Gray Smoke -- under load -- Volvo MD2040 - SailNet Community
 
LinkBack Thread Tools
post #1 of 6 Old 11-02-2009 Thread Starter
Junior Member
 
Join Date: Apr 2003
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Gray Smoke -- under load -- Volvo MD2040

I am noticing a lot of gray smoke in my exhaust when I push it to higher RPMs. What could be the cause? (I don't think it is white smoke, nor black smoke either... seems pretty solidly gray).


I have just changed to larger props (for completely independent reasons)--and the problem got worse. Note, the problem existed before the new props--just not as much. I am replacing the new props with new blades to reduce the pitch a bit, so I can get into my normal WOT range.

The engines have about 2800 hours on them. And have been continually maintained, with oil and filter changes, and fuel filter changes. Etc....

Thanks
hoaga is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 6 Old 11-02-2009
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,377
Thanks: 101
Thanked 304 Times in 294 Posts
Rep Power: 10
     
We had brownish-grey smoke when an injector partially failed (low breakover pressure) - but you could definitely hear the problem too - a nearly mechanical tapping sound at the same time from the un-atomized fuel.

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is online now  
Quote Quick Reply Share with Facebook
post #3 of 6 Old 11-02-2009
Member
 
sigmasailor's Avatar
 
Join Date: Jun 2009
Location: Zuid Holland
Posts: 49
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
You're probably asking too much of your engine and it is going through its knees. Because of the larger props revs are probably too low in relation to the torgue curve (your engines characteristics) and you engines governor is trying to correct that by pushing more fuel in the engine than it has oxygen to burn. Hence the grey/black smoke; lots of unburned fuel and other nasty stuff.
If the problem was there already I would suspect the injectors; all this assuming it is a diesel of course. Yep, Volvo's are diesel....
sigmasailor is offline  
Quote Quick Reply Share with Facebook
post #4 of 6 Old 11-02-2009
Senior Member
 
Join Date: Oct 2009
Location: Gloucester, MA
Posts: 586
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 6
 
Gray/black smoke is a sign of overfueling. Generally, when it is gray, that means that the fuel is not burning efficiently for whatever reason. A very common cause of this is worn out injectors that are popping off at too low of a pressure and have greatly enlargened holes. If you can find someone local with a pop tester, it should not be expensive to have them test it.

Taking some pitch out of your propeller is definitely a good idea.
klem is offline  
Quote Quick Reply Share with Facebook
post #5 of 6 Old 11-02-2009
Senior Member
 
Capnblu's Avatar
 
Join Date: Mar 2006
Location: Squamish
Posts: 659
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 10
 
Blue, or black smoke, oil related. White smoke water / coolant related. First guess head gasket, second guess a crack in block. Course of action? Take an oil sample in to have analyzed, then a wet and dry compression test of all cylinders. Next action will depend on the outcome of the analysis and the wet/dry test.

Why, why, why?
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

I Don't Know! I Don't Know!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Capnblu is offline  
Quote Quick Reply Share with Facebook
post #6 of 6 Old 11-06-2009 Thread Starter
Junior Member
 
Join Date: Apr 2003
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
thanks

Thanks for the info All.
Will be doing some testing this weekend to see what can be figured out.
hoaga is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
White Smoke from Older Diesel at Higher RPMs kcoffey Gear & Maintenance 3 06-24-2004 03:23 PM
More Lessons from the Volvo Ocean Race John Rousmaniere Racing Articles 0 05-02-2002 08:00 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome