[jblouch]

I'm thinking I have to replace the valve guide seals in my 97 M900 (it's blowing oil). Anyone ever done this. . . and if so, can you give me an approximation of the parts list that I'll need to do the job (gaskets, seals, etc, etc). Thanks in advance.

 

[CRASH!]

Hey Jarhead,

I missed something. How did you eliminate rings as the culprit?

'course, maybe you don't have to. You'd have to pull the heads on the way to the rings anyway. Might as well have a look at the valve seals.

There's no head gasket; just two little O-rings for the oil passages. Best to replace those. Then you need new seals. Oh, yeah. You need a $50 head bolt wrench or you have to have a welder make you one.

I'd hope you wouldn't have to mess with the valve clearances afterward, but no FHE here.

This could be a pretty straightforward job.

 

[MarkV]

it's not too bad of job for a valve stem seal... the seal is just a rubber boot that fits over the valve guide. imo it's really the only part that you'll need if being replaced. there are two different materials for the intake (black) and exhaust (green). depending on how bad the seals are leaking and how close you are to the next 6000 mile service you may be able to hold off until the next valve service to do it.

i don't use valve cover gaskets on the 900... last job i just used gray gasket sealer. i didn't like scrapping torn gasket material off the valve head. you'll need valve cover gaskets if you want to replace them though.

my advice for doing the job once the valve cover is off is to plug the oil passage drain hole. i use a large bolt with some saftey wire looped around it to make it easier to grab and hold in place. remove the spark plugs. either then support the valve through the spark plug hole or rotate the piston to tdc... use a clamp around the valve stem to hold it but don't rely on it to hold the valve in place. (been there done that) having the engine turning tool makes turning the engine very easy but it can be done using the bike in fifth or sixth gear and turning the rear wheel. the timing dots on the flywheel will indicate when the piston is near top dead center. there's a pair of dots for each cylinder. remove the rocker spacer clip. slide the opener rocker over. remove the opener shim cap. i use an old tooth brush to wedge and hold the closer rocker down. i use a pencil magnet to remove the halfrings and pull up the valve stem. slide off the closer shim. you can either pull off the seal if intact or remove it at anytime if already split. this is a good time to visually inspect the valve guides for wear too. slide the new valve seal on over the valve stem and push it on to the valve guide. then it's the reverse of dissambly. i use a dab of grease hold the half rings in place when replacing them. you will cuss those things. store them in a safe spot. they are small and easy to lose track of. be sure to replace the rocker spacer clip between the two thin washers. do one valve at a time to prevent any mix up. hth.

 

[CRASH!]

So Mark says to do it with the heads on!

You can then disregard most of my last post as that presumed you were pulling the heads to do the job.

I'm sure it would be easier on the bench, but not enough to make up for the extra work of pulling heads ;D

 

[jblouch]

Thanks for the great how to info. I'm thinking (hoping actually) valve stem seals because the bike/motor only had 300 miles on it when I bought it a month or so ago. It was stored for five+ years and I was concerned about dried out or damaged seals and/or cylinder corrosion that improper storage might cause, and sure enough it's happening. It's burning a considerable amount of oil (3/4 quart since it's initial service two weeks ago) and you can see blue smoke on every shift and blip of the throttle. I suppose it could be rings and/or cylinders but I don't know how you tell. How do you tell?

 

[OT_Ducati]

hey jarhead is the stock crank case breather on or has it been altered? if there is a k&n breather on the crankcase breather valve that has been known for a source of blue smoke, check it out, make sure thats not the problem before you go tearing things apart.

 

[jblouch]

Nope, it's got the stock smog hose and collector box under the seat, with the hose running to the air box. Wish it was that simple. . .

 

[MarkV]

five years is a long time to sit dormant... especially with only three hundred miles. probably going over any rubber fittings and seals is a good thing. i'd check your bearings also... head stem bearings can corrode if dormant and may cause the races to score. you can check the condition of the valve seals by simply removing the valve covers, you'll notice if the rubber is split or not.

keep in mind that a engine that hasn't been fully broken in will burn a bit more oil than usual. not sure if you'd see corrosion on the cylinder walls.... that nikosil is some tough stuff. you could inspect the condition of the cylinder walls by with a flash light... a minimaglite with the fiber optic inspection extension will help... through the spark plug hole.

 

[CRASH!]

You'll ultimately have to do the inspections Mark suggests, but I continue to be hung up on the old adage:

Smoke on acceleration = rings
Smoke on engine braking = valve seals

I've been sitting here for two days trying to construct an argument to support that (mostly because I can't be sure I don't have it backwards and I'm trying to check myself). But I can't get a picture of the relative pressures in the crankcase, cylinder and head during all four strokes that helps me with the explanation.

Maybe someone else can help.

Anyway, you consistently report smoke on acceleration, throttle blipping, etc. Is there any smoke when you chop the throttle at speed? I realize you may need a buddy to check this. I don't want you riding while trying to look over your shoulder, or worse yet trying to see your cans in your mirrors!

 

[jblouch]

I have a good view of the exhaust from my bar-end mirrors and there doesn't seem to be much/any blue smoke on acceleration, but you can see smoke when you close/chop the throttle to shift. Sitting still the same thing happens. You can run the RPM's up and not much happens, but when you back off the throttle abruptly that when you see a puff of blue oily smoke. Does that mean valve stem seals?

 

[CRASH!]

AHA!

I missed that in your previous posts. I thought you were saying that the smoke was on WOT rather than when the throttle is chopped! Turns out it's the other way around.

Yes, according to the old adage, your symptoms mean valve seals.

Since Mark says you can change them without pulling the heads, this sounds like the preferred problem if you have to choose from among the two choices!

Well pull those covers and have a peek. Let us know what you see.

 

[jblouch]

;DThanks all. . .

 

[MarkV]

should be pretty easy to pull the valve covers to check the seals. they're very accessable on the front cylinder. the rear cylinder might require you to remove the battery at least for the intake. don't know how accessable the exhaust valve is on 2v monster... the shock on my 900ss pretty much covers up access for example. one of those adjustable mirrors on a stick will come in handy.

another more remote possibility is the o-rings for the oil passages between the valve head and cylinder aren't doing their job. don't know how long those would stand up without lube over time. i had to replace mine on the 900ss rear cylinder but that was because the heat basically cooked it after 18000 miles. if that's the cause oil will weep into the cylinder... but usually it will also weep outside the cylinder also. not likely but something to look for when inspecting the cylinders.