Tom-D
Taxi to Parking
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Tom-D
Oil analysis didn't see this coming?
Thought you would like to see what $3500.00 looks like in engine parts, for those of you who would consider running with metal in your oil, add this to your overhaul costs.
Tom can you describe what the damage looks like. I'm not sure what I'm looking out.
Yes that is the cost of a new 0-200 crank. + or - pocket change.Is that parts only? If this is the only issue, what does that tear down average labor-wise?
The screens used in those engines don't stop a lot of metal. Much better to have an adapter for the spin-on filters, and cut the filter apart at every oil change to see what's there.
I put a brand new crank in my O-200 also. The engine had 4,500 TT on it. No oil filter just the screen for 4500 hours...
It was the thrust bearing surface worn out that Aircraft Specialty Services red tagged it for. I agreed after measuring it myself.
The engine was not making metal at the time of teardown
While I'm a big fan of remote oil filters, and have one on my engine, I'm not a fan of air 'oil' separators.
I think there is a misunderstanding, prompted by the marketers of the products about what they do. The canister has nothing to do with any chemical separation, it is simply a precipitator which separates liquids and gasses and collects the liquid for return to the crankcase. Surly some of that liquid is oil vapor but the majority of it is the precipitate of the products of combustion. It comes from ring blowby, which is quite significant in aero engines, and from oil guide blowby which usually isn't a lot of the problem.
However, the precipitate that is returned to the crankcase from the canister isn't something I really want back in there. So, I've taken my air 'oil' separator off and gone back to a simple vent tube with appropriate screen to keep out bugs getting back in the engine. Modern auto engine use a check valve and return the products of combustion back to the intake for reburning.
They do wear out, and the FAA stubbornly refuses to authorizes a build up process for them.
A third choice exists for us experimental guys...
I run a crackcase evacuation system that uses vacuum created by the exhaust to burn off any blow-by and as an added benefit I get a perfectly clean belly on the plane. Another plus is it adds a slight vacuum to the crankcase for a bit of added horsepower.... it is literally a win /win/win situation.
http://www.moroso.com/catalog/categorydisplay.asp?catcode=13023
Seen them before. It's a good solution except I don't think I believe the 'added HP' deal unless someone has a dyno with before/after.
It is really simple actually, reducing crankcase pressure increases the delta P across the piston, presto more power!.
More work done on the expansion / exhaust strokes. Lost work during the compression / intake strokes. The delta pressure across the piston should come out at a net zero power change.
Pulling a little more residual out of the cylinders, on the other hand could potentially make a difference.
They claim better ring seating and if the dyno shows a boost, it's doing something. But I wouldn't expect it to be due to just having a vacuum below the pistons (which works against you during half the cycle).
Could a dyno really measure such a small change? I can't even tell the difference between a 150 hp O-320 vs 160 hp O-320
I feel a lot better, I kept looking at Toms pictures and thinking, wow that looks like a new crank, I just can't seen any damage. Now I know why.
Ben,
Would you run your auto conversion if it were making metal?
what would a new crank cost for it? and how many hours would it require to replace it?
Ben,
Would you run your auto conversion if it were making metal?
what would a new crank cost for it? and how many hours would it require to replace it?
I'd be at least somewhat concerned that an engine making more metal than normal, might toss a chunk large enough to obstruct and oil galley and starve a highly stressed bearing.
BANG!!! and a rod hangs out of the case and the windscreen is brown...
Oil filters catch the biggest chunks too.
No sir... First sign of any motor I run is making ANY metal at all is going to get a thorough examination on how and why it's failing... You and I both know ,the first 10 hours or so any motor will produce small glitter in the oil from bushings, rings, gears and various other mating parts seating in together, so a very small metallic sheen on the oil when changed is expected. I am so anal I actually do oil analysis on that first oil change to and use those numbers as a reference... Keep in mind the testing company will usually send you a OMG report since they don't know it is a first run /break in batch.. After that, any abnormal analysis report gets my full attention..
Metal in suspension in the oil acts just like a lapping compound and as for the last "discussion" we had on that topic we all know lapping compound will wear metal down....
My auto engine conversion is based on "off the shelf" parts so future customers can have readily available parts to refresh their motors in case I fall over dead. Since the Ford 302 stroked to 347 cu. in. is a somewhat popular trick, cranks are available from various sources... I use only the best in my plane, and it is a 4340 steel forging.. Ground to std, polished, balanced and ready to bolt in, the crank is about 700 dollars...
ps.. I did see the pics you posted up above and two things struck me.
1- The crank didn't look all that bad...
2- I am amazed they don't offer .020 under bearings.. Reducing the journal size by .010 on each side is not going to effect the strength of it at all.. For all the others reading this that don't grasp what 20 thousand's looks like .. just take 3 pieces of printer paper and that is about how much material will be removed from the crank when ground for a .020 undersized bearing.
Edit.... Oops.. I didn't see your question on time to replace my crank... I consider that a MAJOR overhaul as the entire motor has to come apart so if I had all new parts sitting in front of me, replacing the crank would probabaly take 12-15 man hours.
Pictures are of a brand new crank.....
In regards to taking a crank down .020, there is an STC to do that on O-200's I believe. Other than that it’s really about how much case hardened material will be removed before it loses strength to the point it needs to be case hardened again. Or they just want to sell more parts...
They don't case harden cranks.. it makes them too brittle...
They do Nitrite them though, and you can re- nitrite a ground crank to restore surface toughness.
\I don't know what the deal is either, the .020 under is news to me.That's right. Been a long time since I studied that...
I don't know if the STC holder is the only one who has .020 bearings or what the deal is there.
Edit: IIRC the case has to be modified for the .020 under bearings which added to the descision to just buy a new crank when ours was rejected so many years ago.
Duh.... I must be dumber then I look.... For some reason I thought the pic was of the trashed crank..
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\I don't know what the deal is either, the .020 under is news to me.
I will check on it.
and we will see what the rejection tag says when I get it back.
Do you actually read the posts?
""This is what $3500.00 looks like. "" a new crank.
You and I both know ,the first 10 hours or so any motor will produce small glitter in the oil from bushings, rings, gears and various other mating parts seating in together,
I try to skim through most of your posts.. sir...
My bad for not reading each one , word for word...
companies that do that in the aviation industry aren't in the industry long.Make sure you get your same crank back.... Hate to see you end up with a bad core and they have a good, yellow tagged .010 crank in stock...