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Old Jan 21, 2013, 05:11 PM
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I doubt that the valve issue was even identified. I do know that changing the bearings doesn't fix the valves ... unless by coincidence. I'm surprised that it didn't though. When you dis-assemble the engine and soak it in cleaning solvent, .. it would very likey loosen them up. Then if it was put on a test stand, ... I would expect the temperature and mechanical operation to do quite a bit to finish off that build up.

I would expect to soak any engine in a cleaning agent and clean it back to factory new condition, ... especially on the inside. After thae pre-rinse, .. it would make sense to use some for of air or other pressurized method to blow off the possibilty of debris left during tha cleaning process, ... even if that residue was from the solvent itself. I would also expect to use some form of assembly lube on every moving part during th re-assembly to insure complete lubrication thoughout the entire engine. I would also hand operate every moving part including the valve stems or otherwise and also make any necessary measurements or assessments as required for a certified repair status.

I wonder how much bench time was spent on that repair. I also wonder how much run-time was spent after that repair was made. What was the prop size and RPM at the test stand? Is there any documentation that states any specific information regarding the repair?
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Old Jan 22, 2013, 10:11 AM
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My assessment on the repair is a non-caring mechanic...If you sent my shop a note like that,we would have challenged a mechanic to find and resolve the problem,even at a little shop time expense..

You don't get better at repairs unless you know how to diagnose the problem.and each repair makes it easier to diagnose the next time.

It wouldn't go back there for any reason now.They don't want to get better.
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Old Jan 22, 2013, 05:36 PM
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Sometimes if we confer with fellow mechanics there is an unlimited wealth of knowledge to be gained. I personally value the rescources here in this forum and find that ... "like minds think in a similar fashion". The service tech may have been new or in-experienced which is all the more reason to seek higher wisdom. The foreman of that shop should have been onsite for consultation and support for the repair-tech. As stated many times before .... "two heads are thicker than one".

I don't claim to know everything, ... I will search deeper waters until I get the correct answer, ... because that absolute commitment is required to win the challenge. I will say that when the correct answer is aquired, ... there is no doubt in my mind the the equation is solved and proved wise. As Earl said, ... That process and due diligence is mandatory for growth and harvest.

I would suggest an annual training camp for any service tech. With updates in technology and equipment, ... there is always room for enrichment. Eventually the student should be capable of being the instructor that passes the torch to the next generation, ... imagine that concept. Did you ever have someone give you directions and you got lost because of it, ... the instructor was lost himself. Funny how things work. I believe learning should continue throughout the lifetime. When you compare what you've learned from others .... to what you already know, and then also gain new knowledge along the way from new sources , ... including the old "school of hard knocks", ... then you have gottten the most out of your efforts.

Since machines can't think for theirself, ... then we need to do the thinking for them. When a doctor mis-diagnoses a problem .... bad things can happen. I hope that service tech doesn't ever choose a path that requires effort. If the engine fails during flight ... it could cause serious injury? Not a risk I would want to be responsible for. Seems like just an un-important machine until you look deeper into the continuous service duty requirements of that piece of machinery. Engines don't meet the required factory perfomance specs when a valve-stem overheats or sticks open during operation then delivering a fatal failure result. Poof! you're done flyin.
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Old Jan 22, 2013, 08:37 PM
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FWIW as a service tech for a implement dealer (I'm mostly lawn and garden) I attend update schools for Stihl twice a year, Kohler engines, Kawasaki engines, ExMark mowers and Kubota. Sometimes I think I spend more time in class than spinning wrenches.

Does all that school make me "smart"? Heck no, but it gives me a fighting chance to figure out a problem. I wonder if there is such a thing (school) for these model engine techs? There should be!

Ken
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Old Jan 23, 2013, 10:07 AM
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Considering some of the answers presented here,I'm in agreement with many of you.
I,like Ken, attended service schools for the same Lawncare Companies....And the input from the Mechanics attending was as valuable as the Instructor's.!

Many of the schools taught 'short-cuts'-before a full service on two-stroke engines,remove the muffler and check the piston's exhaust side..Galling or scratching on the piston or rings was an indicator of lack of oil.Most likely a waste of time to service it,before major repairs.

I think the cylinder head in question needs to be completely disassembled and inspected,if for no other reason than to eliminate it from further suspicion.It's a short time effort to do so,and then you'll KNOW ! An overnight solvent soak may be all it needs.
Completely apart allows cleaners to do valve guides which may not allow solvents in,while assembled......
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Old Jan 23, 2013, 11:22 PM
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what kind of cleaning solvent can be safely used on the exterior of engines?
thinner? ethanol?
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Old Jan 24, 2013, 07:58 PM
The Prez....... again
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Quote:
Originally Posted by murcielago View Post
what kind of cleaning solvent can be safely used on the exterior of engines?
thinner? ethanol?
Just about anything can be used. Many use an OLD crock pot and green antifreeze. Several hours in the "soup" and it's good to go. Just don't use an alkaline product like oven cleaner. Those will turn the aluminum gray. Mineral spirits, brake parts cleaner, acetone, lacquer thinner are all examples of solvents to use.

If you decide on the crock pot route, never use the crock pot for food again.

Ken
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Old Jan 26, 2013, 08:28 AM
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I got a crock pot at a yard sale, for practically nothing..Save the animals-replace the A/F to a sealed container, and put the crock pot in a secure place when not in use.

A/f works wonders in renewing dirty engines.
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