Marine Diesel vs. pick up diesel engines

[hatyaiair]

Due to Covid many boaters in the SE Asian Marina where my boat was stored could not return to their boats for over 2 years. Many of us returned to either a seized engine or other issues with the engines such as very low compression due to pitted valves or ring problems. At last count there were 14 seized engines and many other issues. Even my genset seized. This issue hit all manufacturers including Yanmar, Penta and Vetus. My Ford diesel pick up truck which sat for the same amount of time next to the boat only needed the battery charged and fired up on the first crank with no issue. When canvasing the owners on how they left their boats most did change the oil and filter before leaving and flushed the raw water systems with fresh water.

My question is twofold and directed at marine diesel mechanics.

1. What is the difference between a marine diesel and an automotive diesel engine that so many marine ones seized and the pick up fired up on the first crank? One would think that a marine engine would be built to a much higher standard to withstand any issues associated with the salt environment.

2. What could have been done to avoid the seized or low compression issues that resulted from long term storage. I am now so afraid to leave my engines for over a month fearing more issues after spending a fortune to have them rebuilt. I have read many posts on this site about storing marine diesel engines for longer term but so many of the suggestions vary that it would be nice to get a general rule of how to store an engine and avoid future issues. Obviously changing the oil and filter is important. I have heard that the salt air will seep into the intake and exhaust chambers and pit valves. If this is the case how can that be avoided. My Yanmar has decompression levers so I could have fogged it, but what would be the suggested fogger and for how long. I assume this would be done with the fuel supply off and just cranking the engine as you spray the fog in?

[skipperpete]

Well, happy to offer a few helpful hints. The venerable 4-108 perkins was an automotive engine in London taxis and the 6-354 was a truck and tractor engine but mostly agricultural use initially. Most of the higher horsepower truck engines were also marinised by the OEM’s like Cat, Cummins, Detroit, volvo etc but not any use to cruising yachts so we got a whole flock of industrial engines that were adapted for marine use... Yanmar Kubota BMC Nissan Mitsubishi. Some were automotive and marine but no one was lining up to buy a pickup with a 3QM30 or a little Kubota in it.
Ok, the reason..... and pretty much the ONLY reason you have 14 seized engines around you is because of the wet exhaust system that we all have. Firstly, to have 5 or 10 litres of seawater with a high acid content in a container directly attached by a foot or two of 2”-3” rubber hose and exhaust manifold to the polished internals of the engine via whichever exhaust valves happen to be open after shutdown is a recipe for disaster from the first day the new engine was fired up.
But that high humidity exhaust issue is actually manageable, a lot of damage occurs from poorly installed vent loops, overcranking and failed mixer elbows.
I sound a bit grouchy but here’s how to avoid the layup blues.
Take the exhaust hose off the mixer elbow then get a good heavy duty garbage bag and two dehumidifier canisters ( in asia they call em thirsty hippos or closet camels) put em in the bag and zip tie the mouth of the bag over the exhaust elbow... problem solved.
Lots of folks recommend hooking a bucket of sweetwater mixed with glycol coolant to the raw water suction and running the engine but you still have a humid swamp connected to your engine, just a bit less corrosive.
I now have a few opinions on how to bomb proof the fuel system after my own injector pump seized after a layup... and its been 4 years since she was last started. The tropics is the worst for diesel engines, good luck with your engine.

[RaymondR]

Might be just as simple as taking the raw water supply hose off the thru-hull and putting it into a bucket and starting the engine so it pumps glycol thru the engine and into the exhaust then putting a plug into the exhaust's transom fitting. Plug the raw water inlet with a cork and tie the ignition key to the hose so you can't start the engine.

[hatyaiair]

Originally Posted by skipperpete

Well, happy to offer a few helpful hints. The venerable 4-108 perkins was an automotive engine in London taxis and the 6-354 was a truck and tractor engine but mostly agricultural use initially. Most of the higher horsepower truck engines were also marinised by the OEM’s like Cat, Cummins, Detroit, volvo etc but not any use to cruising yachts so we got a whole flock of industrial engines that were adapted for marine use... Yanmar Kubota BMC Nissan Mitsubishi. Some were automotive and marine but no one was lining up to buy a pickup with a 3QM30 or a little Kubota in it.
Ok, the reason..... and pretty much the ONLY reason you have 14 seized engines around you is because of the wet exhaust system that we all have. Firstly, to have 5 or 10 litres of seawater with a high acid content in a container directly attached by a foot or two of 2”-3” rubber hose and exhaust manifold to the polished internals of the engine via whichever exhaust valves happen to be open after shutdown is a recipe for disaster from the first day the new engine was fired up.
But that high humidity exhaust issue is actually manageable, a lot of damage occurs from poorly installed vent loops, overcranking and failed mixer elbows.
I sound a bit grouchy but here’s how to avoid the layup blues.
Take the exhaust hose off the mixer elbow then get a good heavy duty garbage bag and two dehumidifier canisters ( in asia they call em thirsty hippos or closet camels) put em in the bag and zip tie the mouth of the bag over the exhaust elbow... problem solved.
Lots of folks recommend hooking a bucket of sweetwater mixed with glycol coolant to the raw water suction and running the engine but you still have a humid swamp connected to your engine, just a bit less corrosive.
I now have a few opinions on how to bomb proof the fuel system after my own injector pump seized after a layup... and its been 4 years since she was last started. The tropics is the worst for diesel engines, good luck with your engine.

This is really a great response that makes total sense. I will definitely do this from now on and its not a very difficult thing to do. This should be posted in all marinas for folks laying up their engines.
Please share your info on bomb proofing the fuel system! I only put in Biobor to treat it and hope this is enough to avoid fungus etc. in the fuel.

[Searles]

Agree with the above ,most vetus exhaust wet boxes have a drain at the bottom edge built to totally drain the wet exhaust system ,few people use them in storing the engine ,had a Perkins 4/108 in a yacht afloat not starter for eight years ,fired her up old fuel and all ,the exhaust elbow blew apart ,the rest was ok after a full service ,drain the exhaust system .⛵️⚓️