We were pulling our 5th wheel in a mountainous area n/b I-5 n/o Shasta Lake Ca. and were descending a steep grade. The truck was in 3rd gear (auto), the exhaust brake was on and the engine was taching 2500 rpm's when we heard a loud noise and the engine lost power. We were towed to a repair facility where the mechanic determined that a tip had broken off a pushrod (unknown which one) which caused the other one to bend. After this rather long narrative, my question is; is this a common occurrence?
Thanks John

 

Not a common issue at all.

How heavy (GVWR) is your 5th wheel? 2500rpm's down a hill with the ex. brake on is nothing.
I regularily surpass that with the ex brake on and our 10K lbs 5th wheel.

I suspect that you floated your exhaust valves and the piston hit them, bending and breaking the pushrods.
I would recommend that all the pushrods be checked, plus a compression test to make sure no valve damage occured.

I would also recommend that you upgrade your valve springs. Your ex valve springs may be weak.

For your mostly stock truck, I recomend the lighter www.F1Diesel.com 93 lb valve springs rather that the heavier Hamilton's and others.
I've had the F1 valve springs for over 5 years with no issues.

http://sourceautomotive.biz/24vprosportsmansprings.aspx

Since the injectors have to come out for a compression test and for valve spring installation, do both at the same time.

Of course since the injectors are out, all the rockers are removed, that would be an ideal time to install head studs to further increase the reliability of the engine.

 

The GVWR of our 5th whl is 12,500#. I'll take into consideration all of your suggestions.
Thanks-John

 

For a mostly stock truck it is not the norm to bend or break a pushrod. Just buy some stock ones from Cummins and through them back in, adjust the valves, and keep on going.

 

To the OP, Stealth Diesel nailed it for you on a complete response.

Seriously, I'd implement his suggestions.