[jblouch]

What could be the symptoms of a stuck (closed) crankcase breather valve (PCV Valve)? My 97 M900 has started to use oil and I've had the valve stem seals replaced, but it's still using. I'm trying to tic off the possible problems one by one before I get into the motor. When I had the oil filler cap off one time and started the motor, it seemed like there was a lot of pressure in the crankcase (oil flying all over the place out of the filler hole). If that valve get stuck closed, could that cause oil burning? HELP!

 

[Guest]

if it were stuck close then that could force oil past the piston rings. the older valves had two plastic reed valves, so they couldn't realy corrode themselves closed. a metal shim on top of the reed valves kept the reeds from either opening too much (to much bending would eventually crack the reed) or being force closed from above (like some garage monkey pushing a screw driver to bend the metal tabs down). there's the possibility of a large piece of garbage being trapped between the metal and plastic keeping the valve closed. if the rebreather loop to the air box is intact or you have a breather filter on top of the vent this situation would be highly unlikely.

it shouldn't be to difficult to pull the valve off and check it but i'd have to believe there would be an obvious blockage in the vent. the crankcase vent only lets pressure out. if the plastic reed valve would crack it would fail in the open position.

it's completely normal for oil to be blown out of the fill if the cap isn't in place. if you've replaced the valve guide seals and don't have any external leaks then the next place i would look would be the piston rings. only other possibilty i could think of are bad o-rings between the cylinder and valve head but that would most likely be an external leak also.

 

[jblouch]

Thanks for the info. I'm also thinking rings here, but I'm trying to be optimistic by searching for a simple fix. Although the bike is a 97 it only has 1300 miles on it and has been stored for the better part of 6 years. The oil consumption started abruptly at the 600 miles mark after the initial Ducati service was done at the dealer.

 

[Guest]

where was the bike stored? that's a long time with such low mileage, it's not even past ducati's recommended break-in. if it's been in arizona the whole time that's a good thing... at least from a low humidity less corrosion on metal parts perspective. arid and dry is not good from a rubber and vinyl dry rot perspective, i.e. good that you replaced the valve seals. you can still get corrosion/scoring from dissimilar metal contact over time though... for example on bearing surfaces or cylinder walls. could possibly check for that in the cylinders through the spark plug hole with a light. there's a good chance you're going to get some higher than normal oil loss during break-in but it should begin tapering off. course there's the far fetched possibilty of that bike being a domicile... i've had a friend that had varmints take up residence in their stored bike in the air box and exhaust pipes... ;D

 

[jblouch]

I believe it was stored locally here in AZ. I can't detect any deterioration of any of the rubber pieces, gaskets or seals including the original tires (they still have the little rubber nipples from the molding process on them). There are no leaks or anything else wrong that you might think would be caused by long term storage. It's just that it's started to use oil and you can see it on every shift and decelleration (blue puffs of smoke). I was hoping it was the valve stem seals, but I wasn't so lucky. . .

 

[chaf]

Jar,

Have you tried changing the oil? If it started abruptly after the dealer service, I'd suspect that they put in an oil that that engine doesn't like - a switch to synthetic when it wasn't ready for it, perhaps, or maybe just a different brand. In my experience, some engines just don't like certain brands of oil and will consume more that way - for instance, I once had a BMW car that would just drink Castrol Syntec, but it would go 6-8000 miles without needing a quart if I used Mobil 1.

If it were my bike, my first step would be to throw in a good non-synthetic oil and go beat on the bike (within the break-in guidelines, of course) for a few hundred miles, see what happens. Worth a shot, right? And as repair work goes, it's a lot more fun than pulling jugs

M.

 

[jblouch]

Thanks. I've just changed the oil and filter (although it was just done by the dealer) and I put in some good dino oil (Motul 3000 20w50) and will see how it goes. It's been raining so I haven't had a chance to ride, but I don't see any smoke when it's sitting still, whicn is encouraging. The dealer had put in their most expensive full synthetic (Agip T4-$15.00 a quart), so I saved it for later use if the thing "fixes" itself. We'll see.