Changing valve stem seals- M900

[TimM900]

Hi all, is it possible to change the valve stem seals on a 93 M900 without removing the cylinder heads? I found a very old post elsewhere (link below) which suggests it is, but having begun to try it on the rear exhaust valve I am having some doubts.

I have entirely removed the opening rocker and its shaft as it would not move far enough to one side when the clip was off. I can then depress the closing rocker and can see there is enough room to remove the closing shim and half rings. However, I am concerned that there would not be enough room to get the new seal down past the closing rocker, and aren't entirely sure of the best approach for stopping the valve dropping too far while doing all this either.

http://www.ducatimonster.org/forums/...ide-seals.html

All thoughts appreciated

[Mr Gazza]

Hello Tim.
I've just been reading up on how to check and adjust valves. It says that if the piston is at TDC it prevents the valve from dropping into the cylinder.
I've also seen pictures of forceps or something similar, clipped to the stem, but you would need two of those to "leap frog" the seal past.

I imagine that the camshaft has to come out to get really good access?

[slob]

Just the rockers, the cam is well out of the way.
Working on the rear head in the frame is all a bit 'keyhole surgery'.

[jerry]

easy to bugger the new seals when installing often worth having a couple extra

[Darren69]

I've not done the valve stem seals before on a Duc but Isn't there a drift tool for installing them?

[Nasher]

This is one of my jobs for the weekend.

I have the heads off the engine and on the bench ready to install new shims where needed, so easy access, but also the opportunity to take some images.

Nasher.

[TimM900]

Yes, I agree, it looks like both rockers and their shafts need to be removed- which is a bit of an issue as I see a special tool is needed to deal with the spring on the closing rocker. However, removing them would also eliminate the other issue, around that when the piston is at tdc to support the valve, the rockers are not in the best place to be out of the way. Will be interesting to see the photos.

I was only doing this as the original post on the other forum suggested it was so easy...

[Dukedesmo]

Originally Posted by Darren69

I've not done the valve stem seals before on a Duc but Isn't there a drift tool for installing them?

'Proper' valve stem seals are tricky to fit with the heads on the cylinders and valves in place, personally I'd take the heads off and strip them down to do the job properly.

However the seals that Ducati fit to the 900 engines are basically like the tip off a condom and should go on easily enough with the rockers removed.

That said I got some 'proper' valve stem seals for mine - the kind with a metal body and a spring around the top (like on the 4v engines) from; http://av-v.com/ because I don't have much faith in the Ducati seals...

[Mr Gazza]

Tim, I have it on good authority that you can hold the valves up by putting 100psi in the cylinder via a spark plug hole adapter. You can hit the stem with a hammer and it won't budge... Apparently.

It won't necessarily matter where the piston is if you fill it with air, but I imagine TDC would be preferable.
To get the cams where you want them just slip the belt off and it will spin freely.

[Darkness]

Originally Posted by Mr Gazza

Tim, I have it on good authority that you can hold the valves up by putting 100psi in the cylinder via a spark plug hole adapter. You can hit the stem with a hammer and it won't budge... Apparently.

It won't necessarily matter where the piston is if you fill it with air, but I imagine TDC would be preferable.
To get the cams where you want them just slip the belt off and it will spin freely.

An interesting approach: the piston's going to try to go down to BDC at that pressure though........

[slob]

You'll have fun getting the rockers out or valves to seal anywhere other than TDC, unless you have the belts off, in which case be very careful turning it over!
You can hold the valves up with a cable tie but it's fiddly as...

http://www.ebay.co.uk/itm/NEW-PLASTI...3D272577757096

[Mr Gazza]

I think you're right darkness. Soon after I posted it I though that the pressure would push the piston(s) down.

So the routine would be belts off first, both valves positioned closed and piston near BDC. Then pump air.

Before it was suggested to me to use compressed air, I had a similar thought involving feeding a party balloon into the spark plug hole and inflating it in the cylinder... Y' never know?

[TimM900]

Interesting stuff. It'll be good to hear how Nasher gets on with this... not much progress here at the weekend, but I'm convinced that the original link I posted is wrong and you have to remove both rockers to do this. Piston can be at TDC to "rest" the valve on, hopefully, no need to disconnect cambelt. The only current issue is that there seems to be a need for a special tool to compress the closing rocker spring... but I wonder if there are ways around that. As for the seals, these appear to be a suitable type:

http://www.ebay.co.uk/itm/8-X-VW-VOL...cAAOSwstxVZziU

[Dukedesmo]

I have heard of feeding soft rope into the cylinder (whilst leaving a 'tail' hanging out for extraction) to make a soft hold for the valve.

When changing shims I just move the piston into the correct position to stop the valve dropping into the cylinder but forceps are good for holding the valve up to fit retainers, saves the need for an extra hand.

[Dukedesmo]

Originally Posted by TimM900

The only current issue is that there seems to be a need for a special tool to compress the closing rocker spring... but I wonder if there are ways around that.

I've removed/fitted rockers on both 2v and 4v Ducatis without any special tools, the 2v are easier than the 4v but neither are too difficult.