stripped thread timing chain cover - suggestions for a fix please

[AustinW]

One of the bolts that holds the timing cover on has stripped the thread in the timing case. The bolt barely nips up and there's a modest weep of oil on the casing. I am not unduly worried (I just did 15,000 miles around Canada and USA with it like that) but would like to get it sorted at some point. Its a mess rather than drippy leak. I have tried an ever so slightly longer bolt but that still won't tighten and have given the bolts above and below a couple of extra Nm on the torque wrench to see if that would pull the casing in (it might have done, have yet to ride the bike since i did that)

The obvious solution is to take the cover off and fit a helicoil or similar but I will probably screw that up and given the low level of the leak at the mo hardly seems worth it. Any other suggestions or magic potions that I could use that are cheap, easy and impossible to screw up.

(this started after I removed the Cymarc Crud Catcher that I fitted as there was a leak from the lower left (of the bike) bolt - oil was running down the bolt - which was weird as it hadn't leaked before and didn't leak if I replaced the crud catcher bolt with the original. Anyway I eventually took the crud catcher right off, sold it, and refitted all the original bolts - all fine on the original leak but I either cross threaded a bolt or had unwittingly overtightened something at some point and damaged the thread in the casing. The bolt that won't tighten is the upper right of the bolts that would hold a crud catcher in place).

 

[Deleted account 190920001]

You might get away with a slightly longer bolt if there is any extra thread in there. Other than that a helicoil or better still a timesert is the only way that I can think of to fix it.
Is it leaking from the bolt hole or casing joint? If it is the bolt hole then clean out the hole/thread with something like brake or carb cleaner and put the bolt back in with sealer. It will look OK and should stop the leak. If it's the joint then your going to have to fix the thread.

 

[Gargy]

Is there enough surrounding metal to re tap the hole a size up, then drill the casing to suit the new bolt ?

M6 thread needs a 5.0mm hole to tap.
M8 thread needs a 6.8mm hole to tap.
M10 thread needs a 8.5mm hole to tap.

Good luck.

 

[AustinW]

You might get away with a slightly longer bolt if there is any extra thread in there. Other than that a helicoil or better still a timesert is the only way that I can think of to fix it.
Is it leaking from the bolt hole or casing joint? If it is the bolt hole then clean out the hole/thread with something like brake or carb cleaner and put the bolt back in with sealer. It will look OK and should stop the leak. If it's the joint then your going to have to fix the thread.

I tried the longer bolt and thought it was going to work, but just as I thought it beginning to tighten it all went soft and gooey again. I have left it in like that as I thought it was probably as Tight as I would get it. I think it leaking from the bolt so may try your tip on just sealing it up (a very small O ring on the bolt may help too).

Is there enough surrounding metal to re tap the hole a size up, then drill the casing to suit the new bolt ?

M6 thread needs a 5.0mm hole to tap.
M8 thread needs a 6.8mm hole to tap.
M10 thread needs a 8.5mm hole to tap.

Good luck.

Thanks but no, there's not much meat there. If I was going down this route a helicoil would the thing to try first.

 

[Bendy toy]

Helicoil or Timesert to repair the thread. The thread insert is the better option.

A longer bolt might grip but as it's leaking you really need to remove the cover and clean the joint face. Then repair the thread and it's good to go.

You may as well get the cover painted while it's off. The finish won't survive for long if there is even the slightest paint flaw under a bolt head.

 

[AustinW]

Helicoil or Timesert to repair the thread. The thread insert is the better option.

A longer bolt might grip but as it's leaking you really need to remove the cover and clean the joint face. Then repair the thread and it's good to go.

You may as well get the cover painted while it's off. The finish won't survive for long if there is even the slightest paint flaw under a bolt head.

Agree with the thread repair as the "proper" solution, but I was hoping for something quick and easy and cheap. The casing however is already quite badly peeling particularly around the offending bolt. In fact there's loads of places on the bike where paint is flaking away from casings exposing what looks like pretty rotten alloy. Its poor really (2011 bike and 49,000miles and not much winter use). I took a 2001 Honda Transalp around the clock riding it all year and the casings stayed in better condition - there was a lot wrong with brakes, wiring and the plastics though.

you won't like this, but....

place the bolt horizontally on a solid piece of metal. thwack it with a big hammer so it leaves it flat on two sides, but spreads the thread. screw it back in 'til it's tight and forget about it until you have to/want to take the cover of then helicoil it properly.

i couldn't do such a thing myself, or approve of such a thing, and i told you, you wouldn't like it

You are right, I don't like it, but top marks for inventiveness.

 

[cookie]

i didn't like it so much i'd deleted it. obviously not before you'd seen it

 

[Timpo]

I'm not sure which hole you have stripped, but if it is accessible with a battery drill and a tap wrench, I can put a helicoil in it for you if you're stuck...

 

[AustinW]

I'm not sure which hole you have stripped, but if it is accessible with a battery drill and a tap wrench, I can put a helicoil in it for you if you're stuck...

It is very accessible. Rhs of bike 2nd bolt up. I am off for a couple of days today around Shropshire and Wales and will see how it is now after I disturbed it at the weekend. I may well take up your offer.


Sent from my iPhone with a smile

 

[cookie]

I'm not sure which hole you have stripped, but if it is accessible with a battery drill and a tap wrench, I can put a helicoil in it for you if you're stuck...

you'll end up with a big hole in the timing cover if you don't take it off to fit helicoil. probably not important

 

[Timpo]

you'll end up with a big hole in the timing cover if you don't take it off to fit helicoil. probably not important

The hole in the timing cover is a clearance hole for whatever the screw size that is used in that position. The damaged thread is in the crankcase I believe, the only material that will be removed is the remainder of the damaged thread.

 

[cookie]

but you'll to drill need a hole bigger than the OD of the helicoil in the cover for access to fit it in the crankcase.

edit: i think it will be about 7.5mm, so not really an issue.

 

[Bendy toy]

Put up with the oil smear. Then when you can remove the cover. Biostrip will remove the paint without damaging the metal. Then get it painted. You may want to paint the gasket face to stop corrosion seeping under the new finish. Use an RTV gasket if you do that.
If the cover is visibly rough, the hidden area under the alternator base will be hideously cruddy. It might even be bad enough cause the hall sensor O ring to leak

 

[AustinW]

Thanks for all the hints and tips. As an update....after about 500 miles since I put the longer bolt in (but it still won't tighten) and nipped up the two bolts above and below there has been no leaking oil. . I will leave well alone for now.

 

[Bendy toy]

Don't run it through winter with flaking paint. The salt will chew into the metal leaving scars that if you are lucky will clean with a flap wheel.
Mine looked a bit cruddy so repainted for cosmetic reasons. . The metal underneath was really cruddy so very glad I did the job before it was too late.