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View Full Version : Need some advice - steel/aluminum adhesive



DICKEYBIRD
05-17-2007, 05:40 PM
I have an emergency repair to perform on an aluminum auto engine block. A 5/8" O.D. steel pipe heater hose nipple blew out due to shipping damage. The original is a 2" long piece of thin wall steel tubing that was pressed in about 5/8" deep.

The hole in the block is still round and in good shape, the nipple is bent/distorted/unusable. I'm going to make a new nipple at home tonight from a generic, screw-in steel replacement from the auto parts store. The engine is installed in the car and there's not enough clearance to either tap it out to the closest pipe thread or press/drive in the replacement nipple. The nipple I bought has a hex flange and pipe thread but I can turn all of that off leaving a smooth O.D. to work with.

I'm thinking the green Loctite "retaining compound" (I forget the number) will hold it fine as long as the surfaces are clean, dry and the clearance is right.

A) D'ya think a steel nipple is favorite or should I make the new one from aluminum to take advantage of any expansion characteristics.

B) Any idea what the optimum clearance would be for the Loctite?

C) If not Loctite, anything better? JB Weld is good stuff but not sure about it's living around the heat of a modern engine's cooling system.

Yup, all of those "If you don't have time to do it right you don't have time to do it all over again" thoughts are rattling around in my head but I'm thinking there can be an easier way than pulling the engine back out and pressing/threading in a replacement.

Weston Bye
05-17-2007, 07:03 PM
I patched an oil pan with J-B Weld once. Just cleaned up and applied on the bottom. Held for probably 50K miles - more really, It was still holding when I sold the truck.
Another car had a stripped spark plug hole. J-B Weld on that too. 'Course, I got a real good spark plug to put in there, and never took it out.

Both these places will run hotter than a heater hose outlet on the engine, unless maybe your coolant turns to steam.

LarryinLV
05-17-2007, 07:18 PM
Loctite 272 (red) is the high temp (450 deg), high strength stuff for studs and press fit like yours.

Loctite 609 (green) is formulated for improved press fit applications but heat is the release for it

Should not be a serious corrosion problem since the original was tin and this is low pressure. I might turn the nipple a couple of thou oversize, freeze it, brush on a little 272 and push it home.

Is there enough room and bracing in front to use a jackscrew arrangement to press it in. Might want to turn a shouldered slug to fit a bit into the ID and push against that to keep it from collapsing or bending

Ken_Shea
05-17-2007, 10:28 PM
If the repair ends up with a slight leak add a can of stop leak.

Ken

DICKEYBIRD
05-17-2007, 10:33 PM
Thanks fellers. I don't have room for any gadgetry to press the thing in and Larry I love your idea about the oversize/freezing routine but got the willies thinking about it getting hung up about half way in as the alum. block sucked the cold out of the fitting. Memories of stuck-half-on flywheel starter ring gears got me puckered up pretty quick.

I finally ended up turning out a steel duplicate fitting about .002" undersize and adding 3 annular rings about .002" deep to retain some of the locking compound. The green Loctite I have is #648 and after looking it up on the web I think it'll do fine. It says it's good for up to .006" diametrical clearance and up to 300 Deg. F. I gotta pick up some of their fancy primer spray to ward off any remaining evil juju. Wish me luck tommorow!:)

http://i57.photobucket.com/albums/g227/DBAviation/FreelanderHoseFitting.jpg

lugnut
05-17-2007, 10:53 PM
Wes1:mad: , in my opinion, any one that would JB weld in a spark plug, Should have his tools taken away and never allowed to work on a car again!! I can just imagine what you would say if you bought a car and found that one of the spark plugs was JB Welded into itís hole. Looooooooow rent mechanics!!!
Mel

torker
05-18-2007, 03:17 AM
Don't worry about the JB weld and engine heat. We have several oval track cars here that have cracked engine blocks. The guys just patch up the crack with JB and they seem to last forever.
Ummm...I'd JB a spark plug in a hole in a pinch. Hit it with a torch and it'd turn right out. I know it isn't right but sometimes...

Weston Bye
05-18-2007, 08:12 AM
Wes1:mad: , in my opinion, any one that would JB weld in a spark plug, Should have his tools taken away and never allowed to work on a car again!! I can just imagine what you would say if you bought a car and found that one of the spark plugs was JB Welded into itís hole. Looooooooow rent mechanics!!!
Mel

Fear not, the car lived it's full and natural life in my posession.

S_J_H
05-18-2007, 10:00 AM
For what you are doing the loctite will work great. Adding the grooves to the nipple was a very good idea. Ordinary high strength red thread locking compound would have worked great as well.
JB weld is just cheap epoxy and there is nothing special about it. It has it uses but for what you are doing it would be a very poor choice.

Steve

DICKEYBIRD
05-18-2007, 10:24 AM
Thanks Steve, I appreciate your support. I test fitted it this morning and it slid in neatly with just a little bit of wiggle. The hole and the part have been degreased with the official Loctite spray degreaser, primed with Locquic primer and installed with the 638 Retaining Compound. Got my fingers crossed while it's curing!:)