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a15 overhaul...need hone wisdom


81sunnyson

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after tearing down the oil burning a15, none of the rings are broken but i see vertical scratches in the bores and the skirts

of pistons

 

plan to just re-ring but not sure on hone approach and if this doesnt work then will bore the block i guess

 

grit?

 

ball hone or stone?

 

best crosshatch technique?

 

what size ball hone? say to stay close to bore size but i cant find a small hone other than atv sizes

 

 

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cell phone cam not good

 

the scratches run all the way down and are all in same spot, basically here the front notch of pistons is indicating how to install

 

mainly four is my concern because it has a horizontal gouge in middle of bore. catches my finger nail

this cylinder had a burnt valve and no compression for years, always heard piston slap on startup.

i ran a non-fouler til i heard pinging and pulled a plug to noticed the tip broken and huge oil glob. long reach plug possibly and gap pushed in 

 

when i fixed burnt valve in october i took care to keep things clean. gasket held until summer.  oil consumption was same at that point (quart every couples days)

plugs werent oily but oil burned when at high rpm under load etc

 

i warped the head due to busted hose in may

 

this time after headgasket blew i wiped bores with transmission fluid.  prepped deck with block in car so a lot of solvent got into the bores surely.   

i tried to blow out the crud from the gasket scrape but guess it got past rings

 

i went from oil burning only on hwy or hard acceleration to contionous billow at all times

 

no broken rings but all plugs oily, all pistons carbon sludge

 

transmission fluid in bores affecting seal?

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Scratches in bores come from either broken tings or overheating. If it's from broken rings, the scores are usually deep enough to warrant a rebore or at least a power hone. If they are from overheating, they can usually be flex honed out, but the pistons may need some love or even replacement.

 

My rule of thumb is, if I can feel the scratch with my fingernail, it needs more than a flex hone. That's after I flex hone it.

 

Buy the aluminum oxide ball hone or flex hone. Those are the best.

 

Using a battery powered drill on low speed, wet the bore and hone with WD40 and run the piston down and up the bore once in one second for the proper cross hatch. Do this 10 or 12 times per bore.

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First, if you have deep scratches you'll likely need to bore it out and install oversized pistons. If you have a horizontal scratch, are you sure this isn't just a ridge at the lowest point of the piston ring travel? This is common at the top of the cylinder but needs to be addressed.

 

Hones come in all sizes here are a few of mine.

 

20150512_210845_zpsb1ghvizu.jpg

 

 

 

The best thing to do is to post some pictures.. measure the bores yourself and check clearances. What does the piston ring gap look like?

 

From the sounds of this engine, it sounds like its going to need some work to get it healthy again.

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For all the things you have to pay for anyway (gaskets, rings bearings) you may as well invest $50 per cylinder and get it bored to the next oversize and larger pistons. Get chrome rings now because the bore will be perfect. You will now have a new engine not a re-ring that burns oil still.

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i made it go from bad to worse in rush to do head gasket, bad prep work

 

pickup had lots of foreign objects n rtv wads

 

pistons scuffed and carmelized at wrist pins....definately overheated

 

and revvng at 4000 at extended periods temp gauge always climbed with warped head

 

all of the above.

low oil, never drained pan just added as it burned up, crud in lifter bores, crud in pickup, bad timing, bad lash, lean, pinging, piston slap, bent pushrods, burnt valves......

 

a15 ran regardless....great learning tool....first rebuild....wish me luck

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