$600 later - the parts are on the way.

Very odd.

My understanding is that the "composite timing chain" has as its main failure mode a shearing of teeth. What that means is that typically, people go to start their perfectly-functioning 928 and suddenly there is a crunching noise...and then the engine won't turn over. The belt shears teeth, and then the valves hit the pistons and jam the rotating assembly. The car gets towed, and the owner gets the bad news. 1 month later, the car shows up on eBay on the cheap, with a destroyed engine.

Rebuilding the 928 heads is between $4000 and $8000. The 2-valve cars are way cheaper....though I've heard that they typically do more damage to the pistons. Susan at Devek told me a few years ago that a good bore-job and rebuild by them would result in a $25,000 bill. Of course, you are getting a 450 hp engine, and it is brand new. This sounds expensive, but if you try buying a new car with that level of performance...you'll never find it, not even with a corvette.

Devek is out of business, unfortunately~

N!

So, what parts actually failed?

Oh no. Normy might be telling my future. Yes, I could be one of those owners that has the car for sale cheap on ebay if doesn't go well. But, I'll spin wrenches until I find out for sure. I'm not exactly sure of the root cause yet. Good sense would have kept me from ordering parts until I knew more. The belt broke while the engine was hardly laboring and there were no sounds of warning before it broke - it was running and sounding fine, then -pop. That gives me hope the 4.7L is a non-interference engine and the valves are okay. I also think the belt was tracing to the inside and the tension roller is what failed - and maybe because I had the tension set way too tight from redoing the belt without the tension tool.

I'm getting a crank gear, 2 thrust washers, main seal, oil pump gear, belt, water pump, tension roller, idle roller, bushings, shoulder bolt, and the tension adjusting tool.

Same style belt? Square tooth?

Yes. Actually, I had a brand new square tooth belt already and wouldn't want it to go to waste.

Give us some nice close up picts of the belt please, they don't just break without a BIG force. My bet is that something locked up.

Why are you replacing the steel gears on the crank and oil pump?

I understand the not wanting to waste a $35 old belt, I've got two or three used ones myself, but they aren't going on a motor I plan to drive unless I am in the middle of a desert.

The belt I have is brand new still in the box - so it's getting used. Those two gears are pretty shiny and you can tell there's a wear pattern on them. I thought I might have better belt tracking if I got some fresh gears down there. The cam gears still look good - maybe a PO replaced them at some point. That's the only belt picture - the belt is already headed for the land-fill.

I haven't noticed much wear on any of the steel gears, just the aluminum ones.

I could have kept using this oil pump gear. The crank gear is definitely http://www.boazli.com/gears.jpgworn though.

Hi bedinator
like danglerb says..to break a belt like yours did...something locked up....i've done many a toyota timing belt (im cert'ed toyota tech)...and when they look like yours does, and we do get them like that..lol.....its either a waterpump locked or a camshaft seized..if its a 16v...turn the cams around....see/feel if they turn freely...i would check all the turning parts re: oil pump etc, even a idle pully will do this...this wasnt a belt failure....something stopped the belt from turning....every time i see the/a belt failure form old age/wear...all it does is strip the teeth off the belt.

either the WP siezed, or the pivot arm bent and locked something up. Judging from the coolant in the idler roller I would say that the pivot arm failed.

However this engine is non interference. I would replace the water pump regardless though as the force required would have damaged the bearings in it.

Also consider the porkensioner.

I'm driving it again!

Its back together again. I'll be attempting another drive to California before too long. It seems to run the same or better than it did just before the catastrophe.

Great news! Now make sure you got that AAA with extra mileage just in case. We're still waiting on some current pics of your ride.

So going on what you have fixed , I was not clear on the type of replacement parts that you used . DID you get all new square tooth parts or are they now mixed, EG square belt and round crank gear and oil pump with square tooth cams??
Did you replace the water pump?

Hi,

It's all square toothed still. I replaced the steel gears (crank and oil pump), the water pump, the idler roller, the tensioner roller, shoulder bolt and bushings, and belt slide.

-Bed

YOU DA MAN!

As the President of the 928 Preservation Society [something that I just dreamed up, but it tells you how I feel about this hobby], I fully applaud your actions sir!

Good luck!

N!

Normy! Can sit on the Board of your Society? ;) I can be the dude in the corner that says, "Yay" to everything.

You are now the Vice President. Nicole might have something to say about this, since she runs www.hookedoncars.com, and she's the ultimate! 928 hound!

Thanx!

N!