Fuel in oil - where to start? - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest Forums > Gear & Maintenance
 Not a Member? 


Like Tree3Likes
Reply
 
LinkBack Thread Tools
  #11  
Old 07-01-2013
Member
 
Join Date: May 2013
Location: Montana
Posts: 31
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 0
Skagit is on a distinguished road
Re: Fuel in oil - where to start?

Quote:
Originally Posted by hellosailor View Post
Look into buying a "major rebuild kit" for your carb, and check out what's involved in the overhaul.
That's the rub...these stupid carbs have been out of production for decades, and parts are getting tight. There are no kits...just random parts/gaskets/etc at varying prices...most coming from Norway or Sweden.

May be worth a shot though...I'm game for trying. Worst case scenario would be sending a box of parts to the carb guy and saying "fix it".

--Skagit out
Reply With Quote Share with Facebook
  #12  
Old 07-01-2013
hellosailor's Avatar
Senior Member
 
Join Date: Apr 2006
Posts: 10,051
Thanks: 0
Thanked 50 Times in 49 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Fuel in oil - where to start?

I would try asking Volvo, or asking if some other company actually made the carb, and trying to pin down a kit for it. While there may be none, that also would put you at the mercy of a shop and how well they might or might not match up the bits you need. Unless you've got sterling recommendations to someplace that does great work, in which case, please do share the name.
Reply With Quote Share with Facebook
  #13  
Old 07-01-2013
Senior Member
 
Join Date: Jul 2007
Location: Truckee, CA
Posts: 5,812
Thanks: 2
Thanked 89 Times in 87 Posts
Rep Power: 7
dabnis is on a distinguished road
Re: Fuel in oil - where to start?

If you could go on line and find the pressure spec for the original mechanical pump you could compare it with the electric pump, which may be delivering more than the float valve can handle. I put an electric pump on a Ford Engine into a Willys truck. IIRC, it put out about 4 to 5 lbs of pressure, worked great.

It could also be that the float valve tip, generally rubber or Viton? has worn away? Maybe a speed shop or small engine shop might have loose parts like that, if you can get them to talk to you?

Paul T
Reply With Quote Share with Facebook
  #14  
Old 07-01-2013
Member
 
Join Date: Mar 2013
Posts: 47
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 0
El Rubio is on a distinguished road
Re: Fuel in oil - where to start?

I had a similar issue with my riding mower. Apparently, it is common on mowers. I got a rebuild kit and replaced the gaskets and seats. The float would not close the fuel off when the engine was not running and the bowl would fill and overflow into the cylinder. The local mower store told if the rebuild kit didn't fix it, a fuel shut off vale would do the trick. In my case, the kit worked.
Reply With Quote Share with Facebook
  #15  
Old 07-01-2013
Omatako's Avatar
Senior Member
 
Join Date: Sep 2003
Location: Auckland New Zealand
Posts: 2,320
Thanks: 0
Thanked 22 Times in 19 Posts
Rep Power: 11
Omatako will become famous soon enough
Re: Fuel in oil - where to start?

IMHO itís not the carb. If the carb was being so overwhelmed by fuel line pressure that it is contaminating the oil then that engine would run very badly or not at all. It takes very little extra fuel to flood an engine and it takes a huge pressure to overcome a needle and seat and bypass into the full float chamber.

If the needle and seat is dodgy, the engine will also run badly or not at all and the engine would definitely not start if there was enough fuel percolating into the cylinders to run past the rings into the crankcase. That's a really long shot as far as I'm concerned.

If you have a mechanical fuel pump on the side of the engine I would bet a considerable sum on the diaphragm being torn and allowing fuel into the crankcase. Start there Ė take the pump off, open it and closely examine the diaphragm. It will still pump even though it leaks fuel.
__________________

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

__________________

"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."

Arthur C. Clarke
Reply With Quote Share with Facebook
  #16  
Old 07-02-2013
Senior Member
 
Join Date: Jul 2007
Location: Truckee, CA
Posts: 5,812
Thanks: 2
Thanked 89 Times in 87 Posts
Rep Power: 7
dabnis is on a distinguished road
Re: Fuel in oil - where to start?

Quote:
Originally Posted by Omatako View Post
IMHO it’s not the carb. If the carb was being so overwhelmed by fuel line pressure that it is contaminating the oil then that engine would run very badly or not at all. It takes very little extra fuel to flood an engine and it takes a huge pressure to overcome a needle and seat and bypass into the full float chamber.

If the needle and seat is dodgy, the engine will also run badly or not at all and the engine would definitely not start if there was enough fuel percolating into the cylinders to run past the rings into the crankcase. That's a really long shot as far as I'm concerned.

If you have a mechanical fuel pump on the side of the engine I would bet a considerable sum on the diaphragm being torn and allowing fuel into the crankcase. Start there – take the pump off, open it and closely examine the diaphragm. It will still pump even though it leaks fuel.
From earlier posts:

"Are you running the fuel line thru the old mechanical pump?

I have seen this done and if the pump diaphragm leaks AND the drain is blocked [ painted over ] then fuel finishes up in the sump. "

--------------------------------------------------------------------------------

"No...new fuel line is direct...tank -> pump -> regulator -> carb. "

Another thought, if it is an updraft carb I would think fuel would have a hard time flowing past the float and into the manifold? As Omatako said, if it was getting that much fuel past the float valve it would be running extremely rich and rough?

"Regulator"? maybe not working? Either way, it looks like the fuel is draining into the pan or is being ingested through the carb? Maybe try a gravity fed temporary fuel container directly to the carb, by passing the pump? An outboard gas can with a long hose from the cockpit to the engine should be fairly safe?

Paul T

Last edited by dabnis; 07-02-2013 at 12:58 PM.
Reply With Quote Share with Facebook
  #17  
Old 07-02-2013
hellosailor's Avatar
Senior Member
 
Join Date: Apr 2006
Posts: 10,051
Thanks: 0
Thanked 50 Times in 49 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Fuel in oil - where to start?

I don't know the MB10A at all, but generally there are only two ways a lot of fuel will get in the oil. The ruptured diaphragm, which you say is out of the loop and can be eliminated. And then, loose rings, allowing fuel to enter from the cylinders.

If the fuel is just "traces" picked up during an oil test, that can just be from short engine runs that don't cook off the normal fuel and condensate accumulations. In which case you just run the engine longer to burn them off.

But if there's gross fuel contamination, I'm come back to looking at the rings. A compression test, and a leak-down test, to see what's really going on. Bad rings, low compression, that would also contribute to "hard to start", so more dots connect up at the same time.

There are only so many places where the oil "spaces" and the fuel can cross into each other.
Reply With Quote Share with Facebook
  #18  
Old 07-02-2013
Member
 
Join Date: May 2013
Location: Montana
Posts: 31
Thanks: 2
Thanked 0 Times in 0 Posts
Rep Power: 0
Skagit is on a distinguished road
Re: Fuel in oil - where to start?

Quote:
Originally Posted by hellosailor View Post
I don't know the MB10A at all
Wish I could say the same...

Quote:
Originally Posted by hellosailor View Post

But if there's gross fuel contamination, I'm come back to looking at the rings. A compression test, and a leak-down test, to see what's really going on.
It's officially gross fuel contamination...like recoil from the smell of fuel on the dip stick gross fuel contamination. Compression check came in good...95/105 (factory new is 107).

Another thought I had...I haven't busted out my level, but it appears to me that the carb is lower than the bottom of the fuel tank. I wonder if fuel is slowly flowing through the carb and pooling...gravity wins every time, right? The spark plug threads were wet with fuel when I did the compression test and the engine hadn't run in two weeks.
__________________
--Skagit out
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


_____________________________________________
1975 Irwin 28 - hasn't earned a new name yet, but at this point it might not be flattering.
Reply With Quote Share with Facebook
  #19  
Old 07-02-2013
Senior Member
 
Join Date: Jul 2007
Location: Truckee, CA
Posts: 5,812
Thanks: 2
Thanked 89 Times in 87 Posts
Rep Power: 7
dabnis is on a distinguished road
Re: Fuel in oil - where to start?

Quote:
Originally Posted by Skagit View Post
Wish I could say the same...



It's officially gross fuel contamination...like recoil from the smell of fuel on the dip stick gross fuel contamination. Compression check came in good...95/105 (factory new is 107).

Another thought I had...I haven't busted out my level, but it appears to me that the carb is lower than the bottom of the fuel tank. I wonder if fuel is slowly flowing through the carb and pooling...gravity wins every time, right? The spark plug threads were wet with fuel when I did the compression test and the engine hadn't run in two weeks.
That may be a possibility. Some electric pumps will allow fuel to flow through them when they are not operating. If the manifold is lower than the float bowl
fuel may be seeping past the float valve even when the engine is not running.

If it is running OK the "seepage" may not be enough to notice, but may be enough to accumulate in the pan. You might try installing a fuel shut off valve right at the tank.

Paul T
Reply With Quote Share with Facebook
  #20  
Old 07-02-2013
hellosailor's Avatar
Senior Member
 
Join Date: Apr 2006
Posts: 10,051
Thanks: 0
Thanked 50 Times in 49 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Fuel in oil - where to start?

Gravity, yes. If you're going to change the oil anyway, do a simple leakdown test, pull the plugs, fill with kerosene or gasoline, cover (to prevent evaporation) and come back tomorrow. Add a few drops of UV dye if you really want to double-check. Or, just borrow/rent one of the newfangled leakdown test kits that uses air pressure.

Certainly cheaper to check, than to tear into things.
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solid Fuel Stove Fuel HardTAC Gear & Maintenance 24 06-17-2013 08:15 PM
City marina to build self-service fuel station after three years without fuel - Corpu NewsReader News Feeds 0 07-16-2011 11:40 PM
I don't even know where to start. MariaDelMar Introduce Yourself 6 11-05-2009 08:47 AM
Where should I start dryclean General Discussion (sailing related) 5 06-07-2009 02:38 PM
Where to start, what to buy. puntapete Boat Review and Purchase Forum 16 11-05-2006 06:49 PM


All times are GMT -4. The time now is 02:53 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012