fuel and oil leak from drains

[bavareze]

today a friend was watching my plane and told me that, as soon as I started the engine, a liquid started dripping from this hose in the picture.

It smelled like avgas and I was able to trace it up to the mechanical fuel pump.

I wasn't able to find anything about this drainage in the POH.  is this normal (i.e. over pressure relief of some sort) or malfunction?

also I see that a lot of oil is coming through the breather hose from the engine case.  I heard there are some oil separators that can be installed to reuse the oil and prevent spillage on the belly.  do you guys use oil separators? can it be legally installed using an STC?

 

thanks

 

Thanks

[Andy95W]

Oil separators are available. The biggest reason to NOT use one is that they will also put moisture and  corrosive chemicals back into the crankcase. 

Oil is cheap. Cleaning the belly is easy. Replacing a camshaft is difficult and expensive. 

[DonMuncy]

1 hour ago, Andy95W said:

Oil separators are available. The biggest reason to NOT use one is that they will also put moisture and  corrosive chemicals back into the crankcase. 

Oil is cheap. Cleaning the belly is easy. Replacing a camshaft is difficult and expensive. 

I have read/heard Mike Busch (who I generally agree with) express the same sentiments about putting the "stuff" back in the crankcase. But I have questions about how it is bad to take the vapors, etc. from the crankcase and put the same ones back in. Is there some belief that the worst of the stuff is pushed into the separator and the less bad stuff stays in the crankcase. 

[carusoam]

Negative, captain!

The important part...

Fuel leaks coming from either fuel pump are not acceptable...

Something like a diaphragm or seal is no longer doing its primary job.

Probably time for a pump OH. Or get it re-sealed...

Pump cases are built with this in mind... they have nice drain holes. So it looks like they are supposed to do this...

in your case, the pump drain is nicely plumbed with a hose.

Looks like you want to follow up on possible OH directions.

The ships pump run’s continuously... so it is leaking fuel continuously... a fire problem, and a run out of fuel problem...

Got a FF meter? If yes, did you notice an unexplained FF increase?

got a totalizer? Where did all the extra fuel go?

PP thoughts only. Not a mechanic... My O’s electric fuel pump was the one leak I have had... it only pissed on the ground for about five seconds per flight... it took a passerby to say something...

 

Best regards,

-a-

[Yetti]

there is also tube that goes to the bottom of the engine.  search for Maxwell sniffle valve.

The test for the mech fuel pump is.   pump using elect pump.  open mixture.  close mixture turn off elec pump.   Watch the Fuel pressure gauge.   If it leaks down pressure without delay, you need a new mechanical pump. 

They are like replacing one on a chevy V8 engine.  Some say to remove the mag.   If you sacrifice a 5/16 inch allen wrench to the proper size you can do it without removing the mag.

[Guest]

On 1/25/2019 at 8:50 PM, bavareze said:

today a friend was watching my plane and told me that, as soon as I started the engine, a liquid started dripping from this hose in the picture.

It smelled like avgas and I was able to trace it up to the mechanical fuel pump.

I wasn't able to find anything about this drainage in the POH.  is this normal (i.e. over pressure relief of some sort) or malfunction?

also I see that a lot of oil is coming through the breather hose from the engine case.  I heard there are some oil separators that can be installed to reuse the oil and prevent spillage on the belly.  do you guys use oil separators? can it be legally installed using an STC?

 

thanks

 

Thanks

I haven’t worked on a lot of C models, but I find the second fuel line at the firewall fitting interesting.

Clarence

Edited January 27, 2019 by M20Doc

[orionflt]

I have seen some interestinf stuff including the electric fuel pump infront of the firewall, really wondering about that second hose. Maybe it's a dual carb mod for extra horsepower.

Brian

[bavareze]

are you talking about the connection that I circled in green?  the lower hose goes to the carburetor while the upper one goes to the fuel pump.  I figured that box might be the electrical pump.  am I wrong?

[carusoam]

How tiny do you think an electric motor and it’s associated pump are?

One way to find your electric pump, is to have somebody turn it on for you... it makes a fair amount of sound, and has a drain that makes it easy to find. Put up your finger on the drain, you will probably feel the vibration of the motor running....

Search on fuel pumps around here there are quite a few pictures posted. Use the brand name if you want a specific example of what you have...

The factory location of the electric fuel pump is under the floor boards... forward of the fuel selector valve...

Clarence made a reference of seeing one in front of the firewall yesterday... probably not a factory location...?

Typical Mooney drains... (up front)

• fuel pumps each get a drain. (Fuel)
• carburetor over flow has a drain.  Pump the accelerator pump until it overflows to find out. (Fuel)
• Fuel injection system has a sniffle valve that sometimes drains fuel on the ground. (Fuel)
• Battery boxes get drains. (Acid)
• Engine case gets a vent drain. (Air, exhaust, moisture, Oil)
• fuel separator has a drain. (Fuel)

Try to identify all your drains... it shouldn’t be too challenging.

Pp thoughts, not a mechanic...

Best regards,

-a-

[cliffy]

Your mechanical fuel pump diaphragm is leaking. They get old and crack. Don't fly until you get it fixed, replaced, etc. It can be changed by removing the cowl and doing it from below. Can be done with just the side cheeks removed. Going in from the top is frustrating.  

Oil separators are available with STCs but finding a good place to put them might be an issue. Others have done it. There is a smaller diameter one available. 

Breather blowby happens on all engines. How much are you blowing out? Have you noticed a sudden increase in blowby? Are you filling the oil sump to the max of 8 quarts or are you keeping it down a quart or so? Many of us find that by always filling to to 8 quart mark the engine blows out the first quart real quick and then the use becomes a lot less.  How much oil are you using? hours per quart? 

[moontownMooney]

I have read/heard Mike Busch (who I generally agree with) express the same sentiments about putting the "stuff" back in the crankcase. But I have questions about how it is bad to take the vapors, etc. from the crankcase and put the same ones back in. Is there some belief that the worst of the stuff is pushed into the separator and the less bad stuff stays in the crankcase. 

Moisture (which can cause corrosion on it's own, or combine with chemicals in the oil soup to form even more corrosive acids) as well as solvents (e.g., unburned fuel vapor, which deplete the protective oil film on the metal parts) are continuously added to the crankcase volume during engine operation via blow by past the piston rings. This added gas must be vented or the crankcase would build unacceptable levels of pressure. In addition, most of these detrimental additions (moisture and solvents) will remain as a gas at engine operating temperatures. So throwing this excess pressure gas overboard is a good way to get rid of the worse portions of the blow-by constituents which are continually added to the crankcase. The oil separator attempts to scavenge some of the oil which would be thrown overboard with this gas for environmental, cleanliness, and oil cost reasons, but because the separator is imperfect, it will inevitably put more of the moisture and solvents back in the crankcase than if you didn't have the separator at all. The relative amount and its significance, I cannot speak to. PP and AE thoughts only, not an A&P or any other relavant letter.

Sent from my SM-G930V using Tapatalk

[bavareze]

On 1/29/2019 at 8:45 AM, moontownMooney said:

Moisture (which can cause corrosion on it's own, or combine with chemicals in the oil soup to form even more corrosive acids) as well as solvents (e.g., unburned fuel vapor, which deplete the protective oil film on the metal parts) are continuously added to the crankcase volume during engine operation via blow by past the piston rings. This added gas must be vented or the crankcase would build unacceptable levels of pressure. In addition, most of these detrimental additions (moisture and solvents) will remain as a gas at engine operating temperatures. So throwing this excess pressure gas overboard is a good way to get rid of the worse portions of the blow-by constituents which are continually added to the crankcase. The oil separator attempts to scavenge some of the oil which would be thrown overboard with this gas for environmental, cleanliness, and oil cost reasons, but because the separator is imperfect, it will inevitably put more of the moisture and solvents back in the crankcase than if you didn't have the separator at all. The relative amount and its significance, I cannot speak to. PP and AE thoughts only, not an A&P or any other relavant letter.

Sent from my SM-G930V using Tapatalk
 

 

this is pretty much the same theory that applies to most internal combustion engines such as those used on cars (PCV system) and the oil is caught and the gasses are fed to intake to be burned again and nothing crazy happens there.  I got my 88 carrera and my 73 beetle with original engines and they still work within acceptable parameters.

 

On 1/28/2019 at 7:48 PM, carusoam said:

How tiny do you think an electric motor and it’s associated pump are?

One way to find your electric pump, is to have somebody turn it on for you... it makes a fair amount of sound, and has a drain that makes it easy to find. Put up your finger on the drain, you will probably feel the vibration of the motor running....

Search on fuel pumps around here there are quite a few pictures posted. Use the brand name if you want a specific example of what you have...

The factory location of the electric fuel pump is under the floor boards... forward of the fuel selector valve...

Clarence made a reference of seeing one in front of the firewall yesterday... probably not a factory location...?

Typical Mooney drains... (up front)

• fuel pumps each get a drain. (Fuel)
• carburetor over flow has a drain.  Pump the accelerator pump until it overflows to find out. (Fuel)
• Fuel injection system has a sniffle valve that sometimes drains fuel on the ground. (Fuel)
• Battery boxes get drains. (Acid)
• Engine case gets a vent drain. (Air, exhaust, moisture, Oil)
• fuel separator has a drain. (Fuel)

Try to identify all your drains... it shouldn’t be too challenging.

Pp thoughts, not a mechanic...

Best regards,

-a-

yeah, that should be pretty easy, only that I wasn't at the plane when making the assumptions, I was at home.  Been pretty busy these days passing my CFI exam and also rain prevented me from going back to my old mooney, but I'll do this shortly and post results.

 

On 1/28/2019 at 10:21 PM, cliffy said:

Your mechanical fuel pump diaphragm is leaking. They get old and crack. Don't fly until you get it fixed, replaced, etc. It can be changed by removing the cowl and doing it from below. Can be done with just the side cheeks removed. Going in from the top is frustrating.  

Oil separators are available with STCs but finding a good place to put them might be an issue. Others have done it. There is a smaller diameter one available. 

Breather blowby happens on all engines. How much are you blowing out? Have you noticed a sudden increase in blowby? Are you filling the oil sump to the max of 8 quarts or are you keeping it down a quart or so? Many of us find that by always filling to to 8 quart mark the engine blows out the first quart real quick and then the use becomes a lot less.  How much oil are you using? hours per quart? 

Not so much that I have to worry about budget but enough to have the belly greasy most of the time.  so I guess 1 qt every 5-10 hours or so (less when doing long flights, more when circling around doing pattern work).

I also never had a problem with foul spark plugs.

 

 

[carusoam]

Congrats on the CFI thing!   

Vx Climb attitudes puts oil close to the case vent...  high MP tends to have the case pressurized... oil escaping, is what it wants to do...

MSers tend to celebrate when another MSer acquires another set of wings!  Cheers!

Go MS!

-a-

[bavareze]

On 2/17/2019 at 1:06 PM, carusoam said:

Congrats on the CFI thing!   

Vex Climb attitudes put oil close to the case vent...  high MP tends to have the case pressurized... oil escaping, is what it wants to do...

MSers tend to celebrate when another MSer acquires another set of wings!  Cheers!

Go MS!

-a-

thanks!

 

so regarding the red fuel hoses: the upper one is going to the mechanical fuel pump and the lowest red one goes to the carburetor fuel intake.  However, what's behind the firewall in that box I didn't find out.  The fuel pump noise comes from that area but seems to be a little more aft.

 

Could it be that the two pumps are connected in parallel instead of series?

[carusoam]

The interesting thing about the M20C firewall....

On the front... is the engine mount.

On the back... is your toes. 

below the floor board... is where the fuel selector, fuel lines, strainer, and electric fuel pump are hiding...

Most Mooney fuel pumps are in series... Somebody recently posted a case where they were in parallel...(?) follow-up... Floyd posts below, regarding his 63C...

Either case is possible, one has less complexity or failure modes than the other....

Following the drawings Clarence posted above... there is a firewall standoff box 18... that matches your picture...

and a reference to the fuel pump under the floor board 14... and a little nib called 15... looks like a fuel drain for the electric boost pump...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Floyd]

That looks like a 63 M20C.  The electric and engine driven fuel pumps are in parallel. That is besides the point.

The problem he has as mentioned above is the engine drive pump is leaking and needs to be replaced.

My 63 C had the same problem.  Also, I did find a new Tempest pump that fit but the original AC pump has a smaller case then the new ones.

Having the old one overhauled will ensure it will fit. New ones maybe maybe not.

Edited February 26, 2019 by Floyd