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  #1  
Old 07-05-2022, 08:17 AM
Drippy Drippy is offline
 
Join Date: Nov 2015
Location: Vermont
Posts: 146
Default IO540 Oil Leak

I have been flighting an oil leak on my IO540 C4B5 for a few years but it just recently got noticeable worst.

The oil is found on the left side of the motor 2-4-6. It appears to start just forward of 4 but the majority of it is aft of 4 and the confusing part is I am seeing oil on the back of my fill tube.

It recently got worst and now oil will start to stream from back of my oil door on to the cowl and windshield - this was still a very minor amount 1 QT per 3-4 hours.

Trying to back into this - it may be that I don't have a great seal on my oil door and some ram air is flowing up and out the door seam caring oil with it that coats the back of the oil fill tube???

I also see oil on the #4 cylinder fins outboard - a little on 6 as well - but again the worst of it is inboard aft of #4. I see quite a bit below the cylinders aft left side along the seam between the sump and case.

I haven't isolated it to push rods - though I haven't 100% ruled them out.

One thing I did catch was the lower & fwd 3/4in bolt on #4 wasn't fully seated - fwd upper 3/4 bolt on #4 was also loose ~ 1/4 turn - So I removed the baffling and retorqued all the bolts on 2,4&6. Using a A&Ps new Torque wrench. Note I did not loosen any bolts but put the wrench on them in the star pattern and torqued them wet to the values called out by the manual.

That didn't help - now the oil leak is worst - causing oil to go through my side cowl cooling fins and the seam between cowl and firewall and trailing down the left side and bottom of the plane.

Any suggestion would be appreciated.

Thanks
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N95VT
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  #2  
Old 07-05-2022, 12:37 PM
SPB W10 SPB W10 is offline
 
Join Date: May 2018
Location: Nebraska
Posts: 46
Default Oil leak

We stopped our oil leak at our oil filler stub by replacing it. It does not crack like metal where you can see the crack, it gets fissures.
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A&P

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  #3  
Old 07-05-2022, 01:25 PM
Bill Boyd's Avatar
Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,886
Default

User name checks out.

Sorry, couldn't resist. Hope you get it solved. There are tricks for tracing oil leaks - powder, UV: see the archives.
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Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
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  #4  
Old 07-05-2022, 03:11 PM
Planecrazy232's Avatar
Planecrazy232 Planecrazy232 is offline
 
Join Date: Aug 2015
Location: Cape Coral, FL
Posts: 495
Default

Quote:
Originally Posted by Drippy View Post
One thing I did catch was the lower & fwd 3/4in bolt on #4 wasn't fully seated - fwd upper 3/4 bolt on #4 was also loose ~ 1/4 turn - So I removed the baffling and retorqued all the bolts on 2,4&6. Using a A&Ps new Torque wrench. Note I did not loosen any bolts but put the wrench on them in the star pattern and torqued them wet to the values called out by the manual.
Thanks
Are these 3/4 bolts referring to cylinder base nuts? I'm no expert, but I'd be real concerned with loose cylinder fasteners. If they were loose, there could be fretting of the mating surfaces. I would not be comfortable with just a tightening...
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Anthony

RV6-A "Aluminum Mistress"
Too many hobbies- not enough time.
2016, 2017, 2018, 2019, 2020, 2021, 2022 donor and happy to do it.

Last edited by Planecrazy232 : 07-05-2022 at 07:24 PM.
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  #5  
Old 07-05-2022, 05:48 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,317
Default

Quote:
Originally Posted by Planecrazy232 View Post
Are these 3/4 bolts referring to cylinder base bolts? I'm no expert, but I'd be real concerned with loose cylinder bolts. If they were loose, there could be fretting of the mating surfaces. I would not be comfortable with just a tightening...
Aren't these "bolts" actually "nuts"? Or am I confused?
I agree, if the cylinder hold down nuts were loose, an inspection is warranted.
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  #6  
Old 07-05-2022, 08:40 PM
N427EF N427EF is offline
 
Join Date: Oct 2005
Posts: 1,654
Default Drippy??

Seems that you may have jinxed yourself with that "Drippy" moniker?

Quote:
Are these 3/4 bolts referring to cylinder base nuts? I'm no expert, but I'd be real concerned with loose cylinder fasteners. If they were loose, there could be fretting of the mating surfaces. I would not be comfortable with just a tightening...
I totally agree, if your cylinder base nuts were actually loose, you need to have a serious look at you engine.
I do see that you are referring to "bolts", I am confused too??
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  #7  
Old 07-06-2022, 07:14 AM
Drippy Drippy is offline
 
Join Date: Nov 2015
Location: Vermont
Posts: 146
Default NUTS!!!

Seriously it has been that kind of week . . . yes I meant the nuts

I believe the lower fwd 3/4 nut on #4 may have been loose the whole 400hrs due to installation error. I believe the person (me) who rebuilt the motor may have bottomed out/torqued out the wrench hitting the other cylinder and didn't get it tight during installation.

I current plan is to remove the cylinder to check the mating surfaces visual. I will probably ask one of the local A&Ps to come take a look at this as well since I would only recognize something glaring.

If things look Ok I plan to put on a new cylinder o-ring (71481) and install new push tube seals -inboard and out- and examine the push tube spring for all port cylinders.

I am waiting on my spruce gasket order currently, but hope to pull the cylinder this weekend.
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Last edited by Drippy : 07-06-2022 at 11:13 AM. Reason: wrong word
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  #8  
Old 07-06-2022, 08:13 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,288
Default

Quote:
Originally Posted by Drippy View Post
Seriously it has been that kind of week . . . yes I meant the bolts

I believe the lower fwd 3/4 bolt on #4 may have been loose the whole 400hrs due to installation error. I believe the person (me) who rebuilt the motor may have bottomed out/torqued out the wrench hitting the other cylinder and didn't get it tight during installation.

I current plan is to remove the cylinder to check the mating surfaces visual. I will probably ask one of the local A&Ps to come take a look at this as well since I would only recognize something glaring.

If things look Ok I plan to put on a new cylinder o-ring (71481) and install new push tube seals -inboard and out- and examine the push tube spring for all port cylinders.

I am waiting on my spruce gasket order currently, but hope to pull the cylinder this weekend.
I am confused. YOu confirmed bolts not nuts, yet the cylinders are held on to the case via NUTS that thread onto studs protruding from the case. Maybe we are talking about something other than cyl hold down fasteners?

My first guess is the pushrod tube seals. The drips from these can be pretty hard to spot. Best to clean thouroughly then run for an hour then dust with baby powder and blow off excess. Sealing of the cylinders is via an o ring. I am not sure that a hold down nut loose by one flat could cause a significant leak, though an inspection is warranted.
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Last edited by lr172 : 07-06-2022 at 08:17 AM.
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  #9  
Old 07-06-2022, 11:46 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,834
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Quote:
Originally Posted by Drippy View Post
Seriously it has been that kind of week . . . yes I meant the nuts

I believe the lower fwd 3/4 nut on #4 may have been loose the whole 400hrs.... .
Note that Drippy edited post #7 to read 'NUTS'

Another concern to check out would be to carefully inspect the case around the smaller 3/8" studs as they have been taking all the load for the last 400 hrs! There could be stud damage, case thread damage, or even case cracking around those threaded holes...

Carrying the thought process even further. The 1/2" studs hold the case together... meaning holding the main bearing shells in place too. Loose through studs/nuts could have a real potential to cause a spun bearing...
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built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more
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  #10  
Old 07-06-2022, 01:29 PM
Drippy Drippy is offline
 
Join Date: Nov 2015
Location: Vermont
Posts: 146
Default Thank

Thank you for the good input
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