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Stop rebuilding my Universal m25XP or keep going?

Mar 23, 2020
5
Catalina 30 Cheboygan, MI
I am a shade tree mechanic that is also new to keelboat sailing, However, I have *never* messed with the internals of an engine. I picked up a 1988 Catalina 30 for a good price and I don't mind a project. It was inspected by the local boatyard service department prior to my acquisition and the owner was told he "needed a new engine" to replace the failed Universal m25xp, incidentally that employee has since been fired. I have aspirations of eventually moving to a different boat and doing some blue water sailing in 5-10 years and would like to know a thing or two about diesel engines. I tried taking a diesel engine course at the community college, but they are few and far between and any of the technical schools are pricey, so instead I picked up Marine Diesel Engines by Nigel Calder, downloaded the rather excellent service manual for the engine and preceded to do my worst...anyyyway...

I got as far as taking apart the top of the engine and removing the heads. I was inspecting the top of the pistons and noticed some fine metal shavings, but inspecting the cylinder liners...nothing seemed worn....the tops of the pistons looked good. I then inspected the cylinder head itself and saw that in the intake port of cylinder 2, low and behold it was full of the metal that belongs in the air cleaner. I pulled that out and the screen that is supposed to hold the said metal part inside the air cleaner is partially wrapped around the valve. I can see how if the engine was running at all, it would have only been running on two of the three cylinders and it would have been a mess.

My question is....do I continue rebuilding the engine, as planned? Disassembling the rest of the block, cleaning it thoroughly and trusting that I don't get in over my head mechanically? I'm keeping a video diary of every step of the way so I can see how everything was assembled. Or put it back together, having "fixed" the problem and see if she runs and leave well enough alone if she does. Also, if I continue rebuilding, do I replace the sleeves? Or do the rebuild without replacing the sleeves if they pass inspection using a bore gauge? Michigan is on coronavirus lockdown, so shop time isn't available for the next few weeks to have the sleeves pressed out and back in.

Thanks for your input. Even though I don't know what I'm doing, I'll post a youtube of the videos if for no other reason than people can see the engine torn down in case they are taking on the project themselves.
 

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Oct 22, 2014
11,737
CAL 35 Cruiser Portland OR, moored EVERETT WA
The saying... In for a penny in for a pound... seems to fit your challenge. At this stage you have nothing to loose. Go forward and learn. You are way beyond any place I might go. That is unless I took your same initiative.

Will love to follow your progress.

Welcome to the forum.
 
Jan 5, 2017
1,632
Beneteau First 38 Lyall Harbour Saturna Island
When I bought my Ericsson 28+ it had a dead Universal 5411 Did the rebuild myself, sent the head out and had the valves done. Bought all my parts from a diesel place ( try a Kubota tractor place if one is near you ) Rebuild, plus head work came to about $500 cdn. plus my time. It was my first engine rebuild and a great learning experience. Engine ran like a top when finished. Had about 600hours on it when I sold it and bought the First 38.
 
Feb 26, 2004
20,927
Catalina 34 224 Maple Bay, BC, Canada
try a Kubota tractor place if one is near you
This is the answer, given where you live. I happen to have a Kubota tractor dealership 5 km from my house, and they are my favorite marine store! :)

The links below might help, although little of it is as detailed as your work. It sounds to me like your old style air filter disintegrated and dropped its sh*t into one of the pistons.

Good luck, stay with it. I've got 3600 hours on my M25.

Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too :)

Diesel Engine - c34.org

101 Topics with lots of M25 engine material:

 
Nov 6, 2006
8,571
Hunter 34 Mandeville Louisiana
The mechanic probably thought the engine was done because of the stuck open valve from the screen. The bores/liners look fine. I would think that the bottom end is fine too.. while ya have the head off, inspect the heads and combustion chambers, re-seat the valves. Clean and smooth the whitish looking ding on the piston top.. Manually rock the crankshaft with each piston at top dead center and look to see that the one with the fouled port does not have more slack and that all have about the same movement as you rock the crank back and forth around TDC.. If that looks fine, reinstall the head, set the valves, do a good bleed on the injectors/pump, start her up.. I wouldn't go into the rest of the motor unless you just want to..
 
Jun 21, 2004
1,328
Beneteau 343 Slidell, LA
Was the engine running when you purchase or did you only rely on the yard’s mechanic? How many hours on the engine? Would have been nice to get compression readings before taking it apart. There are lots of diesels that can go 10k hours before a major overhaul. You might get by with having a valve job and injectors refurbished or replaced and avoid a total rebuild. A bit more info would be helpful. You’re likely to have lots of other projects on your new to you boat, so why get too wrapped up in a total overhaul if it isn’t necessary? Besides, it’s going to be time for sailing soon enough in MI.
 

Jim26m

.
Apr 3, 2019
470
Macgregor 26M P Cub Boo Mobile AL
@BigEasy :plus:. If the engine doesn't have a lot of hours on it, and the bores aren't in too bad of shape, I would work the head and go. Is there a ridge at the top of the sleeves (where the top ring travel stops)? Can't tell from the pics for sure, but it doesn't look like that engine is worn out yet. If there was a lot of debris in the cylinder that ate the mesh, I might pull that piston and clean out the ring grooves. Maybe run a hone through it if there are light scratches in the bore.

If you have a deep gouge in the bore, then a re-sleeve might be in order. May even need a piston if it got really hinky. You just need to evaluate the extent of the damage.

The valve/seat/guide damage also needs to be carefully determined. You can clean up minor seat damage with lapping compound. If it's all burned and gouged, you are looking at machine shop work or another head.

Even if you can only save the bottom end, you are a good bit of cash ahead.

You got this.

Forge on, and take pics!
 
May 24, 2004
6,120
CC 30 South Florida
In my estimation a head rebuild will restore compression to most engines perhaps extending their useful life. Make sure the bottom engine turns with no screeching noises and that there are no scuff marks on the cylinder liners to indicate a broken ring. Since you have the head off it will be a good idea to take it to a machine shop that specializes in rebuilding heads, checking for cracks, truing the head surface, grinding the valves, testing the springs, cleaning the intake ports and replacing studs. Make sure you replace the head gasket and ports gaskets in the final installation.
 

BillyK

.
Jan 24, 2010
425
Catalina 310 Ocean City, NJ
Keep Going! I've done a couple rebuilds since my first. the pucker factor is high on the first one, but an engine is relatively simple. Just use common sense and thoroughly inspect everything. if it doesn't look right, it's probably not. all the advice on taking the head to a machine shop is spot on.. let them inspect and refinish the seats as well as resurface the head gasket surface. If they can magnaflux it, all the better, that will check for cracks and other defects.... the bottom end of the engine is in all likelihood fine.

these engines are incredibly resilient.. mine sucked a rubber glove into the intake and spit the pieces out of the exhaust two years ago..
 
Jan 5, 2017
1,632
Beneteau First 38 Lyall Harbour Saturna Island
Take lots of pictures while taking things apart. I found them invaluable when putting it back together!
 
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Mar 23, 2020
5
Catalina 30 Cheboygan, MI
I'm leaning toward removing each of the pistons, and measuring the bore in the liners per the instructions in the service manual. My neighbor has a bore gauge I can use. Then I can also measure the gap between the rings and the liner, again per the service manual. I don't like the idea of shavings maybe sitting on the rings waiting to cause damage later so getting as much out as possible seems good. It will also allow me to visually inspect the crankshaft and clean the pan real good. Do I have to worry about any of the oil ports being clogged by the little flakes? If that all checks out Ill leave the bottom where it is....that way I don't have to disassemble the front of the engine and worry about screwing up the timing. The engine spins by hand relatively easily. I'll take the money I was going to spend on a rebuild kit on and have the head done by a reputable diesel shop, replace the hoses, upgrade the impeller to the run-dry and redo the electrical harness.

When removing the pistons, my understanding is that the most important thing is to reinstall them with the connecting rods facing the same direction as how they were originally and in the same cylinders; any other pointers?

So while I have it apart seems like I should get the injectors serviced, do the head gasket, oil pan gasket, intake manifold gasket, water impeller, hoses and filters. Anything else you all would recommend?

I'll put the video together when I'm done. I already found two mistakes I made (Calder says when loosening the headbolts to only loosen
them a little in order, then go through and loosen them the rest of the way, I just loosened them randomly...the other mistake belongs in the blooper reel)....but maybe if someone else can see it tore apart it'll help. I'll post a link once I make it.

Thanks for the input guys! I really appreciate it. What BillyK said about the pucker factor is spot on!
 
Jan 5, 2017
1,632
Beneteau First 38 Lyall Harbour Saturna Island
If you take the pistons out you should replace the rings. I couldn't find a ring compressor small enough for the 5411 and ended up using a hose clamp.
 

Jim26m

.
Apr 3, 2019
470
Macgregor 26M P Cub Boo Mobile AL
@pathfinder,
It won't hurt to take the pistons out and clean everything. Nobody but you has a feel for how much debris got in and where it went. But, if there isn't a ridge in the sleeve where the top ring travel stops, you probably don't have much wear in the sleeve. If you don't intend to strip it and tank it, be careful not to leave any gasket scrapings, carbon buildup scrapings, etc. in the engine. If you wind up having to hone, make sure you prevent the runoff from getting in the crankcase. Use short sections of rubber hose over rod bolts or wrap the rod end with a rag as you are removing and installing pistons. You don't want to scratch the crank or sleeve. As @Michael Davis says, if you pull the pistons, you might as well clean the piston grooves and swap rings. Sounds like you've got a good idea of what you are planning. Do follow torque procedures carefully.

Can't wait for the fire-up video!
 
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Mar 23, 2020
5
Catalina 30 Cheboygan, MI
@pathfinder,
It won't hurt to take the pistons out and clean everything. Nobody but you has a feel for how much debris got in and where it went. But, if there isn't a ridge in the sleeve where the top ring travel stops, you probably don't have much wear in the sleeve. If you don't intend to strip it and tank it, be careful not to leave any gasket scrapings, carbon buildup scrapings, etc. in the engine. If you wind up having to hone, make sure you prevent the runoff from getting in the crankcase. Use short sections of rubber hose over rod bolts or wrap the rod end with a rag as you are removing and installing pistons. You don't want to scratch the crank or sleeve. As @Michael Davis says, if you pull the pistons, you might as well clean the piston grooves and swap rings. Sounds like you've got a good idea of what you are planning. Do follow torque procedures carefully.

Can't wait for the fire-up video!
The sleeves seem like they are in terrific shape. There is a tiny bit of a ridge in cylinder one. But far less than the thickness of a sheet of paper. I'd like to avoid honing just to avoid the debris. Think I could get away with rings without honing?
 
Apr 5, 2009
987
Catalina '88 C30 tr/bs Oak Harbor, WA
Are you pulling the block out of the boat? with the heads off, it will probably only weigh 200-300 lbs so not much to get out. Much easier to work on the bench and then you can inspect and clean out the lower end.
 
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Jim26m

.
Apr 3, 2019
470
Macgregor 26M P Cub Boo Mobile AL
Honing breaks the "glaze" on the cylinder walls such that the new rings and honed wall will wear during the break-in period to seal better. This is what I was taught, anyway. Can you put new rings in the bore without honing them? Sure. I haven't tried it, but I bet there are a lot of quick repairs that have skipped honing. They may not seal as well in as short a time, but I suspect over time it will eventually wear to match up. I would take that ridge out, though, especially if you replace the rings. And if you do that, a light hone at the top may be necessary on #1. You should be able to do that without contaminating the case, though.

Can you tilt the block to angle the bores down? I have an engine stand that allows orienting the block at virtually any angle. I'm thinking if the bores are facing down (or at a down angle), you might do a light hone without getting crud in the crankcase. A few strategically placed paper towels, and a solvent rinse while it's upside down might be a way to go about it. Be careful not to run the hone too deep where it sprays out into the crankcase.

This is what I would try if it were mine. It probably isn't necessary. Engines will run perfectly fine with a whole lot more wear than you describe. I've pulled them apart with ridges as thick as my fingernail. If you decide the risk of contamination via honing is too high for the plan you're following, don't do it. You probably won't notice a difference in this application.
 
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Mar 23, 2020
5
Catalina 30 Cheboygan, MI
Honing breaks the "glaze" on the cylinder walls such that the new rings and honed wall will wear during the break-in period to seal better. This is what I was taught, anyway. Can you put new rings in the bore without honing them? Sure. I haven't tried it, but I bet there are a lot of quick repairs that have skipped honing. They may not seal as well in as short a time, but I suspect over time it will eventually wear to match up. I would take that ridge out, though, especially if you replace the rings. And if you do that, a light hone at the top may be necessary on #1. You should be able to do that without contaminating the case, though.

Can you tilt the block to angle the bores down? I have an engine stand that allows orienting the block at virtually any angle. I'm thinking if the bores are facing down (or at a down angle), you might do a light hone without getting crud in the crankcase. A few strategically placed paper towels, and a solvent rinse while it's upside down might be a way to go about it. Be careful not to run the hone too deep where it sprays out into the crankcase.

This is what I would try if it were mine. It probably isn't necessary. Engines will run perfectly fine with a whole lot more wear than you describe. I've pulled them apart with ridges as thick as my fingernail. If you decide the risk of contamination via honing is too high for the plan you're following, don't do it. You probably won't notice a difference in this application.

That sounds good. I do have a stand that will do that. I just ordered a hone. I'll let you know how it goes!
 
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