Asking for Harmonic Balancer replacement advice

Does your Mitsubishi L300 make a strange noise? Need wheel alignment specs?
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Vehicle: Mitsubishi Delica, L300, 4D56
Location: New Zealand

Asking for Harmonic Balancer replacement advice

Post by InterrobangS »

I have a 4D56 L300. 1996 diesel, 4wd, turbo. There was a catastrophic failure of the balance shaft, I think. All I can tell you is that once we got the van towed back to my driveway all the belts were shredded and the end of the balance shaft, the threaded part, had snapped off with the pulley still attached. Snapped more or less flush with the front case seal.

The van exhibited a problem where it would just completely loose revs. We were driving on a National road in 4th or 5th gear and it was as if you’d just taken your foot off the gas. But I was almost foot flat. It was doing it intermittently for about 50-80km maybe. We hobbled along for a while stopping on the side of the road having a look And then starting again. After a while It would drive for a few minutes ok and then just die on us. Eventually it broke down for good and a mechanic stopped and helped us to try trouble shoot the problem. He couldn’t figure it out, but thought it could be that the fuel pump had been dying and was now dead. We towed it home and my housemate who is a diesel mechanic started pulling things apart and immediately found that all the belts were shredded and the balance shaft end had snapped.

So I have a few questions:

1. I’m guessing the balance shaft end snapping was not the initial cause of the problem. But what could this be a symptom of? Or maybe the pulley snapped off, and after bouncing around in the front case area of belts and shredding them, it caused another more drive related belt to fail.

2. Does the balance shaft snapping maybe indicate a more severe problem inside the engine? Could it have seized?

3. My mechanic friend (who unfortunately has left the country) said that some people bypass the balancer pulley. Could this then be something I can do to avoid taking the engine out? I’m assuming this is an engine out kinda problem to fix.

About 7000kms ago, I replaced the whole head, cam shaft, rocker shaft and all the front case seals, new turbo, new water pump, new exhaust mani, and heaps of other small bits and bobs. I had a compression test done and got real good scores averaging around 85-90% of factory new, if I remember correctly. So I think that the pistons were in good shape. I did all this work myself and would consider fixing this current problem myself if it’s possible. Ie if the engine is not completely buggered after this episode.
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