Is it "dangerous" check and clean the riser on Yanmar 3GM30?

[LorenzoC]

Hi to all, my adventure in repairing my first boat, an Elan 36, seems to a neverending story. I know that every boat owner never finish to repair his/her boat, but I would like to start enjoying it other than repair it.
After the mechanic did the more important repair and the annual service in Pula, where I bought it. It remains to change the sealing of the head of the engine, check/change the stuffy box and check/clean/change the injectors, riser and the exhaust tube. I hope the engine part name are correct because English it isn't my first language .
The mechanic suggested to me found that the oil level is low and it seems to him not enough thick. When I asked him to check the riser he suggested not to do because it is made in cast iron, he need to use acid to clean it and the acid could broke it because it is old.
I saw that the riser is an expensive part, at least 700€, so I wanna ask you: is there a way to check and clean it without damage it?
Could I do it by myself?

Thanks in advance

 

[bignick]

I have a 2gm20 in my Elan 295. I too was a little worried about the exhaust elbow (assuming exhaust elbow = riser) and was considering replacing it with a stainless one. When I removed it I found that inside it looked like new, so I decided just to refit it.
I was planning on pulling it apart again to replace the gasket, but as it doesn’t leak I’ve not bothered and left it well alone. This isn’t best practice, so I would recommend getting a gasket for it.

incidentally, you can get a machined stainless riser for a 3gm30 for 318 euro, plus tax and shipping, from Parts4Engines.
Yanmar 3GM30 Stainless Steel Exhaust outlet kit

There’s also a company in the US that do welded stainless tubular ones, but I’d need to dig out the link.

Either would be at least as good as the Yanmar one, and considerably cheaper.

I would recommend you have a go yourself - it’s not a difficult job to do, but be careful removing it - you don’t want to break anything as it could be very difficult to fix. I soaked the bolts/nuts in penetrating oil for a couple of days first, to make sure they would come out cleanly.

 

[LorenzoC]

I have a 2gm20 in my Elan 295. I too was a little worried about the exhaust elbow (assuming exhaust elbow = riser) and was considering replacing it with a stainless one. When I removed it I found that inside it looked like new, so I decided just to refit it.
I was planning on pulling it apart again to replace the gasket, but as it doesn’t leak I’ve not bothered and left it well alone. This isn’t best practice, so I would recommend getting a gasket for it.

incidentally, you can get a machined stainless riser for a 3gm30 for 318 euro, plus tax and shipping, from Parts4Engines.
Yanmar 3GM30 Stainless Steel Exhaust outlet kit

There’s also a company in the US that do welded stainless tubular ones, but I’d need to dig out the link.

Either would be at least as good as the Yanmar one, and considerably cheaper.

I would recommend you have a go yourself - it’s not a difficult job to do, but be careful removing it - you don’t want to break anything as it could be very difficult to fix. I soaked the bolts/nuts in penetrating oil for a couple of days first, to make sure they would come out cleanly.

Good to know! Thanks for the link, but I think the mechanic was talking about this part:
Yanmar Shop - Catalogue Search Results for 728370-13501

 

[bignick]

it is the elbow, also referred to as a riser, which more often causes a problem. It can either get blocked with carbon deposits, or (more common on Yanmar) corrode internally where the hot coolant water gets injected, so the sleeve that directs the water away from the engine disappears. This makes it more likely for water to get back into the engine, if it doesnt start quickly.

I’ve not heard of an exhaust manifold assembly needing replacement, though I’m sure someone will post soon and contradict me!

 

[bignick]

It seems like your mechanic is recommending some work that I wouldn’t do unless there was a known problem with the engine.
E.g. I wouldn’t take the head off or “change the sealing of the head of the eng8ne” , which I would take to be replacing the head gasket, unless the engine was not running correctly.
I’d also leave the injectors well alone unless you can’t develop full power.

I would change all the belts, water pump impeller, all the filters and replace the oil.
my 1999 boat also has a Volvo drip less shaft seal - no stuffing box To check or adjust.
how confident are you in your mechanic?

 

[vyv_cox]

The part in your diagram is the manifold. I have never heard of a problem with it, so would not touch it unless essential. What makes you think the cylinder head gasket needs to be changed? Again, not an item that commonly needs attention.

My 3GM30F has done 2700 hours, the only major part that needed to be changed was the stainless steel elbow at about 2000 hours. This is a very reliable engine

 

[LorenzoC]

I'm sorry, when I wrote "change the sealing of the head of the engine" I mean the gasket. Also the mechanic surveyor that saw the engine in Pula put the gasket in its list. It is because there is some oil on the engine's head.
My engine is a 3GM30, sea water refresh system. I know that there is a kit to "upgrade" it to fresh water cooling system, but I still don't know the real condition of the engine and if I need to change it, I don't want to spend money on upgrade it.
My boat did 10 years of charter, more or less, so I think the engine is about 4500h. As 99.9% of the boat I saw the engine hours counter doesn't work
The mechanic was recommended to me by a friend that has a Bavaria, he is retired but still works as mechanic in the spare time.
I and the mechanic didn't understand why the oil level it isn't at the max after the service in Pula. So he hypotezed that the engine could have ovalized piston or loosen elastic band (hope the names are corrects). That are the worst scenario, obiously. First he want to check valves and injector.

 

[bignick]

I wouldn’t consider changing to fresh water cooling now - any damage has already been done and it’s not worth it on an old engine.

 

[bignick]

Oh, and make sure you replace the 2 (on my 2gm20) anodes which fit on bolts inside the engine.

 

[Bilgediver]

You appear to be asking about cleaning the manifold you should be able to get an idea of how much carbon is inside by removing the exhaust elbow in inspecting from aft .

I would be much more concerned about the oil appearing "not enough thick" These engines can suffer from dilution of the oil by diesel. This is not good and should be fixed. Does the oil on the engine dip stick smell of diesel? If it does then inspect your diesel fuel lift pump on the engine crankcase. It may need a new diaphragm. Diesel can leak into the oil if the diaphragm is leaking.

 

[bignick]

You may find the following guide useful.
How to inspect a Yanmar GM exhaust elbow - Practical Boat Owner

its a guide on how to remove and check the elbow yourself. Easy to do by yourself with only basic tools.

I would recommend you learn a bit about your engine and do simple jobs yourself. It saves money and may help you get out of trouble when you really need your engine. There is plenty of help available on this Forum if you need it.

 

[LorenzoC]

You appear to be asking about cleaning the manifold you should be able to get an idea of how much carbon is inside by removing the exhaust elbow in inspecting from aft .

I would be much more concerned about the oil appearing "not enough thick" These engines can suffer from dilution of the oil by diesel. This is not good and should be fixed. Does the oil on the engine dip stick smell of diesel? If it does then inspect your diesel fuel lift pump on the engine crankcase. It may need a new diaphragm. Diesel can leak into the oil if the diaphragm is leaking.

I'll ask to check the diaphram too. Thanks

 

[LorenzoC]

You may find the following guide useful.
How to inspect a Yanmar GM exhaust elbow - Practical Boat Owner

its a guide on how to remove and check the elbow yourself. Easy to do by yourself with only basic tools.

I would recommend you learn a bit about your engine and do simple jobs yourself. It saves money and may help you get out of trouble when you really need your engine. There is plenty of help available on this Forum if you need it.

You are right and that is what I woould like to learn and the reason of the thread. Find someone that could give me a guide or link me to a website with some guides.
I already found and downloaded the service manual of all the Yanmar GM series, but that it isn't a guide ?

 

[bignick]

Try this one:
Yanmar 2GM20 engine winterising and service - Triola - Albin Ballad #50
its for basic servicing and winterising a 2gm20, but the principles are the same.

 

[LorenzoC]

Try this one:
Yanmar 2GM20 engine winterising and service - Triola - Albin Ballad #50
its for basic servicing and winterising a 2gm20, but the principles are the same.

Thank you!

 

[LorenzoC]

If someone need the service manual, I couls share it. But I don't know if I could put the pdf file in the post

 

[Tranona]

I'm sorry, when I wrote "change the sealing of the head of the engine" I mean the gasket. Also the mechanic surveyor that saw the engine in Pula put the gasket in its list. It is because there is some oil on the engine's head.
My engine is a 3GM30, sea water refresh system. I know that there is a kit to "upgrade" it to fresh water cooling system, but I still don't know the real condition of the engine and if I need to change it, I don't want to spend money on upgrade it.
My boat did 10 years of charter, more or less, so I think the engine is about 4500h. As 99.9% of the boat I saw the engine hours counter doesn't work
The mechanic was recommended to me by a friend that has a Bavaria, he is retired but still works as mechanic in the spare time.
I and the mechanic didn't understand why the oil level it isn't at the max after the service in Pula. So he hypotezed that the engine could have ovalized piston or loosen elastic band (hope the names are corrects). That are the worst scenario, obiously. First he want to check valves and injector.

If he suspects bore wear or valves that is causing excess oil consumption or poor running then the first thing to do is have a compression test before taking it apart. In charter type use you would expect 8-10000 hours before needing a rebuild.

 

[LorenzoC]

I retrive the original link, so I don't need to put one from my own cloud:
https://www.jeanneau-owners.com/Manuals/3GM Engine Service Manual.pdf

If someone need, this is the Service manual of all the GM engine: 1GM, 2GM, 3Gm, etc