Valve Guides - How do you know they are faulty?

[CairnsDuc]

I keep reading this Forum and have seen on others over the years about people having faulty Valve guides,
Now I have a basic understanding of how they work, but how do you know when they are faulty?

What are the tell tale signs?
Loss of power?
Excess noise/Rattling?
Misfires?

And when did Ducati have this problem, or is a constant ongoing problem?

I don't suspect my S2R is faulty, the subject just fascinates me and I want to learn more.
Thanks. 

[ducpainter]

Smoking on decel is a sign.

They have to be very bad before the bike will run poorly.

[mitt]

-hard starting
-smoke out exhaust
-oil use

the best is to pull a valve cover off and check valve play, but I haven't seen any definitive spec on what is acceptable, and exactly how and where to measure it.

mitt

[Speeddog]

From what I've seen and heard, it seems to be pretty much confined to the DS1000 motors.
They have relatively large valves with 7mm stems, so that doesn't help.
Word on the street is that it may have been due to a bad batch of guides, as it hasn't been an 'across-the-board' issue.

BTW, your '07 S2R800 has 7mm stems, but that's not really cause to worry.

I haven't seen a pass/fail spec on freeplay.
I'll try to find something...

[BK_856er]

I had the heads on my '07 M695 replaced under warranty at about 6k miles due to the melted paint issue.  During disassembly the shop noticed that the guides were already shot.  One of the two new replacement heads (same part number as the S2R800) came in with the "old style valve guides" so the shop had them replaced with the "revised and improved" Ducati valve guides - I'm grateful that they were on top of that one!  As far as I could tell it was running just fine before the head swap, and there was no oil consumption.  I had the DP ecu installed with the new heads, so new-guide comparison is not valid in my case.  I guess the guides need to be pretty bad before you notice running issues.

BK

[Armor]

I have over 17,000 miles in my bike and the valve guides are fine.  2004 M1000DS

[EEL]

So can someone explain how the symptoms are associated with valve guides? I'm having a hard time visualizing this in my head. Trying to piece everything together

Thanks in advance.

[He Man]

When the guides are worn the valve can move around. If it can move around it wont seat properly. During combustion, exahust gases, oil, unburnt fuel/air can leak out through that gap.

But it has to be VERY VERY worn for the symptoms to really show itself. Mine were pretty bad, but the bike still ran decently, but i cant attribute any of hte problems i had to the valve guides because i also have fueling issues.

[Speeddog]

Per the service manual for M1k:

Clearance at assembly: .0012" - .0024"
Service limit: .0031"
Those are measured diametral clearances.

Given the exposed length of valve stem vs. the valve guide length, and the geometry of how the stem rocks in the guide, total freeplay at the top of the valve stem would be about 3x those clearance numbers.

So, allowable freeplay at assembly; ~ .004" to .007", service limit .009".

The bad ones I've seen were about .030" freeplay or thereabouts.

[bigiain]

When the guides are worn the valve can move around. If it can move around it wont seat properly. During combustion, exahust gases, oil, unburnt fuel/air can leak out through that gap.

Almost... The oil consumption/burning problems come from the valve stem wriggling enough to let oil past the lips on the stem seals, not from the combustion chamber/valve head leaks.

big

[CairnsDuc]

Hmmmm, Very interesting, Thanks for the Information. 

Might get the boys at the next service get them to check them out for me, just to be on the safe side.

If it is a problem, may as well get it done under warranty, I'm not far off my 12000km service anyway.

[uclabiker06]

I heard/read that this works:   

1)  Takes open/closing shims off and depress closing rocker.
2)   Now, grab valve stem and try to move it around.  If you perceive any obvious movement it is probably worn.  If you think "it might have moved but I'm not sure if thats what I saw" its probably not worn. (It would be a good idea to compare intake to exhaust valve stems as a gauge because none should move more than the other.)

[brad black]

it's only the 1000 motors that have a known issue.

when we did valve clearances at first services year ago you could get the valves on a 900 and wiggle them around.  they were very loose from the factory, much more than anyone would expect and what most would call worn out.  that's just how they were, never seemed to cause problems.

[uclabiker06]

it's only the 1000 motors that have a known issue.

when we did valve clearances at first services year ago you could get the valves on a 900 and wiggle them around.  they were very loose from the factory, much more than anyone would expect and what most would call worn out.  that's just how they were, never seemed to cause problems.

So is it possible that that's just how the 1000 guides were supposed to be? I wonder if any of the dealerships took advantage of such a subtle spec this by getting new valve guides for bikes under warranty even though the looseness would not have caused problems;  since Ducati pays them for warranty work.

[Gus Duc]

In my case my bike stalled a lot & would randomly run really poor........ tech told me that because of the worn guides the valves would not always seat properly thus loosing compression & cause the inconsistent running issues.  Never used any oil or smoked though & I had mine replaced under warranty @ 10,000 miles.