Broken cam

[SIMMY]

One of my friends brought his 1999 venture 3.4 to me on a tow truck.It was at his mechanics after it died on the road.Diagnosis was a dead fuel pump but he didnt have nearly $1000 dollars so it came to me. Im the local backyard mechanic.Sure enough the pump was dead so I replaced it with a wrecker part.The fuel filter on the line was plugged solid so I changed that too.went to start it and it sounded like an engine with a broken timing belt.After much messing around I pulled the front rocer cover and wound it over with a ratchet on the crank.Only one rocker arm was moving so Im assuming the cam has broken off just past the first rocker.Is this a freak or is has anyone here run into this before?Is the engine trashed or can the cam be changed?Not looking forward to having to take this motor out.Looks like it all has to come out through the bottom.Any advice?

[pocket-rocket]

It's no freak. Most likely it's from a LIM (Lower Intake Gasket) set that went bad and let go too long, leaking coolant into the oil. There's been lots of these out there. Hopefully it didn't spin the bearings in the block making the block useless (like this 3100 I have out of an Achieva that met the same fate) and you can get away with new bearings and cam. You might want to check the main & rod bearings as well, or just replace them all (if the cam area of the block is ok) just to be on the safe side.

[Rootie524]

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[bszopi]

Starting with the introduction of the 3100 in 1993, the cams because a hollow core design. Basically cam lobes seated on a hollow pipe. When a bearing seizes one of the cam journals, but the timing chain continues to try to turn the came, the pipe can not take the force and it shears in 2, resulting in a broken cam. I have half a cam in my garage somewhere. Do a search on here for broken cam and you should find at least a couple pictures of 1, as I know someone has posted some in just the last 3-4 months.

[pocket-rocket]

If it were a chian, none of the rockers would be moving. What happens is since coolant isn't exactly a good lubricant the cam will seize in the bearings. Mr. Crankshaft has more say so than Mr. Hollow cam shaft. Mr Crankshaft wins the fight and Mr. Camshaft gives up the ghost, breaking into two pieces. I can take a pick of what a one piece cam turned two piece looks like with my phone if you like, lol You don't normally hear about it as much as you used to though, because of people catching on to the LIM gasket situation from it being a big known problem.

[SIMMY]

This engine had head and intake done about ten thousand km ago so I guess the damage was done then and just took this long to eat itself up.Guess its time to pull the motor and find out.I HATE WORKING ON VANS.Thanks for the advice

[pocket-rocket]

Starting with the introduction of the 3100 in 1993, the cams because a hollow core design. Basically cam lobes seated on a hollow pipe. When a bearing seizes one of the cam journals, but the timing chain continues to try to turn the came, the pipe can not take the force and it shears in 2, resulting in a broken cam. I have half a cam in my garage somewhere. Do a search on here for broken cam and you should find at least a couple pictures of 1, as I know someone has posted some in just the last 3-4 months.

Now I come back to this thread and see this. You must have been typing as I was