From the “oh shit” files
January 10, 2010 at 9:27 am #3643SafetyFirstParticipant
Or as I like to call it, when a simple 6000 mile valve job goes wrong on a Ninja 250.
The end result is a very unhappy 248cc Ninja engine.
After spilling coolant into the top of the engine (long story,) the focus moved from valve adjust to ‘get that out now.”
After three warm ups and changes of oil, oil filters and checking the oil screen, I figured I was home free. The oil was getting cleaner, no more milky oil, but it was still amazingly liquid. There was still too much water.
Too bad it wasn’t summer.. I bet I could have just left it out in the hot sun with the engine open and let it evaporate out.
The valve adjust seemed a success… it was running better than before, which was ironic being full of coolant. The adjustments were well within spec. They were quite tight, as I figured they were from how it was riding before.
Then it happened. It was idling away waiting for oil change number 4.
After inspection, I found broken rocker arms in the top of the engine. Three out of the four intake rocker arms broke in two. I guess the cast iron gave way. And also missing was a nut from where one adjusts the valve clearance screw on one of the Cyl 2 intake rocker arms which didn’t break in two.
What annoys me most of all is knowing that somewhere in my engine is a nut and a two broken halves of a rocker arm.
OK, what went wrong? Did the nut work itself loose and cause the valve clearance of one valve to go so out of spec it took the others with it?
Did temperature have to do with this? I was doing all this work at 20 degree F temperatures.
And how did the rocker arms break, when they were actually looser than they were before?
And the bigger question… should I just give up and find a new engine? Feel free to take time formulating your answer, I’m broke and I’m not doing anything more ’till it gets warmer in the spring.January 10, 2010 at 4:13 pm #23964BouncingRadicalParticipant
Did you over torque the rocker arm? If it was too tight it may have bound up and when the cam went to push it, it snapped.
I don’t think temp would have had much to do with it, if it went on a fourth heat cycle (cold to hot then back), then better it went in your driveway than on the road.
I guess try getting a telescopic magnet and try to fish out those pieces. It would suck to have to tear open your engine just for those pieces, but it would give you an opportunity to clean everything throughly.
Best of luck, sounds like a tough situation.January 10, 2010 at 6:20 pm #23965MunchParticipant
hmmm….. weould like a better idea of how the cooling system works for that bike…I will go at it from a cars PoV.
Coolant in the upper side…. not bad…UNTIL, you fire up and get compression going, and fail to make sure the cylinder walls are relatively clean and again lubricated before putting a load on the pistons. If some coolant is left to bypass rings it will wash the lubr. off the cylinder walls and even prevent more from getting back on. Creating swelling, stick and snap process.
Did you use a torque wrench to tighten everything down? Was there any use of a thread lock before and after adjustments made. If torque wrench was used……when was the last time you had it calibrated?
As far as the nut goes….. afraid a tear down may be in the near future. Unless you have something that can get into the drain down ports for the oil, if not found in the case.
One scenario from above could have been a result in miss adjustment to where the cylinder could have actually slapped a valve causing the reaction to stress the rockers to the point of breaking.January 15, 2010 at 9:25 pm #24039motokidParticipant
Hydro lock ???
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