|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

04-13-2009, 01:01 AM
|
|
|
|
Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
|
|
Quote:
Originally Posted by Russ McCutcheon
If you say they have very little visible corrosion then they where probably still just fine and would have kept right on if you had not had the unfortunate opportunity of inspecting it early, maybe the shop was more worried the engine mite come back to them before TBO if they re installed your old cam. Send it to ECI or one of the other shops and have it inspected and reground to sell or use later, send the followers to.
|
BINGO!.....
|

04-13-2009, 05:33 AM
|
|
|
|
Join Date: Nov 2005
Posts: 452
|
|
Gasman, I am no expert, but was told by a engine builder that the Lyco cam is above oil level when engine is shut off.
The conti cam is lower and sits in the oil.
As I said this is what was told to me when I had corrosion problems. Hope I wasnt being fed incorrect info.
__________________
EJ
RV7 flying
xp360, CS, All Glass cockpit
Last edited by rv72004 : 04-13-2009 at 05:36 AM.
|

04-13-2009, 06:46 AM
|
 |
|
|
Join Date: Mar 2005
Location: Dallas area
Posts: 10,769
|
|
Quote:
Originally Posted by rv72004
The conti cam is lower and sits in the oil.
As I said this is what was told to me when I had corrosion problems. Hope I wasnt being fed incorrect info.
|
The Continental cam is below the crankshaft, but it does NOT sit in the oil. This is a better position in that "dripping" oil goes onto the cam, but with the engine at rest, the oil drains into the sump.
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
|

04-13-2009, 06:54 AM
|
|
|
|
Join Date: Jan 2005
Posts: 1,025
|
|
Dean,
The camshaft - tappet face is an extremely critical area in the engine. Minor rust pitting is a formula for spalling, which in turn eventually ruins the cam and it?s corresponding tappet or tappets. Some shops/mechanics will be more tolerant in this area, then others but all should be very careful in this area. So what one mechanic might pass, another might fail. There is no cut and dried tolerance unless the lobe or lobes have metallurgicaly failed already. If you did your research and choose a shop/mechanic to do the work on your engine, you shouldn?t be second-guessing their or his decision now. You trusted them enough to send your engine to them and you should trust their decisions. What you consider minor or insignificant, very well might be and then again it might be very bad. Obviouly, your mechanic didn't like what he or she saw and wanted the cam replaced. In most cases rust pitting and the eventual spalling it causes, isn?t a catastrophic failure type thing. It is a relatively slow cancer that will ruin the cam and very likely other parts in the engine, if the cam situation is left to blossom from its initial stages.
To repair a spalled camshaft requires the same amount of work and initial expense of the prop strike inspection you just had done. The engine has to come all the way apart and if nothing else has been affected by the cam failure you just replace the cam, tappets, bearings, rod nuts and bolts and gaskets. If the pistons are shot with metal impregnation they too must go and sometimes also oil pumps are scored and possibly crankshaft journals can suffer significantly as well. So there are other financial internal risks other then just the cam and tappets if it is left to progress. So fixing a bad cam is very expensive, to say the least.
If you engine is apart and a shop/mechanic wants to replace a cam due to rust that you feel isn?t significant, trust me it is way less expensive to change it now then wait until the engine is back together and has run a couple hundred more hours. One poster suggested that maybe the shop or mechanic replaced the cam because they were afraid it might go bad going forward. I would have to agree with that. Obviously, from your description, your cam wasn?t in severe spalled condition but was in a condition the engine people didn?t like. They made a decision in you best interest. As said before, that is what you hired them for! Trust in their decision?? If an engine shop was doing the job they have likley seen hundreds upon hundreds of cams and can make educated decisions. If it was a local mechanic doing the job, he or she may not have as much experience, but if you felt they were qualified to do the job when you hired them, you should should trust in in the decision you made.
It seems you have tried your best to prevent this from occurring. But even the best laid plans don?t always work out. I think you should continue doing what you have done in the past and you might think about some of the other poster?s suggestions and try them as well. Maybe try a different brand of oil to, as oil that is your primary rust deterrent inside the engine.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
|

04-13-2009, 07:18 AM
|
|
|
|
Join Date: Feb 2005
Location: N Mn
Posts: 299
|
|
Mahlon, so well said. The feeling you get at 9500' over rough terrain knowing everyting is right... Pirceless!
The things you think about when there are no good place to land. 
__________________
Frank Karasti
Hibbing, Mn
RV-9A
Flying--------->-
|

04-13-2009, 07:52 AM
|
|
|
|
Join Date: Nov 2005
Posts: 452
|
|
Mahlon , what is your take on Avblend as a rust preventative?
I am using it at the moment but wonder if its worth the effort.
__________________
EJ
RV7 flying
xp360, CS, All Glass cockpit
|

04-13-2009, 07:54 AM
|
|
|
|
Join Date: Nov 2005
Posts: 452
|
|
Quote:
Originally Posted by Mel
The Continental cam is below the crankshaft, but it does NOT sit in the oil. This is a better position in that "dripping" oil goes onto the cam, but with the engine at rest, the oil drains into the sump.
|
Thanks for clearing this up Mel. Do Conti have less cam corrosion generally ?
__________________
EJ
RV7 flying
xp360, CS, All Glass cockpit
|

04-13-2009, 08:13 AM
|
|
|
|
Join Date: May 2006
Posts: 532
|
|
Good question...
Quote:
Originally Posted by rocketbob
Dean, what brand and weight of oil have you been running?
|
I meant to include in my initial post that I use 15W-50 Aeroshell.
Thanks,
|

04-13-2009, 08:32 AM
|
 |
|
|
Join Date: Jul 2006
Location: Corvallis Oregon
Posts: 3,547
|
|
A theory
There has been a lot of talk of the ambient humidity having an effect on the moisture inside the engine..
Well I'm not so sure this effect is that significant...Here is an alternative thought process..
the fuel we burn is a long carbon/hydrogen chain...When we burn this we make primarily CO2 and H20.
I'm wondering if the moisture that ends up in the crankcase comes more from the water vapour generated by burning fuel and gets in the crankcase by piston blowby.
The engine cools and the steam from combustion then condenses out on the internals of the engine.
I have been suspicious of engine dehydrators, but if there is merit to the above hypothesis then ventilating the crankcase with relatively dry air (even ambient air unless its warm outside with high humidity) would be a very good thing.
Any thoughts?
Frank
|

04-13-2009, 08:43 AM
|
 |
|
|
Join Date: Mar 2005
Location: Dallas area
Posts: 10,769
|
|
Quote:
Originally Posted by rv72004
Thanks for clearing this up Mel. Do Conti have less cam corrosion generally ?
|
Yes they do, mainly because of the lower cam location, everything drips onto the cam, whereas on Lycoming, everything drips OFF of the cam. Another anomaly is that the cam lobes are oiled only by "splash", so unless you have the "NEY" nozzles, pre-oiling does nothing for the lobes.
__________________
Mel Asberry, DAR since the last century.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 08:36 AM.
|