Best way to start a cold Mooney (M20C)

[steingar]

The problem is most airplane engines have parts with dissimilar metals.  Those metals contract differently when they get cold.  As a result the fitment between them gets different.  I've been told that starting your average piston engine in extreme cold can damage it.  Of course, lots and lots of cranking also wears through starters and other parts.  Get a red Dragon.  More preheat, less whining.

[carusoam]

Notes added to an old thread….

Cold starting an O360…

Above 20°F is possible…

The evaporation rate of 100LL is very slow at these temperatures…. Extra prime + extra wait time = good evaporation…

Below 20°F it is pre-heat time….

 

Closer to 20°F requires a lot of priming… whatever your max priming experience has been + add some more….

Use extra caution… plenty of excess fuel will be draining onto your nose wheel…  a real set-up for a fire to occur…

 

You only get a few tries at this before the battery is no longer helpful…

 

A lot easier than a hot start of an IO360… but equally doable once you have the skill…

Be a fuel molecule… know how to evaporate! 

PP thoughts from being outside in NJ…

Best regards,

-a-

[Jcmtl]

I just did this yesterday, temps in mid 20s. It took about 5 tries of priming (5 pumps of the throttle), waiting between 30-40 seconds, and cranking.  I was actually surprised the battery lasted (new concorde battery).   I have a feeling that a few degrees colder and this would have been impossible.  
 

 

[Utah20Gflyer]

17 hours ago, Jcmtl said:

I just did this yesterday, temps in mid 20s. It took about 5 tries of priming (5 pumps of the throttle), waiting between 30-40 seconds, and cranking.  I was actually surprised the battery lasted (new concorde battery).   I have a feeling that a few degrees colder and this would have been impossible.  
 

 

Lately I've been giving my plane 10-12 pumps of the throttle and then wait one minute and crank.  It's been starting really fast on the first try doing that while its been really cold.    Obviously every plane is a little different but it's an option.  

[Hank]

My C doesn't like starting below freezing without preheat; plugging in the Tanis for an hour makes all the difference! It only heats the oil pan, though, so gotta give the cold fuel time to vaporize.

This is what I began doing in WV / OH:

• Plug in Tanis / call cell switch to turn on Tanis
• Preflight in hangar, open door, unplug Tanis and push plane out
• Spin prop 2 revolutions by hand
• Get in, fuel pump on til pressure stabilizes, then off
• Mixture rich, pump throttle 5-6 times, leave 1/2" forward from Idle
• Wind and set clock, glance at second hand, spin red hands to overlap
• Put on and adjust headset, check seatbelt
• Check pax, if any
• At about 60 seconds post-winding clock, turn key and push. 

 

[Jcmtl]

10 hours ago, Utah20Gflyer said:

Lately I've been giving my plane 10-12 pumps of the throttle and then wait one minute and crank.  It's been starting really fast on the first try doing that while its been really cold.    Obviously every plane is a little different but it's an option.  

This makes sense to me.  I got it started with 5 pumps x 5 attempts so 25 pumps total waiting 30-40 seconds between pumping and cranking.  I guess your way makes more sense, double the pumps and double the wait.  

[Greg Ellis]

Just after I bought my C model I had issues much like this with starting.  It would take a long time to start.  Pumping the throttle and waiting did not seem to make any difference.  I would do what has been mentioned about pumping it 10-12 times then waiting then trying to start then repeat.  Being new to Mooneys I really had no idea that something was wrong.  Just thought it was normal in cold weather to be like this (it was winter when I bought the airplane).  Previous owner was around when it was happening and he said that it was just that way and took a long time to get started in cold weather.

I had a feeling there was something wrong and was worried that I was wearing down other parts of the engine when trying to crank for so long without it starting (low oil pressure, metal on metal scraping prior to oil pressure building up, wear on the starter, etc....)  I contacted a mechanic that told me that it sounded like the carburetor was not getting any prime from the accelerator pump and that I should consider rebuilding the carburetor.  I did and now 14 years later I can start the engine with 3 pumps in warm weather and about 5 pumps in frigid weather (frigid in Texas may be different than frigid elsewhere) and on about 2-5 blade turns.  Starts right up.

So you may want to consider something wrong with the carb and you may need a rebuild.  On mine, and I am sure all the very knowledgeable folks on here will correct me, but the accelerator pump is what primes the carb in a C model.  It has a diaphragm of some sort in it.  Mine was torn and worn out.  So when I was pumping the throttle thinking I was priming the carburetor, it really wasn't doing anything at all, or very little.

[Utah20Gflyer]

9 hours ago, Greg Ellis said:

Just after I bought my C model I had issues much like this with starting.  It would take a long time to start.  Pumping the throttle and waiting did not seem to make any difference.  I would do what has been mentioned about pumping it 10-12 times then waiting then trying to start then repeat.  Being new to Mooneys I really had no idea that something was wrong.  Just thought it was normal in cold weather to be like this (it was winter when I bought the airplane).  Previous owner was around when it was happening and he said that it was just that way and took a long time to get started in cold weather.

I had a feeling there was something wrong and was worried that I was wearing down other parts of the engine when trying to crank for so long without it starting (low oil pressure, metal on metal scraping prior to oil pressure building up, wear on the starter, etc....)  I contacted a mechanic that told me that it sounded like the carburetor was not getting any prime from the accelerator pump and that I should consider rebuilding the carburetor.  I did and now 14 years later I can start the engine with 3 pumps in warm weather and about 5 pumps in frigid weather (frigid in Texas may be different than frigid elsewhere) and on about 2-5 blade turns.  Starts right up.

So you may want to consider something wrong with the carb and you may need a rebuild.  On mine, and I am sure all the very knowledgeable folks on here will correct me, but the accelerator pump is what primes the carb in a C model.  It has a diaphragm of some sort in it.  Mine was torn and worn out.  So when I was pumping the throttle thinking I was priming the carburetor, it really wasn't doing anything at all, or very little.

I probably should have mentioned that I just got my mags overhauled and installed a skytech starter which cranks much faster that it used to.  The combined affect is my plane starts easier than it used to.   So you have a good point that worn parts may be to blame.   If primed correctly now it starts in about 2 blades regardless of the temperatures.  I do preheat below 30 degrees though and I suspect I could get it started colder.  

[carusoam]

Worn accelerator pumps cause some variation in what we are reporting…. I used 10 pumps in my worn M20C on extra cold days…

Keep in mind… waiting a long time allows fuel to drain out the bottom… that might otherwise get drawn towards the cylinders…

Ideas to help make adjustments… if what you are using could work better… 

 

Best regards,

-a-

[cferr59]

I would advise everyone who pumps the throttle to prime to remove the air filter and have someone pump the throttle while looking into the airbox. You will see that it dumps quite a bit of fuel into the airbox on each pump. After realizing this, I only pump the throttle while cranking the engine. It usually starts with 1 or 2 pumps, but if cold it can take a bit more. I prefer to preheat, but that is not always an option. I suppose the Surefly doesn't hurt, but I never had a starting problem with the SOS.

[Hank]

12 hours ago, cferr59 said:

I would advise everyone who pumps the throttle to prime to remove the air filter and have someone pump the throttle while looking into the airbox. You will see that it dumps quite a bit of fuel into the airbox on each pump. After realizing this, I only pump the throttle while cranking the engine. It usually starts with 1 or 2 pumps, but if cold it can take a bit more. I prefer to preheat, but that is not always an option. I suppose the Surefly doesn't hurt, but I never had a starting problem with the SOS.

If only those ignorant Mooney engineers who wrote the Owners Manual knew as much as the modern denizens of MooneySpace . . . . .