Yanmar Cylinder Liners

[Compass790]

Originally Posted by Eairlie91

Sorry to wake this up again, but hey ho.

I’ve got an issue with my 2gm20, in that when I last tried to start it, it was seized and would not free up with a 750mm breaker bar on the end of the crankshaft. Upon further inspection I found water in the oil, and the air filter, and decided to pull the engine. Once I got it home I pulled the head and found water in one cylinder. I’m thinking the head gasket was probably dead, but I’m also concerned about the number two liner being cracked, as it had a load of water in it, where number one had barely a drop.

I’ve found some of the comments here useful for working out how to pull the liners, I’m just curious as to how easy people found it to fit the new liners?

Are you sure your 2gm20 even has liners?

[Eairlie91]

Thanks for your quick reply!

I did a bit more research last night and found a copy of the workshop manual for the GM series engines. It turns out that the 1, 2, and 3GM engines have liners, but the GM10, GM20, and GM30 engine’s do not which is a nuisance for me! The other difference in the engines is the bore, there’s a couple of mm in it which makes for a larger displacement in the later engines.

Oh well, looks like if one’s cracked, I’ll need a new block 😑

[masonc]

Originally Posted by Eairlie91

Thanks for your quick reply!

I did a bit more research last night and found a copy of the workshop manual for the GM series engines. It turns out that the 1, 2, and 3GM engines have liners, but the GM10, GM20, and GM30 engine’s do not which is a nuisance for me! The other difference in the engines is the bore, there’s a couple of mm in it which makes for a larger displacement in the later engines.

Oh well, looks like if one’s cracked, I’ll need a new block [emoji58]

Can you clarify this, does my 3GM30F have liners? I have a spare engine, thinking of refurbing it (although it works fine)

[Eairlie91]

I can confirm for you that the 3GM30F does not have liners, as it has an alphanumerical suffix after the GM designation. The F stands for fresh water cooling, I.e. you’ll have a heat exchanger on your exhaust manifold.

Once I jump back on my computer later I shall post the link the the GM series workshop manual, accessible free of charge.

[Wotname]

FWIW, while the 1GM10, 2GM20(x) and 3GM30(x) do not have liners, Yanmar does supply oversize pistons for these engines. At least they did the last time I checked .

[Eairlie91]

I imagine they still do, for a price of course! I just need to work out if my cylinders are cracked, or my block, as if they are I’m going to need a new block 😑

[GordMay]

Originally Posted by Compass790

Are you sure your 2gm20 even has liners?

Item 7 Part #121450-01100 - Cylinder liner

[Wotname]

Originally Posted by Compass790

Are you sure your 2gm20 even has liners?

Originally Posted by GordMay

Item 7 Part #121450-01100 - Cylinder liner

Gord, that is for a 2GM and 2GMF, not a 2GM20 or 2GM20F. Different engines!
The x20 (and x30) don't have liners.

[a64pilot]

You can usually have a dry liner replaced, it takes a machine shop of course, but it usually can be done.

[GordMay]

Originally Posted by Wotname

Gord, that is for a 2GM and 2GMF, not a 2GM20 or 2GM20F. Different engines!
The x20 (and x30) don't have liners.

You're absolutely right! Sorry 'bout that misdirection.
Per Page 1-4*, the 2GM20 (F/C) has a “Sleeveless” cylinder.
* Service Manual ➥ http://www.nhmr.nl/media/org/4d7ea5e...76389ee424.pdf

From 2013 ➥ Does the Yanmar 2GM20 have dry sleeves? [Sitemap] - Cruisers & Sailing Forums

[a64pilot]

Most all engines have sleeves, a few like Briggs and Stratton lawnmower engines and some motorcycles don’t.
The difference is wet sleeves are user replaceable, dry sleeves can usually be removed by a machine shop, a new one pressed in and bored to correct size. Many people like me don’t like replacing a dry sleeve, we believe that cylinder will run hotter etc., but it’s done often and does work.

I have even seen some parts manuals depict a dry sleeve and give it a part number, the usual way to tell is if there are no sealing O rings in the parts manual, it just might be a dry liner.

[Eairlie91]

This is the manual I'm using, I now just need to work out how I'm removing the governor weights retaining nut so that I can remove the crank shaft, similarly, the camshaft nut so that I can pull that too, and have the engine in it's base components for inspection, re-paint, and rebuild. any advice folks?

GM Series Workshop Manual

[Compass790]

It should tell you in the manual how to remove those parts.
I wouldn't be too quick to blame the block for the water. First thing I'd be checked is yr exhaust mixing elbow. They are notorious for failing & dumping water in the exhaust. Buy or make an s.s replacement elbow if that is the problem