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Old 08-02-2014, 11:51 AM   #1
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Default Should I replace the rings?

Question for the engine-building masses.
My motor has been built, re-built, and still when I get on the gas hard (no turbo ATM), I can smell oil. Engine will burn oil over period of time.

Question is, should I rebuild? Can I just swap the rings? (and head gasket)?
Or, do I need to do more?
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Old 08-02-2014, 02:04 PM   #2
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Who built/rebuilt it the first two times? What is your break-in procedure? What oil was used during break-in?

You cannot just slap rings in an engine without doing a hone at bare minimum. If you do this, the engine is effectively new for break-in purposes and should be treated as such (varying RPM, high-low load cycles, no synthetics until oil consumption is gone).
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Old 08-02-2014, 02:06 PM   #3
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Built by Chris Akira Takemoto
Rebuilt by my local mechanic
Don't remember
Don't remember

Thank you
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Old 08-02-2014, 04:05 PM   #4
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Andrew, I understand that you've built your share of engines.
Me? I'm a complete newbie in that respect. So, I'm hoping you could steer me right.

Am I correct in assuming that if I smell oil burning out of the exhaust pipe, it's probably the rings? (Only under WOT and backing off WOT)

If I'm gonna replace the rings, do I need to replace anything else? I think front and rear seals are a must (considering they're only pennies), head gasket, but rod pins, studs, bearings, etc? I understand if I replace the bearings I'll have to machine the crank, right?

What else should I know?
To hone the bore, I have to completely pull the crank & pistons, yes?

Thanks!!!!

P.S. Is this method still the best way to break an engine in? Or, do you have a better way?
Thanks again!

Last edited by alik; 08-02-2014 at 05:46 PM.
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Old 08-02-2014, 09:46 PM   #5
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Leakdown testing is the way to detect poor ring seal. A fully broken-in engine that is running properly will be ~2% leakdown. Tired race engines that burn a little oil are 8-10%. Tired street engines are 15%. Anything over 20% should be opened and rebuilt. You can also pull the header and look for a wet exhaust port, or scope the cylinder and look for excessive carbon deposits in relation to the age of the engine.

Mototune's break-in instructions are pretty good. His fundamentals are correct - if you want it to seal up tight, beat on it from the moment you start it. In my experience, ~90% of the break-in process happens within the first 30 minutes of an engine's life.

To hone the block, the engine needs to be 100% disassembled, all the way down to the oil squirters, since your machinist will need to hot-tank the block before it goes into the boring machine. You are essentially starting from scratch when it comes to the actual assembly portion. I personally am not a fan of reusing bearings, although if they are low-hour and look good, it's hard to justify throwing them out. Rod bolts can be reused with careful measurements that reference the original stretch specs used to assemble your engine, but if your machinist/mechanic just torqued them to spec, I would replace them as a precaution. ARP head/main studs can be reused, since they are not TTY fasteners. All the gaskets for the shortblock should be replaced.
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Old 08-03-2014, 12:22 PM   #6
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Thank you!
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