How many hours does a DIY diesel rebuild take?

[TXProud]

Originally Posted by Oldwheels

My advice is DONT. There are places that will sell you a rebuilt exchange. If you do not have e tools and experience you will be money and time ahead.

This really is the correct answer. It’s gotten to the point that a crate engine is cheaper than rebuilding when factoring time and parts.

[Goodxcharly]

I know this isn’t the answer you want but I wouldn’t waste my money on a rebuild. You really depend on these engines when the going gets rough and I would look for savings with other boat projects.

Buy new and you will sleep better knowing everything’s new.

[phorvati]

Originally Posted by TXProud

This really is the correct answer. It’s gotten to the point that a crate engine is cheaper than rebuilding when factoring time and parts.

There is the aspect of learning how stuff works, and therefore having better independence and knowledge of a system you have to rely on heavily. For me, DIY was less about saving money, more about knowing how it works and what it takes to keep it ship-shape. Knowing how to fix it is priceless, and you don't get that by swapping or crate-ing the block.

[waterant]

i'm currently in the process of rebuilding a Yanmar 6LYA 6-cylinder diesel engine.



The engine was completely seized. I took it out of the boat in September 2022, and right now, it's waiting in my garage for the camshaft to be polished and the crankshaft to be grinded by a machine shop (the original promised completion date was at the end of December ).

You need a lot of equipment, tools, money, and time to rebuild a diesel engine of this size. so far, I spent around $2000 on tools and equipment (including the gantry crane and platform to take 1200LB engine out of the boat and bring it home), ~$9000 on engine parts (from Japan and US suppliers) and probably another few boat bucks I did not account for.

Quotes for a rebuild from the local shops (Ontario, Canada) were $20-30k to start and, considering my experience with the shops so far on smaller jobs, it would take at least a year. so I'm glad i went DIY (at least for now). If DIY was not an option or my project will fail, I will be looking for a rebuilt engine to buy. problem is, there are not many of these models available on the market and my boat has 2 of them so i can not just put a different engine in.

it's not as complex as I thought, but I do not know how successful this rebuild will be until I can start this engine again.
Ask me again in a couple of months

More details and the progress is here:
https://www.trawlerforum.com/forums/...6ly-66188.html

Hope this helps and good luck with your project

[Epikur]

Doesn‘t matter how long it takes.
After the rebuilt/overhaul its your engine.

[Rick Williams]

don't do it if you're in a rush! Since it's from a boat it's not just a humorous aside that it will take longer and cost more than you can imagine but if you do rebuild your engine, you'll literally know it inside and out and you'll be friends instead of wary partners.
The satisfaction of rebuilding an engine outweighs the learning curve if you have the patience to get to the end.

[Epikur]

Why ‚rebuilt‘ an engine in the first place.
- Check the compression
- maybe grind the valves
- check the injectors
- time the pump
- Check the fuel pre-pump
- Check fuel system
- Install a fuel polishing filter (cycle fuel ober filter back to tank)

- pressure wash & paint white

That‘s about it.

[RaymondR]

The first thing you need (if one exists) is the "shop manual" for the engine. This will inform you of the disassembly, condition checks, and reassembly procedures required.

[Icarus]

Originally Posted by Gard

Presuppose a first timer is to rebuild a 2-6 cylinder diesel inboard, from start to finish. What is a reasonable estimate of hours spendt (in total and on each sub oroject)? Assume a common engine with decent accessibility to rebuild kits and other parts (i.e. a Yanmar or Vovlo Penta of less than 30 years. Assume also an engine that has not been under water, isn't seized, isn't cracked and was running on rebuild (albeit with some issues lol ke excessive smoke, poor power, rattling, excessive vibrations, difficult to start, over heating... or the likes).


...Research engine removal?
...Rigging for removal an actual removal?
...Research rebuild?
...Doing the rebuild?
...Research reinstallation?
...Reinstalling?

Assuming a DIYer having access to fairly simple tools only, which jobs will likely need to be farmed out?

What are likely the biggest problems one will face?

The reason I ask is that I plan to buy an older boat and want to take into account a rebuild that may need undertaking within a few years after purchase.

Please, if you have, include reference to engine model, skill level, reason for rebuild, the state of the engine prior to rebuild, or anything else that could be useful to know.

There is no one answer fit all.
A 6cyl engine is a different beast than a 2cyl engine.

Where is the engine located, access? Lifting? Transport?
Mechanical knowledge and I don't mean just knowing how to do an oil change.
Analyse what actual needs 'rebuilding' and why.
Rings? Bearings? Fuel pump?

Tools
Workshop manual..tolerances, assembling instructions etc
Parts, some are not easy to obtain.
Access to a good machine shop...specialised in engine rebuilds...

Time frame? Depends how skilled you are..average 3 weeks to 6 weeks, depending of unforeseen problems.
Cost....? 5k to 10k+

I refurbished a number of marine diesels Perkins 6cyl, Lister 3cyl, Isuzu 3cyl..2cyl, Stuart and Turner, Perkins 4108...

Manny times a cylinder head, valve, injector job is enough.

Others, cooling system, heat exchanger, pumps, hoses

Electrical, starter motor, alternator, wire harness, panel etc

[Ballsnall]

32 hours.

[MVDarlin]

My answer, "how long is a piece of rope" depends, anticipate unknowns, plan for the worse and hope for the best. Replace everything. I would allow at least a month. Cylinder sleeves and machining will require head and block removal. And double the time if you have twin engines. I have had one complete overhaul and one top end done. Don't be in a hurry.

[vinayfm]

I faced the same question a while ago. It was a hercules 27hp engine from late WWll ! I had bought that engine for a boat I was building, but it needed a check over.
I found a derelict one shorter after buying the first one for no money and brought it to my shop. I dismantled it and reassembled it a few time as a learning curve. Then rebuilt the good one. It was very instructive, without major risks and educated me so repairs could be performed by me at sea! The only thing I did not do was the injectors.

[Shaneesprit]

Originally Posted by Oldwheels

My advice is DONT. There are places that will sell you a rebuilt exchange. If you do not have e tools and experience you will be money and time ahead.

Exactly right, I have a lot of experience.
My method would be to plan like this. (Removing Engine and Refitting Engine myself) sure I could easily rebuild everything myself and have many many times, a rebuild is not like your just changing a part or a gasket.

1 Day Choose engine rebuild company and discuss requirements, insist on Fuel pump and Injector Service. Might as well service the Alternator and starter while your there.

1 Day ensure you have Tools and lifting equipment.
1 Weekend - Remove Engine
1 Day send Engine for rebuild.
Order anything you broke getting the Engine out.
Wait a couple of weeks. (Well you would have an old boat so spend the time fixing other things.
1 Day collect Engine
1 Weekend Refit Engine
1 Day re commission. Might take a few more days to complete

[RocketScott]

6 Months...