Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 12-01-2017, 09:52   #16
cruiser

Join Date: Jan 2012
Location: Pangaea
Posts: 10,856
Re: Yanmar won't go beyond 2200 revs. Help!

We've experienced the same over the past couple of years. Causes were growth on the prop, growth on the hull bottom, prop pitch issue and one occasion a burned up turbo caused by a delivery crew failing to revv and blow out the carbon each hour while underway during a 1400 mile passage. One more idea, your turbo could just need a cleaning if you've failed to follow the manufacturer's recommendation to revv your engine once ever hour.

We have the same engine, same size boat, your issue is definitely some sort of resistance either prop pitch or marine growth causing your engine to bog down a bit, which then causes carbon to build up in the turbo. If you don't blow it out with high revvs each hour, the result is where you are today.
__________________

Kenomac is offline   Reply With Quote
Old 12-01-2017, 10:52   #17
Registered User
 
01kiwijohn's Avatar

Join Date: Mar 2014
Location: Tacoma, Washington, USA
Boat: Casacde 36
Posts: 542
Images: 1
Re: Yanmar won't go beyond 2200 revs. Help!

If it's consuming too much fuel, the fuel supply is probably not the cause.
With a new exhaust elbow, probably not that either.
Pull the hoses off the turbo and check for obstruction in both the turbo and the intake air heat exchanger. While you're at it, hows the air intake in general?
Next check the exhaust for obstructions, downstream. Maybe even try by passing the muffler to facilitate this.
I've just worked on a similar model/ vintage and the turbo bearings were shot, causing the impeller to rub against the housing, greatly slowing it down. This resulted in the intercooler becoming clogged too.
Let me know if you need more help
__________________

01kiwijohn is offline   Reply With Quote
Old 12-01-2017, 12:32   #18
Registered User

Join Date: Apr 2012
Location: Currently in Spain
Boat: Island Packet 420
Posts: 298
Re: Yanmar won't go beyond 2200 revs. Help!

Have you checked to make sure your tach is reading correctly?
sailing_gal is online now   Reply With Quote
Old 12-01-2017, 13:20   #19
Registered User

Join Date: Sep 2011
Posts: 9
Re: Yanmar won't go beyond 2200 revs. Help!

My 3YM20 had similar limited RPM after returning from Hawaii and motoring at low speeds for prolonged periods, eventually would not even start. Turned out to be clogged EXHAUST HOSE. Yanmars need periodic exhaust system purges to blow out accumulated carbon sludge, especially at prolonged low pressure idling / slow speed. Purge is done by revving engine in neutral while observing what comes out of exhaust outlet.
SAMUELBURNS is offline   Reply With Quote
Old 12-01-2017, 14:31   #20
Registered User

Join Date: Jun 2010
Location: Launceston, Tasmania, Australia
Boat: Bavaria 36 - "Sweet As"
Posts: 14
Re: Yanmar won't go beyond 2200 revs. Help!

Sounds very much like a fuel supply issue. Even though you have measured healthy fuel consumption I would be following BoatBod's advice to conclusively eliminate a fuel supply issue as cause. Draw fuel directly from a jerry can. Note that a blockage in the fuel return line can also produce fuel supply like symptoms.
Sweet As is offline   Reply With Quote
Old 12-01-2017, 15:16   #21
Registered User

Join Date: Aug 2015
Posts: 461
Re: Yanmar won't go beyond 2200 revs. Help!

Quote:
Originally Posted by Sweet As View Post
Sounds very much like a fuel supply issue. Even though you have measured healthy fuel consumption I would be following BoatBod's advice to conclusively eliminate a fuel supply issue as cause. Draw fuel directly from a jerry can. Note that a blockage in the fuel return line can also produce fuel supply like symptoms.
Thanks for the support! The advice I gave was based on the first steps either I or one of my mechanics would take if the boat arrived in the Yanmar dealership I manage with the symptoms described. The OP may choose to start there or look elsewhere first, but eventually it's going to come down to fuel supply.

Diesel engine rpm is regulated by controlling fuel delivery. If excess fuel is provided beyond which the engine can burn, there will be copious black smoke. This would be the case of a physical limitation adding friction to the drive train. (Prop fouled, shaft jammed etc).

If insufficient fuel is provided, the engine runs happily along at reduced rpm just as if you didn't open the throttle enough. No smoke, no fuss, just not enough power until the fuel is completely cut off and the engine stalls.

If the turbo had failed (impeller stuck, insufficient boost), the fuel rack will be unaware and will be over-fueling the engine more and more add the throttle lever is advanced. Once again this causes black smoke at the transom, and an increase in EGT if you have a probe to measure that.

Clogged engine exhaust and/or elbow is a valid possibility add it affects the engine's ability to breath. With a Yanmar 4JH, depending what type of elbow may make this a likely or unlikely possibility. The big heavy duty rectangular elbows are extremely robust and almost never clog up. The lighter weight round and u-shaped elbows are garbage and fail regularly. Check the condition of the interior of the hose too. I've seen delamination cause similar symptoms.

I given you my $0.03 so feel free to ignore it and look elsewhere, but please report back your eventual findings.
boatbod is offline   Reply With Quote
Old 12-01-2017, 15:30   #22
Registered User

Join Date: Feb 2015
Location: Rappahanock River, Va
Boat: Caliber 47
Posts: 180
Re: Yanmar won't go beyond 2200 revs. Help!

Agree with the fuel usage skepticism ....I like doing simple things first.
1. New primary filter
2. New secondary filter
3. Blow out fuel lines ( if u can)

BTW....I would think a Hylas would have a vacuum gage....if yes is in in the Yellow or Green?

Does it have an electric fuel pump.... if yes is it working? It may not be and your engine still run?
Caliber40 is offline   Reply With Quote
Old 12-01-2017, 17:31   #23
Registered User

Join Date: Apr 2013
Posts: 931
Re: Yanmar won't go beyond 2200 revs. Help!

I'm only at a basic mechanic level, albeit with a lucky Beta, but a few things I'd consider -

Are cylinder temps equivalent at idle & are they also equivalent under load?

How is the gearbox? Give it a service. Laser temp it while running - maybe compare to "normal" from a sister ship.

How are the fuel lines? Age? Invisible pinhole leak? Replace the fuel lines (and if no change you might keep the old fuel lines as spares)

When you get it figured out you might combine your smart phone video with a laser temp so you get a real record of 80 degree weather 2600 rpm temps are such and such which will only help in the future.
SecondBase is offline   Reply With Quote
Old 12-01-2017, 17:35   #24
Registered User

Join Date: Apr 2013
Posts: 931
Re: Yanmar won't go beyond 2200 revs. Help!

And read Scott Fratchers Tonga Charters laser temp guide. http://www.tongacharter.com/report-lasertemp.htm
SecondBase is offline   Reply With Quote
Old 12-01-2017, 18:45   #25
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Between Caribbean and Canada
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 6,130
Re: Yanmar won't go beyond 2200 revs. Help!

Before you go off the deep end on all this find out if the engine behaves differently in forward, reverse, and NEUTRAL.

the kicker for me was the engine would only reach 1,600 in ANY of the three positions. I know about squat about fuel pumps but from staring at the drawings I thought it might have some kind of mechanical governed. It sure acted as if it did.

I had just suffered a bout of bad fuel and sucked some crud into the filters. We sent the pump out for repair. The shop told us there was nothing wrong with the pump. It was just very dirty. Cleaned, reassembled and calibrated, reinstalled.

Just my experience.

IF you get something substantially above 2,200 in NEUTRAL ignore this post.
hpeer is offline   Reply With Quote
Old 12-01-2017, 21:22   #26
Registered User

Join Date: Nov 2008
Location: Seattle
Boat: Wauquiez Centurion 49
Posts: 759
Images: 13
Re: Yanmar won't go beyond 2200 revs. Help!

Hobiehobie, when you voyaged from Ft Laud to the islands, did you run your motor at lower rpms to save fuel for hours on end? If so, you cannot do that with a Yanmar. It must be brought up to higher rpms every hour or so. I had the exact same problem a few years ago. The items to look at would be the turbo, injectors, and fuel injection pump.
CAELESTIS is offline   Reply With Quote
Old 13-01-2017, 03:17   #27
Registered User

Join Date: Nov 2014
Boat: Hylas 54
Posts: 184
Re: Yanmar won't go beyond 2200 revs. Help!

Thanks all for your wide ranging and thoughtful suggestions.

1. Take out the boat today on new tank of apparently clean fuel, see how she does in neutral, under load
2. Dive on prop again and check for fouling, turn prop in neutral see if there is any resistance, check feathering of Max prop
3 Change fuel tanks see if there is any change to eliminate pick up pipe issues

I have already: changed primary and secondary filters, checked sump of all four tanks for crud (none), checked prop for fouling (none...although I need to make sure it turns freely in neutral).

Will report back.
Hobiehobie is offline   Reply With Quote
Old 13-01-2017, 03:54   #28
cruiser

Join Date: Jan 2012
Location: Pangaea
Posts: 10,856
Re: Yanmar won't go beyond 2200 revs. Help!

Quote:
Originally Posted by Hobiehobie View Post
Thanks all for your wide ranging and thoughtful suggestions.

1. Take out the boat today on new tank of apparently clean fuel, see how she does in neutral, under load
2. Dive on prop again and check for fouling, turn prop in neutral see if there is any resistance, check feathering of Max prop
3 Change fuel tanks see if there is any change to eliminate pick up pipe issues

I have already: changed primary and secondary filters, checked sump of all four tanks for crud (none), checked prop for fouling (none...although I need to make sure it turns freely in neutral).

Will report back.
After you check these items, if you still have the issue.... it's the turbo. It might just need a cleaning or the turbo bearings and/or the fins might be finished. The reason you can't revv past 2200, is because your turbo is not kicking in and the engine is lacking in horse power. It's in fact operating like a lower powered normally aspired engine without the upper power band.
Kenomac is offline   Reply With Quote
Old 13-01-2017, 04:29   #29
Registered User

Join Date: Aug 2015
Posts: 461
Re: Yanmar won't go beyond 2200 revs. Help!

Quote:
Originally Posted by Kenomac View Post
After you check these items, if you still have the issue.... it's the turbo. It might just need a cleaning or the turbo bearings and/or the fins might be finished. The reason you can't revv past 2200, is because your turbo is not kicking in and the engine is lacking in horse power. It's in fact operating like a lower powered normally aspired engine without the upper power band.
Seized turbo can cause low rpm symptoms, but usually accompanied by black smoke from the excess fuel injected but not burned.
boatbod is offline   Reply With Quote
Old 13-01-2017, 04:51   #30
Registered User

Join Date: Oct 2011
Location: Canada
Boat: CT 56
Posts: 545
Images: 3
Send a message via Skype™ to undercutter
Re: Yanmar won't go beyond 2200 revs. Help!

Quote:
Originally Posted by boatbod View Post
Seized turbo can cause low rpm symptoms, but usually accompanied by black smoke from the excess fuel injected but not burned.
This situation brings to mind another boat with similar low rev issues but he definitely has black smoke and I believe a heavily over pitched prop. You seem to be the guy to ask Boatbod, What should the difference be between top end RPM between an unloaded and loaded engine?

I would have thought it would be negligible and dependent on governor settings when in neutral. Any of my heavy equipment never saw much difference and my boat doesn't either.

Maybe a fuel supply problem as you suggest would explain the OP's dilemma and your recommended procedure for identifying the problem would then be implemented as it is obvious that an engine running under load consumes more fuel than one in neutral at the same RPM.

Thanks for your help.
__________________

undercutter is offline   Reply With Quote
Reply

Tags
yanmar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Marine Generator. Low revs or high revs? Russell7171 Engines and Propulsion Systems 8 26-05-2013 07:33
Generator won't run full revs Jolly Roger Auxiliary Equipment & Dinghy 10 31-07-2012 10:51
Yanmar Down on Revs Dockhead Engines and Propulsion Systems 20 03-06-2012 04:38
Yanmar 3ym30 big smoke at revs Al. Engines and Propulsion Systems 9 08-05-2012 18:23

Advertise Here


All times are GMT -7. The time now is 14:35.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.