Light oil mist on cowl and windshield m20f

[TonyPynes]

Looks like my new 1970 M20F with less than 50 hours on all new or overhauled forward of the firewall has a crankshaft seal leak. Had light mist on cowl and windshield after 6 hour trip.

 

I took cowlings off yesterday and found oil on bottom of crankcase and on injection module which I first thought might be leaking crankcase but I then found oil on the inside of flywheel(?)  behind prop. (I ordered service manual and parts book.)

 

So what is the collective wisdom? 

I am thinking crankshaft nose seal since I don't think a crankcase leak could puddle behind the flywheel but a crankshaft seal might spray the lower crankcase. I might be wrong.....

 

Prop itself was clean with no oil. Top of engine was clean with no oil either.

 

Thoughts on why a newly overhauled engine might have a leaking seal? 

[takair]

I have a 64E, with an IO360-A1A.  A few years ago I had a similar problem after overhaul by a reputable shop.  After about 10 hours I would get the mist on the windshield.  By 20 hours it was really bad.  I went through about 3 seals before they decided the seal was not centered and replaced the case.  Now I have over 500 hours with no problem.  That was an extreme.  Very likely you just have a leaky seal due to improper installation.  There are at least two types available and each has unique problems.  Split seal can leak at the split.  The solid can be damaged when installed.  In both variations, they can leak where they are bonded in the case.  If the case is not clean when bonded, the adhesive won't take.  If you can get your ahnd up to the seal, see if it is dripping or wet there.

[John Pleisse]

Start with the prop and work your way back to the crank seal...I would bet it is the prop.....If it it the engine, put the screws to FWD. Politely remind them of your patronage and fixed costs you will absorb.

 

 

[takair]

Good point, could simply be the prop o-ring!

[John Pleisse]

Quote: takair

Good point, could simply be the prop o-ring!

[TonyPynes]

FWD?

[Guest]

 

 

I had the same problem after overhaul. After two prop seals within the first 20 hrs I had my regular mechanic look at it and he found the wrong seal number installed. He put the correct one in and no problems .

Don't know if it's your problem but prop seals are very easy to replace.

[jelswick]

I had the same symptoms, not on a recently overhauled engine, and it turned out to be the prop seal leaking.  I don't recall the amount, but do remember it wasn't as expensive as I thought it might be to replace. 

[mooneygirl]

Aside from the possible prop. seal, crank seal possiblities, you might have all the case through bolts checked for correct torque/tightness.  That was my experience with having mist on the windshield/cowl. 

Whoops, I thought this was posted under my account, Mooneymitch, sorry Jolie.

[Shadrach]

If the prop hub is leaking you will see grease stains on the face (back) of the prop propigating from the hub. This often happens when a mechanic or owner who doesn't now any better over-greases the prop (many still beleive that grease should be pumped until dirty grease is pushed out of the opposing zerk; this is wrong.).

I think that a prop o-ring is unlikey to be the issue, unless it was damaged, reused, or forgotten (would be pretty messy).

My guess is that it is the crank seal, which is not a real big deal replace.  While I prefer the "stretch seal" that stretches over the prop flange, split seal can be installed without removing the prop. I installed a split in 2006 and have had no trouble with it. 

Before you replace the seal, make sure that the breather is open. A R&R'd crank seal will just leak again if the crank case is pressurized. 

[Guest]

 

 

 

 

 

Sorry I miss spoke, after looking through my logs it was indeed my crank seal   that  I had issues with oil leaking ( mist ) and  not my prop seal. 

 

Anyway good luck. 

[TonyPynes]

Thanks for everyone's input. Hopefully I will hear this week that it can be fixed at a reasonable price. I will post results here.

[rbridges]

I hope it's relatively simple and inexpensive.  I know you were excited about the purchase/trip, and I don't want this to sour your experience.

[TonyPynes]

Now if I can just get a mechanic to call me back. It must be great business for A&Ps these days. One never calls me back even though he was a personal friend referral and I have emailed and left a VM. Another I have to call to talk to him as he will never call me. Seems the only ones that call back are farther away. Are A&Ps so busy they are pushing off work? Must be nice to have so much work you call back who sounds accomodating.

Maybe it is me and I sound like a jerk in my emails and VMs. I will have to ask someone to review my messages. Cant be my breath as I havent met them yet. 

[Shadrach]

Quote: AustinPynes

Now if I can just get a mechanic to call me back. It must be great business for A&Ps these days. One never calls me back even though he was a personal friend referral and I have emailed and left a VM. Another I have to call to talk to him as he will never call me. Seems the only ones that call back are farther away. Are A&Ps so busy they are pushing off work? Must be nice to have so much work you call back who sounds accomodating.

Maybe it is me and I sound like a jerk in my emails and VMs. I will have to ask someone to review my messages. Cant be my breath as I havent met them yet. 

[TonyPynes]

Really?

A week or two later (several attempts by phone and email) and no contact is to be expected? ??

My view is he is probably a great mechanic and has all the business he needs and really doesnt want more. Which is cool. I wish I could use him but before I beg and travel to him in the hopes he might have time to see me or even be there I will look around first. My money and time are too important to me.

Thankfully I have other choices to try. This was more of a venting post. Vent is over.     I also dont wait past 15 minutes at a doctors office either.  But that is just my philosophy on respecting everyone's time and expecting the same in business transactions.  OK vent is really over now.

 

[DaV8or]

Quote: AustinPynes

Really?

A week or two later (several attempts by phone and email) and no contact is to be expected? ??

My view is he is probably a great mechanic and has all the business he needs and really doesnt want more. Which is cool. I wish I could use him but before I beg and travel to him in the hopes he might have time to see me or even be there I will look around first. My money and time are too important to me.

[TonyPynes]

I had someone look at my problem of oil over the cowl and was told all they could find was my oil filler tube was loose. They tightened that up and ran the engine and could not see anymore oil anywhere. So I will test fly it and see if we can find anymore. Surely it wont be that easy.

[KSMooniac]

Hopefully they thoroughly cleaned the engine, otherwise you'll never be able to pinpoint the source of the leak.  Oil will migrate all over the place during flight...

[TonyPynes]

The engine has less than 50 hours on pretty much all new or overhauled forward of the firewall. It looks like a brand new engine top to bottom. So nothing to clean up. Will hear more Monday.

I just dont know if oil from the oil filler tube could get all the way to the front of the engine and inside the flywheel behind the prop. Prop is dry of oil.

[TonyPynes]

Update

So I have had the crankshaft seal replaced and the prop o ring. She still leaks no change at all. Will not leak running on the ground but about an hour in the air and there she starts. No leak underneath either.

The MRO here thinks it is a crankcase half seal lower front at a knuckle.

I don't think so. How could it get all the way up front to the back of the flywheel?

I just flew her back from Myrtle Beach and can tell it is no longer a light mist but streaking on the cowling and this time put a nice light coating on the passenger side. She is officially grounded except for fixing this leak.

I have a Mooney experienced mechanic I will take her to this week. I had figured that a Lycoming engine and hartzell prop would be common enough that any mechanic could help me so I tried on field MRO. Maybe I am wrong.

I am going to use my borescope to check out the crankcase halves today.

[takair]

Austin

Did you get a chance to look at the crank seal?  If so, was it worn evenly and smooth?  Can  you get a finger or borescope up near the seal to see if it is clean?  I had mentioned in an earlier post my experience.  The seal wear was a tell tale sign.  The crank halves could also be leaking in the same area giving a similar symptom.  The halves are sealed with a silk thread.  Crude but effective, unless the thread does not go to the end. 

[TonyPynes]

I will check the seal they put in and see if it is wet. If I can get to it with a bore scope. They said after I test flew it last time and had more spray the crankshaft seal was dry.

[TonyPynes]

I had to use my borescope with some help from my Iphone to get some pics of my engine leak. Took a hundred but these are the interesting ones. Wet doesn't show up well with a borescope.

I do have two pics that worry me. one shows a fix that is strange and I didnt notice when I was taking the pics. THe other is a bolt that doesn't look tightened.

 

For those with no life whatsoever I posted them in my gallery.

 

 

[takair]

My wife might agree with your "no life statement" too.....anyway, I looked.  That "troublesome photo" deserves more investigation.  Hard to get oriented, is that the alternator bracket in the photo?  What is the open hole at the top of the photo?  Looks to have bare threads, like something recently came out.  The crinkling can be as simple as paint or perhaps an ugly weld? 

That is quite a bit of oil for so little run time, even for a leaking nose case seal.  It is worth checking that your crankcase breather is not plugged.  Have been told that it can cause oil to push out the nose seal....and even push out the seal.  I suspect that's not it, but it's an easy one to verify.