Broken timing gears!

[abrankod]

Well, one of my buses bit the dust yesterday. Driver said "oh well the bus just shut off while I was driving" as usual.



I get out there, thinking it was just something stupid like fuel filters plugged up due to the sudden cold snap NYC got. So, I change the filters, and go to start... Cranks over nicely, but no start... So, I hit it with a little starting fluid as a starved IP sometimes needs a little umph to get it going. Nothing. I crack the lines... and I see no fuel... So, now I get creative... Open the oil fill cap, and crank... ROCKERS NOT MOVING... UH OH SPAGHETTIOS... Heavy duty tow truck



So today, I stopped by the shop to take a look at wtf. Pull the timing cover and sure enough, 4 teeth are broken off of the camshaft gear and the crankshaft gear has 2 chipped teeth, AND the camshaft timing gear is walked off the cam as far as the timing cover let it go...



Next week I'll pull the whole thing apart and see what the heck is going on.



Anyone know any common failure points to look at? Nothing feels seized, but that doesnt mean that the valves didnt get bent, so its getting a full teardown, but if anyone knows any starting failure points, I'd be happy to hear.





-Dan

 

[Greenleaf]

Are you sure you posted this in the correct foum? You didn't say what the engine is..... 12 valve I assume? VE pump? How many miles? You see the dowel pin in place? Are case mounting bolts in place? (bet one is missing )



Anbyone around here know anything about buses? Anyone?

 

[tugboatphil]

Scott... . working late today??

 

[abrankod]

its a 96 thomas rear engine school bus with a 12 valve and a p pump. Other than that, its the same as any other 12v engine out there... Sigh. I hate working on engines when its cold out.





-Dan.

 

[rlyons]

Sounds like the dowell pin or a bolt fell out to me.

 

[Philip]

Camshaft retainer bolts are known to come loose. If they do it falls into the camshaft gear train.



2 TDR members had that happen about 3 years ago. It took the nose off the camshaft.

 

[therabbittree]

abrankod are you familar with the KDP problem?. . the gear case locationing pin falls out and get srun between the gear train... sounds like the dowel pin stuck and the shock poped the cam gear off the cam maybe . . sounded like you said the gear is moved but the cam is still in the engine corectly..... ? most of the cam gears are pressed on and marine ones are bolt on cam gear. . looks like the killer dowel pin. . if I was you, I would at least do tabs over the pins in allyour busses... mine save more of these problems in the future or order the kdp tool and do all the busses. . the the screw so they can't fall out.

later,

deo

 

[dclassens]

I hate to sound like a parrot, but I also think it is the cam retainer bolt, or Killer Dowel. It make me cringe to think that when either of the work out, the only place to go is ride the gear until serious breakage!! good luck

Dave