freeway and caused a massive overheat :P So now I'm re-rebuilding lol. Looking at the old pipe I am kicking myself for even having tried to re-use it, the end that is supposed to slip-fit is deformed enough that it's not surprising it didn't hold.
Good news though is that the engine is currently out of the car, reassembled on stand, so it should be easier for me to get at it to install. I like the channel lock idea - will prob give that a shot when I get back to working on it this weekend.

Ricky SE3P

iTrader: (10)

You could try to chill the pipe to get it to shrink using dry ice. Whatever you could do to get it as cold as possible before trying to fit the replacement into the iron, while heating the iron with a heat gun on high. Hopefully a method like that will make fitting the new pipe much easier.