destroyed 12 valve pics
12-06-2006, 05:18 PM
#1
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destroyed 12 valve pics
The ole girl just doesn't like to be run hard i guess. Driving down the road this past Saturday it starts to cut out and pop at higher rpm's. Figured it would be alright till i got home... WELL it wasn't a good idea to drive it home! Took no.1 valve cover off and noticed the exhaust valve wasn't rocking. Next day i tore it down only to find i bent the push rod in an S shape, broke a valve off, destroyed a piston, chipped the deck of the block, and smashed an injector tip flat. WooHoo how fun! New motor time!
12-06-2006, 05:32 PM
#5
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Ive seen pics of that very same failure someplace before. Wonder how common a failure that is.
Wonder if the gear caused the failure, or you had valve float and piston contact first. The bottom of a valve will certainly provide enough leverage to snap that cam gear. everything from springs to pushrods would be suspect.
Wonder how much a reman 12v motor is from a reputable outfit like jasper or something...
Wonder if the gear caused the failure, or you had valve float and piston contact first. The bottom of a valve will certainly provide enough leverage to snap that cam gear. everything from springs to pushrods would be suspect.
Wonder how much a reman 12v motor is from a reputable outfit like jasper or something...
12-06-2006, 05:38 PM
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Thats not too bad considering a transmission build-up is about that cost. Hope youre good with a cherry picker and can at least lower the labor cost
A new motor might be a good reason for a cam upgrade
A new motor might be a good reason for a cam upgrade
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12-06-2006, 05:58 PM
#9
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Yikes! Sorry for your troubles Wait'll these pics get over to The Diesel Stop et all....there'll be ''see what you get with the 'reliable' old 12v'' threads left and right
Wait'll these pics get over to The Diesel Stop et all....there'll be ''see what you get with the 'reliable' old 12v'' threads left and right
12-06-2006, 06:39 PM
#10
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My bet is the cam gear was the initial cause.
I know your sig says you killed the KDP but the cam gear breaking off like that is one of the things a dowel pin bouncing around in the case can do. If the dowel pin goes between the cam and crank gears, or cam and injection pump gears, it breaks the gear off the camshaft. The camshaft stops rotating causing valves to stop operating, leaving some valves open and some closed. The crankshaft continues to rotate slamming pistons into valves, and possibly ruining block, crank, rods, cylinder head, and valve train. Almost no reusable parts in this case, a complete engine swap could be required, surprised you were able to drive it home.
I know your sig says you killed the KDP but the cam gear breaking off like that is one of the things a dowel pin bouncing around in the case can do. If the dowel pin goes between the cam and crank gears, or cam and injection pump gears, it breaks the gear off the camshaft. The camshaft stops rotating causing valves to stop operating, leaving some valves open and some closed. The crankshaft continues to rotate slamming pistons into valves, and possibly ruining block, crank, rods, cylinder head, and valve train. Almost no reusable parts in this case, a complete engine swap could be required, surprised you were able to drive it home.
12-06-2006, 07:47 PM
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Hey look at the bright side you will get to build a motor how you want it now. Thats pretty cool until you think of the cost. Hope all goes alright. No one like to see pictures like that. Good luck.
12-07-2006, 04:05 AM
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My bet is the cam gear was the initial cause.
I know your sig says you killed the KDP but the cam gear breaking off like that is one of the things a dowel pin bouncing around in the case can do. If the dowel pin goes between the cam and crank gears, or cam and injection pump gears, it breaks the gear off the camshaft. The camshaft stops rotating causing valves to stop operating, leaving some valves open and some closed. The crankshaft continues to rotate slamming pistons into valves, and possibly ruining block, crank, rods, cylinder head, and valve train. Almost no reusable parts in this case, a complete engine swap could be required, surprised you were able to drive it home.
I know your sig says you killed the KDP but the cam gear breaking off like that is one of the things a dowel pin bouncing around in the case can do. If the dowel pin goes between the cam and crank gears, or cam and injection pump gears, it breaks the gear off the camshaft. The camshaft stops rotating causing valves to stop operating, leaving some valves open and some closed. The crankshaft continues to rotate slamming pistons into valves, and possibly ruining block, crank, rods, cylinder head, and valve train. Almost no reusable parts in this case, a complete engine swap could be required, surprised you were able to drive it home.
12-07-2006, 08:05 AM
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Yeah, except that he drove it home, and only one valve - the exhaust valve in that cylinder - was damaged.
Looks more like piston to broken valve to cylinder head juncture broke the cam gear, probably precipitated by valve float.
Stock valve spring tension is low to ensure long life for the cam lobes with the flat-tappet lifters - they look like an upside-down nail - used in low-rpm engines.
Stock valve spring tension is designed to hold just above stock governor spring limits - good idea to limit rpms to less than 2700 with stock valve springs at over 100kmi on engine, imo.
Looks more like piston to broken valve to cylinder head juncture broke the cam gear, probably precipitated by valve float.
Stock valve spring tension is low to ensure long life for the cam lobes with the flat-tappet lifters - they look like an upside-down nail - used in low-rpm engines.
Stock valve spring tension is designed to hold just above stock governor spring limits - good idea to limit rpms to less than 2700 with stock valve springs at over 100kmi on engine, imo.
