finally had a failure---guesses

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Happyboy · #1 Post by **Happyboy** » Mon Oct 12, 2009 4:48 pm

Well, I finally had a bit of bad luck. Not real sure what quite yet as I haven't torn into the motor and won't for another day or so. Here are the details surrounding the ride and possible offenders....

Was dune riding for much of last week. I have a pod filter and left the tank cover off to improve air flow. First day there everything went well. It rained that night and I forgot to put a bag over my filter so it got wet that night. The next morning the motor cranked but wouldn't fire, guessed I had some water in there. Pulled the filter and dried it, pulled the plug and it looked good. Still changed the plug and hosed the piston area out with air to make sure it was dry. She fired right up afterwards. I also have had a very small coolant leak recently that would just drip from the impellar cover. It was just a drip but as the motor would get hot it would drip more and more. Usually less than quarter bottle per hard ride. Rode for 2 more days with random stalls, reason unknown. I did notice going into the last day the bottle was empty, so I topped it off with water. I appeared that it was only down about a bottle full. On the last day, on the last ride, on the way back to camp, she stalled with a burp from the intake. Went to restart and the motor turns over but very, very fast as if there is no compression. I can only compare it to what happened with my civic a little while back when the timing belt stripped. The motor would turn over very fast with no compression type noise. No clanking or sudden lockup on the stall. It almost sounded like a 1 way bearing, but I would release the clutch and start and it would push the tires over so its not he clutch or bearing. The coolant bottle is still mostly full, only down about 1/5 of the way from my leak.

I should make this a contest or something....maybe put the users pic up on the home page for the correct guess. Diagnoser of the month or something.

I want to hear details not just busted so and so.

All I have done so far was to pull the quad into the garage. Have not done anything to it but I will add details in the days to come.

I am guessing busted timing chain or something along those lines. Only thing I wonder is why there was no noise. hrmmm

kevin444 · #2 Post by **kevin444** » Mon Oct 12, 2009 5:07 pm

my last failure was in the dunes as well; however it was 120* out "4th of July" in Utah. quad ran perfect all weekend and out of know where she just stalled; no noises or clunks, etc. after going over the entire checklist of whats wrong, we gave up and packed her up. the only thing we could come up with was a ring went and i lost all my compression. ti was not until we tore her down to find that the decomp exploded took out the exhaust cam. a large piece of the decomp wedged itself into the cam and luckily the shear pin did its job before more damage was done. we would have never thought since it was so quiet when it broke; just another dale story.......

i'm thinking you may have a similar situation due to over heating since you were going through coolant. it may have stared with the leak, but worked its way to the sleeve or else where......keep us up to date when you tear it down...

....good luck....hopefully it will be a quick / inexpensive rebuild since the season is here...

Kevin

cannondale27 · #3 Post by **cannondale27** » Mon Oct 12, 2009 5:51 pm

Of all the failures I had only two were really loud like a shotgun blast. One was when crank broke and other was when JE wristpin sheared in half after piston failure and I was a idiot and tryed towstarting it.

I am guessing you cracked your piston resulting in massive compression loss.

As long as you don't try starting it especially by pulling the damage will be minor since the pistons are designed to crack without breaking apart. Not related to any other symptoms. But there is always a cause. Sorry it had to happen but at least was end of your week.

2000ex · #4 Post by **2000ex** » Mon Oct 12, 2009 8:51 pm

I would lean towards a cracked piston as well. If the timing chain let go you would have had a loud mess of a sound, and generally if the rings let go it is a thing that happens over time with slow loss of compression unless you sucked in some major sand/dirt into the motor.

kdeal · #5 Post by **kdeal** » Mon Oct 12, 2009 8:57 pm

Sorry to hear about your troubles. At least it was on the last ride on the last day!

I believe your coolant leak on the outside of the motor is not related to your problem. That is just a leaking oil seal on the outside of the intake cam probably caused by too much sealant on that seal. This causes the seal to distort and leak water in the chamber between the seals and out the weep hole.

I think both of the above guesses are very good. Your Civic problem was similar but not the same. In this case you are probably turning over all of the components in the motor and still have a major loss of compression. On the Civic, you were only turning over the bottem end components due to the busted timing belt. You would not be turning over any valve train components and with a cylinder or two having valves already open, you would have no compression.

So unless you broke a timing chain, it will not be the same thing.

If the water you ingested was relevant (and I hope it wasn't) you could have bent anything in the compression process as water does not compress that easily. (Think connecting rods or cylinder head leakage) I am hoping that you have a valve partially hung open due to a minor parts breakage. I would be looking for a bent valve not sealing or the piston damage Steve mentioned.

Good Luck.

speedracer · #6 Post by **speedracer** » Mon Oct 12, 2009 9:52 pm

Cracked sleeve?

2000ex · #7 Post by **2000ex** » Mon Oct 12, 2009 11:49 pm

I was thinking cracked sleeve the initial few seconds but water or coolant does not compress well as Ken stated. It would not turn over that fast if the cylinder was full of coolant which it would be with a cracked sleeve.

Happyboy · #8 Post by **Happyboy** » Tue Oct 13, 2009 1:51 am

update.....

i was considering a cracked sleeve but not because of fluid in the cyliner. I had been riding it no problem for 2 days after the rain.

So, i pulled the plastic off and then the intake. Intake valves are there and shut. I turned the motor over and........the intake valves did not move.

That is all for tonight. After being away from the wife for days i am only spending 10 minutes per night on this bad boy. hehe

So this does narrow it down some what to the timing, cam portion. I just hope if i bent a valve it ain't bad. We'll see though.

cannondale27 · #9 Post by **cannondale27** » Tue Oct 13, 2009 3:38 am

A cracked crank will do that also.Pull flywheel cover of and see if its wobbling like mad.

kdeal · #10 Post by **kdeal** » Tue Oct 13, 2009 10:44 am

If the valves aint moving it could be a worn cam. That still doesn't solve your no compression issue if they stay shut. They must be leaking somewhat. A bent valve could be your answer. But they both would have to be bent. What do the exhaust valves look like?