Rebuilding engines - what's involved, when to do it, how much will it cost

[Irish Rover]

My power catamaran is 20 years old. It has 2 x 75HP Yanmar 4JH3-TE engines which have 3,650 on the clocks. When I bought the boat in 2017 they had 2,500 hours and the advert for the boat included this info:
" Major maintenance (injectors, pumps, filters, etc. at 2000 hours. [1,600 approx hours since full rebuild "
I've had no trouble with the engines since I bought the boat apart from both heat exchangers developing small leaks and needing repair. I probably change the oil and filters a but more frequently than recommended and all other maintenance items are done regularly and on time. The engines are not currently giving me any trouble. The boat is used almost daily year around.
I spend around 2 months cruising around the Aegean Islands in summer - I'm just recently back from this year's trip. I've encountered some hairy weather on my trips and my biggest concern is always that one or both engines will pack up when I'm far from home. I'm grateful for the last 5/6 years of trouble free boating and I'd dearly like to be relatively sure of a few more. So, what to do?
I read about owners getting their older engines "rebuilt" but I'm not sure if that term has a fixed meaning or what exactly is involved. Is that something I should be thinking about or should I just motor on with routine maintenance until something goes wrong? Any opinions, suggestions, advice welcome. Thanks.

 

[Tranona]

You are using your engines "properly" - that is a lot. Unlikely ever to need a rebuild in the sense of replacing or refurb the internals of the engine. Expected life of the basic engine is in the order of 8-10000 hours so they are about half way through. Boat engines fail from lack of use. Shirt periods of running followed by long periods of doing nothing. The Volvo 2030 in my charter Bavaria did 3500 hours in 7 seasons charter work and 3 seasons holiday use, plus motoring all the way from Corfu to Spain!. Was running as well as when new.

Change the oil and filters regularly, feed it good clean fuel, keep the cooling systems clean and they will just keep going.

 

[jwfrary]

Your basic engine is strong and I would up the figure to 15k for the core engine if your looking after it!

Its almost always an ancillary that fails so the remidy is to make sure your well stocked, things that are usually missed, fresh water pump, thermostat, alternator all things that stop you!

You could consider a second set of injectors, you can pull and replace a set very quickly and then get the set you moved over hauled and roll them over to your other engine, just keep them in a zip lock bag with some light oil in there and they are good indefinely.

Likewise people often don't have the gaskets required onboard, heat exchange gaskets and exhaust gaskets are pretty essestial to have with you.

Unless it's something falling off (which by meticulous inspection can be guarded against, engines rarely fail catastrophicly tge warning signs start many hours ofter 100s of hours before. So if your well prepared then I dont think you have an issue.

 

[jamie N]

Your Yanmar engine has so much going for it, in that you look after it, and that the base engine is a Toyota item.
On a car or a truck, an hour of operation is about 30 miles/50kms., so your engine has about 100K, 160kms on them, whilst having being serviced.
For an example, an average truck mileage is about 125K/year, with an equivalent amount of servicing it seems.
'Stuff' from Google of course...

 

[roaringgirl]

I have a 4JH2TE. It has done 5000 hours and still going strong. The mechanical lift pump failed not very long ago and I replaced it with an electric one. If I can find the budget, I'll fork out for a pre-emptive turbo-rebuild soon, but that's all.

 

[Fr J Hackett]

The turbo would be my only concern as an item that could possibly fail.

 

[westernman]

Heat exchangers, starter motors and mounts are the weak things on Yanmars.
The engine itself will last pretty much forever if you look after it.

 

[Stemar]

The VP2003 we fitted to Jissel had spent 15 years in a charter boat when we got it, and was still going strong another 17 years later, when we sold the boat in spite of being way too powerful for a 24 footer.

Everything I know about diesels tell me that if the engines start well on a cold day, pull well and have good oil pressure and low oil consumption, they're good to go, and will give plenty of warning before they give problems, irrespective of age - fuel supply and cooling issues aside, but those apply to brand new engines too.

Just one thing to add. We had to pull the engines on Jazzcat to get at corroded water pump bolts, and discovered severe corrosion on the sumps after many years in a damp bilge, so a good poke around your sumps might save a problem.

 

[Neeves]

Just one thing to add. We had to pull the engines on Jazzcat to get at corroded water pump bolts, and discovered severe corrosion on the sumps after many years in a damp bilge, so a good poke around your sumps might save a problem.

I'd second Stemar's comment. Our next door neighbour has a 40' MoBo and the sump had been sitting in bilge water and corroded. This necessitated removal of the engine - which is not something to which one looks forward. Our sumps, Volvo 2020s, sit in a Volvo supplier standard pad/cradle and the base of the sump sits below the top of the pad. This means the sump can sit in water, if you leave water in the 'bilge' of the pad, and you actually cannot see the base of the sump unless you use a mirror.

Its an easy check - the consequences of ignoring the possibility are huge.

Jonathan

 

[PeterWright]

Hi,

Apart from having a good basic engine which you look after properly, you are lucky in having 2 main engines. Apart from the risk of getting contaminated fuel in your tank, failure of both engines at the same time is pretty unlikely and failure of one engine, while inconvenient, is relatively easy to handle.

Rebuilding your engines will not reduce the probability of taking on contaminated fuel, so I would focus on making sure contaminated fuel cannot get from the tank to the engines. Dual Racor (or Racor lookalike) filters with a changeover valve so you can swap to a clean filter with one turn of a valve is a very good start and of course carry plenty of spare filters so you can replace the dirty ones immediately ready for the next changeover.

Peter.

 

[38mess]

I only just binned a Perkins M30, same engine as a Volvo 2030 that had over 10 k hours on it. A rare but known problem on these engines with high hours is the injection chamber nozzle works loose and falls into the number 3 cylinder which is exactly what happened.
On strip down apart from the piston, head and con rod everything else was in tolerance. Impossible to repair the head and almost impossible to get a good spare head.
I managed to source a low hours decent replacement engine for not a lot of money.

 

[srm]

I did a total rebuild of a boat's engine: bearings,, re-bore,, new piston rings, overhaul of injectors and pump, new timing chain, etc.
But - only because the raw water jacket around the exhaust outlets had corroded and there was salt water in one cylinder and the oil. Before that the engine had been totally reliable.
I took the engine to the local college's Car Maintenance evening class and did the work in their workshop with a lot of help from the lecture;, it helped that I was also a lecturer there.

 

[ChromeDome]

Your Yanmar engine has so much going for it, in that you look after it, and that the base engine is a Toyota item.
On a car or a truck, an hour of operation is about 30 miles/50kms., so your engine has about 100K, 160kms on them, whilst having being serviced.
For an example, an average truck mileage is about 125K/year, with an equivalent amount of servicing it seems.
'Stuff' from Google of course...

Agree that your engines should provide trouble-free service for years to come. This particular model is not Toyota based, but still a very reliable piece of kit.

If curious and want to know a bit more, take samples of used engine oil and have it analyzed.
Like you I have no issues with my engines but had the oil analyzed and just received the reports back. Pleased that all is as good as I could hope for.

Just wanted to follow up on the analysis of the two engines.

Reports are detailed as mentioned in earlier post (20 particle measurements (PPM) and 8 properties stated)

Port: The good news is, they look alike in testing, and that's exactly what we like to see for twin engines, since they see the
same care and operating conditions. Metals are testing at good levels and in a typical balance for a marine
diesel, so internal parts appear to be wearing well. There's no contamination to mention (like fuel, coolant,
or excess dirt), and the TBN is very strong.

Starboard: Looks a lot like what we found for the port side. As we mentioned in the other report, that's a good sign that both engines are wearing normally. The flashpoint is high enough to show no measurable fuel dilution, and low potassium/sodium tells us coolant
contamination isn't a concern. Insolubles at 0.1% are evidence of effective oil filtration, and the TBN of 10.6
shows a very strong supply of active additives remaining.
Nice results!

 

[Winston Collinge]

I have a Colvic Atlanta fitted with its original Thorneycroft T108 (BMC1800) 47 HP engine. It hardly uses any oil, starts first time and very economical. However its noisy and not really powerful enough to push the boat against strong Irish Sea tides. I'm considering replacing it with a more powerful quieter engine. I'm thinking of a low revving engine 50/55 HP and looking for recommendations.

 

[Tranona]

I have a Colvic Atlanta fitted with its original Thorneycroft T108 (BMC1800) 47 HP engine. It hardly uses any oil, starts first time and very economical. However its noisy and not really powerful enough to push the boat against strong Irish Sea tides. I'm considering replacing it with a more powerful quieter engine. I'm thinking of a low revving engine 50/55 HP and looking for recommendations.

Welcome. Simple answer if buying new. Beta with Volvo D2 50 as second choice.

 

[Winston Collinge]

Welcome. Simple answer if buying new. Beta with Volvo D2 50 as second choice.

Yes, the Beta 50 is the closest match as far as the engine bed is concerned and comes with a good reputation.

 

[Tranona]

Would not worry too much about the engine beds "fitting" as Beta will make brackets to mate the engine to your existing mounting points. not difficult to do the same with the Volvo. The key things to look out for as regards installation are making sure there is enough clearance, the service items are accessible the exhaust will link up if re-using the old system and the fuel and electrics are up to the latest standards. In my experience it is often better to replace these items as they are likely to be 30+ years old anyway.

 

[jwfrary]

A yanmar 4jh57.

Quieter more efficient cleaner.

Common rail but I don't buy into the you can't fix it yourself argument, not many yacht owners can change an injector on a mechanical engine let alone a fuel pump and associated overhaul. So it's likely your going to be using an injection shop minium so what's the difference.

I dislike the beta heat exchangers to ve honest they are cheaply made and fail quickly without regular cleaning and replacement of orings.
.
Volvo make a better marination but the control systems are still an issue.

Sole diesel are quite well put together mitsubhi block which there's loads around of. Very popular in the med with commercial fisherman.

Beta used to be cheap but they aren't now and the quality hasn't changed.

 

[srm]

However its noisy and not really powerful enough to push the boat against strong Irish Sea tides.

Does it push the boat at near hull speed? If so a new engine will not get you home any faster.

 

[Winston Collinge]

Does it push the boat at near hull speed? If so a new engine will not get you home any faster.

We're getting nowhere near the hull speed & that's what we would like to improve on.