I am going to replace the Yanmar 1GM10 on my boat with a reconditioned 2GM20, has anybody got any experience of having done this? Is it necessary to remove the galley top to do this or can it be done with just the front panel removed (which includes the under sink door and which slides in). I am hoping it should be fairly straight forward. I intend to mount the engine with the front mounts in the same place but the rear mounts further back which will shorten the prop shaft by about 4" as there is plenty of prop shaft to shorten but may need to open up the aft engine bulkhead and then get at the shaft coupling from the side panel in the cockpit locker. Any guidance would be appreciated.

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Hi Martin....... My Parker27 came with a 2GM20. It fits quite tight and I have a tough time accessing things like the water filter (better from the side panel), checking oil (better from the front) and bleeding air if I drain the fuel tank, but it can be done. Also....I can get my hands in from the side panel to check transmission oil and check the exhaust pipe and water cooling but can't reach in to touch the shaft bolt connection to the transmission.

To connect the shaft to the transmission, enlarge the rear bulkhead hole where the shaft comes out(it's not a support)just a place where the water filter and shaft oiler is located, you may be able to work from the shaft side through the cockpit access..you will need a skinny guy to slip into the cockpit locker and work through access port...or lay on stomach under cockpit floor. While you are at that location...you may check and replace the exhaust water lock and hoses. I had to replace the water lock and it required me to snake myself there.

As for removing the sink to slide the engine in, it may not be necessary since you simply slide the front panel out exposing everything.

On the 2GM20...do make sure that you change the bolt that tightens the generator belt...come up with a better system to do this from the front....my generator always gets a loose belt and I have black dust from the belt.

Hope this helps.

Marv Kowalewski, Parker 27, The Happy Seal

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Thanks for the info Marvin. I had figured I would need to enlarge the opening in the rear bulkhead so it's good to have that confirmed. The present position for my water filter is on the starboard side panel just behind the step but I may have to reposition if that proves to be a problem. I will be fitting a 65Amp alternator as I have 170Ahr house battery and 50Ahr starting battery (recommended ratio is 3 or 4 time charging amps so 55Amps to 73Amps charger recommended). Whilst doing this, I will check the fitment to ensure I can tighten it in situ. I might consider repositioning the fuel filter as well if I can find a place to put it without snagging other fittings. I have installed an Eberspacher heater under the cockpit sole and the outlet duct passes through the engine compartment high up on the port side before bending down at the front to the outlet at floor level. Glad I don't have to remove the galley as that would be a complete pain. I will probably have to temporarily put the engine in place to mark the holes for the engine mounts, then pull it out again to drill the holes before repositioning. I'm going to get a piece of 2.5mm steel plate to position over the sill of the engine bay and into the saloon floor space to facilitate sliding in and out. Hope it all goes together reasonably well. I believe the engine has a flexible coupling included which will help with alignment.

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Sounds like you have spent some good time sizing things up....AND I especially like the "slide in" approach. If I ever have to remove engine--that will be the way to do it.. THANKS.

You appear very handy so here is some more info in the electronics arena..

I am not sure that you need a bigger alternator. Think about this idea...
I use high amp batteries but do not use any alternator but the standard one provided. I got the idea from an "old salt" in practical sailor .....here is how I can adjust my charging system to supply charging to "fill up" a large amp battery. The alternator supplied has a built in regulator which monitors or "senses" that the battery voltage of about 13.5 is reached and they turn the charging down to float. If you take the sense wire from the alternator and run it through an adjustable voltage circuit you can "trick" the sense wire running to the alternator to stay charging longer....meaning maintaining a voltage lower than 13.5 and thus the alternator keeps feeding the battery(s).

Here is a commercial unit from Balmar: see the drawing

Digital Duo Charge -
DDC-12/24
Dependable engine starting requires
a dependable charge source for your
starting battery. The Digital Duo Charge
automatically tops off your starting battery
whenever your house battery is
being charged – even if batteries are
different technologies.

http://www.balmar.net/20...Balmar-Product-Guide.pdf 

Marv Kowalewski Parker 27, The Happy Seal

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Thanks for your reply Marvin, I have already fitted a Merlin four stage smart charger as well as their Smartbank Iite which which is an electronically controlled relay that parallels the two battery banks once the starter battery has reached full charge, it also works the other way when the engine is not running and the house batteries are fully charged from either shore power or solar panels ( I have three, two 18W, one either side of the cabin top behind the windows and one 68W on a hatch garage I fabricated from GRP, colour matched to the original grey and incorporating an instrument binnacle). Nonetheless, with a 4.5Amp Waeco compressor coolbox plugged in 24 hours a day, albeit running only 20% of the time, the solar panels only just keep the batteries topped up and that only in the summer, also If you read all the experts on electrics including Nigel Calder, whose excellent book on boat maintenance is my marine bible, they will all tell you that you should still have between a quarter to a third of your battery capacity as charging capacity, even with a four stage charger, solar panels and wind charging if you are so inclined, otherwise you are going to spend a lot of time with your engine running or your batteries are never going to reach full charge, which will accelerate their wear. The clincher is I already have the alternator which at the moment is fitted to the 1GM10, hence the need for more engine power. I believe the 2GM20 has a 55A alternator fitted but thats at the bottom end of the scale so the 65A alternator will give me a bit more juice, 70A would have been better but then you start to get into the area where you need a twin or multi groove fan belt setup. To save power elsewhere, I have converted all the lighting to LEDs including the galley strip light and masthead light and i'm considering changing the instrumentation to the Raymarine i70 system which is very low powered whilst giving a lot more information and connectivity to my tiller pilot for sailing to a wind angle on top of the usual compass course. I'm going to be busy this winter!

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Well...you certainly have thougth all this out. Really excellent logic. That's great because it insures your success with the transition. Let me know how things go....especially the slide in idea.

Oh.. Last question...do you think you'll have to change props? I have a Boston Whaler...when I changed to Honda 90 outboard from an Evinrude 90 ...I had to reprop. I will look at my Parker 27 to see if I can figure out what's on there ...it's a folding style.

Marv

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I will be using the same prop, which is a 13x9 two blade Varifold. According to the calculations I got from Brunton, from whom I purchased the prop (originally specified for the 1GM10 with a 2.6:1 gearbox) it should work with a Beta 14 or 16 or a Nanni 2.16, all with 2:1 gearboxes. They specified a 13x10 for the 2GM20 because they reckoned that it generated 18 hp plus with a 2.1:1 gearbox it was not spinning the prop quite so fast, however only the latest 2GM20s generate 18hp, the earlier ones, including the one I have bought only generate 15.5 hp so it should be more in line with the Betas or Nannis, add the additional load of the larger alternator and I don't anticipate a problem, It will still be quicker than the present set up which is only giving me 4.5 knots average.

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Hi Martin.....

Perhaps you would know.... I always wondered how to figure out... what is my gear box ratio?

I do know, since boat was purchased in 1989, that I have the "old" 2gm20 motor with sea water cooling. It is a very good match for this boat.

Thanks

Marv Kowalewski

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Hi Marvin, If you look at the rear face of the engine, normally on the larger part of the gearbox housing above the actual gearbox itself, you should find a plate about 2"x 3" which will have the gearbox ratio stamped into it. There are three ratios on the Yanmar 1GM10 and 2GM20 (interchangeable gearboxes) 2.21:1, 2.62:1 and 3.22:1. The reverse gear ratios on all the boxes is 3.06:1. Sometimes the plate may be on the port hand side of the gearbox, which on the Parker 27 means getting out a mirror, reaching through the side access panel in the quarter berth and reading the plate backwards! Alternately you could try using a smart phone camera if you have one and taking a couple of snaps. To help with removing the old engine and with the installation of the replacement, I have cut an oval hole in the port side bulkhead, behind the fuel tank, which I removed to flush out and clean. Although the tank will just fit through the cockpit locker access, the mounting lugs would not, so I cut one pair off (the forward facing ones) and I will use a piece of 1" square iroko screwed into the forward bulkhead to hold it back in place with just the rear two lugs bolted through the side panel. This will make it easier to get at the port rear mounting points and also the gear lever attachment. As a matter of interest, what size and pitch prop do you have and how many blades?

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Hi...

My boat is on a lift here in Florida. I need to get a dinghy to go under the boat.

I will check tomorrow on the following:

gearbox plate
prop size (hopefully stamped somewhere.


Thanks

Marv Kowalewski

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Hi again...

I am picturing your efforts... whew...but it will be worth it. That the tank can't be removed intact is too bad..I haven't thought about it but just last week I did drain (pump out) all the fuel and replace. Usually done once a year when it runs low. In Florida, fuel will grow bugs did you know...we have an additive to stop that. There are whole business here to drain and clean fuel in boats.

More info and question...
So since you are near the refridge..maybe you should check it out.....how it works..cleaning and such. (is it a Thermocouple type?) I haven't had a bit of trouble with mine..but I did try to remove it to see if it can be done (had a thought to change the Formica top of the sink....spiffy up the thing)...... it seems like the refridge can't be lifted straight up and out without removing the sink top.

More....
Also....this time while draining fuel (and water), I broke the little thumb screw under the water filter...had to take it out...lucky I had a die for the rethreading. I replaced it with stainless and a couple rubber washers. You may give that a look see as well as all the hoses which are all nice and hard and difficult to remove as I am sure you found out.

Finally....
I had a tough time after replacing hoses, and the water filter etc...to bleed air and get the fuel to run...I had to use a siphon bulb which worked ok.

So I will write tomorrow.

MK

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We have the same problem here in UK with fuel bug, especially with forecourt (motor) diesel which I use rather than red diesel which has potential problems with customs duty issues on the Continent. I use an additive but even so you can still get a build up of sludge and since I had no idea when it was last cleaned out properly (probably never) I decide to pull it and give it a proper steam clean. There was a lot of muck a slimy sludge in the bottom so it was worth it. On British boat, the galley toolbox is just that, a passive toolbox, no electrics or mechanical cooling, hence the reason I have a portable Waeco 22 litre compressor toolbox under the table in the saloon. The fuel filter seems fine and I've never had problems with drawing fuel through to the engine even after I disconnected the fuel line at the tank to fit a 'T' piece to supply fuel to my Eberspacher (Espar), although I have since removed that and fitted a separate tank as I was getting fuel starvation issues on the engine as it would draw air in from the Espar. In fact I just replaced the hose completely to bypass the 'T' piece etc and pumped the small priming lever on the engine pump till fuel came out of the two screws which I loosened in turn as per Yanmar's bleeding instructions and she fired up straight away. Takes about one minute and both screws and the pump lever are accessible form the opening under the steps on the 1GM10. I will need to check where they are on the 2GM20 but I believe the pump is in a similar position to the 1GM10.
My fuel filter is on the rear bulkhead, the same as yours but I may move it a little closer to the side access panel in the quarter berth as i found it a bit difficult to reach both hands in to drain the filter and hold a container underneath at the same time. My inlet water trap is mounted immediately behind the step in front of the engine and I hope to be able to leave it there as it's very easy to get at although I had to make up a wooden 'spanner' to fit the plastic screw on lid as sometimes it was impossible to undo without a lot of grunt. I also fitted a stand pipe using a piece 10mm tube into the inlet which is none standard on Vetus filters. Before that, unless I turned the inlet water tap off when the engine was not running, the water in the trap would slowly syphon away and I would end up with no cooling water the next time I started the engine. I believe some water traps have this feature as standard but not the Vetus ones. having said that, they are quite large, about 5" dia and I may have to fit one of the smaller ones if their is insufficient space with the new engine in there.

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Hi Martin,
Will you be selling the old gm10? I am looking for an engine and based in Chichester.
Thanks
J

Hi James, yes I will be selling the 1GM10, however I have someone who I am waiting to see if he wants to go ahead and purchase it as he is considering putting it int his Cormorant but is not sure if he will have the time to do it, if he does not want it then I will let you know.

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Hi Martin, thanks for reply, I have sent you a private message with my email address on. Please let me know as soon as you hear from your friend as I am planning to start my install as soon as I can.
Kind regards,

James

Hi Martin,

How's it coming? No I haven't forgotten to do as I promised..re prop size etc.... our tides are not cooperating for me to dunk the little dinghy especially during a time when I am working on the boat.

Just got back from work... it's low tide now so will wait till later to get under the boat.
hey...looks like your going to be able to recoup something for the 1GM....

Later.. Marv

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I'm hoping to pull the engine sometime next week, it's all disconnected apart from undoing the four clamp bolts on the drive shaft. I'm going to get my local friendly welder to weld up some thick wall 2" box section steel into an incomplete ( three side) of a box with some lifting eyes on the out side of the two opposite sides so as to be able to lift the engine from directly above it without removing the galley top, I will then lift it back into the cabin and then attach a conventional direct lift with a chain hoist to lift it into the cockpit and thence over the side onto the ground . The replacement will be a reverse of this. I realised i would not be able to slide it out as originally planned as the oil pan is in the way. Will let you know how it goes.

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Gosh.... I forgot about that lower oil pan below.......but seems to me if you saw out the lower front crosspiece you will have a good shot at pulling it forward.

As for the 2GM20 I am sure you measured.....you would need to saw that crosspiece part out to slide her in.

By the way ..once mounted in the well. ...I can almost stand a can of oil between the top of the engine and the underside of the counter top. ...about 7 to 8 inches. Should easily clear to drop down into the small bilge well.If I can give you any help....measurements etc....let me know..I am working on the boat tomorrow and Tuesday. I painted the floor after I derusted it and Jayne took all the cushions and did a dry cleaning and strong vacuum... removed spots etc.
I did the wood (teak) with Danish oil..and things look almost new! (Danish oil takes a long time to dry though.
I am working to restore the outer skin top and hull with a product called Polyglow....I have it on my Boston Whaler and it is an excellent "gel like" finish.

Sounds like you are well planned ..but if I can help..write.

Marv

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Hi martin.....

per our discussion.... my prop is a folding DARGNL?? (can't make it out) made on Poole..
sixe printed on it ... 14X11

Is that good or bad???

Marv

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Hi Marvin, it will be a Darglow prop and 14x11 is good size wise, the reason I went for a 13" inch diameter was because I was concerned about tip clearance causing interference with the hull, so it's interesting that you have a 14" inch prop without any problems, also the pitch is higher than I would expect but if it works then that's great. Brunton who supplied my prop quoted me a figure of 13x10 for a Yanmar 2GM20 with a 2.21:1 gearbox however that's assuming it is the latest version of the 2GM20 which outputs 18 hp at 3600 rpm whereas the version I have is an earlier version which puts out 15 hp at 3400 (it seems that Yanmar have managed to up the max rpm on the later version hence the increase in power)

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