Troubles with 3HM35F - Yanmar Engine

[Mic Bery]

Hello



I recently purchased a sailboat with a Yanmar 3HM35F and was beginning to see/feel how great an engine she is. In till the other day, I returned from a cruise and began a basic engine check.



I pulled the oil dip stick and the engines oil was contaminated with water.

And it was up over the sticks full line by about an inch and a half.



I checked my fresh water rad for level and it was where it was the day before I left. So I tasted a bit on my finger and yes it tasted salty.



So the first thing I did was drain the oil, and it so happened, a fellow next to me was changing his motor oil. I asked if I could take it all off his hands. Of course he was thrilled. I pour half into my engine, turning the motor over (with decompression value open) a few times hoping it would take what contaminated oil was left out with it.



I then changed the oil filter and refilled with fresh new oil, turned the engine over a few more times (as above) and then took a look at the dip stick, which looked good and clean, I believe I have it cleaned out.


Now ... where do I start to figure out this problem? I ask what do you think happened?



Mic

[DeepFrz]

Have you read any of the other 1,000 or so threads on CF about water contaminating engine oil?

[Mic Bery]

Thnx for commenting DeepFiz, I am new to the forum and just figuring things out.

[DeepFrz]

Welcome aboard Mic. Use the "Google Custom Search" button under the search column and you will get lots of info.

[Wotname]

Welcome aboard CF, Mic Bery. You should find what you need from Deep's suggested search however if not, come back and collectively we should be able to help.

Meanwhile for a starter, it seems you have two issue's, raw water entering the coolant side of the system and then the coolant side is entering the engine crankcase.

The raw water side on the 3HM35 is quite seperate to the engine and the only real connection is at the mixing point on the exhaust so it hard to see how raw water could enter the crankcase while the engine is running. This leads one to think the coolant is getting into the engine and as the coolant is salty, it suggests the raw water is getting into the coolant - presumably in the heat exchanger.

Do you have the 3HM35 service manual?

[GordMay]

Greetings and welcome aboard the CF, Mic.

Yanmar Service Manual: 1GM10, 2GM20(F), 3GM30(F), 3HM35(F)(C) ➥ http://www.jeanneau-owners.com/Manua...e%20Manual.pdf

[JimsCAL]

The water in the cooling system tasted salty? Since that's antifreeze, not sure what you are tasting. A leak in the heat exchanger would result in the expansion tank overflowing, not water in the oil. Thats a lot of water. Most likely cause is the head gasket or backing up from the mixing elbow is you had a hard start with the raw water seacock open.

[Mic Bery]

Thnx guys for your comments, I have been reading and reading the previous threads as DeepFiz has suggested, and yes, I had downloaded this manual prior to signing up here at CF. I will keep reading ...

[foothillsailor]

Assuming that you did not have a hard start and had satltwater you have not flooded saltwater back up into your cylinder/engine the two most likely culprits are (1) failed seals on your saltwater pump's drive shaft that let water migrate along the shaft and into the interior of the engine (remove the pump and have it rebuilt) or (2) failed heat exchanger (remove it inspect and have it pressure tested by a radiator shop).
I had a similar problem (on a Westerbeke - problem was the saltwater pump) but the important thing to do as soon as possible is to run the engine up to normal operating temperature in order to remove any residual water that may remain in the engine even after you have changed the oil ---- after identifying the source of the problem then and after running up the engine and determining no further water intrusion then I would again fully change the oil and the oil filter (oil is a lot cheaper than rebuilding or replacing an engine). ANY saltwater left in the engine will be extremely corrosive .

[Wotname]

This is an interesting fault so I do hope Mic Bery posts how he solves it.

We know the boat/engine is new to him.

He has been using it but recently the oil was found to contaminated with water and the level has risen in the crankcase.

He reports the fresh water in the rad (header tank?) was salty to taste and the level was normal. I assume there is no antifreeze in the fresh water side. While this is unusual, it is prudent to always assume a previous owner did not maintain the engine properly unless there is evidence to the contrary.

Originally Posted by JimsCAL

The water in the cooling system tasted salty? Since that's antifreeze, not sure what you are tasting. A leak in the heat exchanger would result in the expansion tank overflowing, not water in the oil. Thats a lot of water. Most likely cause is the head gasket or backing up from the mixing elbow is you had a hard start with the raw water seacock open.

A breach in the head gasket could allow fresh water (but not raw water) into the crankcase but it would also lower the level in the header tank unless there is also a leak in the heat exchanger allowing raw water into the fresh water side.

Raw water backing up from the mixing elbow into the cylinder would more likely result in a hydrolocked engine, a bent conrod and other trouble to say nothing of being hard to start.

I don't wish to sound alarmist but it is not beyond possibility that serious engine issues existed that the previous owner managed to paper over until the boat was sold. It won't be the first time!

I have an acquaintance who inspected a boat three times and ran the engine each before he purchased the boat; all seemed normal. The first day he owned it, the engine made oil into milk. He discovered later the previous owner knew the engine was doing this and changed the oil every time someone inspected the boat prior to it's sale.

[Wotname]

Originally Posted by foothillsailor

Assuming that you did not have a hard start and had satltwater you have not flooded saltwater back up into your cylinder/engine the two most likely culprits are (1) failed seals on your saltwater pump's drive shaft that let water migrate along the shaft and into the interior of the engine (remove the pump and have it rebuilt) or (2) failed heat exchanger (remove it inspect and have it pressure tested by a radiator shop)..........

The 3HM35F has a belt driven raw water pump and not a shaft from inside the crankcase. This keeps the raw water circuit away from the engine except at the heat exchanger and the exhaust mixing point.

[Mic Bery]

Thnx for your responses I like this ... been busy figuring out the problem, taring down the coolant components to inspect. I tell you, I m going to take a small diesel engine course after I figure this hiccup out. I have it all back together now, and will fire it up tomorrow. Question - I will have to prime my fuel lines first, before I start it, and I`ll keep the sea cock closed while do. Would it be prudent to pull the coolant propeller, so not to heat it up, or leave it be?

[Wotname]

Originally Posted by Mic Bery

Thnx for your responses I like this ... been busy figuring out the problem, taring down the coolant components to inspect. I tell you, I m going to take a small diesel engine course after I figure this hiccup out. I have it all back together now, and will fire it up tomorrow. Question - I will have to prime my fuel lines first, before I start it, and I`ll keep the sea cock closed while do. Would it be prudent to pull the coolant propeller, so not to heat it up, or leave it be?

I would leave it be and disconnect the belt drive of the raw water pump (and leave the sea cock closed). You can run it for some time before the coolant will heat up - just let the thermostat do it's job. This way you should see if the coolant is still getting into the oil or not.

If it seems OK, then refit the raw water pump drive belt, open the seacock and try again.

[NYSail]

Mixing elbow rusted through....... salt water back filling engine.

Great engine..... had one on last boat and over 10 years of ownership changed the elbow 2 times. And that was with me never idling engine and always running her hard.

Good luck
Greg