How many hours does a DIY diesel rebuild take?

[Cheechako]

Originally Posted by 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.

Of course this is living in a dream world where nothing goes wrong, no new problems pop up and no special tools are involved....

[kenbo]

It's virtually impossible to answer your question as presented. Everyone has a different definition of an engine rebuild. I've been involved in building gas race engines and the machine shop time is enormous.

I've rebuilt 4,3 and 2 cylinder marine diesel engines (Kubota and Mitsubishi based only) and the time it takes varies with the budget and desired outcome. But if you don't consider some machine shop time you're not rebuilding, your just swapping out parts.

You won't have a feel for the time commitment and cost until you have the head off, measure the bores, inspect and measure the valves and do a simple dye penetrant test of the deck and head.

The bottom end on a good diesel engine is rugged and doesn't have the balancing requirements of a high revving engine but you should at least have the crank checked for trueness and polish the journals and crank pins if every thing is within tolerances.

If you don't already have the guages and micrometers in the proper size, buying what you need for a one off rebuild doesn't make economic sense. Better to bring the block, crank, connecting rods with bolts and disassembled head to a machine shop and have them measure and magneflux everything before you buy any parts. Then you can make informed decisions about a path forward. Plus having a machine shop clean everything after any maching is performed sure beats your dishwasher.

But like I said, everyone's definition of an engine rebuild varies, as does the outcome.

[NorthCoastJoe]

I would say DO NOT do it. In my early 20's I worked in a shop rebuilding automobile engines. We had everything needed in the shop and sometimes you ran into a time suck problem.

Marine engines have a whole level of issues related to the environment they must work in. I have done a few marine rebuilds not in an engine rebuilding shop, but in my home shop. The amount of extra time & money spent on machine shop work made it not worth the effort.

I would rather get a good used engine or buy something new. Save yourself the frustration.

[Montanan]

Just buy a new boat. Problem avoided.

[Fore and Aft]

Gard another option is to keep an eye out on the internet for a new never used motor than someone has purchased and is now selling. A quick look for your hypothetical engine found a new Beta 75hp for $16,000.
There was another thread on here where the OP was looking at an engine replacement. I quickly found them their exact motor fully rebuilt for sale on Gumtree and sent them the link. They purchased that engine and installed it. My own 20hp Yanmar 2GMF I purchased brand new for $3500.

Cheers

[phorvati]

Originally Posted by boatpoker

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 !

On my previous boat i had rebuild a Westerbeke 40/4-108 Same block as Perkins 4-108 which turned out to be a BMC/Layland block. Not sure what Westerbeake 55 block cross references to, but once I discovered that 4-108 is used in all the London taxi cabs, finding parts was a lot easier.

I guess part of a decision to rebuild should be a research as to what agriculture or other commercial purpose if any, your marinized block cross references to. this makes finding parts a lot easier.

[boatpoker]

Originally Posted by phorvati

On my previous boat i had rebuild a Westerbeke 40/4-108 Same block as Perkins 4-108 which turned out to be a BMC/Layland block. Not sure what Westerbeake 55 block cross references to, but once I discovered that 4-108 is used in all the London taxi cabs, finding parts was a lot easier.

I guess part of a decision to rebuild should be a research as to what agriculture or other commercial purpose if any, your marinized block cross references to. this makes finding parts a lot easier.

I've been assured that the 55A is a Mitsubishi and by others it's an Issuzu and several other brands. None of these very definitive statements were correct as none of the several brands had any model with the same bore and stroke.

Westerbeke flat out refused to tell me the original mfg. even tho' they no longer support or sell this engine.

[fstbttms]

How long is a rope?

[mglomstead]

I rebuilt a Chev V8 and Chev straight 6 in my younger years. With the V8, my second rebuild, I remember pouring over rebuild books and engine specs to make sure I did things right - so that my pride and joy wouldn’t implode some day. It was a great learning experience.

That said, today, I’d buy a short or probably long block instead - save a lot of time, perhaps even money when considering machining costs. Assuming you have the time, price out the alternatives?

[mcarthur]

Originally Posted by boatpoker

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.

Eeek! I can't imagine how we'd go with 1300+lb (600kg) in an alum hull with small-human only access.

Anyone found a bigger set of can openers for 12mm plate?

[Gard]

Not sure I would want to go the route of a replacement engine unless it was of the same make and model. Engine mounts, electrics, instrument panel, sail drive... it adds up in work and costs unless the old can be used or easily swapped.

I kind of want to do a rebuild, for the fun and challenge of it. But I also know that with the amount of hours required, lead times, etc - and available time vs all my passions fighting for my attention - that such a rebuild would take me ages. If it would take 25 hours, then bring it on. 50 hours, then probably.100 hours, then probably not for me. 150 hours and it is a hard no.

Although I want to do it, I also want to use the boat in the season. I guess one option could be to buy an identical used engine to do the rebuild on, and then swap and sell the old one (or rebuild the old one as well)... or to buy an allready rebuilt engine, swap, rebuild the old and sell it.

[JPA Cate]

If you decide to go for a rebuilt engine, do research the outfit carefully. Some friends of ours bought a rebuilt replacement engine, only when it broke down in its first year were they able to discover that the block and head had been repainted, so that it looked new, but there was wear inside that would never have occurred in just one year. Very sad, and no recourse.

So, I would say, if you have time and patience, you need to decide if you want to teach yourself how to work on a diesel engine. You will be able to access manuals and You tubes. If you already have plenty of tools, you won't have to add many more tools to your inventory. If you would enjoy it, go for it, you will understand your engine when you put it back together.

On the other hand, if the idea is only driven by the concept of saving money, then the guys above are probably right that you'll be better off financially with new or rebuilt. If you don't like inanimate objects getting revenge on you for working on them; if you don't like black greasy dirt under your fingernails; if it's beneath your dignity; or even if speed is of the essence, let someone else do it, and feel grateful.

Ann

[Knot workin]

I work as a diesel Mechanic and have rebuilt many diesel engines of all brands.

A few questions come to mind
1. why do you want to rebuild
2. what is wrong with the engine
3. how thorough do you want to be
4. can you buy or borrow the special tools needed.

It hard to answer your question without those answers.


In my experience the engine would need a good check over, If it is just worn it might be feasible to rebuild it but if it has any damage a reman engine will be cheaper in the long run and probably come with warranty.

If its due to poor performance getting the engine properly checked out could find out if the engine is sound and maybe the performance issue is a fuel issue or intake etc and by a much cheaper fix.

[David Mathis]

You are likely to come out ahead by getting a rebuilt engine from a reputable builder. You get a core charge for your old engine to offset the cost. If that isn't an attractive option, get a rebuilt short block and send the head out for new valves, guides, seals, springs, and seats if they're needed. Injectors should be sent to a shop to have them checked then rebuilt or replaced as needed. If you don't have the tools needed and at least a little experience inside a diesel, attempting a complete rebuild may not be the best approach. While the engine is out, it's worth sending the alternator to a shop for a rebuild.

[sinnerman]

As some of the other replies have stated, you would not want to do a full rebuild on your own, unless you have done engine rebuilds before AND have access to some of the specialized tools needed.

If you mess up on critical items like crankshaft bearing clearances, timing of the valve/ injection pump gears, you can wipe out the engine.

That being said, changing out the cylinder head/head gasket is a definite DIY project. You can take the head to a shop and have it rebuilt, or buy a replacement rebuilt head and install it.

If the cylinders will need honing, and maybe boring (and therefore oversized pistons or new sleeves in the block) you need special equipment and tools. Same with replacing crankshaft bearings, measuring the cylinder to head clearance etc.

Removing/installing the engine yourself, replacing motor mounts , alignment are also DIY and doing it yourself will save you big bucks.

You can remove the engine in a weekend with a helper. Same for changing the head / head gasket (if there are no surprises like frozen / sheared bolts).

Lack-of-power/hard to start can be due to bad injectors, leaking valves, incorrect valve clearance (lash) adjustment or poor compression.

People tend to ignore the injectors. They need to be treated like spark plugs, and be removed periodically for cleaning and testing.

Same for the valve clearance - it also gets ignored and needs to be re-adjusted periodically. Too much clearance reduces power, too tight clearance can cause the valves to stay open and burn/leak resulting in lower compression, less power and hard starting.

Some blue smoke on start is normal, especially if it has been sitting a while. Blue smoke while running can be worn piston rings/cylinders, a gummed up piston ring, or worn valve seals.

The first steps would be:
/1/- Remove the injectors. If they have heavy black soot, the air/fuel is not burning correctly/completely which can be a bad injector or low compression. Take them to an injector shop for test. You will need to know what the specification for "cracking pressure" is for the injectors when you take them there. (in the engine manual) .

/2/: With the injectors removed, do a compression test. (You can also perform a test with the injectors installed if you have an adapter for the glow plug). Compare the test results to the specs. For most engines all cylinders should be within 10% of each other..

/3/ Adjust the valve clearance (with the engine COLD). I always note the as-is clearance before I adjust them.

/4/: Re-check compression after valve adjustment.


I performed steps 1-4 on my old Universal(Kubota) diesel:

All three of the injectors were leaking (dripping fuel after firing) & had poor spray patterns. The valve clearances were WAY out-of-whack.

After installing new injectors and adjusting the valves, it now starts easier, runs smoother (less vibration) and has more power. Even with two of the three cylinders having marginal compression.

My two cents.

Cheers