Yanmar cylinders slightly oval

[Nicholson58]

Originally Posted by IsaakOker

Sorry for not giving more info initially.

I removed pistons before honing !😅

And the measurements for absolutely everything(combustion chambers, block, rod, crankshat, everything is as new)

The only measurements that aren’t ideal are the cylinders not being entirely round.

Cleaned everything out thoroughly! Ready to reassemble.

The only other big issue I have is the alternator tensor bold going though the water pump housing is stuck and head broken off so I’m going to apply head later on this week and try to loosens it that way.

Ps: going to install new rings obviously!

I hope you noted the position number and orientation for each piston. They should ideally go back exactly as they had been. - same for the rings if you retained the old rings. New rings will be perfectly round and may take a while to seat. Check the push rods for straightness too.

[Icarus]

Originally Posted by IsaakOker

Hahah ok.



1100h



Veeeey Long story short, bought the boat after it had been sitting for years with fresh water in cylinders so rusted slightly.



Honed them very lightly just to get some hatches going and measured.



I though oval cylinders could mean risk for piston tilting and eventually getting stuck and therefore bending rod, etc.

I would think the cylinder rings might have rusted after sitting in water for a years, which isn't a good thing.
Honing a cylinder bore without removing the piston? I think that's not a good idea.
At the least the pistons should get removed and the rings and bore ought to be checked.
Don't worry about the bores slightly out of round if within specs.

[skipperpete]

I’ve been following your engine thread since mid 2019 and just had a look at your original photo’s of the cylinders. It’s been quite a long haul for you to reach the final assembly stage since the initial hydrolock, well done, it’s nearly time for you to get some use of your boat and go sailing.

[Rob H]

The amount of .002 Is insignificant and the engine should run for a very long time.

As long as you pulled it down correctly, pulled pistons, know you have freed, cleaned the rings and protected everything like crankshaft during honing and cleaned up, it should be good to go!



Good Luck

Rob H.

Edgewater MD.

[IsaakOker]

Hi to all of you! Just realized you had continued answering !

And yes, I definitely have to go sailing…
We were quite unlucky when we went back to see our families just before COVID hit and couldn’t come over until now so the poor engine has been sitting a few years more but actually, it hasn’t deteriorated even more!

Anyways, got the pistons in, and everything seems great.

Finally got a torque wrench and have put the oil pan back on so now it’s cylinder head assembly as I’ve done the valve job too.

I am hesitant to attach the head as I have the alternator bolt stuck in the coolant pump housing and can’t get it out, literally just broke the head off flush with the pump housing so am going to start a new thread asking for opinions on how to get it out 🤔

[Celestialsailor]

The first question that should be asked is...What are you using to measure this? Telescoping gauge? Bore gauge with standard ring? I.D. mics?