Yanmar 4JH3TE, 75 hp - turbo

[HappyMdRSailor]

Originally Posted by Matt Y

HappyMdSailor and others, thanks for the perspective. I spoke with two long-time Yanmar service center owners today to obtain pricing to address some deferred maintenance on the same engine. I shared our concerns regarding the risk of bore glazing/ polishing from the 1800 rpm operation, and both said not likely an issue. Both said WOT would tell a lot. One of them will conduct the engine survey. Will report back...

Fantastic to hear that professional opinions agree.... I think you're getting a winner Matt... The opposite of a worrier engine.... I mean it would have been GREAT to get an engine with 341 hours on it! But... Methinks your powerplant is just broken in nicely... Can't wait for your summary report!

Originally Posted by mub

Having just rebuilt the turbo on my perkins engine I will give you the "wisdom" from my turbo guy.

My turbo had 3000 hours over 20 years. Its failure was due to corrosion in the exhaust from short running the engine (docking).

The other turbo killer is post shut down heat soak - which cooks the oil in the turbo leading to bearing failure.
He suggested having the clean out 'burn' at the beginning of the use day rather than the end. Idle for as much as a minute then clean it out.

When you have the exhaust elbow changed have them look at the turbo exhaust side for corrosion and feel for wobble.

Mub

Sent from my HTC One X using Cruisers Sailing Forum mobile app

Agreed on many points.... Often I will let the turbo engine idle down a minute... shut her down... cool off for 15-30 min, and then restart for a minute to recirculate the "cooled oil"... I'm eventually going to install the same system my car has.... After the engine is shut down, the electric coolant pump circulates the coolant through the turbo for 15 min on a timed relay... Food for thought... and pretty simple...

[a64pilot]

I've run turbos for many years, there is an absolute truth to prevent coking in a turbo center section thereby destroying the bearing, one should allow an engine to cool for several min. at idle before shutdown, unless the center section of the turbo is water cooled, my Duramax powered truck for example. But,
Isn't that the way out boats are operated? You may run one hard, but it's back at idle for a considerable period while docking or anchoring anyway, maybe I'm just a wuss, but I don't shutdown until I'm completely tied up or anchor confirmed well set.
I used to think a pre-luber was the cats meow, I mean everyone knows the majority of engine wear occurs at start-up, right?
Then I drove a Hybrid vehicle for a few years and currently 120,000 miles. Thing is constantly shutting down, and re-starting, by current thinking, the engine should be worn out in 10,000 miles, but 120,000 miles later, the oil barely changes color between oil changes, indicating almost zero blowby, so how is that possible?
In short, I think if you keep them serviced, oil, fuel systems, exhaust elbows regularly replaced, valves properly adjusted and don't ever let water in the engine, run them correctly, I think a sailboat engine should last essentially forever?
Unless of course you have a motor vessel with those big white sheet thingies

[jeremiason]

It is a fine engine... It is fairly easy to work on. If you buy the engine I would consider having a 1000 hour service, which includes cleaning and testing of the diesel injectors.

You will find that running this engine at lower RPMs will increase you fuel mileage considerably.

I have the same engine. I normally run it a little faster at about 2400 RPMs and make 7.5 knots boat speed. That burns about a gallon an hour. At 1800 RPM's you are burning about 3/4 gallon per hour or less.

Of course the above is on my C-470, but similar boats like Beneteau 473 will do the same.

One thing I would suggest, if it hasn't been done. The factory Alternator is a 80amp Balmar and it sucks! The most I ever saw out of it was about 65amps. Might want to consider a high output alternator.

I put an ElectroMaax 160amp Alternator on mine before I started cruising and am very happy with it.

Good Luck!

[Matt Y]

Originally Posted by mub

Having just rebuilt the turbo on my perkins engine I will give you the "wisdom" from my turbo guy.

My turbo had 3000 hours over 20 years. Its failure was due to corrosion in the exhaust from short running the engine (docking).

The other turbo killer is post shut down heat soak - which cooks the oil in the turbo leading to bearing failure.
He suggested having the clean out 'burn' at the beginning of the use day rather than the end. Idle for as much as a minute then clean it out.

When you have the exhaust elbow changed have them look at the turbo exhaust side for corrosion and feel for wobble.

Mub

Sent from my HTC One X using Cruisers Sailing Forum mobile app

Mub:

I am curious, when was the last time prior to this re-build that the turbo inter cooler had been broken down?

Thanks,
Matt

[Matt Y]

Originally Posted by jeremiason

It is a fine engine... It is fairly easy to work on. If you buy the engine I would consider having a 1000 hour service, which includes cleaning and testing of the diesel injectors.

You will find that running this engine at lower RPMs will increase you fuel mileage considerably.

I have the same engine. I normally run it a little faster at about 2400 RPMs and make 7.5 knots boat speed. That burns about a gallon an hour. At 1800 RPM's you are burning about 3/4 gallon per hour or less.

Of course the above is on my C-470, but similar boats like Beneteau 473 will do the same.

One thing I would suggest, if it hasn't been done. The factory Alternator is a 80amp Balmar and it sucks! The most I ever saw out of it was about 65amps. Might want to consider a high output alternator.

I put an ElectroMaax 160amp Alternator on mine before I started cruising and am very happy with it.

Good Luck!

Hi Tom:

Thanks for the suggestion. Yes, the 1,000 service, with injectors and valve adjustment is already being factored in at overdue since at 3,000 hours on the engine and 8-years of continuous live aboard use this has not been done yet.... There is already a 2nd high-output alternator set-up with external regulator and temp sensing at batteries...

While on the topic of deferred maintenance... the seller reports following OEM recommended intervals for replacement oils, filters, coolant, impeller and belts for which there is a historical regular engine maintenance log. The exhaust elbow was just replaced in 2014 and had been previously replaced in 2010. Otherwise the seller reports there has been no other service performed on the engine... so I figure the following is overdue:

• raw water heat exchanger needs removed/ cleaned - last time was in 2010 (OEM recommends 2,000 hours or 2-years);
• engine thermostat original never inspected- needs removed/ inspected (OEM 1,000 hours or 4-years);
• engine oil cooler never removed/ cleaned, needs removed and cleaned (OEM 1,000 hours or 4-years);
• trans oil cooler never removed/ cleaned, needs removed and cleaned (OEM 1,000 hours or 4-years);
• turbocharger inter coolernever broken down/ checked, needed (OEM recommends 1,000 hours);
• turbocharger shaft play never checked, needs checked (OEM recommends 1,000 hours);

• fuel injector spray pattern, condition and timing has never been checked (OEM recommends 500 hours);
• valve clearance never checked (OEM 500 hours);

So... with that laundry list, factored in as overdue and needing to be attended to, are there likely to be any big, costly surprises once it comes apart? I am thinking mostly that the dissimilar metals in the turbo might after 8-years of non-servicing now be fused together, making a rebuild impossible and thus requiring a turbo replacement! I have received a $2,500 price in this outcome. Is this likely and how to know prior to purchasing or do I just need to factor it into the purchase price?

Based on 8 years of basically only replacing fluids and the exhaust elbow, are there any other big costs likely to come to light once I start to do the maintenance after the purchase?

With much appreciation,

Matt

[a64pilot]

You would know right away if the turbo wasn't spinning, power would be WAY down, almost certainly be a lot of smoke too