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25-12-2020, 12:56
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#1
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Registered User
Join Date: Aug 2015
Location: Port Townsend, WA
Boat: Tashiba-31
Posts: 480
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Black Smoke at startup
I have a Yanmar 3GM30F with 1030 hours on it. Normally the engine starts almost immediately and has never smoked. If I'm not out sailing, I try to run the engine every month for 30 minutes. The last two times I started the engine, it took longer to start and when it finally did, it belched out a large cloud of black smoke, then settled down and ran normally.
Is this something I need to be concerned about? What might be wrong?
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25-12-2020, 14:11
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#2
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Registered User
Join Date: Oct 2015
Location: Minnesota / Florida
Boat: Westerly Fulmar 32
Posts: 475
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Re: Black Smoke at startup
Mine does it... I wouldn’t worry about it just yet. You may want to rebuild the injectors at some point. But a puff of black smoke that goes away right after start up is not an issue... I have a history with farm machinery.
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25-12-2020, 15:25
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#3
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Registered User
Join Date: Jul 2015
Boat: Bruce Bingham Christina 49
Posts: 3,328
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Re: Black Smoke at startup
Black smoke is most likely from excess fuel being dumped into the cylinders while you are cranking when it's slow to start.
Not a big Yanmar guy, but depending on the vintage of your motor seemed to remember the 3gm30f motors as having fuel line and a check valve problem causing starting problems. Is this only since it's been cold?
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25-12-2020, 15:33
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#4
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Registered User
Join Date: May 2015
Location: edmonton alberta
Boat: 1992 lagoon 42 tpi
Posts: 1,729
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Re: Black Smoke at startup
How long since you cleaned or changed the exhaust elbow. They tend to cake up and can blow some dust out with startup. That also can cause it to take longer to start.
Im not a mechanic, so only going with personal experience... but When I changed mine it cleaned up the initial exhaust and they started way easier
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25-12-2020, 15:40
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#5
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Marine Service Provider
Join Date: Jan 2011
Location: St. Petersburg, FL
Boat: Retired Delivery Capt
Posts: 3,684
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Re: Black Smoke at startup
Quote:
Originally Posted by chris mac
How long since you cleaned or changed the exhaust elbow. They tend to cake up and can blow some dust out with startup. That also can cause it to take longer to start.
Im not a mechanic, so only going with personal experience... but When I changed mine it cleaned up the initial exhaust and they started way easier
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DING DING DING— winner.
As I recall the elbow should be changed around your run hours.
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ishmael
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26-12-2020, 09:30
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#6
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Registered User
Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 2,501
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Re: Black Smoke at startup
Quote:
Originally Posted by Snore
DING DING DING— winner.
As I recall the elbow should be changed around your run hours.
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Wow, really? I had 5600 hours on my 4-108 and have about 4500 on the replacement Beta. Neither has had a need for changing or cleaning out the exhaust elbow. Elbows clog up from not running engine hard enough and not hot enough. I have heard many reports of exhaust clogging but why replace the elbow if it is not rusted through? Take it off and chisel/wirebrush it clean.
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26-12-2020, 10:57
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#7
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Registered User
Join Date: Jan 2007
Location: On board
Boat: Tom Colvin Gazelle 42ft
Posts: 325
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Re: Black Smoke at startup
Quote:
Originally Posted by chris mac
How long since you cleaned or changed the exhaust elbow. They tend to cake up and can blow some dust out with startup. That also can cause it to take longer to start.
Im not a mechanic, so only going with personal experience... but When I changed mine it cleaned up the initial exhaust and they started way easier
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Good comment. Ignore it, a partially blocked elbow, and you will regret it. It is a Yanmar problem caused in part by poor design.
Jim sv Gaia
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26-12-2020, 11:01
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#8
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Registered User
Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 10,208
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Re: Black Smoke at startup
As a swag, some oil if leaking down through a valve guide while sitting. If it starts and burns off, I would not be overly concerned.
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26-12-2020, 11:02
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#9
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Marine Service Provider
Join Date: Jan 2011
Location: St. Petersburg, FL
Boat: Retired Delivery Capt
Posts: 3,684
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Black Smoke at startup
Quote:
Originally Posted by stormalong
Wow, really? I had 5600 hours on my 4-108 and have about 4500 on the replacement Beta. Neither has had a need for changing or cleaning out the exhaust elbow. Elbows clog up from not running engine hard enough and not hot enough. I have heard many reports of exhaust clogging but why replace the elbow if it is not rusted through? Take it off and chisel/wirebrush it clean.
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Yea the double walled elbows are prone to wear through failure.
Perhaps a Google of Yanmar mixing elbow will provide some interesting pics
Better yet here is a link https://www.google.com/search?q=yanm...h2KmtvJ3OH3q3M
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ishmael
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26-12-2020, 21:26
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#10
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Marine Service Provider
Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,803
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Re: Black Smoke at startup
Yes agree with checking elbow first but BillO asked an important ? Did the problem only occur once it got cold. I recommend a fair bit of throttle advance when engine is cold on yr Yammer.
Worst case scenario is ring breakages or piston probs. Search for sailorchick posts, those engines did have some problems with piston/rings but elbows is the first check with those low hrs .
If you need to replace elbow much better to go for ss option rather than Yanmars.
Start off with the simple stuff 1st.
Post how u go or have any more questions
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27-12-2020, 04:24
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#11
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,365
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Re: Black Smoke at startup
I think the Op needs to run his engine hard under load more.
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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28-12-2020, 08:46
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#12
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Registered User
Join Date: Jan 2019
Posts: 6
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Re: Black Smoke at startup
I have the same engine in my IP. No glow plugs so cold start is slow and I get smoke once she rumbles to life this time of year. I am in Virginia chesapeake bay country.
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28-12-2020, 10:00
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#13
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Registered User
Join Date: Feb 2016
Location: Portsmouth, NH
Boat: Bayliner, 4588, 45'
Posts: 207
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Re: Black Smoke at startup
Quote:
Originally Posted by dmksails
I have a Yanmar 3GM30F with 1030 hours on it. Normally the engine starts almost immediately and has never smoked. If I'm not out sailing, I try to run the engine every month for 30 minutes. The last two times I started the engine, it took longer to start and when it finally did, it belched out a large cloud of black smoke, then settled down and ran normally.
Is this something I need to be concerned about? What might be wrong?
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If you are running the engine every 30 minutes is it getting up to operating temperature? It takes my engines 20 minutes under load. idle speed.
I would not run it that frequently unless absolutely necessary and then only run it under load and always get up to operating temps.
__________________
Irony
4588 Bayliner
Portsmouth, NH
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