coming home the other day and stopped at a convienience store...got out and heard a new noise....kinda like something was slapping around in the motor....but i couldn't really tell where exactly....not a steady noise either....kinda intermittent....was wondering if it might be timing chain worn out and slapping against the cover....the car has about 180,000 miles and is driven about 650-750 miles a week....thanks for your help



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Scott Downs
85 Trans Am
305 tpi/700r4
3.73 w/255/60R15
plain firebird nose(for better engine cooling)
T-Tops, pwr everything
been to about 140mph

 

COuld be the timing chain, you can get an indication of the amount of play in the chain by pulling the distributor cap, and wach the rotor as you rotate the motor back and forth (best to pull the plugs out so you don't twist the HB bolt off) by the crank bolt...watch the mark on the balancer vs. the timing tab...as you go back and forth, keep your third eye on the rotor when it starts to move, look doan at the timing mark and see where it lines up on the tab, now go the other way and see how far it goes before the rotor starts to move again.

Anything more than 2 degrees shows wear/stretch...but does not take into account any wear in the cam and distributor gear. But if it's the chain rattling, you'll see a pretty big swing before the rotor moves.

 

Any others?

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Scott Downs
85 Trans Am
305 tpi/700r4
3.73 w/255/60R15
plain firebird nose(for better engine cooling)
T-Tops, pwr everything
been to about 140mph

 

it is absolutely impossible for the timing chain to slap the cover

my guess is if you're hearing anything from the timing chain at all it would be the jerking that it would be doing at idle.. the sound would be negligable though, hard to hear...

best way to figure where the sound is coming from is to buy a set of mechanic's stethoscopes and listen for what the sound is like, more than likely you're hearing excess valve lash (ie. noisy rockers / rockers arms that are loose)

if your car has 100K on it, change the timing chain if you're up to a fairly hefty task

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Webmaster: www.IROC-Z.org

 

ok first off NOTHING IS IMPOSSIBLE!!!!....i have seen where a timing chain has been so worn out that it was slapping the cover....evidenced by the scrapes and gouges on the cover itself....

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Scott Downs
85 Trans Am
305 tpi/700r4
3.73 w/255/60R15
plain firebird nose(for better engine cooling)
T-Tops, pwr everything
been to about 140mph

 

I've seen several small block Chevys with timing chains so worn that they would slap the cover. All of them had the "plastic" gear.

Sounded somewhat like a rod bearing going bad at the front of the engine.
jms

 

I would actually drop the oil pan and check thrust bearing endplay. I had the same noise in my truck and it ended up being the rear main bearing(thrust). With that many miles, that would be my bet.