mbe headaches again, 3rd time

[tknight]

I can't beleive I have had to get all the exhaust studs in my head replaced for the third time, they keep popping the heads off or pulling loose and breaking the stud off holding the exhaust manifold on, first time was at 112k and it was done in warranty, yippi! Second time it was at 230k and cost me over a grand in labor and parts to replace 8 bolts, this time at 350k I just had to have more yet replaced, I had all 8 of them done, and had the manifold machined flat and true, and I personally confirmed it at the machine shop with a laser tool I borrowed from a friend. I also watched while the new bolts were tourqued to the proper spec, glad I have a co-operative mechanic!
What gives, I know it's an aluminum head and it expands and contracts, but this is nonsense and needs to stop, Has anyone else had this same headache and if so, is it common?

tk

 

[Slo-Ride]

Knight,
Since nobody has responded yet I'm thinking its not to common?? I know I haven't ran across or heard of anyone yet with this problem. 3 times around, that really blows.
Only thing I can think of, (since you stated it pulling the heads off)
Is it possible the exhaust piping is putting some sort of torque (strain) on the manifold? Maybe missing some mounting clamps down stream??? mounted improperly?? Loose motor mount twisting the pipes?? Oversize holes in the Manifold??
If was just loose bolts each time I would lean towards oversize holes in the head itself. But as far as breaking em so often I am at a loss. Hopefully the dealer will help you since you have records of this ongoing problem. (Don't hold your breath)

Sorry bro not much help from me..

 

[Murraycroexp]

Closest I ever had was engine to tranny bolts shearing off at the bolt heads. GM engine, though. Turned out that the crankshaft was a little bit out of balance and some freak vibration made the bolts unhappy. Went through 2 trannies before finding the right tech that had seen it in drag cars before. Good luck.

 

[highway star]

Is that the 900 series MBE? I've had the same issue, just had it repaired again a couple of weeks ago. Also, the pipe that comes out of the turbo has been an issue. The flange just disinegrates.

 

[tknight]

I'v had no exhaust issues what so ever, still on original pipes , all hangers are there as it came off when trans was replaced to make more room, everything is tight truck runs smoothe as glass very little vibes.i'm pretty sure it has to do with expansion of the head, it's alluminum afterall, and heating makes it swell hence the torqued bolts shear when stressed by this, if they used a different grade metal bolt other than the black oxide grade 12 i beleive they would stretch a little prior to shearing, that's my theory and I'm sticking to it, Frightliner is still picking their noses and butt cracks while insisting it's never happened, before, yea and Hurricanes are safw for picnicers on the beach!

tk

 

[spongebox]

Does your exhaust system have a flex tube between the pipe coming down from the manifold and the first exhaust hanger? Had a similar issue with a mbe engine, the dealer told me to put in a flex pipe between the manifold and first exhaust hanger after that no problems, the truck went a few more years with no issues, this was several years back but I believe the truck is still running and no issues..

Sent from my VS910 4G using EO Forums

 

[tknight]

Actually yes that was done when I had the truck built new as the sleeper required a vertical stack they rerouted most of it to accommodate my little home away from home

 

[purgoose10]

I can't beleive I have had to get all the exhaust studs in my head replaced for the third time, they keep popping the heads off or pulling loose and breaking the stud off holding the exhaust manifold on, first time was at 112k and it was done in warranty, yippi! Second time it was at 230k and cost me over a grand in labor and parts to replace 8 bolts, this time at 350k I just had to have more yet replaced, I had all 8 of them done, and had the manifold machined flat and true, and I personally confirmed it at the machine shop with a laser tool I borrowed from a friend. I also watched while the new bolts were tourqued to the proper spec, glad I have a co-operative mechanic!
What gives, I know it's an aluminum head and it expands and contracts, but this is nonsense and needs to stop, Has anyone else had this same headache and if so, is it common?

tk

Some mechanics refuse to replace the seals (gaskets) on the exhaust manifold when they re-install the manifold. Those seals on a MBE fit into a groove. If they are bad you cannot get a good torque on the manifold bolt because you don't get a positive seal in the head. Could be the problem maybe not, hard to say w/out seeing it. Some will say if thats the case why does it not leak exhaust? It doesn't take much during the heating process when the engine heats up to operating range for the head to expand and not the exhaust manifold, thats when the bolts can loosen or break.

 

[tknight]

All new gaskets every time I'm like anal about getting parts back even something as simple as a hose clamp
More people should demand their old parts helps keep em somewhat more honest when they are under scruitny

 

[Skyline]

Just came across this bulletin to dealers in 2005. ( www.ddcsn.com/cps/rde/xbcr/ddcsn/6-MBE900-05.pdf ) I do not know if this explains any of your replacement gasket problems, but thought I would post info anyway. Regards

 

[LDB]

With one failure on record already at 112k it seems the 230k event should have also been warranty.

 

[usafk9]

With one failure on record already at 112k it seems the 230k event should have also been warranty.

Don't count on it. Ours is in the shop for that issue plus a few others now. Our reman engine's warranty is 100k/one year. Picked it up 1/19/13. Warranty should be finished in a little more than a month from now.