Yanmar 1GM10 - advice?

[Tim Good]

In a prospective boat is a Yanmar 1GM10. A common engine for boat built in the mid 80's I gather.

This particular engine has no history other that the engine number (04033).

Can someone with some knowledge let me know a few things please. If it is original and therefore about 25 years old, is it likely to be on the away out or will it continue to provide useful service if maintained well?

What specific things can I look for when sea trialing it and is an engineers pressure test worth doing?

Many thanks for any advice in advance.

 

[Pleiades]

Yanmar 1 GM

Have used a 1 GM for 13 years heavy use - wonderful marine engine - nothing better at that size imho. When I sold it with the boat it ran just as well as it did when new and good for another decade I imagine before a major overhaul. It is difficult to predict the longevity and condition without knowing the history and use of a particular engine. Has it been regularly serviced, has it ever been overheated, frozen,had sea water at it from deck leaks etc etc? A good inspection will easily pick up some clues, preferably by a marine engineer if not confident about mechanicals.
Yanmar were cursed for a few years by faulty Yanmar issue impellors for the 1 GM - the bonding was wrong spec and the shaft pulled away from the rubber prematurely. They were also plagued by other brand impellors which although identical in appearance to the correct fit were slightly wrong sized and hence wore out quickly.
Another problem common problem was exhaust elbow corrosion - not a problem if the manufacturers warnings issued to Yanmar Agents were complied with at servicing and inspection time.

Hope you get a good one.
Robin
Pleiades of Birdham
MXWQ5

 

[Tranona]

Very little to go wrong. Had mine for nearly 20 years and then changed to a more powerful Nanni. Old engine now doing sterling service in another boat.

Weak points as already suggested are exhaust elbow, external oil pipes which can corrode, water pump which is a nice cocktail of materials - fine if no leaks but can corrode the surrounding casing and fastenings. Speedseal a useful mod. Anode cunningly hidden behind alternator and often ignored. Cooling system pipes need periodic cleaning. Sometime poor electrical connections in wiring loom and panel. Fuel filter housing bit of a pig to get to seal properly. Sounds a lot, but all easily solved. Basic engine gives few problems except if water gets in because of corroded exhaust elbow or lack of antisyphon valve.

Virtually no changes in whole life of engine, so current spares fine for old engines. Can be a bit cruel to engine mounts at high engine hours.

 

[pete]

My 1GM10 is nearly 23 years old and still has very good compression. As mentioned I check the exhaust bend for internal porosity and the exhaust port in the head for carbon at end of each season after changing the oil and flushing with antifreeze, and the oil pipes under the water pump (I have never had a problem with this) but I do check the pump occasionally for leaks.
Brilliant little engine.

Pete

 

[sailorbaz]

Yanmar 1GM10

Mine's No. 00149 and was installed in my boat in 1985 and it's done about 1000 hours. The previous owners have kept a very detailed log of all maintenance. It had a new cylinder head in 2002 because the water passages were corroded. It's had the mixing elbow replaced once. The external oil pipes don't corrode if you don't let the bilge water rise to their level - i.e. keep them dry. I've just serviced it and it runs very quietly with very little vibration. The main things to check if there is any vibration are the rubber engine mounts and the alignment of the prop shaft.
http://www.ybw.com/forums/attachment.php?attachmentid=17119&stc=1&d=1333164124

Sailorbaz

 

[Niander]

Good idea to paint The external oil pipes or coat in grease
if water pump seal goes it drips seawater onto the high pressure oil pipes!
Obviously will then corrode through...so have a good look at them
Generally a very good engine
as said change the anode that helps stop internal corrosion of engine
and change all filters ,check valve clearances,change the engine and gearbox oil
if not worn it will last for years

 

[Tim Good]

Mine's No. 00149 and was installed in my boat in 1985 and it's done about 1000 hours.

So SailorBaz's is 1985 and numbered 149 then this one certainly can't be original in a 1986 boat if numbered 4033? It certainly doesn't look old but then you can never tell if they have been given a lick of paint.

 

[Tranona]

Difficult to tell just looking as there is little physical difference between a 1983 and a 2012 engine. Also provided you don't get water leaks the paint stays good. So condition and maintenance history more important than age.

 

[TQA]

TESTS

1 Does it start easily from cold. When you test this make sure it really is cold, owners have been known to sneak in early.

2 Run it at full throttle for at least 15 minutes on the sea trial and look for overheating, expect some rise but it should level off.

3 Did the full throttle test produce lots of smoke. Copious amounts of blue smoke indicates oil useage, black smoke indicates fuel injection issues and white smoke means you MAY have overheating issues.

If it starts easily without 'easystart spray' and runs at full throttle for 15 mins without excessive smoke it is most likely OK. Some small evidence of black smoke is OK.

 

[tom_sail]

TESTS

1 Does it start easily from cold. When you test this make sure it really is cold, owners have been known to sneak in early.

2 Run it at full throttle for at least 15 minutes on the sea trial and look for overheating, expect some rise but it should level off.

3 Did the full throttle test produce lots of smoke. Copious amounts of blue smoke indicates oil useage, black smoke indicates fuel injection issues and white smoke means you MAY have overheating issues.

If it starts easily without 'easystart spray' and runs at full throttle for 15 mins without excessive smoke it is most likely OK. Some small evidence of black smoke is OK.

That was a very useful reply, thanks. I was little worried by mine producing black smoke on full throttle buts it's a small amount just a haze of grey/black smoke.

 

[Spyro]

That was a very useful reply, thanks. I was little worried by mine producing black smoke on full throttle buts it's a small amount just a haze of grey/black smoke.

That can also be caused when engine is over propped or a dirt prop or hull. Also can be a a sign of a blocked exhaust elbow.

 

[basil421]

My 1GM10 has the engine number 21447 and if the information I have from previous owners is correct it was installed around 2004/5 if that's any help.

 

[tom_sail]

That can also be caused when engine is over propped or a dirt prop or hull. Also can be a a sign of a blocked exhaust elbow.

Agh I hope it's not the latter. I have got an enormous 3 bladed prop on a 26 foot boat. It doesn't spit out black constantly just a little for the first few seconds of full rev, almost like it's carbon deposit getting flushed out, which is why I do it quite often, it does smell bait though.

 

[JeffBoath]

Had one in my Invicta 26, great engines, it never let me down and was over 20 years old, apparently they like to be run hard (so I'm told by a marine engineer), spares can be expensive, especially replacing the exhaust elbow! I had total faith in mine, it helped me out in many a crappy beat to windward!

 

[Severnman]

Get your replacement exhaust elbow from ExhaustElbow.com. US company, delivered quality product much much cheaper than Yanmar in a few days. No connection; just a happy customer.

 

[KenMcCulloch]

ANother satisfied user. I had one for 4 years in a Folkboat and can confirm much of what's already posted as good advice. My only addition would be to check and adjust the valve clearances regularly. With mine I had some starting problems which simply adjusting the tappets improved greatly.

 

[geepee]

+1

Got one earlier this year, £65 inc f&d and made from stainless, versus a Yanmar elbow at circa £130 which will last a couple of years .........

 

[Sniper]

On the basis of these recommendations, I've just ordered a S/S elbow from the States

 

[Tim Good]

My 1GM10 has the engine number 21447 and if the information I have from previous owners is correct it was installed around 2004/5 if that's any help.

Thanks for that! Come on everyone, what are your engine numbers and years?

 

[Rob_Webb]

Agh I hope it's not the latter. I have got an enormous 3 bladed prop on a 26 foot boat. It doesn't spit out black constantly just a little for the first few seconds of full rev, almost like it's carbon deposit getting flushed out, which is why I do it quite often, it does smell bait though.

I think that's pretty normal, the black is usually unburnt diesel from the engine slightly overfuelling until it reaches full speed (engine and boat). In the same way that if you acelerate sharply from idle to say 50% throttle, you will see a small amount of black until the engine settles at the new fuel burn rate.

If you never get any black at full throttle it's possible your throttle cable could do with a tweak adjustment as you may have a few more potential revs in the engine that you aren't obtaining with your throttle lever wide open.