Exhaust bolts keep breaking

[meekotd]

I have a 94 XP. It runs great but the exhaust system keeps breaking one or more of the stainless hex bolt or studs on the exhause manifold. Are there any trick out there to keep this from happening? I must replace these after every 8 or 9 hours of operation. Everything seems to be fastened in place very well but the bolds keep breaking. I have a 95 xp and have never had to do anything to the bolts.

Any ideas will be appreciated

 

[El Toro 33809]

A few things you could check:

1) Motor mounts & exhaust mounts. Are they all in place and secure?
2) Have the bolts been torqued to the proper specs and in the proper order?
Finally,
3) Is the driveshaft properly aligned with the motor?

 

[Dr Honda]

You probably have them overtightend, and the gaskets are old.

Put in new gaskets, lock washers and bolts. (all of them) and then only tighten them to 18 Lb-ft of torque.

 

[Dave_eng]

Sure sounds like the engine is not being held in place properly by the motor mounts and the exhaust system is having to act as a restraint. You may see polished areas on the inside of the hull from the tuned pipe rubbing.

Try rocking the engine and have a friend check for rubber separation. When the engine is just sitting you wont see any problem with the mounts.

Davep

 

[Seadoobuddy]

There was a thread last summer about same problem. if i remember correctly it was either wrong bolts (i doubt it) or bad motor mounts (I think it was this).
Try searching for the thread.

Do what Dave & El Toro, Dr H suggests.

 

[murjiim]

use grade 8 bolts.

 

[Dr Honda]

use grade 8 bolts.

AUGGGHHHHHHHH!!!! NO !!!!!!!! If you do that... they will snap even quicker. With exhaust parts... you need softer bolts so they can stretch/expand with the heat. Grade 8 bolts are very hard, and have high tensile strength... and because of that... they don't liked to be stretched. AND... when they do get stretched, they shatter.


Not to mention... there isn't a "grade 8" stainless bolt. Depending on the alloy, they are either 3 or 5. (aprox)