What to replace on 2GM20?

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ridgy

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Next on the job list is sorting my new to me 2GM20, aged at least 25 years.
I've run it on the hard and it started instantly after no use for 3 months and ran perfectly with no smoke for several minutes so I'm not touching the internals.

However I do have the opportunity to replace ancillaries as I'm taking it out (or rather sliding it forward) in order to replace the stern gland.

Normal service items are a given e.g. engine oil, gearbox oil, oil filter, primary/secondary fuel filters, pencil anodes, impeller, belts
I will also get the starter and alternator refurbished.

Parts4engines offers me a few other things I could change easily:
Fuel lift pump (£45)
Thermostat (£25)
Water pump rebuilt kit (£49)

And a big one that I have heard of failures:
Stainless exhaust outlet (250)

I'm inclined to preemptively replace these to unless there are reasons not to?
Any other bits that I've missed?
 
I spent a couple of hours pumping Rydlyme around my engine, after I noticed a bit of salt buildup when I changed the pencil anode, using some 19mm hose and a spare bilge pump in a bucket of 50/50 Rydlyme. I put the thermostat into the bucket while the Rydlyme did it’s thing and after 20 mins it was shiny and clean.
22 year old engine that doesn’t miss a beat, very little smoke, starts on the button on frosty January mornings, and I’d like to keep it that way.
 
if the water pump rebuild kit includes the shaft seals and bearings, I’d go for it.
My local marine diesel engineer warned me that the water seals on the pump can stick to the shaft and tear on first restart if the engine sits for a few months, so I gently turn the engine by hand with the decompression lever up before starting if I have left it any length of time.
If the shaft seals fail, it drips water from a tell tale hole onto a steel oil pipe and rusts it.
I have the stainless exhaust mixing elbow.
 
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Dellquay13 said:
If the shaft seals fail, it drips water from a tell tale hole onto a steel oil pipe and rusts it.
I have the stainless exhaust mixing elbow.
Click to expand...

Isn't this true just for the 1GM? I don't think my 2GM20F has a hole (though I may be wrong on this), and at any rate I don't think it has an oil pipe anywhere near the water pump (I'm slightly more confident about this than my previous statement).
 
sailoppopotamus said:
Isn't this true just for the 1GM? I don't think my 2GM20F has a hole (though I may be wrong on this), and at any rate I don't think it has an oil pipe anywhere near the water pump (I'm slightly more confident about this than my previous statement).
Click to expand...
Please pardon my error, I thought the water pump was shared on both models, replacing the seals may still be prudent.
 
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My 3GM30F is now coming up to 25 years old. It is in remarkably good condition, starts and runs well at about 2800 hours . Much of the kit on it is original, even hoses, but it has had a new exhaust elbow and water pump. As a raw water cooled version yours will undoubtedly benefit from the Rydlyme treatment but otherwise I would assess and only change what is needed.
 
ridgy said:
Next on the job list is sorting my new to me 2GM20, aged at least 25 years.
I've run it on the hard and it started instantly after no use for 3 months and ran perfectly with no smoke for several minutes so I'm not touching the internals.

However I do have the opportunity to replace ancillaries as I'm taking it out (or rather sliding it forward) in order to replace the stern gland.

Normal service items are a given e.g. engine oil, gearbox oil, oil filter, primary/secondary fuel filters, pencil anodes, impeller, belts
I will also get the starter and alternator refurbished.

Parts4engines offers me a few other things I could change easily:
Fuel lift pump (£45)
Thermostat (£25)
Water pump rebuilt kit (£49)

And a big one that I have heard of failures:
Stainless exhaust outlet (250)

I'm inclined to preemptively replace these to unless there are reasons not to?
Any other bits that I've missed?
Click to expand...
Lift pump maybe, but i would buy yanmar. When you have the two in your hands you will see the difference in quality. Note the copper washer on the inside of the exit banjo of the lift pump is thick. Can change to dowty type. Really easy to strip threads in lift pump.
If you change the thermostat you may trash hoses at £30 ish each. Unless change to silicone.
Pump rebuild. They all have drip if leaking. If you go rebuild route there is a strong argument for replacing the shaft £60 ish. The seal us a friction fit so the shaft is likely to be scored. The score will wear a new seal. You can polish it out supposedly, but it is a lot if work and even at 2500 grit you are never sure it is smooth enough. So string argument for buying replacement pump complete with pully that you can just swap out if required. £280 ish.
 
The normal service items in your list seem very sensible as does redlyme treatment.
Personally I would leave the alternator and starter alone if they work well. I would inspect the exhaust elbow and leave the rest from your list.
I would be pretty anal about the fuel tank and treat it for bug and suck out the bottom before changing fuel filters.
Sometimes disturbing things causes secondary problems.
One word of caution. If you have slid the engine forward and it is not held steady then be careful not to-get trapped as you work on it- it may slide more than you want!
 
It is certainly possible and quite easy to polish the seal mark out of the pump shaft. Mine has run drip-free for over 500 hours since I did it. Chuck it in a drill and slowly work your way up to 2400# and mirror finish. It might take you an hour or so.

And re rusting oil pipes, the 2GM family has one which runs from near the starter around behind (ie aft of) the block. Due to its location it is very easy to ignore and is known for rusting out eventually with the risk of total oil loss and seized engine. How do I know this? Well I had a miraculous stroke of luck when mine partly ruptured, leaving just enough oil to get me into harbour. Another 30 minutes of engine run-time and I'd have had a bilge full of oil, a dead engine, and a 25 knot lee-shore situation. Lucky me!
Inspect it and replace it if you have any doubts. It's only a bit of pipe fitted with flare connectors, so a diesel mechanic or injector workshop workshop will be able to make a new one up for you if you take in the old one for them to match, at a tiny fraction of Yanmar's price.
Cheers, Graeme
 
from my experience on my 25+ yo 2GMF
service kit for the raw water pump
lift pump (I'd replace altogether)
diesel pipes
replace all copper washers with dowty ones
check main filter and the two screws on top, v.easy to strip the threads!
check clean exhaust elbow
 
Agree about the oil pipe, mine was rusty but still intact. Easy job to replace when you can get at it, but a pig with the engine in-situ. I got my local garage to make one up with brake pipe and brazed banjos. Cheaper than the Yanmar part.
My 2GM eventually died from a porous cylinder head, which I made worse by giving it a de-coke. What I thought was carbon was in fact rusty metal. Found out after paying for two head gaskets at many
umpteen quid each. A new head would have cost almost as much as a new Beta 20.
 
i have a 35 year old 2GM20 Raw water engine on my boat

Since getting the boat in 2017, I have replaced the following:

Engine mounts, now have Polyflex
New Drive plate (clutch)
Refurbished starter motor
New fuel filter assembly
New fuel hoses
New thermostat
New water pump
Anodes
Refurbished injectors
 
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