Can I fix crack in Cylinder head Cover

[BriTXbike]

82' 850G
So I was re-torquieng the bolts to the Cylinder head cover, which are now allen head bolts. Anyways I was tightening the bolt closest to the end cap on the spark plug side when POP! After close inspection there is a decent crack along the bolt shaft. Didn't think it was a big deal but when I took her for a run, umm yeah it's bigger then I thought as it's all the way through the cover. I'm currently looking for a replacement but is there any type of compound I might be able to use to seal it up, at least temporarily? Also would any other size engine crank case cover fit my 850?

[Hotblack]

I'm wondering if it got bigger as you ran it. JB Weld claims you can even repair cylinder blocks with it, hmmmmmm I don't know.... However the valve cover would be worth experimenting on. I wonder if sylicone gasket sealer might plug it temporarily. The JB Weld, if it worked, would add strength to it though.

[Evil Hobbit]

I fixed a crack in a block on a 70's honda 350 and it held for years and I've fixed cracks in others that didn't last a day. So do it and pray. BTW drill a hole at the end of the crack to stop the crack from going any further.

[DMPLATT]

I fixed a crack in a block on a 70's honda 350 and it held for years and I've fixed cracks in others that didn't last a day. So do it and pray. BTW drill a hole at the end of the crack to stop the crack from going any further.

Excellent advice.

I'd go with JB Weld. Just degrease it well before applying.
I had an '85 Nighthawk that I cracked the Oil Filter cover on. I JB Welded it and re-machined it and it never leaked again. The stuff is amazing. Just like aluminum when it hardens. I doubt you will have any trouble at all.

[BriTXbike]

Ok so my other question then is JB it from the outside or from the inside? Also anybody know if I can use a cover from another engine?

[Clone]

Could it be prohibitively expensive to take it to a shop and have the aluminum welded? That would be the definitive fix! If you use a stop gap fix, then it may eliminate the possibility in the future of fixing it right.

[gremlin]

have it welded it will fix it for good. you can even make the weld smoth and paint it or polish it.

if you want to use the jb weld. clean it realy good. take a few days of cleaning it and recleaning it. the oil will soak into the metal and it will fail. when thay say it must be free of oil you must do every thing to get all the oil off.
use the right jb weld too. http://jbweld.net/products/industro.php INDUSTRO WELD Part No. 8280
thats the ticket if you want your cover to stay in place.

[ddaum]

Uh Oh!

I was tightening the bolt closest to the end cap on the spark plug side when POP!

What caused the break? Did you over torque? Uneven gasket? I'm getting ready to inspect valves and replace the valve cover gasket on my 550. I will also be replacing the original bolts on the valve cover and breather cover. Is there anything particular that I need to look out for so that this doesn't happen to me?

[Boondocks]

Ok so my other question then is JB it from the outside or from the inside? Also anybody know if I can use a cover from another engine?

Since you will be replacing the cover anyway, I would apply the JB Weld on both sides. Clean the crack area well with a heavy duty solvent like MEK, acetone, lacquer thinner, etc. and rough up the surface with sandpaper to prepare the piece for best adhesion. You shouldn't have to clean it over a period of days if it is done thoroughly in the first place. Run the solvent through the crack long enough to remove any oily residue and it should be ready to patch after sanding.

I patched an alternator side cover with JB Weld this way. The crack is on the underside and is submerged in oil. It hasn't leaked since.

[BriTXbike]

ddaum as far as the reason, I really don't know other then maybe to much torque. I'm not sure how many people are using them here but I purchased a Silicone gasket so servicing the valves and what not would be easier. Between the gasket and allen bolts you really don't need that much torque. I just happen to put some locke tight on each bolt this time to prevent them from coming loose again. No problems with the gasket and I recommend them to everyone.

[jimcor]

Have it welded. Shouldn't cost more than about $20 or so. Yes, you can use JB Weld, but if you can find a good welder he can save you a bundle of bucks and hassles as your biking days roll on!

I found a guy to reweld the chain guard mounting tab to my swingarm; $15. Guy was proud of his work and it was text book welding. Poker chips all in a row. Praised him for the job, cause he deserved it. Made both of our days.

[Clone]

I didn't think it would be more than about $20. Often you will spend more time and effore not to mention money to do a quick fix, that doesn't work out to be that quick instead of taking the part to get it fixed right.
Experience has taught me this lesson.

[bwringer]

Brian, I just sent you a PM -- the original valve cover from my '83 GS850 is sitting in a box in my garage, just waiting to fly to Texas and get installed on your bike.

My bike's still an '83, but the engine is mostly 1980 due to an unfortunate series of mechanical events in the original engine.

[BriTXbike]

GOD BLESS THE INTERNET! BWringer saves my Ass once again. I love this site! I PM'd you bw. Paypal works for me

[ddaum]

NOOoooooooo!

What caused the break? Did you over torque? Uneven gasket? I'm getting ready to inspect valves and replace the valve cover gasket on my 550. I will also be replacing the original bolts on the valve cover and breather cover. Is there anything particular that I need to look out for so that this doesn't happen to me?

Guess what? IT ENDED UP HAPPENING TO ME TOO!
Even after I posted here and was trying to prevent it!
Read HERE