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Low Oil Pressure Running Rough


Cwalsh7997

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1 hour ago, M20Doc said:

You'd think with a history as long as that of Lycoming's they would have camshaft so figured out by now.

Clarence

All the new ones have roller cams now.  We build lots of IO-260-L2A's with roller cams, I have never seen one with a cam problem.  I have seen lots of old engines with this same issue.  Unfortunately the cases are different, so converting to a roller cam at overhaul is not an option.  Unless of course you send the old one back to Lycoming in trade for one of theirs.  

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It's a shame somebody can't develop an STC mod for new rollers in old cases. Most of ours are too old for Lycoming to accept in trade as I understand. And new engines are exorbitant!

Sent from my iPad using Tapatalk

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1 hour ago, cnoe said:

Since I was quoted I guess you were directing this question to me, so...

I have the IO360-A3B6D w/ 559 TSMO at my last oil change. My camshaft and lifters were "new", not reground (circa 2008).

I have found a very few (3-4) tiny thin shiny specks in my filter on a couple of occasions but they didn't stick to a magnet and typically dissolve when rubbed between my fingers. I suspect that they're carbon. I actually expect more particles to be found in a healthy engine than what I've seen in mine so far.

My last oil analysis showed: aluminum 6, iron 19.17, copper 3.00, nickel 1, chromium 2, and silver <1. Iron has always been 20 or less except for one analysis when it was 27.02 at the end of last winter when my flying was less active. I chalked that up to minor cylinder corrosion.

I've averaged 160 hours/yr flight time for the past 30 months. Still I worry about self-destructing camshafts and followers.

Also, I use Phillips XC 20W50 w/Camguard. Even if it does nothing more than give me false peace of mind it's worth it to me.

If anybody has more advice to stack the odds in my favor I'm all ears. I'm interested in the centrilube mod but it will (hopefully) be a while before I get to personally spec out a rebuild.

The only sure fire cure I've seen for cam and lifter spalling is a roller cam factory engine. Unfortunately it's priced the same as a shop overhaul plus a TDI and and a new cam and lifters too  

 

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2 hours ago, jclemens said:

As stated before, there is no oil analysis.  I don't know what good it would do now.  It's pretty obvious that there was metal in the engine.  This engine is going to get the what would pass for an overhaul if it wasn't aviation.  It will be a "Repair" only because we don't plan on doing the fuel or ignition systems.. All the internals will be dimensionally inspected and dealt with accordingly.  We won't be doing NDT,  a little metal contamination doesn't warrant the crank to be magnafluxed.  It will go on the crank polisher and get cleaned up.  It will be reassembled with all new bearings, new cam followers, new cam, new set of pistons and rings, and new a gasket set.  

Migh as well spend the additional 5 grand and get an overhaul for it. The 600 hours SMOH in the log devalue the engine more than then extra cost of the job. 

It sucks. I know, Becuase it happened to me.

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7 hours ago, jclemens said:

All the new ones have roller cams now.  We build lots of IO-260-L2A's with roller cams, I have never seen one with a cam problem.  I have seen lots of old engines with this same issue.  Unfortunately the cases are different, so converting to a roller cam at overhaul is not an option.  Unless of course you send the old one back to Lycoming in trade for one of theirs.  

Just curious Jake, what did the ex. valve look like in regards to signs of coking previously?

Any truth to the really high prices to replace the roller lifters whenever the case is split, or is it not mandatory and you can run the rollers until you major?

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11 hours ago, jclemens said:

...The cam follower is an ECI part and you can see the date 12/08 on it.  All the rest are the same date, they are all fine.  They will all get replaced with new along with the cam during this repair anyways.  The cam is also an ECI part, it was probably purchased together as a kit with the cam followers...

Trying to differentiate between metallurgy and lack of use. 

Do we have an example here of ECI bad metallurgy? Does ECI manufacture their cams? Does Lycoming? Is it conceivable they obtain them from the same source?

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8 hours ago, jetdriven said:

Migh as well spend the additional 5 grand and get an overhaul for it. The 600 hours SMOH in the log devalue the engine more than then extra cost of the job. 

It sucks. I know, Becuase it happened to me.

To take this to an overhaul would bump the price up substantially.  If it was only 5K it would be a no brainer.  As it is right now, the repair won't be much more than that, whereas an overhaul would be in the mid 20's.  I usually agree that overhaul is a good idea, but in this case the engine is only 8 years old.  At the rate it is flown he will be at overhaul in 2-4 years anyways.

2 hours ago, mike_elliott said:

Just curious Jake, what did the ex. valve look like in regards to signs of coking previously?

Any truth to the really high prices to replace the roller lifters whenever the case is split, or is it not mandatory and you can run the rollers until you major?

All the cylinders actually look great.  We have the valves out and none of them have and unusual deposits or show any sign of leaking.  The jugs will get cleaned up today and checked dimensionally.  from what I saw yesterday they will probably get the seats touched up and the valves lapped back in and reassembled with new rings.  A worn guide can cause a sticky valve that can contribute to this type of failure, but sometimes they just fail anyways.  We have never had to split a open a roller engine anytime other than major overhaul.   Yes, it's true the rollers must be tossed and new ones installed, they are a few thousand more to overhaul because of this.

 

57 minutes ago, PTK said:

Trying to differentiate between metallurgy and lack of use. 

Do we have an example here of ECI bad metallurgy? Does ECI manufacture their cams? Does Lycoming? Is it conceivable they obtain them from the same source?

Lack of use certainly contributes to the problem.  Most cam failures I have seen were on engines that were put back into service after a period of inactivity.  ECI has PMA approval for all their parts, I think they manufacture them.  

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Here are a few more photos from today.  Case is back together with the new cam and followers, cylinders are all cleaned up with new rings and a fresh valve job, couple shots of the oil pump some were worried about, the accessory case and the sump.  Should be all back together tomorrow.  Goal is to have it running before the weekend.

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7 hours ago, carusoam said:

JC,

mind if I ask a question?

What are the N & C marks on the gear pump teeth about?

Great photos.  Thanks for sharing.

Best regards,

-a-

 

The N is for Nitrided, the C is for Carburized.  See SB 524 for reference.

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Also an AD for oil pump impellers.  According to my IA there were three different gear changes at or around the same time.  It causes lots of confusion if your maint book says "changed oil pump gears"   eventually the came up with the correct match of pump gears after several gyrations.  http://www.faa.gov/regulations_policies/airworthiness_directives/search/models/?id=5DE5ACBD6CBC8B2A8625684D00643AC1

 

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Aviation gear pumps are interesting.

- oil pressure is developed by the oil being delivered up stream by going around in the open pockets between the teeth. When the teeth mesh, the majority of the oil is squeezed out of the pockets on the high pressure side.

- simple, only one gear is driven. The other one follows, being driven by the meshing of the gears and locked in place by the pump's body.

- susceptible to failure due to dirt, chunky bits, or lack of oil.  A good reason to check oilP upon start-up.

- selection of gear materials of different hardness allows one gear to wear preferentially at the slowest rate possible.

- the pump's design makes it pretty simple to swap out the gears.

- CNC milling has made these complex gears pretty low cost to manufacture.

Fun stuff,

-a-

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56 minutes ago, cnoe said:

Must be a slow week around there. It sometimes takes me longer to get a burger and fries 'round here than your near-overhaul.:)

It is, I think we only have 9 or 10 other planes apart right now......:rolleyes:

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Rereading this thread in an hour straight this morning makes it just amazing for me

to realize that this Repair is happening in only 9 Days!!

This thread starts with the simple report of a poorly, rough running engine,

and now,,, we are waiting to hear it run...

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Actually, six days.  We diagnosed the issue on Friday the 8th.  Closed on weekends. Pulled the motor off on Monday, tore it down, and ordered parts.  Cleaned everything up on Tuesday and put the bottom end back together.  Repaired all the cylinders and finished the assembly on Wednesday. Installed all the repainted and repaired baffles and accessories on Thursday and hung it on the aircraft.  It will run today.  But who's counting ;)

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Rereading this thread in an hour straight this morning makes it just amazing for me

to realize that this Repair is happening in only 9 Days!!

This thread starts with the simple report of a poorly, rough running engine,

and now,,, we are waiting to hear it run...

Was thinking exactly the same.

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