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Toyota 13t hemi ticking/tapping noise

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Lately I have this dreaded ticking/tapping noise from the engine underneath. No noise at idle only evident when revving. Connecting and main rod bearings were replaced, adjusted valve clearances, piston pin bushings still good. What else should be checked. Any help would be appreciated. Thanks

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I'd be checking gudgeon(wrist) pin to piston clearance and ring clearance. 

Pin clearance should be no more than 1/2 a thousands of an inch and ring clearance should be no more than than 2 thousands of an inch. The rings can be checked with feeler gauges but the pins really need to be checked with a bore gauge(too tight for telescopic gauges) and micrometer.

No sign of valves just nicking the pistons?

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"No noise at idle only evident when revving "

That's a bit odd.. what happens when you slowly increase or decrease the rpm? Does the ticking suddenly arrive? Appear slowly and get worse?

Is it both when under power when driving and/or compared to just revving it in neutral when its doing no work?

What sort of rpm does it appear at?

One cylinder only??  Does a screwdriver in the ear or a stethoscope give any clue as to which cylinder?

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21 minutes ago, altezzaclub said:

"No noise at idle only evident when revving "

That's a bit odd.. what happens when you slowly increase or decrease the rpm? 

It can usually be a sign of over clearanced pins in the pistons. In saying that, it usually only seems to occur in really long stroke engines. The noise will usually be at around 2,000-3,000rpm. An over clearanced pin will not usually make too much, if any noise at idle.

 

 

 

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44 minutes ago, kickn5k said:

I'd be checking gudgeon(wrist) pin to piston clearance and ring clearance. 

Pin clearance should be no more than 1/2 a thousands of an inch and ring clearance should be no more than than 2 thousands of an inch. The rings can be checked with feeler gauges but the pins really need to be checked with a bore gauge(too tight for telescopic gauges) and micrometer.

No sign of valves just nicking the pistons?

I already checked on that sir, everything is tight and clearances still falls under minimum specs.

I have this odd exhaust manifold flange that connects with the exhaust pipe should there be any clearance between the two mating surfaces, mine has a 1/8 of an inch clearance even with new flange donut gaskets installed, could this be the culprit?

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1 minute ago, kickn5k said:

It can usually be a sign of over clearanced pins in the pistons. In saying that, it usually only seems to occur in really long stroke engines. The noise will usually be at around 2,000-3,000rpm. An over clearanced pin will not usually make too much, if any noise at idle.

 

 

 

It gets louder as engine rpm increases and engine load.. Machine shop said piston pins still good, mains and rod bearings replaced but still has knocking sound. Could be an exhaust leak?

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" mine has a 1/8 of an inch clearance even with new flange donut gaskets installed, could this be the culprit? "

That's OK so long as its even all the way round.  Mine leaks but it just makes the motor noisier rather than a distinct noise.

You'd see black marks if it was leaking, and "knock" isn't the word to describe an exhaust leak.  Not a broken ring?

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