Potential disaster

[PS172]

Hi, Iam new to the forum, doing preventive timing belt change on my 91 with 53 k miles, the front camshaft exhaust gear lip was found to be loose, infact she fell off when the belt was being tightened up at the tensioner. The lip can be clipped back with slight finger pressure but also will go off the same. Now if that happens while the engine is running it will fall right into the belt causing a skipping or rupture of it.
The timing belt was original, no previous maintenance done, so it may be a defect from factory.... how many can be affected, we may might wonder...will like to have any feedback on the above finding, thanks..

 

[RSO 34]

The timing belt was original, no previous maintenance done, so it may be a defect from factory.... how many can be affected, we may might wonder...will like to have any feedback on the above finding, thanks..

Are you saying you have a 21 yr old NSX that has never had any maintenance done?! If so, "potential disasater" is an understatement.....

 

[PS172]

Yep, bought it about 6 weeks ago, the car was stored for many years, overall is in great shape.... not my fault about maintenance...but the issue in question is not maintenance dependent is an incidental finding with posible catastrophic outcome.

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Well on second thoughts must be a case of bad machining of the groove where the ring lip is supposed to fit. Maybe something akin to the infamous snap ring... if so only a few gears will be affected. Now i need a replacement front exhaust cam gear.... anybody got one???

 

[R13]

Any chance you could post some semi-detailed photos of what you're talking about? That usually helps the mechanical gurus better understand the situation you're facing.

 

[Larry Bastanza]

I have seen this before once, but on the rear intake cam. A few cures:

1. Replace Gear

2. Remove gear and either weld the ring in place, or epoxy the ring in place CAREFULLY

3. Remove the ring and reshape it to be "out of round", then press the ring back onto the gear.

HTH,
LarryB

 

[davidf]

Or remove it and overnight it to Larryb for repair. :wink:

 

[PS172]

Thanks, will try a few stitches with the TIG torch, should be safe if welded properly

 

[Larry Bastanza]

Just make sure no weld bead end up on the inside(belt side)

 

[PS172]

Sure, thanks

 

[angus]

I would really like to see some pictures of this issue, it may help to identify the problem for others in future.

 

[Larry Bastanza]

Another alternative may be to "swedge" the gear lip about 180 degrees apart, or even every 90 degrees and spread the gear lip to tighten the fit of the ring on the gear.

Thinking outloud

Regards,
LarryB

 

[PS172]

The picture is in the first post, the cam gear and the detached ring.. for those interested.

 

[davidf]

Can that ring come off during engine operation? Where would it end up if so?

 

[PS172]

Most likely will be entangled in the crankshaft pulley causing catastrophic engine damage, similar to the one caused by the harmonic damper failure....not good

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[ATERPAK]

Well this should not just be pressed on to be secure. It's lucky that the cam belt self-centers during operation but I'm with Larry that it should be either spot welded on or even pressed back on with some JB-weld to secure it. I would not just press it back on and hope it stays in. It is very interesting however that just when you think you've seen everything on car parts and such, if you hang around long enough, you'll see something even more strange. Good luck on this fix.

Al

 

[PS172]

Already TIG welded, and back in place will put the belt on during the next weekend:smile: