I bought a Catalina 30 '84 early this year with a universal m25. The problem is that when in gear it won't go above 2000rpm (In neutral +-3000). When I bought it I cleaned the tank, replaced filters (primary and secondary) and hoses, replaced lift pump, checked the exhaust for back pressure, cleaned the prop and shaft (it was extremely fauled) and still 2000rpm. One interesting thing is that it gets to exactly 2000rpm tied to the dock and underway. The engine starts easy, it doesn't smoke apart from some blue smoke for the first 10 scs or so. The engine has 750 hours only...I am new to diesels but it looks like not enough fuel is getting to the engine so my next step would be to send the injection pump and injectors to a diesel shop, but some expert told me that it's extremely rare for an injection pump to go bad with only 750 hours. Any thought will be more than appreciated. Thanks
Universal m25 low rpm under load
- Thread starter MafaldaII
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here we go...another UNmechanic giving advice
http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-m25-specifications.html Looks like it's designed for 3000rpm max, cruising range 2100ish
http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-m25-specifications.html Looks like it's designed for 3000rpm max, cruising range 2100ish
your prop may be damaged
Propeller Size Help from http://www.tacomapropeller.com/ The correct propeller size allows the motor to achieve maximum RPM within the manufacturer's maximum rated RPM range at wide open throttle. If you are below the rated RPM range you need to purchase a propeller with less pitch. If you are over the maximum range you need to purchase a propeller with more pitch. One inch of pitch equals approximately 200 RPM on outboard and sterndrive applications. Inboard applications depend on reduction gear ratios and operating conditions. Is your current propeller the correct size? The following test run is required and is the most accurate way to correctly prop your boat. Run the boat at wide open throttle with the normal weight load and provide us with the following information, * What is your current propeller size? (Size and stock number can be found on the propeller) * What is the maximum rated RPM range for your motor? (refer to your owners manual or contact your boat dealer) * What wide open throttle RPM can you achieve? (If the RPM continues over 200 beyond maximum back off)
Propeller Size Help from http://www.tacomapropeller.com/ The correct propeller size allows the motor to achieve maximum RPM within the manufacturer's maximum rated RPM range at wide open throttle. If you are below the rated RPM range you need to purchase a propeller with less pitch. If you are over the maximum range you need to purchase a propeller with more pitch. One inch of pitch equals approximately 200 RPM on outboard and sterndrive applications. Inboard applications depend on reduction gear ratios and operating conditions. Is your current propeller the correct size? The following test run is required and is the most accurate way to correctly prop your boat. Run the boat at wide open throttle with the normal weight load and provide us with the following information, * What is your current propeller size? (Size and stock number can be found on the propeller) * What is the maximum rated RPM range for your motor? (refer to your owners manual or contact your boat dealer) * What wide open throttle RPM can you achieve? (If the RPM continues over 200 beyond maximum back off)
Max RPM
I would agree with other posters on this and first check the prop. If the engine starts and runs fine, sounds good, doesn't smoke, certainly sounds like a prop that is too big for the engine. I don't think it's the governor as it will rev to max RPM in neutral. The governor works strictly on the engine RPM, so it doesn't know whether it's in neutral or under load. My first thing would be to check out the prop for damage and correct size.
I would agree with other posters on this and first check the prop. If the engine starts and runs fine, sounds good, doesn't smoke, certainly sounds like a prop that is too big for the engine. I don't think it's the governor as it will rev to max RPM in neutral. The governor works strictly on the engine RPM, so it doesn't know whether it's in neutral or under load. My first thing would be to check out the prop for damage and correct size.
Stop please with governors on M25 engines
see: http://c34.org/bbs/index.php?topic=177.0 for some other discussions about this issue.
see: http://c34.org/bbs/index.php?topic=177.0 for some other discussions about this issue.
Prop issue
Thank you all for your responses. If the prop has a problem or is too big shouldn't I be seen black smoke?
Thank you all for your responses. If the prop has a problem or is too big shouldn't I be seen black smoke?
Not a good indicator
Hull speed is fine but if your engine is not running the correct RPMs, you will shorten it's life. Get a scope and check the tach Clean the prop Verify you have the correct size prop Verify you can rev in N to 3000 rpms(again, dependent on tach accuracy) Tim R.
Hull speed is fine but if your engine is not running the correct RPMs, you will shorten it's life. Get a scope and check the tach Clean the prop Verify you have the correct size prop Verify you can rev in N to 3000 rpms(again, dependent on tach accuracy) Tim R.
Me two cents, too
Check the gearing in your transmission - I know this sounds silly! but my father's 33' boat, that he purchased as an insurance writoff (it is a twin engine gashog) had the engines rebuilt, every pump in that thing replaced, props refinished, etc etc. We put it in the water, and the port engine just wouldn't rev up! We noticed, too ,that the boat had a hard pull to starboard at idle. Turning the engines by hand, we counted revs on the output shaft - the transmissions were not geared the same. Turned out that, during a past rebuild ,someone had installed the gears on the wrong shafts during installation! It did not take long to get the gears changed, but pulling the transmission was not fun (we removed it with 3 guys by hand, at the dock) I suppose the problem could have been remedied with a new prop on that motor, but that just isn't right..and it's more money!
Check the gearing in your transmission - I know this sounds silly! but my father's 33' boat, that he purchased as an insurance writoff (it is a twin engine gashog) had the engines rebuilt, every pump in that thing replaced, props refinished, etc etc. We put it in the water, and the port engine just wouldn't rev up! We noticed, too ,that the boat had a hard pull to starboard at idle. Turning the engines by hand, we counted revs on the output shaft - the transmissions were not geared the same. Turned out that, during a past rebuild ,someone had installed the gears on the wrong shafts during installation! It did not take long to get the gears changed, but pulling the transmission was not fun (we removed it with 3 guys by hand, at the dock) I suppose the problem could have been remedied with a new prop on that motor, but that just isn't right..and it's more money!
WOW!
I can't believe it. I just purchased a 2001 Catalina 310 that had the same exact problem. The previous owner had the fuel injectors cleaned and that solved the symptom--motor ran fine after that. Also had the fuel tank cleaned, etc. just as you describe. However, shortly after the purchase, the fuel pump failed, was rebuilt and failed again. As best as I can understand, the seal around the sea water pump has cracked and allowed water to seep into the oil, which in turn lubricates the plungers for the fuel pump. The water somehow gums up the plungers causing the fuel pump to fail. I am still not repaired (waiting on a part) but hope to be sailing soon.
I can't believe it. I just purchased a 2001 Catalina 310 that had the same exact problem. The previous owner had the fuel injectors cleaned and that solved the symptom--motor ran fine after that. Also had the fuel tank cleaned, etc. just as you describe. However, shortly after the purchase, the fuel pump failed, was rebuilt and failed again. As best as I can understand, the seal around the sea water pump has cracked and allowed water to seep into the oil, which in turn lubricates the plungers for the fuel pump. The water somehow gums up the plungers causing the fuel pump to fail. I am still not repaired (waiting on a part) but hope to be sailing soon.
Low RPM's Under Power
I would start with the prop size/pitch. Please note that the theoretical hull speed for the C30 is approximately 6.7 knots (LWL=25', square root of 25=5, multiplied by 1.34= 6.7). I have seen one owner say that he had a 12x12 (12 inches in diameterx12 inches of pitch) 3 blade, in the archives of this site. For reference my C36 with 30hp comes from the factory with either a 15x10x2, or a 15x9x3 prop.
I would start with the prop size/pitch. Please note that the theoretical hull speed for the C30 is approximately 6.7 knots (LWL=25', square root of 25=5, multiplied by 1.34= 6.7). I have seen one owner say that he had a 12x12 (12 inches in diameterx12 inches of pitch) 3 blade, in the archives of this site. For reference my C36 with 30hp comes from the factory with either a 15x10x2, or a 15x9x3 prop.
Fuel injector cleaner method
It may be the fuel injectors. One simple way to deal with that as a first step would be to use injector cleaner. The way to zap the injectrs with it is to use injector cleaner to refill the bowl of the fuel filter. We do it when we change the fuel filter, but you could do it anytime. JUst drain the fuel filter, fill it up with injector cleaner, and run the engine (might have to bleed first). Here's a link to an easy M25 bleed method: http://c34.org/bbs/index.php?topic=2884.0 A source for fuel pumps: http://c34.org/bbs/index.php?topic=2515.0 Rebuilding one makes no sense. There is a link in this post to injectors, so read the replies and click on the links and rad away.
It may be the fuel injectors. One simple way to deal with that as a first step would be to use injector cleaner. The way to zap the injectrs with it is to use injector cleaner to refill the bowl of the fuel filter. We do it when we change the fuel filter, but you could do it anytime. JUst drain the fuel filter, fill it up with injector cleaner, and run the engine (might have to bleed first). Here's a link to an easy M25 bleed method: http://c34.org/bbs/index.php?topic=2884.0 A source for fuel pumps: http://c34.org/bbs/index.php?topic=2515.0 Rebuilding one makes no sense. There is a link in this post to injectors, so read the replies and click on the links and rad away.
check your exhaust temp at the head
while at cruising speed that will tell you alot. 800-900F is what it should be more than, its working too hard you'll burn it up. 600+- too lean not enough fuel. we mechanics can tell alot about your engine by this temp reading
while at cruising speed that will tell you alot. 800-900F is what it should be more than, its working too hard you'll burn it up. 600+- too lean not enough fuel. we mechanics can tell alot about your engine by this temp reading
One obvious thing to check..
One obvious thing to check is your throttle linkage. Make sure the throttle cable can move the throttle arm the full path. Beyond that you have air, fuel, prop and of course make sure your tachometer is actually reading correctly. Here's a link to the photo tachometer I use:
One obvious thing to check is your throttle linkage. Make sure the throttle cable can move the throttle arm the full path. Beyond that you have air, fuel, prop and of course make sure your tachometer is actually reading correctly. Here's a link to the photo tachometer I use:
intake blockage
Then there's the chance someone put a rag in the air intake ,forgot about it and sucked it in . Yes it happen and to a friend of mine .Engine ran fine on /off morring. When he gave the boots to it at the cannal it would not come up to power smoked like mad and quit . Upon a machanic inspection he went right to the manifold and pulled out the rag.
Then there's the chance someone put a rag in the air intake ,forgot about it and sucked it in . Yes it happen and to a friend of mine .Engine ran fine on /off morring. When he gave the boots to it at the cannal it would not come up to power smoked like mad and quit . Upon a machanic inspection he went right to the manifold and pulled out the rag.
Check Your Tack
Check the tack to make sure it is giving accurate reading. My rpm's improved when I had the bottom cleaned and I cleaned the prop and cleaned out the mixing elbo. I would check the mixing elbo if you are handy and will not cost as much as changing the injectors or pump. Nick
Check the tack to make sure it is giving accurate reading. My rpm's improved when I had the bottom cleaned and I cleaned the prop and cleaned out the mixing elbo. I would check the mixing elbo if you are handy and will not cost as much as changing the injectors or pump. Nick
Paper, or Plastic?
Mafalda, The difference between the neutral max rpm and the in-gear max rpm suggests the problem lies outside the engine. And sure, you hear stories of how previous owners did this, or did that, over-propped, or whatever; but those anecdotes illustrate the exceptions, not the rule. It's unlikely your po caused this by making a modification to the factory set-up, statistically speaking. Still, the prop is the main suspect. But instead of worrying about whether the previous owner re-propped, I'd simply dive on the prop and see whether it has a barnacle problem or has knitted itself a sweater out of a length of line or a plastic bag or something: you'd be surprised how small an object can cause this very problem. Until you visually inspect the prop, don't worry yourself with other, more complicated (and time-comsuming, and expensive) theories. Dad always said, "Check the simple things first." Fair Winds, Jeff
Mafalda, The difference between the neutral max rpm and the in-gear max rpm suggests the problem lies outside the engine. And sure, you hear stories of how previous owners did this, or did that, over-propped, or whatever; but those anecdotes illustrate the exceptions, not the rule. It's unlikely your po caused this by making a modification to the factory set-up, statistically speaking. Still, the prop is the main suspect. But instead of worrying about whether the previous owner re-propped, I'd simply dive on the prop and see whether it has a barnacle problem or has knitted itself a sweater out of a length of line or a plastic bag or something: you'd be surprised how small an object can cause this very problem. Until you visually inspect the prop, don't worry yourself with other, more complicated (and time-comsuming, and expensive) theories. Dad always said, "Check the simple things first." Fair Winds, Jeff
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