Rusted block bolt. WTF happened?

[Buff CB]

So here is the biggest obstacle I've faced so far. I've pulled the cylinder walls and find this orange rod. I have to say I'm quite baffled how this happened. Here is what I don't understand.
-It's an air cooled engine so no coolant running in the block
-The gaskets on either side of the bolt are in good shape with no breaks near the bolt.
-The bolt exists in it's own chamber running in the block. So once any oxidation that occurs would use up all the oxygen in the hole and the process would stop. But this rod is severely rusted with orange dust everywhere.

WTF




Does anyone have any ideas how this could happen? And the next question is what do I do to fix it?

Do I try to remove the bolt with out shearing it and where do I find a replacement?

Do I leave it in and clean it up and so some rust prevention?


I am truly baffled.

 

[bobjohnson]

Did you buy this bike new? One possibility is someone had it apart at some point, and decided that rod was fine to use. Ive seen worse done to these old bikes.


More likely, the cap bolt was slightly loose or had something jammed under it, allowing water down the shaft. Either that, or the mating surface or the cap bolt has a defect in it that you cant see. Something that made the cap bolt not sit completely flush.


Id remove and replace that. Shouldnt be too hard to find another one on ebay or maybe even through honda. Squirt a ton of PB Blaster down there, let it sit for a day, and then try and get it out.

 

[bikeboy]

Not too sure what happened, but if you look at the corresponding bolts in the other 3 positions, they all have some sort of debris around them? The rear right seems covered in grease-crud, and the front 2 are also not as clean as the rest. Maybe just a design issue with the bolt galleries? IIRC some model DOHC (CB1000C?) had a drain-hole missing from the base of some studs, and those bolts would corrode. The fix was to drill some holes to let any captured water drain out.

not all that familiar with you model however.

cheers
ian

 

[Buff CB]

Update:

So I've managed to pull off the pistons and started taking off the cylinder bolts only to find that four of them just won't come off. I've been using the double nut technique and it worked great for the others but I just cant seem to break the other four loose.

I've been soaking them in WD-40 to help ease them out and I've also tried heating the bolts with a blowtorch and letting it cool to see if the expanding and contracting would shake any rust off but no luck.

Does anyone else have any ideas as that might get these four free. I'm hoping for a better chemical agent that might work better than WD-40 because rusted ones feel like they are going to snap from the torque I've been putting on them.

Thanks a bunch

 

[bikeboy]

Does anyone else have any ideas as that might get these four free. I'm hoping for a better chemical agent that might work better than WD-40 because rusted ones feel like they are going to snap from the torque I've been putting on them.

If you can get it to a shop, I'd highly recommend that. The bolt is unlikely to snap before it cracks the casting around it. Something like this:

Yep. That's my block that just got ruined.


If you can turn the stud, you may find it takes some of the thread with it, which just keeps building up as it drags more around, than snap!


Not saying it *will* happen. Just that it could. Proceed with caution my friend. It could be a very expensive exercise.


If you can get a pro to tackle, I would do that.


cheers
ian

 

[Big R]

Yuck. That hurts to even look at.

I recommend something other than wd-40. There was a thread a little while ago dealing with penetrating oils and wd-40 wasn't too high on the list.

 

[Hoosier Daddy]

Big Rich is right, WD-40 is not a good penetrating fluid, it's a Water Dispersant (thats the "W.D."). That study showed one that worked the best was a 50/50 mix of ATF and acetone. Croil (sp?) and PB Blaster were high on the list as well. I'd soak it at least 24 hours,When you give it a try get as low on the stud as you can and apply some heat to the block with a propane torch if possible. The Aluminum will expand faster that the steel stud and open up just a little.

 

[Buff CB]

Well i did the best I could but the last two were just too rusted to handle any torque so now I have two nubs I need to get machined. Oh well, I was headed to the machine shop anyway so I'll just add this to the list.

 

[Midcoastcustoms]

Bummer about the broken off studs. Get a can of aerokroil the stuff is like magic in a can. Im from MN everything is rusted but with kroil and the torch or mapp gas you can usually get things apart.

 

[rockcitycafe]

was probably a leaky head gasket/surface, allowing combustion gas to get through to the stud, that gas is both loaded with moisture and acidic

 

[Buff CB]

was probably a leaky head gasket/surface, allowing combustion gas to get through to the stud, that gas is both loaded with moisture and acidic

You know thats probably what it was. When I took apart the block the gasket seemed deformed on the inside around that bolt hole. I'll take note of that when I reassemble it. Thanks!