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post #1 of 10 (permalink) Old 07-28-2020, 08:20 PM Thread Starter
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Question GVC190 N5BR - BOOM!

Hello everyone.

So, got a free troybilt pressure washer with a Honda GCV190 N5BR engine on there - wouldn't run.

First, had no OHMs...replaced ignition coil - had spark.

Next, discovered it was the exhaust valve completely shut and the piston rings shot causing lack of compression (0, to be exact).

So, long story short, did a refurb on it...got new rings, valves (lapped them properly), made sure to follow the entire service manual on torques and feeler gauge depths, used assembly lube...yadda yadda yadda...tried to do it as best as I could being the novice I am.

Well, she started right up and felt strong. Let her run for about 10 minutes - then shut her down so I could attach the water pump. Got it attached - ran for another five minutes - felt good...then...BOOM.

*Took it apart and you can see the connecting rod completely exploded
*The piston is scored on the exhaust side and the piston skirt blew up.
*The cylinder wall is lightly scored 'til you get to the bottom of the stroke, then it left a nice indentation.
*killed my crankshaft

I need to know why - I don't really care if I spend more than the motor is worth, this is a learning experience for me.

I've looked at the Echo Failure Analysis Report and the only one it kind of reminds me of is the "lean seize." Although, I ensured there were no gaps via utilizing proper gaskets, used RTV properly per Honda Service youtube videos...maybe I had the gas to lean? I don't know.

Any help would be appreciated so I can avoid this error again upon reassembly.

Thanks - Mark
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post #2 of 10 (permalink) Old 07-29-2020, 09:28 PM
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Not sure how closely you checked the rod when you went through it, but maybe someone overheated/ran it low on oil and the rings just gave up before the rod did somehow. If that rod was 90% ready to go, maybe it just needed 10 minutes of run time to give up. Sometimes the aluminum rod caps can fatigue while running hot and look just fine, only to blow up later. The aluminum wipe on the crank journal is what really makes me think the rod just let go.

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post #3 of 10 (permalink) Old 07-29-2020, 09:36 PM Thread Starter
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That's great information...as you guessed, I didn't really inspect the rod at all when reinstalling, other than cleaning it up.

Would that be only visual indicators or is there another way to test integrity? Maybe just better to spend the $15 on a new one each to ya rebuild.
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post #4 of 10 (permalink) Old 07-30-2020, 09:31 AM
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Did you degrease the motor when you took it apart? The current pictures would indicate there was no oil in the crankcase and the moving parts seized. Lean seize is associated with 2-cycle motors and is caused by lack of lubrication.

Experience is something you don't get until just after you need it.
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post #5 of 10 (permalink) Old 07-30-2020, 09:38 AM Thread Starter
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Yep, I cleaned it up after "the boom" in the hopes I could reuse the cylinder case...until I saw all the scoring on the cylinder wall...

Pre-boom, made sure it was filled to the line with Honda small engine motor oil.
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post #6 of 10 (permalink) Old 07-30-2020, 12:40 PM
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This past winter I bought a Toro 721 single stage snow blower with a blown rod for $50. The guy bought it new and used it for about an hour before the engine grenaded because he thought the engine came with oil in it. The piston and rod looked like yours when I took it apart. I was lucky enough that the block was still good and a new piston assembly and honing saved the motor.

Since you had oil in yours, I have no explanation. Sorry.

Experience is something you don't get until just after you need it.
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post #7 of 10 (permalink) Old 07-30-2020, 02:11 PM Thread Starter
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As suggested earlier, I think the likely culprit was the previous owner ran it with low oil; thereby, weakening the rod...I didn't think to inspect it too well upon reassembly...

That scenario makes sense to me.

Do you think my wall is too far gone to be honest? How to that affect the piston fitting in if they smooth some of the wall out...rings expand enough to keep compression?

I'm probably gonna spend the $45 for a new cylinder assembly, to be honest.
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post #8 of 10 (permalink) Old 07-30-2020, 04:03 PM
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I know this is a learning experience and I usually feel the same way. There has been many times I have put more money into a project than it was worth just so I could prove to myself that I could fix it.

The cost of parts to repair your motor would not be cost effective. Cylinder, piston, rod, rings, gaskets and ? are close to $100 (used parts). You could get a new 212cc Harbor Freight Predator in the USA or a 212cc from Princess Auto in Canada for $100.

I admire your spirit but I would find a new project to learn on.

Experience is something you don't get until just after you need it.
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post #9 of 10 (permalink) Old 07-30-2020, 05:11 PM
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Quote:
Originally Posted by marknyoung View Post
...Do you think my wall is too far gone to be honest? How to that affect the piston fitting in if they smooth some of the wall out...rings expand enough to keep compression?

I'm probably gonna spend the $45 for a new cylinder assembly, to be honest.
I'm like you. I think of the cost as tuition. I say do it. Even it it fails again, you'll learn something from it that is priceless - experience, although I certainly understand Grunt's point.
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post #10 of 10 (permalink) Old 07-30-2020, 07:28 PM
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Looks like you have some pretty decent scoring in the cylinder wall. If you run your fingernail around the bore and it catches, it's probably not worth putting new rings/piston/rod in it. It's an aluminum bore engine, so not very forgiving. If you're having fun, roll the dice, but that looks like a parts motor to me now. On a side note, I see power washers with these light-duty OHC Hondas blown up all the time because these are really intended for mowers and not the punishing constant load of a power washer pump. Seems like they overheat and get dropped or stuck valves a lot in this application, although they're great on mowers.

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