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Volvo Penta AQ 140 -- Lots of Gas Leaking into Bilge

J

john_lofquist

Member
I'm slowly restoring a Volvo Penta AQ 140 engine so it can serve as a spare.

Recently I found the appropriate fuel line for engine ..... I installed it......
and tried starting the engine. It started ....and ran for a minute or so.....
rather roughly..... and stopped. At point I heard what sounded like fluid dripping
into the back area of the boat's bilge ...... the dripping continued ......
more like streaming than dripping....... I'm guessing that there is something haywire
with the carburetors ...... which can be fixed, I assume.......
but I am really stumped as to why / how all the gas can find it's way to the bilge.....
because of the limited space, it is very hard to see exactly where the gas is leaking from...
seems to be dripping off the edge of the oil pan ..... from the back underside of the engine....
I just can not tell at this point ..... I'm wondering if this signifies a larger problem for this engine.

Any thoughts / advise is appreciated.

Thank you.

John Lofquist
 
There are a couple of things that come to mind right away:
1) The soft washers for the banjo bolts are for one time use. They deform a considerable amount so that may be one sourch of the leak.
2) The banjo bolts themselves are easy to crossthread into the carbureator body. The mistake can have you looking for carbureators on ebay (I'm afraid I know this first hand).
That's just a few things that I know of but there's really know way to tell until you actually get in there to look. A mirror may be helpful in the cramped quarters.
 
*
Thanks for your comments.**
*
The mirror idea is a good one .....* since the leak is in the back
of the engine itself ......**I was a bit worried that the entire thing might just explode in flames....
I sopped up all the gasoline mess ......* perhaps almost a pint of gas ........
and decided to leave it alone until I can determine how it is that all this gasoline is finding
its way down there.**
*
The carburetor side of the engine shows no gas leaks ...... I stalled new metal gaskets on both
the banjo bolts on the fuel line and on the neoprene line*from the fuel pump to the forward
flame arrestor *....**6 gaskets....... no leaks there........* seems fine on the outside.
*
However, I wondering if somehow the float mechanism inside the carburetor(s) is somehow stuck allowing
maximim gasoline to enter the engine and drain down inside ?** If the gas is leaking out of the
underside / backside of the engine ....* that can't be good.** I would think that the engine would be
sealed and leakage wouldn't happen.** But I really don't know ......*
*
Thank you.
*
John Lofquist
*
*
 
The mirror idea worked great. Used a small flashlite as well.

I turned the engine by using a breaker bar and socket...... gas poured out of the flywheel housing......
as I turned the bar ....... more gasoline poured out ...... I had disconnected the fuel line to the fuel pump
so that this gasoline drainage situation didn't get out of hand ...... whatever gas was in there quickly drained out.

So, I'm guessing that the carburetor (s) are flooding the engine ..... and the gas is overwhelming the system....
and finding its way to drain out...... does it make sense that it would come out of the flywheel housing ?
How does that happen ?

Also, the bottom portion of the flywheel is exposed....... using the mirror, I could see the gas leaking.....
and the flywheel teeth etc ....... perhaps there is something missing here....... perhaps a part is missing.....
thus, allowing the gas to drain out.

Any ideas on this would be appreciated. Trying to learn all I can about this engine.

Thanks.

John
 
If the fuel pump was leaking into the block, I would think there should also be oil coming out with the gas. Check the oil level and see if it's unusually high and if it smells strongly of fuel. My guess at this point is that the gas is leaking into the sump and coming out through the rear crankshaft seal or through a missing casting plug. Short of a fuel line leak, a fuel pump failure and leaking into the sump is the only thing that makes sense to me.

The additional line to the carburator is supposed to be a safety feature in case the fuel pump diaphram leaks. The fuel is supposed to be drawn into the carb instead of leaking into the bilge or dumping into the block. The fact that that line and filling on the pump exists indicates that you have a marine fuel pump but that doesn't mean that it's not leaking.

Edit: I just took another look at a sketch and saw that the earlier models may not have the leakoff line going from the fuel pump to the carbureator. I could be wrong about that line and it could very well be that you have one of the models that was put out before the requirement.

It would be highly unusual for the carbs to flood so bad that the gas would leak past the rings and pour into the sump in the quantities you're indicating.

You said that the lower portion of the flywheel is exposed. There is supposed to be a half round metal plate or shroud bolted to the back of the block back there. That missing isn't a show stopper but will definately allow oil to splash everywhere if the rear main seal begins to leak.

Be careful around the fuel vapors in an enclosed area. Bad things can happen if there's a spark or if you keep your head down there too long!
 
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Hi, I had a car come into our shop, years back. I checked the fuel level on the dip stick and could not see an oil mark. I added oil and checked again. Still no oil. After adding two more quarts, and still no reading, I raised the car and pulled the drain plug. Wow, gas came out with such force that it knocked over the drain stand. After cleaning up the mess, I figured what was wrong. The fuel pump leaking, had filled the oil pan to the level, that the reading on the dipstick was way higher than I was looking.
Check your fuel pump!!!!!
Art
 
Thank you for your comments and help. I certainly appreciate your input.

The gasoline had definately gotten into the oil. The dip stick smells of gasoline..... and the fluid level
is now way high on the dip stick. So, I will have to deal with that.

Regarding the fuel pump as the source of the leaking gas, I can easily remove it ..... but what would I be looking for ?
What would I expect to see inside the pump that would tell me that it is defective ?
As a test, this afternoon I disconnected the metal fuel line at the fuel pump and held my finger over the fuel exit hole
on the fuel pump while I turned the engine over by hand ... with a breaker bar ..... so I could listen to any leaking or dripping.
No dripping fuel .... nothing seemed to leak .....

Again ..... thank you for your input......it helps a lot.

Sincerely,

John Lofquist
Beaver, Washington
 
Since the top is cripmed to the bottom of the pump, there's nothing on the pump to take apart. The diaphram is dry rotted, has a leak, or is just plain shot. ny pressure it's developing is being used to push fuel into the block. Here'a a replacement: http://www.marineengine.com/newparts/part_details.php?pnum=SIE18-7286&ptype=&Engine=&Model=.

Drain the oil, replace the pump, and get back on the water before we're done for the season :).

You might need to look for a slightly different fuel line fitting connector but that's just part of working on *%#@$ old boats.
 
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Thank you for your suggestions on this spare engine project.

I have an identical engine in my Glasply .... it runs great ...... quiet ...... smooth..... and economical......

My objective with this particular extra engine is to work on it over time .... and get it established as a totaly reliable
spare engine.

I certainly appreciate your ideas, suggestions and help.

Sincerely,

John Lofquist
Beaver, Washington
 
did someone put a electric boost fuel pump ahead of engine mechanical pump,solex carbs will not tolerate fuel pressure above 3psi at carbs,if so disable it.
 
There is only a mechanical fuel pump on this engine. Since I do not know the history on this engine etc., I'm left to
guessing about it. I have concluded that the fuel pump is newer than the engine ..... I can not tell for certain that the
fuel pump needs replacing .....it might need to be replaced ..... my focus is on the forward carburetor.......
I attached my Yamaha outboard gas tank hose to each carb separately ..... and hand tested the ability of each carb
to hold a small amount of hand pressure........ by squeezing the bulb in the neoprene gas line.......
the aft / rear carb filled with gas ..... and held the pressure ..... I could not detect any additional gas leakage into the
bilge........ no so with the forward carb ........ it would not hold a small amount of hand pressure ....
and new gas leaked into the bilge.

So, I will attempt to "rebuild" the forward carburetor .... as a first step....... might rebuild the aft one too.....

I have read the Seloc Manual many, many times regarding this rebuild process ...... I have a few questions:

1. Do I remove both carburetors ? I tried removing one ..... could not get it free of the acceleator connections.
I can easily remove both ..... but then what ? How do I separate the carbs from the linkage ?

2. The repair / rebuild kit shows several washer parts ....... How do I know which ones go where ?

Thanks.

Sincerely,

John Lofquist
Beaver, Washington
 
The linkage becomes obvious once you remove the cable. Once you get one carb loose and above the studs, start wiggling it and the rod will fall off. It might be easier to make a sketch so you can remember how it goes back on. As for the washers, the soft aluminum washers are for the fuel line. These undergo considerable deformation when compressed so are a one shot deal. For the rest of the washers, it's probably best to match them up as you remove the parts from the carbureator.

Keep us informed and let us know what you find. A leaking carb filling the crankcase up with fuel sounds unusual. I hope you've drained the oil by now. The gas will wash the oil out of the bearings pretty quick. They'll be nice and clean but they really like oil better than gas!

The call on the fuel pump is certainly up to you but it sounds like cheap insurance to replace it.
 
Good morning .... and thanks for your help on this project.

Yes, the gas / oil combo is out of there...... new oil goes back in later today.......
new filter as well .....

Thanks for your comments regarding the removal of the carburetor ..... I started ..... took off the stud nuts....
but the linkage would not let go ....... so, I just stopped at that point ....... forcing things never works for me.....
better to stop ...... and figure it out / ask questions ...... etc.

Your comment "cheap insurance" is certainly valid ...... we often fish for salmon 10 to 15 miles off shore......
in the Pacific Ocean ...... gas leaks are just not acceptable........

More later.....

Sincerely,

John Lofquist
Beaver, Washington 98305
 
Sounds like the forward carb float may be too high? This would allow the fuel pump to over-fill the bowl and it would over-flow....?
 
Thanks for your input.

I have removed the forward carb from the engine and have taken it apart ... carefully. It is really hard to know what
is haywire for certain ...... there were all sorts of flecks of dirty debris in the carb bowl ...... gunky areas.....
and minor signs of discoloration where, I suppose, moisture had settled in and started acting on the metal.
The diaphram is quite miserable looking and needs to be replaced. Anyway, I've removed the various parts
according to the manual ..... and have cleaned them carefully with carburetor cleaner. Everything looks ok now.
I'm waiting for the repair kit to arrive by mail. I will check the carb float ... although, perhaps by replacing the needle and seat
the issue will be resolved. More later.

Thanks .... John L
 
You can check the existing float for leaks now. Not all aftermarkets kits come with a new float so be prepared to not have a replacement. If the tang on your existing float is deformed or bent, that's a big problem as there is float no adjustment on that particular carbureator.

It's also a good idea to blow out all the passages with compressed air to make sure you've got everything clean.

A big advantage of having two carbs is that if you get stuck on something, you've got the other one for a reference. Of course, that's assuming that the other one is put together correctly!!!!!

Good luck and let us know how it turns out.
 
Thank you for the u-tube video .... and the comments.

The Sierra cab kit arrived yesterday. Since the carburetor is now quite clean, I did blow compressed air
into the passages etc ..... to clear flecks or dirt / debris that might still be there .

The Sierra kit has a new needle and seat sealed separately in its own little plastic bag.....along with three washers.
A gray washer .... a brick red colored washer ......and a copper washer. No instructions.
The Seloc manual does not say anything about these washers either.

Anyway, I spent most of the afternoon putting the carb together and taking it back apart..... tried all the combinations
of those washers. It seems to me that the copper washer is the one to use. Otherwise, the float is somehow
locked in place ....it seems to bind on the metal of the carburetor housing..... now, if I rotate the carb upside down
and back rightside up, I can hear the float moving inside the unit. With the other washers, it did not make any
such sound ..... the float seemed stuck in there somehow. Will install the carb on the engine later.

Sincerely,

John L.
 
First of all, I certainly appreciate the help & comments regarding this carb project. I'm really a green-horn on this
sort of activity ....but I want to learn as much as I can about these AQ 140 A engines.

I re-installed the forward carburetor...... and the fuel line... etc ........ the engine started .......ran .... but very rough
sounding ....... best of all, no gas leaks ....... checked the oil ...... looks good ...... can not detect any gas in the oil....

I inspected the old needle and seat part ...... it seems to be worn in some way ....to such a degree that it
didn't close properly ..... thereby allowing gas to flood down through the engine into the oil supply .....and then
into the bilge..... perhaps the float setting played a role in this too ...... I just don't know......what I do know
is that the " re-built" carb seems to be working properly.

Thanks for everyone's help on this.

Sincerely,

John L.
Beaver, Washington
 
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