How many hours does a DIY diesel rebuild take?

[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.

[PineappleOrange]

I don't have experience rebuilding engines, but from what I gather off the internet and various YouTube videos, I'd venture a guess of a 1-2 weeks for a simple rebuild.

Heat exchanger, belt(s), gaskets, o rings, cleaning, painting, mounts, re alignment, coolant flushing, oil and filter changes, injector lines, transmissio/throttle cabling, etc.

I don't know how much time I'd add if you needed cylinders rehoned or sleeve, block machined, etc.

I think the hardest part would be dealing any seized bolts that break off, or forgetting to order a part that holds up the rest of the job. Tooling could be a nuisance too.

I'm curious what other have to say. I have a Volvo Penta D2-75 that will be in need of some love myself. It seems like one of those questions where there are so many factors, it is hard to give an estimate.

[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.

[Gard]

Would that be one to two 40 hour week, or a couple of hours every day after work and 8 hours on two Saturdays and Sundays.

Seized bolts is a surely one of those things that can make a simple job hell, especially if bolts that hold the engine case together snaps.


I assume that once the engine is out and on a work bench, dismantling it into atoms should be done in a few hours (if bolts don't fight back).

Putting everything back together with new parts, right measurements and torque, would probably take twice the time.


Cleaning and prepping the dismantled engine itself parts would probably take longer than dismantling? I once used our dishwasher to clean a motorcycle engine case - it worked wonderfully! However, next time I would source a throw away dishwasher as I had to spend more time cleaning the dishwasher than it would have taken to clean the parts by hand.

[siamese]

I'm an amateur engine rebuilder, having done two VW beetle engines (the old beetle), from the crank on up, and a 1961 Chevrolet 235 c.i. inline six, not including the crank.

I couldn't give you a time in hours, because not all your time is going to be spent at the bench swinging a torque wrench. Unless you're planning to lap in the valves yourself, you'll be sending the head out to be done. With my Chevy, they called me back and said magna fluxing it revealed a crack. So that meant sourcing another head. Oh, and the second one had a crack, too. And, hopefully the shop doing your head gets the job done in the time they quoted you.

Then there's the block and it's sleeves. Are you going to hone the cylinders or send the block out. And, maybe the cylinders are no longer perfectly round. They can become elliptical shaped over time, and you'll need to evaluate whether you can simply hone, send it out for a rebore (likely), or have a new sleeve(s) pressed in.

There are going to be some unexpected occurrences, IMO. Like when threads get stripped out, or bolts break off, etc..

It should just be a block and a box of parts that goes together like a precision puzzle. Then you turn the key and vroom. It could go that way, but that's not the only way it can go.

So, for an amateur, I'd look at it in days or weeks rather than hours. Time for others to do their part, and time to solve unexpected issues.

I'm going to say anywhere from two to six weeks. Maybe less (nah), maybe more.

In response to those who say "don't", I would say there could be wisdom there.

[Bill O]

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.

^^^^ Above are very good words of wisdom.

Youtube is a wonderful thing to watch how other people have done it, but it's not always as easy as it looks.

Buying a short or long block from a reputable rebuild source can many times be much cheaper for the parts than for you to purchase them then install. Then to purchase all the tools needed for the job, etc. is another expense. Once you assembled the motor and test it, you get the great reveal to see if you did it properly (or possibly tear it down again)

If you have a lot of time and want to learn, then go for it. Always good for people to actually do things and learn from the experience.

[abroadreachtrvl]

The 130 hrs over 3-4 months estimate given earlier sounds about right.

I did everything but the machine work myself.

Disassemble and inspect everything first as you can quickly exceed the price of a low hours used or rebuilt engine if you need more than what's considered a basic rebuild.

[Bowdrie]

Even with all the tools, an engine stand is almost mandatory.
Being able to rotate the block as you work is a huge timesaver.

[phorvati]

Rebuilding diesel is not like rebuilding a gasoline engine. you don't have the tools to do full rebuild. You will need to part it out, and send parts to engine service vendors. IP needs to go the injection pump place for servicing, likely 1-2K cost, injectors get serviced as well, likely 500$. Depending on your engine, various servicing like sleeves and guides need to be pressed. Block and head go to engine service shops like simplex. Then there is the issue of clearances. Different engines have different specs. You will get into subjective back-and-forth discussion with service company as to what is considered OK. Then there is the head, (cracks might be OK or might need to be stitched), again subjective stuff. Head is a lot more sensitive than gasoline engine head. On top of it, timing and assembly between diesel and gasoline engine is like Varsity vs JV in high school sports. Chances of screwing it up are much higher and mistakes are more devastating in terms of hours to fix. And then at the end you have to put all the marinizing parts back on after having them rebuilt/serviced by their own service shops. Like pumps, heat ex-changers/coolers, manifolds, starter/alternator. Then there is spec-ing new hoses and wiring which is closer to gasoline engine parts.

You will never make it through this by thinking how many hours to do it. Even a professional rebuild shop runs a risk at estimating the hours. With that approach, you are already setting yourself for bad experience!

[sailingharry]

One question that needs to be asked is degree of rebuild. I had a Honda Civic, an engine with a reputation for blowing head gaskets. In the time I owned it, it blew it twice. In both cases, I did about an 80% rebuild right in my driveway. Pan off, head off, pistons out, head sent out for planning. I honed the cylinders, re-ringed the pistons, lapped the valves, new valve seals and gaskets all around. The block never left the car. All in, maybe 10 to 20 hours, probably less.

Just removing the engine from the car could have doubled the labor, sending the block out for a reboring would add considerably more. But I wasn't having problems with my crank or the block, so short changing that part wasn't a significant compromise. I never regretted skipping that part either time, and when the head gasket blew a third time I scrapped the 22-year-old car.

My point is only that this is not a single scope of work. You need to assess why you are doing an engine rebuild, and if it needs to be an all-in, engine out rebuild or a targeted rebuild. If you can get the pan out with the engine in place, and if your cylinders are sleeved, you don't necessarily have to remove the engine. Removing an engine from a car is a pain, removing an engine from a boat is a monumental task!

[deblen]

Youtube has several videos that may help you decide:


https://www.youtube.com/results?sear...+marine+diesel

[CrispyCringle]

Id expect it to take several months. You cant just work on it 8 hrs a day and bang it out. You will need to research stuff, endless trips to buy a certain tool, waiting on venders, waiting on parts, spending a day on each rounded nut and broken off stud. There are ALWAYS a few stuck bolts and other issues that seem to make a simple task take forever.

If you have no schedule to keep, Id say go for it. You will learn a ton. But if you need it by a certain date, just save a lot of cursing and gnashing of teeth and buy a rebuilt.

[AKA-None]

Or as I found once
Rebuilt it all nice and sweet
Reinstalled
Cleaning the workbench I found a misplaced circlip
Yeap it went waaaaay in the back inside
Undo everything and start over

Stuff happens

[Cheechako]

It depends a lot on what you mean by "rebuild" vs "overhaul".
How dirty is the engine? Gummed up badly?

You can do the minimal: rings, bearings, hone the cylinders, grind the valves and leave things like camshaft, camshaft bearings and the myriad of other things alone. Decades ago we did this a lot on cars. Engines wore out fast back then and were terribly gummed up from running 30w non detergent oil. They may have 1/16 to 1/8" of black goo in many interior surfaces.
If you have a clean engine, on your shop floor, with minor cylinder ridge, you can probably do a minor overhaul in 2-3 days and send the head out for rebuild if you have the right tools (ridge reamer, cylinder hone, torque wrench, micrometers etc).

To completely Rebuild, you can measure every little thing, determine it's wear, boil out the block to get it clean, replace etc. Rebore, maybe grind the crank etc etc. ..... just replace everything. This would be a "rebuild" .

For that, just buy a block that's had it done.

[boatpoker]

Originally Posted by Gard

What are likely the biggest problems one will face?

The only guarantees are that there will be surprises (ugly) and it will take longer and cost way more than you think.

My first total rebuild was an HT6 354 Perkins and it took me five months learning as I went.

I recently abandoned a rebuild of my Westerbeke 55A with only 2625hrs on it after a timing belt slip hammered the valves into the top of my pistons ... After spending the time removing and dismantling I found it impossible to get parts or help from Westerbeke. It's in the dump now !

Theres a new Beta 4 cylinder in now and we'll be test running it tomorrow.

4 months and $40K later ... It took six guys to muscle the new 600lb. engine into place the other day. You can see 5 in this photo, the sixth is pulling from behind the engine.