Thread: Steel Aluminum Glue

Hello all

I am working on a project involving aluminum cylinders on a motorcycle engine that originally had cast iron. The inlet manifold of the original design screwed on to a steel nipple that was screwed into the cylinder barrel (side valve engine). I would like to glue or bond an unthreaded steel nipple into the barrel.

Therefore I require a glue that will hold steel to aluminum, be airtight and withstand a few hundred degrees.

I know there are some good aerospace products out there so please hit me with your suggestions, even if you think it is hard to get.

Thanks Steve

Hi Steve,

Will the difference in expansion between the two different metals have any effect ?

Click Bond. We use their CB200 acrylic adhesive at work for aerospace stuff. I've used it to glue aluminium cover to cast iron and it may as well be welded on. CB200 is only good to 250F/120C, but they make a high temp epoxy called CB394 that's good to 350F/175C. Their range is here https://www.clickbond.com/downloadfi...3692378858.pdf

Originally Posted by BaronJ

Hi Steve,

Will the difference in expansion between the two different metals have any effect ?

Good question, it may and that was some of the logic of bonding it in. This is my thought process, since this is the inlet tract it will have cool air coming in and the barrel will be heated by the running of the engine. The aluminum will expand and in theory try and pull away from the steel sleeve.

Using the logic that a valve seat expands at a different rate and generally does not cause cracking this may work.

It was also why we did not want to screw the nipple in as it would loosen when the engine was hot.

Steve

Originally Posted by elanjacobs

Click Bond. We use their CB200 acrylic adhesive at work for aerospace stuff. I've used it to glue aluminium cover to cast iron and it may as well be welded on. CB200 is only good to 250F/120C, but they make a high temp epoxy called CB394 that's good to 350F/175C. Their range is here https://www.clickbond.com/downloadfi...3692378858.pdf

Thanks for the link, it looks like it may be suitable. Can it be separated chemically, or does it need to be heated above its bonding temperature.

I know there are some seriously good products out there, but being an inlet manifold I'm guessing its going to be a real PITA if it fails.
You'd need to make sure the joint design was suitable for an adhesive bond as well as just having something strong that can handle the temperature.

If the original design was screwed in is there a particular reason you want to avoid that approach?

I've always been happy with JBWeld expoxies, but haven't actually used the high temp ones:
https://www.jbweld.com/product/highheat-epoxy-putty
https://www.jbweld.com/product/j-b-extremeheat

Steve

No idea, we've never tried to take it apart

Originally Posted by OxxAndBert

If the original design was screwed in is there a particular reason you want to avoid that approach?

Steve

The main reason for not wanting it screwed is the aluminum may expand enough to loosen the thread. I would not be keen on using an aluminum nipple as alloy into alloy can gall.

Steve

What about brass? Similar expansion to ally (still less, but much closer than steel) and naturally corrosion resistant

There's a few loctite products that are good for >200ºC - there was one that was even good for 230ºC that I used on my Dispersed Oil Particulate generator that might be worth a look.

Originally Posted by elanjacobs

What about brass? Similar expansion to ally (still less, but much closer than steel) and naturally corrosion resistant

This is certainly something to consider. Thanks

Originally Posted by Reidy41

The main reason for not wanting it screwed is the aluminum may expand enough to loosen the thread. I would not be keen on using an aluminum nipple as alloy into alloy can gall.

Steve

I’d have thought that a decent anti seize compound would prevent any galling but I understand the concern.
Using an o-ring to do the sealing part (if possible) would also likely help with any tendency to loosen.

Edit: scratch the o-ring suggestion - they won’t handle the temp.

Steve

Hi Steve, Guys,

An "O" ring might not work but a copper compression one would !

Originally Posted by Reidy41

The inlet manifold of the original design screwed on to a steel nipple that was screwed into the cylinder barrel (side valve engine). I would like to glue or bond an unthreaded steel nipple into the barrel.

Every motorcycle, go kart and garden tool I've ever owned had steel studs screwed into an aluminium cylinder head for securing the carby and muffler. It's a well proven method. I realise your engine has a slightly different arrangement, but we are still talking about steel screwed into aluminium. It seems like you're trying to solve a problem that doesn't exist.

Originally Posted by jack620

Every motorcycle, go kart and garden tool I've ever owned had steel studs screwed into an aluminium cylinder head for securing the carby and muffler. It's a well proven method. I realise your engine has a slightly different arrangement, but we are still talking about steel screwed into aluminium. It seems like you're trying to solve a problem that doesn't exist.

I understand what you are saying but there are a couple of differences here. The nipple is about 40mm diameter which is a lot different to a 8mm bolt when it comes to expansion. The thread also forms part of the sealing in this design.

Thanks for all of the input from everyone. The brass setup has the most merit. It is amazing how helpful all of the comments have been as the design will probably change a little from what I asked, but I would not have got to where I am without all of the comments

Steve