We just arrived back from the Lower Keys in Florida and I was wondering (IF) a larger engine with more than 21hp has ever been replaced in a 1984 MK III . I put a three bladed prop on and it helped even with a clean bottom I'm only doing 6 knots motor sailing is great but, I'm thinking because of the hours on the exisiting engine 3800 if installing an engine with more hp that would be compatable with the Universal xp25. Thanks, Chip in Venice, Fl
Universal 25XP
- Thread starter hathanger
- Start date
Do you have the original Universal M-25? It is 21 HP. It was superseded by the M-25xp, which was then superseded by the M-25xpb, which is still being made.
Are you asking about replacing an M-25 with a new M-25xpb?
If you are, I can offer the following. My boat came with the M-25 (not the original engine but an earlier repower). I replaced it with an M-25xpb. It was not a drop in replacement. The M-25 had a three point mount while the M-25xpb has a four point mount. Also, the M-25xpb is larger physically and heavier. It is taller.
Are you asking about replacing an M-25 with a new M-25xpb?
If you are, I can offer the following. My boat came with the M-25 (not the original engine but an earlier repower). I replaced it with an M-25xpb. It was not a drop in replacement. The M-25 had a three point mount while the M-25xpb has a four point mount. Also, the M-25xpb is larger physically and heavier. It is taller.
I wonder if the existing 21 hp is the whole problem.
It just seems like.... that E-35-3 probably has enough waterline to motor at 6.5 to 7.0 with a clean bottom, any day of the week.
By comparison, I just brought our boat home a couple hours ago from the yard -- new bottom paint. Admittedly it's as fast right now as it's gonna be...
Our engine has two more hp, being an M25XP. I was doing 7.0 at 2400 and 7.5 kts at WOT (about 2900 rpm because we are still slightly over pitched).
Three blade fixed prop. Not so good for sailing, but way nice for motoring.
One observation from up here in the cheap seats, if I may... be sure (really sure) that your prop is correctly pitched and actually measures out to the stamped pitch on the hub. Last year I had to spend some unexpected $$ to have our Michegan three blade 'sailor' prop brought to the same spec for all blades. One was over a half inch off from the factory!
So some careful measurements may in order.
That's just a guess or course, and worth about one internet cent.
Good luck,
Loren
It just seems like.... that E-35-3 probably has enough waterline to motor at 6.5 to 7.0 with a clean bottom, any day of the week.
By comparison, I just brought our boat home a couple hours ago from the yard -- new bottom paint. Admittedly it's as fast right now as it's gonna be...
Our engine has two more hp, being an M25XP. I was doing 7.0 at 2400 and 7.5 kts at WOT (about 2900 rpm because we are still slightly over pitched).
Three blade fixed prop. Not so good for sailing, but way nice for motoring.
One observation from up here in the cheap seats, if I may... be sure (really sure) that your prop is correctly pitched and actually measures out to the stamped pitch on the hub. Last year I had to spend some unexpected $$ to have our Michegan three blade 'sailor' prop brought to the same spec for all blades. One was over a half inch off from the factory!
So some careful measurements may in order.
That's just a guess or course, and worth about one internet cent.
Good luck,
Loren
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M.MMMMMMMMMMMM, I've never had the rpm's over 2200 because I was told that's the max !!! If this is wrong advise how high can I take her because at 1800 to 2200 with a new bottom job I was motoring 6knots. The engine purr's at 1800 and 2200 it gets noisey in the cabin! Is 3800 hours alot for the engine ? She's well maintained even babied.
Prop Pondering...
http://www.westerbeke.com/onlinemanuals/200151_m15-m25-5411-5421_technical_man.pdf
Found this manual on line. Looks original. It states that cruising rpm should be 80% of maximum rpm, given as 3200 rpm. That puts your cruising rpm at 2560 rpm.
If you are motoring well below that you are losing some horsepower, i.e. you are not really getting 21 horses to that prop. As you note, you should be getting more speed out of the boat as well.
Your boat could possibly be "over propped" (have too much pitch). Even if the original prop was correct, a prior owner could have unknowingly installed the incorrect one.
There are quite a few threads here on finding the proper prop pitch for different models -- some site searching may be helpful.
Hope this helps a little.
Cheers,
Loren
http://www.westerbeke.com/onlinemanuals/200151_m15-m25-5411-5421_technical_man.pdf
Found this manual on line. Looks original. It states that cruising rpm should be 80% of maximum rpm, given as 3200 rpm. That puts your cruising rpm at 2560 rpm.
If you are motoring well below that you are losing some horsepower, i.e. you are not really getting 21 horses to that prop. As you note, you should be getting more speed out of the boat as well.
Your boat could possibly be "over propped" (have too much pitch). Even if the original prop was correct, a prior owner could have unknowingly installed the incorrect one.
There are quite a few threads here on finding the proper prop pitch for different models -- some site searching may be helpful.
Hope this helps a little.
Cheers,
Loren
That would be sweet to get many hours on a diesel , but it probably depends on the maintenance that is performed ! In Florida a marine mechanic told me to change oil every three months even if the engine doesn't run because of the condensation. So, as Forest Gump says, " I went and did it" ! Thanks for the feed back! Chip
Tach Reliable?
I do rememberreading somewhere that diesel tachometers may not be that accurate. I know that if I cruise at 80% of max rpm that I use fuel at an alarming rate. (We used fuel so quickly one trip that we actually ran out.)
I "listen" for the sweet spot when we motor while watching the boat speed. My 32-200 seems to want to move best at about 4.75 knots. At this rate the engine RPM's are below the suggested 80% of max. RPM.
FWIW your engine tachometer may not be reliable.
Paul
I do rememberreading somewhere that diesel tachometers may not be that accurate. I know that if I cruise at 80% of max rpm that I use fuel at an alarming rate. (We used fuel so quickly one trip that we actually ran out.)
I "listen" for the sweet spot when we motor while watching the boat speed. My 32-200 seems to want to move best at about 4.75 knots. At this rate the engine RPM's are below the suggested 80% of max. RPM.
FWIW your engine tachometer may not be reliable.
Paul
We are also "sweet spot" sailors. We run the tach about staright up...(2000-2100??) and that gives us about 5 knots. Anymore than that and we feel like it is working too hard. i really would like to know what IS the best rpm to run. Is it listed in the manual someplace and I am just missing it???
My manual recommends a cruising "range" of I think 2000-2500 RPM (Universal M-25xpb). The redline is 3000. The 80% RPM, mentioned by Loren, would be 2400, so it appears the factory contemplates cruising at less than the 80% figure.
For people who find the recommended RPM range too noisy, is there a down side to running your engine for extended periods of time below the "cruising range" specified by the factory ? I don't know, but in a Kubota's case it would surprise me unless the engine is way undersized for the size of the boat.
For people who find the recommended RPM range too noisy, is there a down side to running your engine for extended periods of time below the "cruising range" specified by the factory ? I don't know, but in a Kubota's case it would surprise me unless the engine is way undersized for the size of the boat.
Throttle UP
I'm not a mechanic but am acquainted with one of the best ones in the NW. He always advises that diesels be run at their maximum cruising rpm's. i.e. they like being under a load.
If you run one at lower rpm's, you not only lose real horsepower, your engine may not fully combust the fuel. From cylinder and ring problems to carbon build up in the exhaust elbow, it's just not good for them.
He usually advises all boat owners to run their diesels at full rpm/speed (i.e. to where it starts smoking) every month for a half hour or so.
I do believe this. I am one of the dredge operators for our club and year after year our 150 hp John Deere six cyl. diesel in the dredge is trouble-free, being run at full-rated 2000 rpm six hours a daily shift. "It's loud and proud, and we all wear ear protection!"
Of course this all cycles right back to whether any given boat has the correct prop to actually acheive full rpm's. A LOT of boats do not, whether sail or power. Blame it one the prior owner(s), but the problem is very real.
And then there's regular maintenance (yeah, right - "regular") of all those rotating parts aft of the engine block.
We just replaced the original shaft last week. With the new mounts a few seasons ago we are now... for the first time in years... noticing very (!) little vibration.
That new shaft with new coupler, ready to install, was $550. Given that no one likes spending money, I do understand why so many boats have not had maintenance like this performed.
Given that the bulk of our Ericsons are at or beyond a quarter of a century in age, a LOT of these boats suffer from "deferred maintenance".
Back to "the door we came in" for this thread, the horsepower of an engine is certainly important, but even more important is getting all that power converted into thrust.
Aside: back some years ago when I was spec-ing out a coolant-driven cabin heater, the technition at the former (wonderful store) Doc Freemans in Seattle told me that diesels combust their fuel to produce, in about thirds, useful rotational torque, excess heat, and friction losses. I would note that when it's 40 degrees F and we run our engine at 2500, we can heat up our interior to over 80 deg. easily with the little Heatercraft blower on Low fan setting. Engine never cools below thermostat setting.....
OTOH, at an idle, enough heat is being removed from the coolant loop by the cabin heater to push the guage readout down by ten degrees. It's a very efficient little radiator.
My point, and I do have one, is that these little aux diesels have to work hard to move our boats at hull speed and that, when new, they are rated at enough to do that, but there's likely nothing to spare. You want to be balanced and properly propped to benefit from every horsepower that you paid for. It's best for you - to get you through that choppy narrow channel on a windy day - and best for your engine to enjoy a long life.
Loren
I'm not a mechanic but am acquainted with one of the best ones in the NW. He always advises that diesels be run at their maximum cruising rpm's. i.e. they like being under a load.
If you run one at lower rpm's, you not only lose real horsepower, your engine may not fully combust the fuel. From cylinder and ring problems to carbon build up in the exhaust elbow, it's just not good for them.
He usually advises all boat owners to run their diesels at full rpm/speed (i.e. to where it starts smoking) every month for a half hour or so.
I do believe this. I am one of the dredge operators for our club and year after year our 150 hp John Deere six cyl. diesel in the dredge is trouble-free, being run at full-rated 2000 rpm six hours a daily shift. "It's loud and proud, and we all wear ear protection!"
Of course this all cycles right back to whether any given boat has the correct prop to actually acheive full rpm's. A LOT of boats do not, whether sail or power. Blame it one the prior owner(s), but the problem is very real.
And then there's regular maintenance (yeah, right - "regular") of all those rotating parts aft of the engine block.
We just replaced the original shaft last week. With the new mounts a few seasons ago we are now... for the first time in years... noticing very (!) little vibration.
That new shaft with new coupler, ready to install, was $550. Given that no one likes spending money, I do understand why so many boats have not had maintenance like this performed.
Given that the bulk of our Ericsons are at or beyond a quarter of a century in age, a LOT of these boats suffer from "deferred maintenance".
Back to "the door we came in" for this thread, the horsepower of an engine is certainly important, but even more important is getting all that power converted into thrust.
Aside: back some years ago when I was spec-ing out a coolant-driven cabin heater, the technition at the former (wonderful store) Doc Freemans in Seattle told me that diesels combust their fuel to produce, in about thirds, useful rotational torque, excess heat, and friction losses. I would note that when it's 40 degrees F and we run our engine at 2500, we can heat up our interior to over 80 deg. easily with the little Heatercraft blower on Low fan setting. Engine never cools below thermostat setting.....
OTOH, at an idle, enough heat is being removed from the coolant loop by the cabin heater to push the guage readout down by ten degrees. It's a very efficient little radiator.
My point, and I do have one, is that these little aux diesels have to work hard to move our boats at hull speed and that, when new, they are rated at enough to do that, but there's likely nothing to spare. You want to be balanced and properly propped to benefit from every horsepower that you paid for. It's best for you - to get you through that choppy narrow channel on a windy day - and best for your engine to enjoy a long life.
Loren
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I'm not a mechanic but am acquainted with one of the best ones in the NW. He always advises that diesels be run at their maximum cruising rpm's. i.e. they like being under a load.
If you run one at lower rpm's, you not only lose real horsepower, your engine may not fully combust the fuel. From cylinder and ring problems to carbon build up in the exhaust elbow, it's just not good for them.
He usually advises all boat owners to run their diesels at full rpm/speed (i.e. to where it starts smoking) every month for a half hour or so.
I do believe this. I am one of the dredge operators for our club and year after year our 150 hp Joh Deere six cyl. diesel in the dredge is trouble-free, being run at full-rated 2000 rpm six hours a daily shift. "It's loud and proud, and we all wear ear protection!"
Of course this all cycles right back to whether any given boat has the correct prop to actually acheive full rpm's. A LOT of boats do not, whether sail or power. Blame it one the prior owner(s), but the problem is very real.
And then there's regular maintenance (yeah, right - "regular") of all those rotating parts aft of the engine block.
We just replaced the original shaft last week. With the new mounts a few seasons ago we are now... for the first time in years... noticing very (!) little vibration.
That new shaft with new coupler, ready to install, was $550. Given that no one likes spending money, I do understand why so many boats have not had maintenance like this performed.
Given that the bulk of our Ericsons are at or beyond a quarter of a century in age, a LOT of these boats suffer from "deferred maintenance".
Back to "the door we came in" for this thread, the horsepower of an engine is certainly important, but even more important is getting all that power converted into thrust.
Aside: back some years ago when I was spec-ing out a coolant-driven cabin heater, the technition at the former (wonderful store) Doc Freemans in Seattle told me that diesels combust their fuel to produce, in about thirds, useful rotational torque, excess heat, and friction losses. I would note that when it's 40 degrees F and we run our engine at 2500, we can heat up our interior to over 80 deg. easily with the little Heatercraft blower on Low fan setting. Engine never cools below thermostat setting.....
OTOH, at an idle, enough heat is being removed from the coolant loop by the cabin heater to push the guage readout down by ten degrees. It's a very efficient little radiator.
My point, and I do have one, is that these little aux diesels have to work hard to move our boats at hull speed and that, when new, they are rated at enough to do that, but there's likely nothing to spare. You want to be balanced and properly propped to benefit from every horsepower that you paid for. It's best for you - to get you through that choppy narrow channel on a windy day - and best for your engine to enjoy a long life.
Loren
To clarify a couple points.
A diesel does not need to be running 80% of redline, or maximum cruising speed, in order to achieve complete combustion. Diesels have been used in passenger automobiles for decades and run at a comparable RPM range to gasoline automobiles, which is considerably less than 80% of redline.
As for the idea that diesels like a load, I think it would be more accurate to say that diesels excel at using their horsepower to handle loads. If you put too much load on a diesel it will interfere with combustion. To over prop an engine is to put an excessive load on the engine and it will smoke. Change the pitch and the engine can spin freely, you're freeing up the load. In effect you're using engine horsepower to free up the load and the best way to do that, since horsepower equals torque times RPM, is to keep the revs up.
The John Deere dredge engine is 150 HP. That engine not only turns a 24" plus or minus diameter cutterhead on a shaft 12 feet down in the river, it also runs a pump that shoots the broken loose sand 100 feet away and up a river bank and into a reservoir. All from 150 HP. Of course its going to need its maximum HP, which means maximum RPM. If you took that engine out of the dredge, inserted it in a trawler, and just let it spin a prop in water, would it need to run continually at maximum revs to be happiest? You could ask Norm. I'm skeptical.
The idea that these engines are under powered by nature for their appointed task, and therefore need to run to allow as much HP development as possible, is a good one. But you're not always going to have the same relative boat to engine HP match. And not all engines have the same torque curve. The differences in torque curve between two Kubota, contiguous in the model line, can be considerable even though the differences in fully developed HP might not seen that impressive.
Wandering Diesel Comentary
We may be closer to agreement on the optimal running loads of diesels than it might appear at first reading.
The automotive reference did get me to thinking, though.
Unlike vehicles, the bulk of our small one to three cylinder marine diesels are derived from stationary and tractor applications. In that use they are designed to run at fairly constant rpm's for long continuous periods.
Even in vehicles, I understand that the engines in trucks like it best when they are fully warmed up and running down the road, with a load. (Where the now-fading practice of idling those big engines all night at the cold truck stop leaves my arguement is another story! Maybe idling is not completely evil after all? Oh My, maybe I'm wrong again...)
Anyhooooo.... our dredge has two big "loads" on it. The main centrifugal pump is moving a water/sand slurry thru several hundred feet of 6" pipe and up a bank to a discharge into a settling pond. It also is constantly driving a honkin' big hydraulic pump to power the motor on the rotating "digger head" and run the two swing cable winches and and the two spud winch motors. Raising the Digger Head also can take a lot of pressure- enough to pop the relief valving sometimes.
Pressure on the cables can hit 1500 to 2K before internal valving limits the force.
("PDX" is also an RCYC Dredge Operator, if you can't tell...)
:nerd:
That comment about the torque curve is right on, too. The new Betamarine diesels use a more efficient Kubota diesel engine, and I note that the Betamarine 20 or 25 is proving to be as-strong-or-stronger than the 80's Universal M25 or similar Yanmar engines that are being replaced in sailboats in the 34 to 36 foot range.
Certainly, HP is important, but seems to be only one factor we should look at when comparing "small" diesels.
Cheers,
Loren
We may be closer to agreement on the optimal running loads of diesels than it might appear at first reading.
The automotive reference did get me to thinking, though.
Unlike vehicles, the bulk of our small one to three cylinder marine diesels are derived from stationary and tractor applications. In that use they are designed to run at fairly constant rpm's for long continuous periods.
Even in vehicles, I understand that the engines in trucks like it best when they are fully warmed up and running down the road, with a load. (Where the now-fading practice of idling those big engines all night at the cold truck stop leaves my arguement is another story! Maybe idling is not completely evil after all? Oh My, maybe I'm wrong again...)
Anyhooooo.... our dredge has two big "loads" on it. The main centrifugal pump is moving a water/sand slurry thru several hundred feet of 6" pipe and up a bank to a discharge into a settling pond. It also is constantly driving a honkin' big hydraulic pump to power the motor on the rotating "digger head" and run the two swing cable winches and and the two spud winch motors. Raising the Digger Head also can take a lot of pressure- enough to pop the relief valving sometimes.
Pressure on the cables can hit 1500 to 2K before internal valving limits the force.
("PDX" is also an RCYC Dredge Operator, if you can't tell...)
:nerd:
That comment about the torque curve is right on, too. The new Betamarine diesels use a more efficient Kubota diesel engine, and I note that the Betamarine 20 or 25 is proving to be as-strong-or-stronger than the 80's Universal M25 or similar Yanmar engines that are being replaced in sailboats in the 34 to 36 foot range.
Certainly, HP is important, but seems to be only one factor we should look at when comparing "small" diesels.
Cheers,
Loren
You're definitely not wrong about the pitfalls of running an engine (either gas or diesel) at idle for hours on end. Carbon, carbon, and more carbon. But in the old days they kept big commercial diesels idling all night because they wouldn't be able to start them again the next morning if they turned them off without plugging them in for the night. The glow plug system used back then wasn't effective at starting a cold engine, even with a charged up battery. 1950s Mercedes passenger diesels were the same.
Thankyou all for the input it is MUCH appreciated !! NOW, if a pereson wanted to remove the original 25xp engine and install a more powerful engine which engine would you choose that would be compatable to the transmission ? I' m just tossing the question in the air and see what comes down ! Thanks, Chip - ( right now I'm on the hook in CAYO COSTA NATIONAL PARK just pass the Boca Grande Channel in Florida - don't want to go home just yet !!!! )
Florida - don't want to go home just yet !!!! )Morgan Stinemetz
Moderator
Not national park
Your must be on the inside at Cayo Costa, Pelican Bay. Be sure to go to the inn on the other side of Cayo Costa, Cabbage Key. Food is average or better, but the atmosphere is out of this world. Great place to get over served. There are feral hogs on Cayo Costa, but it's a state park, not national.
Your must be on the inside at Cayo Costa, Pelican Bay. Be sure to go to the inn on the other side of Cayo Costa, Cabbage Key. Food is average or better, but the atmosphere is out of this world. Great place to get over served. There are feral hogs on Cayo Costa, but it's a state park, not national.
Rocinante33
Contributing Partner
To answer your question about what would fit as a replacement, I would start with this; this has the dimensions of your current engine (in inches). http://www.westerbeke.com/productBrochures/universal_m25xp.pdf
Beta marine seems to have really good, Kubota based marine engines. Have alook at these. They have the dimensions in mm, so you need to convert the M25xp dimensionss to mm. Here is the 28 HP version. Looks good to me.
http://www.betamarinenc.com/Beta 28 & 30 HE TMC40 100amp (inch) 100-05767.pdf
Here is a list of all their various models and sizes.http://www.betamarinenc.com/enginemodels.html
I think Beta Marine would be real helpful and tell you if your current transmission would work with their blocks. I would think about a a new tranny too, as long as I was changing the engine.
Beta marine seems to have really good, Kubota based marine engines. Have alook at these. They have the dimensions in mm, so you need to convert the M25xp dimensionss to mm. Here is the 28 HP version. Looks good to me.
http://www.betamarinenc.com/Beta 28 & 30 HE TMC40 100amp (inch) 100-05767.pdf
Here is a list of all their various models and sizes.http://www.betamarinenc.com/enginemodels.html
I think Beta Marine would be real helpful and tell you if your current transmission would work with their blocks. I would think about a a new tranny too, as long as I was changing the engine.
More commentary on diesels and their operation? Automotive or terrestrial diesels are a bit different in that they see a varying load and have a transmission that allows the operator to keep the engine in its "sweet spot" regardless of speed and gradient. Not so in a boat. The prop is a compromise. That is why correctly propped, the engine will be spinning at 80% of its maximum. If you had a variable pitch prop then you could match the load to the speed.
That said, 3800hrs is not a problem if the engine is in good condition, properly maintained, a diesel should outlast the sailboat. That said, some engine installations are a compromise. Undersized exhaust piping, heat exchanger, limited fresh air supply will all compromise an otherwise good engine as much as the incorrect prop. Make certain that the exhaust is unobstructed and of the correct diameter. Backpressure will kill power in a NA diesel engine. Overheating or just running too hot will shorten the life of the engine. A supply of fresh air, running a ventilation fan, etc. when motoring for an extended period will keep the engine making as much power as it can.
I noticed a large difference in power just upgrading the massively undersized exhaust hose on my boat. Have a look at yours. Make certain your tach is accurate. Mine was reading 400rpm HIGH at cruise. I was running at what I thought was 2200 but it was really 1800. Make a huge difference to actually spin a healthy engine at 80% power.
RT
That said, 3800hrs is not a problem if the engine is in good condition, properly maintained, a diesel should outlast the sailboat. That said, some engine installations are a compromise. Undersized exhaust piping, heat exchanger, limited fresh air supply will all compromise an otherwise good engine as much as the incorrect prop. Make certain that the exhaust is unobstructed and of the correct diameter. Backpressure will kill power in a NA diesel engine. Overheating or just running too hot will shorten the life of the engine. A supply of fresh air, running a ventilation fan, etc. when motoring for an extended period will keep the engine making as much power as it can.
I noticed a large difference in power just upgrading the massively undersized exhaust hose on my boat. Have a look at yours. Make certain your tach is accurate. Mine was reading 400rpm HIGH at cruise. I was running at what I thought was 2200 but it was really 1800. Make a huge difference to actually spin a healthy engine at 80% power.
RT
brianb00
O - 34
Small leak in XM25 at HP injection distributor ?
Hello All,
I have a Univ. 25XP with a slight leak. I am wondering if any one else has a similar experience. There are three injector lines that go from injectors to the high pressure pump. I get a very light seeping of fuel from beneath the fitting that screws into the pump. This then connects to a compression fitting and hard line leads to the injector. The leak occurs even with the engine not running but the lift pump on. I have not taken the fitting apart yet and am imagining I will find a brass compression gasket beneath the fitting. Anyone with experience with this ?
Thanks,
Brian SV RedSky
Hello All,
I have a Univ. 25XP with a slight leak. I am wondering if any one else has a similar experience. There are three injector lines that go from injectors to the high pressure pump. I get a very light seeping of fuel from beneath the fitting that screws into the pump. This then connects to a compression fitting and hard line leads to the injector. The leak occurs even with the engine not running but the lift pump on. I have not taken the fitting apart yet and am imagining I will find a brass compression gasket beneath the fitting. Anyone with experience with this ?
Thanks,
Brian SV RedSky