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-   -   Universale m -18 RPM won't go over 2000 (https://www.sailnet.com/forums/diesel/331974-universale-m-18-rpm-wont-go-over-2000-a.html)

sailing11 11-24-2019 08:01 PM

Universale m -18 RPM won't go over 2000
 
Hi,
I have a catalina 27 with an inboard Universal m-18 diesel engine. About a month ago, I noticed that the RPM would not go over 2000 when in gear. Typically I cruise at 2200 RPM and could go up to 3000 if I wanted to. It will still go up to 30000 RPM when in neutral. Air filter looks like and I just dove under and removed some barnacles from the prop and some muscles from the hull. I thought this may solve my problem but it hasnt. I still cannot get over 2000 when in gear. Any ideas?

Thanks

tempest 11-24-2019 09:05 PM

Re: Universale m -18 RPM won't go over 2000
 
You mentioned air, Have you checked fuel filters? Primary/Secondary ?

chef2sail 11-24-2019 09:52 PM

Re: Universale m -18 RPM won't go over 2000
 
elbow with carbon.

sailing11 11-24-2019 11:42 PM

Re: Universale m -18 RPM won't go over 2000
 
not yet. That is next on the list. It's just weird that the RPM go up to normal when its in neutral.

Minnewaska 11-25-2019 06:22 AM

Re: Universale m -18 RPM won't go over 2000
 
RPM under load and not under load are commonly very different. You have some kind of backpressure or starvation, most likely. Backpressure could be a blocked exhaust elbow or a seized stuffing box. There is always a chance it's your transmission, but not likely. Starvation could be from clogged fuel filters or very dirty/clogged injectors. Possibly the fuel pump, but confirm the easy and more likely stuff first.

Can you audibly tell the engine is not making the same rpm that it used to underway? That big a difference should really sound different too. I never fully trust the onboard tachometers. You can buy a laser tack on Amazon for $20 and test the real rpm yourself. It's only a reflective piece of tape on a spinning part of the motor and your point the laser at it, while the engine it run up.

Final thought. You noted what rpm used to get to at wide open throttle. But is that was it was rated to get to at WOT? Hopefully so.

tempest 11-25-2019 07:37 AM

Re: Universale m -18 RPM won't go over 2000
 
Did you change the fuel filters in the spring? Did you happen to change the Micron # to a smaller one? What Micron are you using?

NCboatrx 11-26-2019 05:02 PM

Re: Universale m -18 RPM won't go over 2000
 
If you can reach 3,000 in neutral but only 2,000 in gear, this points to something fouling the shaft or an incredibly filthy bottom and propeller.

If you can disconnect the shaft from the transmission, run the engine in gear. If you can reach 3,000 in gear then the transmission should be ok. If you still have an RPM problem, the transmission is likely at fault.

sailing11 12-08-2019 09:58 PM

Just changed the fuel filters and still have the RPM problem. I’m leaning towards the next step being to get a diver and see if there’s a rope around the shaft. Someone told me it may be hard to see as if it’s really in there good, then I’ll likely have to get a haul out to see it.

Curious what you guys would advise my next step to be? Am I on the right track with getting a diver next?

Capt Len 12-09-2019 12:21 AM

Re: Universale m -18 RPM won't go over 2000
 
So , what did the elbow inspection tell you?

PhilCarlson 12-09-2019 06:27 AM

Re: Universale m -18 RPM won't go over 2000
 
Quote:

Originally Posted by sailing11 (Post 2051640304)
Just changed the fuel filters and still have the RPM problem. Iím leaning towards the next step being to get a diver and see if thereís a rope around the shaft. Someone told me it may be hard to see as if itís really in there good, then Iíll likely have to get a haul out to see it.

Curious what you guys would advise my next step to be? Am I on the right track with getting a diver next?

Heavy black exhaust/soot as RPMs increase would indicate resistance on the driveline. If you're not seeing that then probably not your problem. Others have mentioned the Exhaust Elbow as a likely culprit.


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