HiAce 1KZ Timing Belt Failure

[Amazon Prime]

Hello,

I have a 1996 HiAce Super Custom (KZH106W) that I imported from Japan last year. Everything had been great up until last week when the timing belt let go at 60mph on the highway. It seems that the bolt that holds the idler pulley in place worked itself loose allowing the pulley assembly to fall off, resulting in a slack belt that was subsequently shredded to bits. What a bummer, and I'm kicking myself now for not replacing the belt immediately when I got the van. The belt had less than 100k km on it, so I put it off. Oh well, no sense dwelling on that now. The 1KZ-TE is an interference engine, so I'm expecting bent/broken valves at a minimum. My plan is to remove the head to assess the damage, and go from there. Depending on the tools required and my confidence level (never done valves before), I may attempt to rebuild the head myself. I have my fingers crossed that damage to the piston faces is minor enough that I can lightly sand and polish any burrs or nicks to prevent hot spots. If they're banged up really bad I'll cross that bridge when I get to it.

It seems like there are some some folks on this forum with a lot of experience working on toyota diesel engines. I would appreciate any feedback or advice regarding my plan of attack and the task at hand in general.

Thanks!

[Andywear]

Sorry to hear that man.

But happy to hear you are willing to try it yourself :thmbup:

the insta pics from vanlifenorthwest sometimes show them pulling the whole motor out of the cab and other times leaving it in.
Do you have a garage and plenty of room?

[Amazon Prime]

Yes, fortunately I have a large indoor workspace. Hopefully it's just the heads that need work and the motor doesn't need to come out, but if it comes to that so be it.

I've got the intake plumbing, exhaust and turbo all removed from the drivers side of the motor at this point. Today I hope to get the intake manifold off and remove the head. Progress has been slow since this is my first time working on the van and I'm having to identify and locate all the components as I go. But I haven't broken anything. Just a snapped bolt for the exhaust manifold cover that I'll need to extract, and old plastic clips on electrical connectors that break when I detach them, and will need to be zip tied or safety wired when i reassemble. Fortunately it looks like all the parts that are in bad condition and need to be replaced are in common with USDM Toyotas and readily available here in the USA.

[Amazon Prime]

Ok, I've gotten the head off and have a pretty good idea of the extent of the damage.

The cam is snapped in 2 places. You can see dents from the cam lobes on the intake valve shims of cylinders 1 and 2. Perhaps this is where the unstoppable force met the immovable object. The second bearing cap was completely shattered as you can see in the first pic. The bolts for the front two bearing caps were bent quite a bit. Also the right side mounting post for the bearing cap that broke has some damage.
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As far as I can tell, the valves didn't touch the pistons. The order of the pictures is front to back - Cylinder 1, 2, 3, 4.

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Pistons look untouched as well. #1 has pitting on the piston face and scoring on the cylinder wall, but I don't think that's associated with the timing belt failure. Maybe a melted injector or glow plug tip in the past. Again, 1, 2, 3, 4.

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So with the damaged bearing cap mounts I guess i need a new head. not sure if Ill buy one that's ready to install or build one myself. I'm also wondering how much of a problem the pitting and scoring in cylinder 1 is. Do I need to pull the block and have it honed or re-sleeved? Or can I just clean up the pitting and forget about it? I'm also going to disassemble the head to examine the valves more closely. Looking through the intake and exhaust ports they don't look bent or broken. I'm scratching my head a bit as to how that's possible.

[JDM VANMAN]

Sorry your going thru that with your van but please show us more when you have a chance!!! :thmbup::clap:

Thank you

JDM