I was Bored so Pulled the Head on my Yanmar

[a64pilot]

I'm sure you know to keep form glazing the cylinder walls, you need to get a good, hard run on her, full RPM or close to it for an hour or so. Delay this for too long and the rings many never seat

[sailorchic34]

Originally Posted by a64pilot

I'm sure you know to keep form glazing the cylinder walls, you need to get a good, hard run on her, full RPM or close to it for an hour or so. Delay this for too long and the rings many never seat

You know people say that all the time. Problem is the 3gm is oversized for my boat and even 2800 RPM just pushes the tail down without any increase in speed.

I ran the engine for 6 years at 2000-2300. When I pulled the head, there was not a bit o glaze on the cylinder walls. So from personal experience, that whole glazing issue is a total non issue.

Plus I have pretty much zero blowby, so I can say the rings are sat in, nicely.

[HappyMdRSailor]

Originally Posted by sailorchic34

You know people say that all the time. Problem is the 3gm is oversized for my boat and even 2800 RPM just pushes the tail down without any increase in speed.

I ran the engine for 6 years at 2000-2300. When I pulled the head, there was not a bit o glaze on the cylinder walls. So from personal experience, that whole glazing issue is a total non issue.

Plus I have pretty much zero blowby, so I can say the rings are sat in, nicely.

(insert inappropriate juvenile giggle)

[sailorchic34]

Originally Posted by bobconnie

SC, I questioned the Yanny dealer down here on the Bayou (on the sly) and he told me that yanny had a run of bad pistons with bad ring grooves! But the factory only fixed some that were under a year old ! Just sayin it did not come from anything you did !! And I knew you could fix it !!! Grats !!

Thanks for the conformation, Bob. I had heard of too many instances of ring groove failure on early 90's 3gm's, for it to be anything other then a manufacturers defect. Once, maybe twice is a fluke. Four or five times, and its either out of spec materials or machining was off.

[zeehag]

diesels run at idle constantly on land. why suddenly is it that when they are on land they allegedly glaze when at idle.......makes no sense to me whatsoever.
i am glad benni that you got the problem solved before it was a true problem and therefore much more pricey to repair...........and requiring more different colors of engine paint....

[sailorchic34]

Luckily my engine only required 2 colors, so not too bad repair wise. ;-)

[sailorchic34]

Originally Posted by HappyMdRSailor

(insert inappropriate juvenile giggle)

Why do I even try.... ok, ok, the stern of da boat.. ;-)

[HappyMdRSailor]

Originally Posted by sailorchic34

Why do I even try.... ok, ok, the stern of da boat.. ;-)

Try as you might... You're stuck with me....

I do temper myself on occasion...I left "blowby" unscathed....

[a64pilot]

Originally Posted by zeehag

diesels run at idle constantly on land. why suddenly is it that when they are on land they allegedly glaze when at idle.......makes no sense to me whatsoever.
i am glad benni that you got the problem solved before it was a true problem and therefore much more pricey to repair...........and requiring more different colors of engine paint....

Glazing is a result of several possibilities, one is light rust on the cylinders like when an engine sits unused, each time it's run the rings clean off the rust of course eventually leaving a polished cylinder wall.
Over heating can result in a glazed cylinder wall too, unsure of the mechanism of exactly how that happens, but it's the reason you don't want to idle an airplane engine for long.
If the engine isn't broken in properly, you can get glazed cylinder walls, but once broken in, excessive ideling won't glaze cylinder walls, it will lead to "stacking" a whole other issue.

You don't want glazed cylinder walls for several reasons, the crosshatching in cylinders is important as it hold oil, oil of course cools and lubricates, Polished cylinder walls have excessive blow-by, that leads to high oil consumption and high oil temps due to hot gasses blowing by the rings into the crankcase as well as oil contamintaiton.

http://coxengineering.sharepoint.com...reglazing.aspx

http://www.plantengineering.com/indu...ca8f03440.html

Only point is, it's maybe not a good thing to "baby" your engine, especially when newly rebuilt, more so even than a brand new engine.

I think you two already knew this, but others may think the best way to break in an engine is by babying it, but you baby the bearings to break them in, but run it hard to break in the top end.
Personally I'll start babying one in the beginning followed by short pulls at full throttle, as I get more time on the engine, the pulls get longer and the rest between pulls shorter

[sailorchic34]

Originally Posted by HappyMdRSailor

Try as you might... You're stuck with me....

I do temper myself on occasion...I left "blowby" unscathed....

And I thank you for your restraint. ;-).

[sailorchic34]

Luckily my engine does not sit unused that much. Usually give it a good run, once or twice a week. Today is one of tho-se days too. The joys of the full timer. No rust on my engine. In my talks with an engine guy, he did say rusting was a concern with engines that sat a lot. Least on the cylinders with an open valve.

[HappyMdRSailor]

Originally Posted by sailorchic34

And I thank you for your restraint. ;-).

I think they call that symbiosis.... I'll be the mushroom...

(thanks for the fun chickee... gotta tear myself away now...)

[svJasmine]

I read this thread a couple of years ago and now I am doing the same with my 3gm30f.

Have it out of the boat and having fun.

[Badsanta]

What kind of problems did you have and what ones are you finding? Keep us updated. Thanks

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[svJasmine]

Sorry for the late reply.

There was a problem with the vented loop and a bit of water entered the cylinders. Then sat for months while I was away. It has been bored 0.10 over (.25mm), and awaiting full rebuild.




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