deepwoods
Is there anyone out there that has experienced a problem with valve settings not holding the adjustment?  We have a 2016 20K 6730 Gen standby.  I have NEVER seen a engine (GT990) that had done this. First we normally checked the lash every year, then every 6 months and then we started experiencing starting problems and it was always the lash.  Set the valves and it fired up every time.  The dilemma is its getting worse.  The dealer told me that Generac is now calling for adjustment every 200 hrs instead of 400.  We are not getting anywhere near 200 hr.  They adjusted the valves last Friday and by Monday the machine is struggling to start again. 

I wanted to replace the rocker, jam nut or pivot screw the dealer does not think that is the problem, I even suggested loctite.  Adjusting to 0.003 normally find it at 0.005 and sometimes 0.002.  Torque Nut at 174.

Sure hoping someone can shed some light on this.
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deepwoods
Whoops Typo error on the engine it is a GT-999.  I heard this engine is actually built by Kawasaki?
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78buckshot
I check and adjust lash on each yearly maintenance on approximately 200 machines, I have not experienced the issue that you are describing. Typical findings are that the exhaust valve lash will get smaller and the intake will stay the same or get larger but both require pretty minor adjustment. I did have a Briggs and Stratton VanGard twin that had a big change in one valve in a year, I removed the head to inspect and determined it was the exhaust valve sinking into the seat, put it all back together with original parts and adjusted it, it's still running and has not given me any more trouble. I have not heard any rumors about Kawasaki, the 999 and the 990 look identical and as far as I know they are built by Generac.
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deepwoods
Hey Buckshot good to see you are still on board!
I appreciate you weighing in.  I just got a memo from the dealer and he stated that he ordered a head.  So I suspect that he is thinking along those same lines.  Last year when the recommended valve adjustment was cut in half (400 to 200) I thought there might be a manufacturing flaw in one of the valve components, but I don't know if they would fess up to that.  My main question was all along the root cause of the problem.  I spent a long career as a lead mechanic working on just about every type of engine that makes anything move.  From Jets to automotive to heavy equipment to lawn and chainsaws.  Glad to be retired but still like to get my hands "dirty".  With all that said, if you have not seen any of this on other GT- 999 units I can figure this is just that we pulled the short straw with this bugger and will get it right.  When you talk I listen, when you type I read!
Much appreciated !
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grsthegreat
generac builds their own standby engines. not kawasaki. i also have never had any issues. i torque them to 168-174 in lbs for the 7-8 and 16-22 kw units and 53 in-lbs on the 9kw and 72 in lb for the 11 kw as per generac specs.
i also almost always check valves during maint on all the units i service, except sometimes when unit only has 10 hours on it since the last service.
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deepwoods
Thanks for additional information, been trying to gather as much information on this as possible.  Our dealer is top notch and has been since day one, but my back ground always wants to know WHY.  Aviation is very big on Root Cause and Analysis for all the obvious reasons and I have applied that philosophy to all things that "Tick".  While I fully understand the valve settings as part of the maintenance program its the failure to start and the time frames associated with the problem.  The last 8 months especially had reduced the "cycle" from adjustment to no start from weeks to days.  The inspection or adjustment is no big deal, but "Murphy's Law" would apply that things happen at the worst possible time.  The fact that the starting and not starting can be measured in 0.002 makes the process of "maintaining the setting" after you torque the nut" critical.  I think we can all agree that whatever is going on here is out of the norm and I am crossing my fingers that the head replacement removes the boogeyman once and for all.  And to clarify every no start condition, the corrective action was ALWAYS the valve adjustment.

Thanks again, and all the best!
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Birken Vogt
I have a customer that had one that had an old one that had had some mechanic in there before me replace both heads for some reason.  Both exhausts behaved like this, sinking rapidly until the valves were sticking up noticeably higher and spring tension was loose.  Wound up replacing the whole unit as it was on its last leg anyway.
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78buckshot
deepwoods, is it only on one cylinder that the valves won't stay in spec, tech is suggesting replacing one head and valve assembly?
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Brian Baughman
deepwoods wrote:
Whoops Typo error on the engine it is a GT-999.  I heard this engine is actually built by Kawasaki?


The engine is designed and built by Generac in Whitewater, Wisconsin.
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deepwoods
In response to Buckshot, the dealer adjusted the valves on May 11, 2020 (no start complaint).  August 28, 2020 we adjusted the valves again for a no start condition.  Each time the corrective action was spot  on.   The dealer checked the unit on Sept 8 (again a no start) and stated that he found 3 of the 4 valves "tight".  He also found a problem with the Controller and ordered one.  They also adjusted the valves to specs.  On Sept the 10 we made a trial run on the generator prior to leaving and found it was barely started same symptoms as always, cranks falters on the ignition and run cycle.  The dealer is headed back up tomorrow.  It would be my guess that he is going to replace one side to see if the condition gets better or remains, sort of a trial and error.  Like I said they have been great since day one, we are in a very remote area and big timber is everywhere and when they fall they always seem to find the primary wire and poles.  And that repair process can be an eternity, on a scale of one to ten, our priorities with the power companies is somewhere around 17.
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78buckshot
Well all we can do is keep our fingers crossed that it rectifies the problem, hopefully under warranty.
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Peddler
I would guess that the valves are not the problem at all and the controller certainly isn't the problem.  I would bet the coils are at issue and the valve adjustment is just cover for not knowing what the starting problem is otherwise.  I could see one valve constantly changing if the stud was striped or the lock nut but not 3 of 4 when they were just adjusted.  Something else is at play here.
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deepwoods
Appreciate your opinion and all are welcome.  The faulty controller issue is unrelated to the no start, another problem in itself.  They cancelled the appointment  for tomorrow and rescheduled for the 18th.  The controller did not come in and they don't want to make two trips up.  I agree that there is something out of the ordinary going on since this started.  I do not have a lot of exposure to this engine but I am learning from the people that do, so I appreciate anything I can pick up along the way.  I can tell you that when you crank the engine with the plugs on the wire but out, it fires like the forth of July!  I will also add that I have had more then a few people (not on this site)  tell me that they had issues with valve adjustments on this engine.  Why would the manufacture change the parameters from 400 hrs to 200hrs?  And in all honesty I have not seen that in writing from the dealer or the manufacture.  I was told by a Generac Tech that was the case. This is NOT our first generator but it is our first Generac.  We had a several Onan's and a Honda.  The Honda was to small for our needs but that darn thing NEVER gave us a problem in 6 years.  Oil and filters and plugs period.  The 6730 was purchased in late 2016, and we had a great "ride" until 2019.  Just a matter of figuring out what he heck is going on.  The dealer is great but again there are times when he is not available because of work load etc and we do not have the luxury of waiting for minor repairs.   Warranty is in place until 2023 and again the dealer recognizes our skill sets and has been fantastic
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78buckshot
I think the maintenance interval may have changed with a model year change but I have not seen them retro-actively apply any specs. deepwoods, do you know how many total run hours you have on it?
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