engine replacement questions

[Gary Ambrose]

I have a number of questions regarding engine replacement especially on a 1986 Universal M-25.

1.  If a compression test is done at what compression does one seriously consider replacement?

2.  How many engine hours is everyone really getting from the M-25?

3.  If one must replace the M-25 is the M-25XP the only replacement engine now available from Universal? The idea being that it is more economical in terms of alignment of exhaust etc. to replace with the closest possible fit. I am hearing from some that rebuild may not be the best way to go

Does replacing with the M-25 XP require building new fiberglass stringers?  The current stringers and engine mounts are at 11" on center. Our mechanic says the M-25XP is 16" on center and will require the new stringers.

These questions are by way of research. We must replace a broken/cracked flange on the engine side of the shaft and the age of the engine (1986 and hours 1600) raises the question. Ours seem strong but we will do a compression check to make sure we are still solid and have no more shortened sailing seasons again.

Many thanks to all for your help!

[Ray & Sandy Erps]

I used to rebuild diesel engines a long time ago.  We rarely used compression tests as a diagnostic tool but instead used oil consumption and oil analysis for traces of bearing material as a guide.  If a diesel motor's compression gets low, it will be hard to start.

I currently have around 2200 hours on our M25-XP.  The motor still starts and runs well and I expect it to go 3000 hours before I even start thinking of a rebuild and then it will probably be a limited rebuild (head redone and roll in new crankshaft bearings.)

Change your oil often, burn clean fuel, watch your valve lash and coolant level and your motor will run another 15 years.

[Stu Jackson]

Gary

I'm not quite sure where your flange problem is physically located.  We have a 1986 M25 with 1,715 engine hours, and it runs great.  Ron Hill has over 4,000 hours on his M25XP.  I've been using Mobil 1 synthetic oil for last three years, and dutifully replace the transmission fluid, and all the other maintenance things required.  We replaced the exhaust riser two years ago after it broke, and that story can be found on the Tech Notes Online section of the main website.  Also installed the hump hose to the muffler.  Also look in FAQs and Projects for the replacement of the alternator bracket if you or a PO haven't done so.  As far as replacement swap out, you'd have to measure, measure, measure.  I don't recall anyone here doing that in the almost eight years I've been involved here with Aquavite, although one member deos have a Perkins (I think) replacement.

[Tom Soko]

Gary,
Except for a marginal cooling system, everything I've heard about the M25 and the M25XP has been positive.  They are based on a Kubota tractor engine block, and have been known to go for many thousands of hours.  In your engine manual you should have an installation diagram with measurements.  You can compare that to:
http://www.westerbeke.com/drawings/M_25XPB.pdf
I think if you look at the diagram, you will find you can either use the 16" or 11.5" mounting holes.  I'm pretty sure the M25 and the M25XPB are about as close as you can come to a bolt-in replacement.

[Stu Jackson]

Gary

Tom's input is right on.  The cooling system is marginal because of the size of the HX.

I also forgot to mention that I installed a larger 3 inch heat exchanger about two year ago.  This is a great addition, which I urge you do to.  When you do that, just be careful that you maintain access to the dip stick for the transmission fluid.  

If you're lurking around here a lot you've probably heard my history with the engine, all good.  The 3 inch HX is also mentioned in "way back" tech notes, available to C34IA members on line and with their free CD-ROM.

[Ron Hill]

Gray : You've told me nothing that would justify a new engine or a rebuild.  I've got an M25XP with 4500 hrs in 18 seasons, suspect the engine will outlast ME.  
Right now it's running better than it ever has.
I believe the engine bed req. are the same for all M25 series engines .  Call Westerbeake to confirm.    

[SteveLyle]

It looks like you can get an M25xpb with either 11.5 or 16 inch mounting centers.  But I doubt that you need one.

I'm with Ron - 1600 hrs isn't a lot, if the engine hasn't been abused you should get several multiples of that out of it.

The engine's strong - it's the friggin exhaust riser that's the weak spot - which I'm dealing with now.

Would love to hear the story on the broken/cracked flange.  Never heard that one before.

http://www.westerbeke.com/technical/Engine%20Replacement%20Guide%20Revised%202%2D14%2D05%2Epdf

[Gary Ambrose]

Hi Steve,

Here is the flange story. First we purchased our C34 last August. As part of the purchase the owner (after survey) agreed to replace the stuffing box and cutlass bearing. When the shaft was removed (original bronze) it had a bend in it. The owner was very conscientious and also agreed to a new stainless shaft. So, we started with all of that new plus alignment. Both a preliminary out of water and follow up check in the water.  All seemed fine.

This year late in the season we seemed to have some abnormal vibration. It was cyclical and at all rpms. It ran best at 2200. I checked the motor mounts because the engine was vibrating in gear too much (it was smooth in neutral) and found all the bolts to stringers not really very tight.  Tightened all, no change, so feared alignment was off.  Went to boatyard so they could do alignment.

On the end of the shaft is a flange that couples to a similar flange on the engine. In between we have a vibration dampening poly-like donut. I believe they are called a transmission saver because they help to dampen vibration. When the shaft was disconnected, after two bolts were removed, the dampener dropped down to the bilge because two ears on the engine flange were cracked off. They were old cracks and the broken bolts were on the same side of the flange not opposing as one might guess. That, it seems would create an opportunity for flex between engine and shaft. The dampener prevented seeing anything amiss behind it (survey could miss that). While the alignment should have occurred between the two metal flange surfaces rather than they poly donut surface, it probably was not, thus the donut could stay in place and hide the broken flange from being seen as there are four bolts on the engine side and another four on the shaft side.

So apologies for being so wordy! I am grateful for your belief in the M-25 engine life...our mechanic seems to believe in re power and new over older.
We will take all your advice and replace the broken engine flange, do an alignment, and continue onward....many many thanks for easing the doubts I had voiced.

[SteveLyle]

I'd suggest a new mechanic, or at least don't claim ownership of him (you called him "our mechanic").   At best he should be "a mechanic".  Hope he's not related to  you.  This site is full of cases where people have gotten bad advice from so-called professionals (and to be fair, there's been some bad advice pass on by us amateurs, as well, no doubt).

Anyway, welcome to the world of old boats.  They are absolutely full of old systems, and sometimes it is best to replace them - cause new isn't just newer, it's better.  But more times than not what's on them is repairable.  Or is actually working fine.  Just not shiny anymore.

Here's some good advice - if you don't have a solenoid wired into your glow plugs, do it.  Quick, cheap, and you'll start with half the pre-heat time, or less.

Best of luck,
Steve

[Stu Jackson]

Here's the solenoid glow plug reference:

http://www.c34.org/projects/projects-glowplugs.html

[Ron Hill]

Guys : Don't let anyone jerk you around about engine shaft alignment.  It must be done metal transmission flange to metal shaft flange with the boat in the water (for at least 24 hrs - best 48hrs) with the rigging tuned.

My first and only encounter with a diesel boat mechanic - was when I hired one to adjust the valves on my M25XP (1990?).  In short order I found out that I knew more about adjusting valves than he did!  I'd had a VW bug and did that on my back looking up!!  We stopped right there!!!

It's hard to find a GOOD diesel BOAT mechanic as they are "far and few between".
You were lucky to find those cracked flanges - a sign of a great mechanic!

[Ray & Sandy Erps]

I echo the observation about assuming that boat yard mechanics know what they're doing.  I just had maintenance done on my boat.  I had the yard replace the cutlass bearing, figuring they would have some special tools that might save some time/work.  Boy was I wrong.  Had to pull the shaft anyway and then the guy got out the "BFH" (big funny hammer) and started pounding away at the strut to drive the bearing out.  Geez, I used a puller and a deep well socket to push out the one on my other boat.  Then when I checked the drippless seal after they reassembed it, the collar seal was pushed up against the carbon seal to the max and the carbon seal wasn't centered around the shaft so I ended up re-doing it anyway.  Argh!  Wonder how long that seal would have lasted before a failure if it hadn't been caught?  

Anyway, the mechanic recommending the re-power has a bit of a conflict of interest, as that job would line his pockets with a considerable amount of cash.

[Stu Jackson]

Engines, electrical and hull integrity:  all seem to be safety related issues.

While we all can't and won't become expert diesel mechanics, there ARE many things we can and should do to maintain not only our investments but our family's and friend's safety.

Regular maintenance, a reasonable familiarity with the parts and features that are prone to failure (shucks, think they're even mentioned around here?) and some common sense, sure go a long way.

That comes right after figuring out and remembering, which way the pointy end is!

I haven't found a diesel mechanic either - I'm beginning to think they don't exist, and IF they do, you HAVE to hover over their shoulder as they are working.

Ain't that what you wished your Mom would stop doing to you?!?