Diesel fuel in the oil sump

Oct 30, 2019
34
Hi All

Engine problems again.........

A previous owner replaced the original engine in my Vega with a Yanmar
2GM 13hp model. I suspect this was probably a second-hand or
reconditioned unit rather than brand new and as a result I have no
idea how old the engine might be, nor the hours on it.

Never-the-less it has given good servive over three seasons. During
this summer however I noticed a distinct smell of diesel in the cabin
when the engine was running but could not see any obvious leak
although there was always a residue of fuel under the engine after
use. Today I set out to trace the leak and do an oil change and
immediatly noticed that the oil seemed very thin. Smelling it I can
detect diesel.

Calder refers to leaking internal fuel lines as a possible culprit,
but with this engine all the fuel lines are external. The same source
suggests that worn rings, bores etc will suck oil up into the firing
chamber rather than allow fuel down into the sump. The mechanical fuel
pump is situated just above the dip-stick hole but the dip-stick has a
rubber collar that makes a very good seal and a metal skirt that
should prevent anything finding its way in.

Anyone had similar experience or have any ideas how the fuel is
finding its way into the sump?

David
"Little Star" V1696
 
Nov 8, 2001
1,818
Hi David

Had the same problem with a Vega called Debonair, she had the Volvo MD6A
but the oil kept rising on the dipstick. Turned out to be the seal
between the high-pressure injector pump and the engine itself. Cant be
more precise on teh Yanmar as I have never worked on a Yanmar. Hope this
helps.

Dont forget the Vega Forum: HYPERLINK
"Pro Movies 60"www.albinvega.proboards60.com

Cheers

Steve Birch (Technical)
 
Oct 30, 2019
1,459
David: I have the same engine in Sin Tacha. I found the Yanmar shop
manual for free download at http://www.motoren.ath.cx/

Go to "Yanmar" on the sidebar and download the "GM-HM" file. It's a
PDF file and is over 60 megs.

It covers one, two, and three cylinder models including the 2GM 13
hp, and has a trouble shotting section. I have not had this specific
problem on mine so cannot offer any advice.

Hope this helps.

Peter
#1331 'Sin Tacha'
 

dk8521

.
Oct 30, 2019
58
If the injecters aren't atomizing properly there could be unused fuel
migrating down from the cylinders.
Dick
 
Nov 8, 2001
1,818
Hi Seb

The forum is how it is, it's free so not a lot I can do with it. There
may be things taht can be done with Proboard but Im not good enough. I
am looking for a more skilled Moderator to help out.....

I like the Yahoo Group as well and a great place to store files, photos
etc but not much use as an interactive forum. I check both so I see them
as working together.



Steve Birch (Technical)
 
Oct 30, 2019
80
Hi Peter

Thanks for the link - what a wonderful site! Highly recommended to
anyone with a Yanmar (or any other make by the look of it) fitted in
their Vega.

David
V1696 'Little Star'
 
Oct 30, 2019
80
Hi Steve

Thanks for the suggestion. Now I have a copy of the workshop manual
(thanks to Peter ('Sin Tacha') I hope to be able to trace potential
sources for the leak and check them out. Good job I found it out now
and not on my way to Turkey!

All the best

David
V1696 'Little Star'
 
Oct 30, 2019
1,459
David,
When you find the cause of your problem I'd be really interested to
know ... just in case !

Peter
#1331 'Sin Tacha'
 
Dec 15, 2006
139
Hi David,

I would guess you have one of two problems 1)Injector pump is leaking
fuel into engine or 2)Mechanical fuel pump has a hole in the diaphram
and is leaking into the crankcase. You might try www.yanmarhelp.com
It is a site dedicated to yanmar marine engines and also has a forum.
You can search the forum archives there. My guess is someone else
there has had the same problem. Let me know how your engine is working
out. I am thinking of putting one in my vega.

Larry
Automechanics teacher
California
Vega 1493
 
Oct 30, 2019
80
Hi Larry

Another really useful site - many thanks. I could not find anything in
the forum so will post the question. The fact that I obviously have a
slight fuel leak (from the smell and residue) leads me to believe it
may be a gasket problem - I'll wait and see what the forum kicks up.
I have been very happy with my 2GM. Starts first time every time,
would like a little more power when heading into a strong wind so the
later 2GM20 version would be advantageous. Also the original 2GM is
getting a bit long in the tooth now. It is a tight fit, everything on
the sides of the engine are difficult to reach - difficult to get the
dip-stick back in for instance. Whoever installed this one used the
original engine bed and the two aft mounting positions but both
for'ard mounts are offset slightly. Don't know if this was original
but it looks a bit odd so I wouldn't think so.

Hope this helps

Cheers

David
V1696 'Little Star'