Cylinder bores out of round - how much a acceptable?

[Thuppu]

You are lucky to have a 200k block with such small wear.Usualy 0.05 mm at this level of km.And thys only if it was running ok.If not 0.2 mm can be seen.Are your gauge "contact tips"small enough to get in the max ring travel at tdc?

It's inpossible to feel the ring notch in TDC. 0.2mm is quite much, would need rebore to oversize.

[Thuppu]

Thomas if its just a thrown together engine for daily duties I wouldn't worry at all about 0.02 out of round

As JP told me "You worry too much"

Alex, the problem is that I have a few k€ oilburner(and I don't speak of an diesel engine) that I thought I did right. You get little paranoid...

[pasbogdan]

You are lucky to have a 200k block with such small wear.Usualy 0.05 mm at this level of km.And thys only if it was running ok.If not 0.2 mm can be seen.Are your gauge "contact tips"small enough to get in the max ring travel at tdc?

[Thuppu]

Hmm, whos block has wear out? So also a 5cyl block with wear that stays in the specs are uncommon? A block with 200-300k should be in 100% factory specs?

[popdemonic]

If anyone can tell me you guys have seen the bore exceeded maximum limits before?i have own this car for almost 10year and never seen

any I5 motors got the bore out of round or wearing out before.

[Thuppu]

It's like the first one with a gauge. Should be a pro tool, did loan it from work just for checking the bores.

Did also measure the pistons, with a micrometer. They where 0.01-0.02 under nominal measures, so should be in specs.

[repo]

Is Your bore gauge like this:

http://diesunlimited.tradeindia.com/mitutoyo-bore-gauge-917460.html

or this:

http://www.directindustry.com/prod/m...79-666289.html

As first one repeats really well, latter reallyreally does not.

And first one will measure roundness just fine.

[Error404]

Thomas if its just a thrown together engine for daily duties I wouldn't worry at all about 0.02 out of round

As JP told me "You worry too much"

[Thuppu]

Strange...Usualy they are perfect round at bdc and weared at tdc.If you have a block with 0.02mm wear at tdc with 280k you should make a topic with it.It will be my and many others to see such thingSo still in perfect shape.
You use a 2 point or a 3 point bore gauge?

Of course it has wear. Overall wear is like 0.03-0.05mm. Just asking what is the tolerated out of roundness..? 2 point gauge, otherwise I can't see the roundness.

[UrS4boy]

If I can nitpick on one thing...So I'd say all the measurements should be between 80.93 and 81.09mm.

If you are going there, which I don't think is correct, then the readings would have to be between 80.98 mm and 81.08 mm, i.e. a potential difference between minimum and maximum of 0.16 mm - which seems high.

[pasbogdan]

Strange...Usualy they are perfect round at bdc and weared at tdc.If you have a block with 0.02mm wear at tdc with 280k you should make a topic with it.It will be my and many others to see such thingSo still in perfect shape.
You use a 2 point or a 3 point bore gauge?

[Thuppu]

Where on bore you get the 0.02mm?It is wear on the top or out of round?Did you measured bores when they were bored and honed?I found a big important shop here that made me 81.5mm bores 0.02mm out of round.My luck was they made clearances for stock pistons not for fpc.Honed again with new honing stones and it was 0.005mm..

Out of round, and it's stock bore, driven about 280k km.

[pasbogdan]

Also note that the manual says not to measure the bores when the engine is mounted on a repair stand, as it could affect the readings. Of course it doesn't tell you what the engine *should* be mounted on when measuring!

It will not change anything in 0.01 sizes.Not even torqued head gets distorsions that you see with a 0.01mm gauge.Done that with stock bolts.Maybe arp will be different story...

[pasbogdan]

Where on bore you get the 0.02mm?It is wear on the top or out of round?Did you measured bores when they were bored and honed?I found a big important shop here that made me 81.5mm bores 0.02mm out of round.My luck was they made clearances for stock pistons not for fpc.Honed again with new honing stones and it was 0.005mm..

[elaw]

If I can nitpick on one thing...

The text in the manual states "Deviation from nominal dimension: max. 0.08mm". The way I read that, it's not max. 0.08mm deviation between all the measurements, but rather that none of the measurements can be more than +/- 0.08mm from the cylinder bore spec, which is shown as 81.01mm on the next page (for zero oversize). So I'd say all the measurements should be between 80.93 and 81.09mm.

Also note that the manual says not to measure the bores when the engine is mounted on a repair stand, as it could affect the readings. Of course it doesn't tell you what the engine *should* be mounted on when measuring!