This is about my daily driver Caprice (85 305). I am getting a new noise out of the engine area, which is a combination of scraping and ticking. The ticking sounds like a card stuck in the spokes of a bicycle wheel. I can't hear the noise when I pop the hood and stand next to the engine and rev it. The noise occurs under load, like a spark knock, but also is present decelerationg from 2nd to first gear (auto trans), which spark knock would not do, I think.
I am just worried that it is the timing chain. Don't want to be stuck somewhere. Sounds like it is coming from around the trans, or rear of the engine, actually. Have had a trans leak for a few years. 330,000 on the engine and trans, all original. You can hear the
How can I rule out timing chain ? Is this clicking / scraping sound the sound of a loose chain ?

Thanks

 

probably not Tchain. They just jump or break without you knowing in most cases.

 

Sounds more like a collapsed lifter to me.

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"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

Or perhaps an exhaust leak.

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"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

I have a similar sound coming from my engine bay, but only when its cold and under load. I do know that there is an exhaust leak somewhere, so it may be that.

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Smeg
89 GTA 5.7 TPI

 

Is it a constant ticking? or does it get faster as the car gets faster?

 

with 330,000 miles on the chain im sure its strected to high hell and wouldnt be a bad idea to change, it, but sounds like possibly loose main bearings, they will tick under load and when the engine is cold and stop as the engine gets hot as they will expand.

 

GTA,

You can check for a loose chain by removing the distributor cap, rotating the engine by hand (or socket) clockwise to TDC at the crank timing marks. Once the marks are lined up, rotate teh engine backward until you see the distributor rotor move in the opposite direction. This shoudl be almost immediate, but any lag or delay means some timing chain stretch.


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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

Thanks for the replies. Good to hear it is probably not the chain. To answer the questions, the clicking/rattling sound doesn't really vary with the speed of the engine, it's either there or not, sort of like spark knock. And sometimes it is not there at all. And it shows up when cold, warm, or hot. It comes and goes. Oh yeah, there is a popping sound too, sometimes, not always, on acceleration. I suppose it could be a bunch of things, but I am glad to hear it's probably not the chain.

 

Yeah, what Vader said. Or another way I have found to diagnose whether the timing chain is bad or not, is to use a timing light and watch the timing mark at idle, and if you see the mark kinda wander around 4 degrees or more, that's a indication that the chain is loose. I have found that to be the easiest way to determine a worn timing chain. Simple as hooking up a timing light.

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-1983 L69 Camaro Z28 305 H.O. (Bored .030 over,Teflon oil seals,Melling H.V. oil pump,Hyperetic pistons,chrome-moly rings,2040 Crane compu-cam) T-tops, 3:73 Open rear, BW T-5, Rebuilt E4ME 4 Barrel, Duel Snorkle Air Cleaner w/K&N Filter , Rhino Clutch, Crane 2040 Compu-cam, LS1 valve springs, porting, PST front end kit. Now for paint, interior, etc...etc.... Also:
2000 S10 4.3L 4WD LS
1995 Ford Thunderchicken, 4.6 V-8

 

Confuzed1,
Last time I did the timing it was moving around only about 1 degree, which I assume is OK. I am going to use the Vader Method (tm) to check it tomorrow. Depending what I find out, I then may have to figure out what effect the stretched chain would have on the "real" timing.