Not really a new topic. Cam failures 8V.

[Morizzi]

Tappets show progression of failure patterns. By the time you get to the stage the last two are at you will find junk through the motor and it needs more than a simple cam replacement!



The cams are interesting. Note that damage first occurs on the nose circles. It is only when the tappets get to the final point of dissolution that you begin to se developing da,age on the opening flanks.

Pete

Hard for me to see tappet rotation being the issue due to the circular nature of the wear.

If I was truly curious I'd take a tappet and get the hardness tested but I'd have hoped Piaggio would have done that by now.

Oil film strength may be another factor. You've mentioned the emulsified oil due to condensation before. If so and if you are getting cream up here then the breather system isn't doing its job either.

Are the valve springs progressive? If so then if the valves are too tight or any angle off 90 deg of the rocker arms to stems/lobes will add extra pressure.

Just throwing in a few abstract thoughts.

Rod

[acogoff]

     This may be unrelated, but I recall about 15 years ago rotax was having problems with their 912 aero engines when running leaded fuels and full synthetic oils. It seems the full synthetic oils were poor at suspending lead particles and condensation debris and it was leading to severe wearout problems in their reduction gear boxes. The fix was to run a semi synthetic or dino type oil that met the engines specs and reducing the use of leaded fuels to only occasionally or not at all. The similarity that occurred to me was the "failure to suspend".  Which would lead me to suspect the synthetic oils may still be lacking in some areas.

[Vasco DG]

Interesting pics. Would the initial wear at max cam opening not point towards valve adjustment that is too tight?

Kurt

No, think about it. If the gaps are too tight the tappets will ride the base circle, the nose circle is always load bearing as that is when the valve is at maximum lift. If the gaps are too tight and the tappet rides the cam there is no point in the cam's rotation where oil can get betwixt lobe and tappet so a boundary lubrication situation will occur but the point of maximum load on the cam will be on the opening flank just off the ramp where the tappet is really staring to load up and accelerate.

You can see on the cam lobes that were running the absolutely cactus concave tappets that the opening flanks had started to erode. On the 'Early Stage' failure the most obvious damage is evident on the nose circles alone.

Pete

[Tazturtle]

Thanks Pete. Excellent points.

You've really thought this through thoroughly and methodically.

Kurt

[Penderic]

Don't the tappets rotate /spin as they are moved up and down by the cam lobes?

And spinning under pressure and with insufficent lubrication would cause that pattern would it not?

I am guessing that moist cool air flowing over the cams during warm up might mist up the metal lobes and displace a bit of the lubricant on the tappet surfaces causing metal contact? Cool running engines can get a layer of "mayo" on the insides from the water inside not boiling out.

Especially bikes in cool moist climates with short commutes could have a moisture buildup problem inside the motor.

[Vasco DG]

Thanks Pete. Excellent points.

You've really thought this through thoroughly and methodically.

Kurt

Kurt, I'm a mechanic. It's my job. Being a 'Parts Replacer' is not being a tradesman.

Pete

[MotoG5]

Pete,
Many thanks for the pics. If you find the time a tutorial on how us Flat Tappers should go about doing an at home cam/tappet check would be of great help. At least that way one could monitor the situation and not have to run the risk of letting things go too far. A roller conversion is bad enough with out contaminating the motor with swarf. As for your previous information on what to look for in the day to day operation of the bike I have a question. When one can see and hear the idle "Chuff/Spit Back" through the TB's how far has the damage advanced? Its obvious from your observations that one does not want to wait for excessive valve train noise to be an indicator. The no load 2 to 2.5k rpm misfire tip can be caused by any number of other ignition issues and I am afraid that one could drive a guy nuts worrying about possible cam issues. All of your effort in helping deal with this is hugely appreciated. ;-T

[Vasco DG]

Doing a chech at home, at least a preliminary one, is very easy. Just pull the rocker covers and check the valve lash. Correct clearances were originally  0.1 mm inlet and 0.15 mm exhaust on the A5 motors but this was changed to 0.15mm inlet and 0.2mm exhaust on later engines although there were no changes that would have any bearing on this in the engine itself. If it is known that the clearances were set correctly then they shouldn't change by much more than a thou or so in between services. If you check them and find that they have opened up appreciably then alarm bells should start ringing and it's time to investigate further. I would suggest that at that point it's time to get the bike to your dealer as if you start disassembling stuff further you are going to make it very hard to press a claim for replacement if you as a 'Non Approved Technician' start digging in further. If you choose to though the next step is removing the cambox and rocker gear which is pretty easy and if you wish I can describe the procedure.

Also there is no need to be excessively 'Grateful' to me for sharing the info. A problem shared is a problem halved after all. I just don't like being taken for granted, having my intelligence insulted or simply seeing the simple rules of social etiquette ignored, thassall.

Pete

[lucky phil]

From the pics it appears Guzzi still persist with lubricating the cam lobes via the splash and hope methodology like the Daytona engine, pls correct me if i'm wrong.
What I do know is as my Daytona engine goes back together with new cams, rockers and lifters it will also have 1mm lubricating holes located just before the opening ramp on all the lobes.
Why you wouldnt put the oil directly where its needed is beyond me. I could wear it if these engines had bullit proof lifters but they dont.
Not saying its going to be the answer but it sure as hell will be an improvement.
Ciao   

[Vasco DG]

There is such an abundance of oil up there I don't think that in itself is an issue. As noted it is the nose circles that seem most prone to wear rather than the opening flanks.

Pete

[oldbike54]

There is such an abundance of oil up there I don't think that in itself is an issue. As noted it is the nose circles that seem most prone to wear rather than the opening flanks.

Pete

Any chance this is being caused by a slight woogity between the cam bearings ? Maybe an issue with the castings the bearings are riding in ?

  Dusty

[MotoG5]

Doing a chech at home, at least a preliminary one, is very easy. Just pull the rocker covers and check the valve lash. Correct clearances were originally  0.1 mm inlet and 0.15 mm exhaust on the A5 motors but this was changed to 0.15mm inlet and 0.2mm exhaust on later engines although there were no changes that would have any bearing on this in the engine itself. If it is known that the clearances were set correctly then they shouldn't change by much more than a thou or so in between services. If you check them and find that they have opened up appreciably then alarm bells should start ringing and it's time to investigate further. I would suggest that at that point it's time to get the bike to your dealer as if you start disassembling stuff further you are going to make it very hard to press a claim for replacement if you as a 'Non Approved Technician' start digging in further. If you choose to though the next step is removing the cambox and rocker gear which is pretty easy and if you wish I can describe the procedure.

Also there is no need to be excessively 'Grateful' to me for sharing the info. A problem shared is a problem halved after all. I just don't like being taken for granted, having my intelligence insulted or simply seeing the simple rules of social etiquette ignored, thassall.

Pete

Got it. My bike is out of warranty but your caution on having a dealer do the cam box and rocker gear removal is taken. I would still be interested in at least having a description of the process just in case I do decide to take a look on my own.
Thanks 

[Wayne Orwig]

From the pics it appears Guzzi still persist with lubricating the cam lobes via the splash and hope methodology like the Daytona engine, pls correct me if i'm wrong.

I may be wrong, but I thought the cam retaining cap acts like a bucket covering the cam lobe. So the cam is constantly dipping into that oil that collects in it.
At least I thought it might be designed that way.

[lucky phil]

Any chance this is being caused by a slight woogity between the cam bearings ? Maybe an issue with the castings the bearings are riding in ?

  Dusty

Understood Pete, my thoughts were that as the cam rotates and comes off the base circle and onto the opening ramp a lubrication hole right there may just provide a wedge of oil  to carry onto the nose of the cam.Cant hurt.
Ciao

[Vasco DG]

I may be wrong, but I thought the cam retaining cap acts like a bucket covering the cam lobe. So the cam is constantly dipping into that oil that collects in it.
At least I thought it might be designed that way.

Yup, I can do some pics over the next few days if people want.

Look, I'm not ruling anything in or out as to the ultimate cause but heat, climate and usage are definitely contributing factors. Just look at the history.

Pete.

[pete mcgee]

Lots of good info and hard work in this thread, thanks Pete.

Looking at the photos to me looks like a lubrication failure so your suspicion that there is a water buildup in the oil may have legs.
A couple of questions,
Have you found any mayo around these bits when you have adjusted valve clearences or pulled them out?

Any oil samples taken from the bikes with failures and sent off for analysis?

Any cams and tappets been sent off for a metalurgical inspection?

Both of which I know cost a bit of money but they may rule out shoddy manufacture or oil issues.
Are all the failure bikes using the same oil brand?
Back in the first post you stated;

[pete mcgee]

"They usually manifest themselves immediately after a service. I have no certain idea why. The only thing I can think of is that the high carbon content of the dirty oil may contribute some form of added protection and once new, clean oil is in circulation it all goes pear shaped very quickly."

Mate I've never seen carbon in oil lubricte anything, my experience is on pratt and whitney r2000 radials, masters of carbon and sludge production and an antiquated lemans is pretty much the opposite, plus I dont feel a modern fuel injected engine would produce enough carbon to do what your finding IF the oil has been changed at anywhere near the factory interval.

I do feel the the factory has either stuffed up with the specs on the surface prep on both the cams and tappets or have stuffed up the oil specification or a combination of both.
Keep the photos and reports comming, its an "interesting" problem, at least from this end with my arse on the sofa with a beer in hand.
Cheers Pete

[Vasco DG]

Pete, I also think it's a shit theory! Unfortunately it's about as logical as anything else I can think of! :D

If you look at the history though the first failures occurred, or at least we're noted publicly, in Spain and Greece, (At least according to my records.) the problem then manifested itself far more forcefully in both the UK and the Low Countries and it was at this point that it started to become evident to me that there was a climatic factor.

Early in the saga it became evident that the problem was far more prevalent in areas where there was a lot of rain, a lot of congestion and cooler winters or at least periods of the year.

I did get early tappets harness tested and they did seem to be soft. But if that was the sole cause why did my old shitter soldier on for so long when lots of others were going TU? It certainly doesn't explain why the later tappets fail or why, apart from climate, it is so random.

Examples? Mark S. Who posts as Mark III had an A5 motored G12 virtually identical to mine. It too never shat its tappets before I did the first upgrade, (That was a saga! An embarassing one! ;D) and shortly before its untimely demise he flogged it mercilessly across the entire 'Wide Brown Land' at sometimes high speeds and in harsh conditions. Like my A5, although not as bad, (Nothing is as bad as mine!) it was a raucous, noisy horror! But it never went wrong. I know of other early models that similarly soldier on seemingly impervious.

Then there are the ones that 'Fail Early, Fail Often!'.

I'd love to have a definitive answer and explanation as I love the 8V and hate the fact it still seems to have this Sword of Damaclese hovering above it! I am sure it is at least in part heat related and do NOT believe that it is a QC issue per-se. Beyond that I continue to amass data and examine the physical evidence available to me. I don't claim to have all the answers but at least I'm looking for them and to me that is better than just wailing and crying into my beer or condemning the whole engine/marque because of something that isn't fully understood.

As I've said before, I'd happily get on my horrible old Munter and ride to Perth tomorrow. If it hasn't broken by now it probably won't in my lifetime. Yes there obviously is an issue and the factory could of been more pro-active in dealing with it but I'm not going to slash my wrists over it. I'll take the Guzzi 8V over the motor in the 1200 Cappo any day. The Cappo is a bland, characterless turd. I'll put up with a bit of grief to avoid riding a turd! Fact is though I haven't had to. In 80,000 km my bike has been as reliable as an anvil!

Pete

[Dick]

I did get early tappets harness tested and they did seem to be soft. But if that was the sole cause why did my old shitter soldier on for so long when lots of others were going TU? It certainly doesn't explain why the later tappets fail or why, apart from climate, it is so random.

Examples? Mark S. Who posts as Mark III had an A5 motored G12 virtually identical to mine. It too never shat its tappets before I did the first upgrade, (That was a saga! An embarassing one! ;D) and shortly before its untimely demise he flogged it mercilessly across the entire 'Wide Brown Land' at sometimes high speeds and in harsh conditions. Like my A5, although not as bad, (Nothing is as bad as mine!) it was a raucous, noisy horror! But it never went wrong. I know of other early models that similarly soldier on seemingly impervious.

Then there are the ones that 'Fail Early, Fail Often!'.


Pete

Your tappets haven't failed, nor Marks. Have you ever had either of the good tappets tested for hardness for comparison to failed tappets? Until you test a batch of them, you really can't rule out quality issues, IMO. From what I've read hear regarding the Hydro engine, it turned out to be a spring issue causing the failures. I don't know if that has stood the time test, though? Could it be the same issue with the 8v ? Maybe some springs are shimmed too tight and are coil binding, or maybe a lighter spring is needed? It seems Guzzi has been dealing with this for a while now. They need to put it to rest. That, or it's just a forum problem.  ;D  

[Wayne Orwig]

Maybe some springs are shimmed too tight and are coil binding, or maybe a lighter spring is needed?

That is my though too.
If you have a bad one, it will reappear on that same lobe because of the excess spring force.

[lucian]

Disturbing finding yesterday on my A5 griso. Removed the rocker covers to find both, half covered in yellow smooze. Interestingly  they were only coated on the forward half of the cover, as if the vent at the rear seems only to work on the rear half of the compartment. I should mention that the charcoal canister had been removed by the p.o. and the tubing leading to it remains dangling underneath the bike. After a spirited romp I noticed some of the dreaded mayo dripping out of the larger hose to the non existing canister which looks like it must route to the blow by tank . Anyway I cleaned off the covers, checked valve clearances, which are still in spec .10and.15, and changed the oil and filter which looked like new. I wonder if the vent system is  functioning normally without the canister plumbing intact? Could this be contributing to the mayo production? I am also concerned about the tubing to the blow by and the tank itself being full off this crap. I can see in the ends of the tubes that they are lined with the emulsified oil and therefore have a reduced I.D. Wouldn't this diminish the effectiveness of the vent system? I am also wondering if the mayo only being on the forward half of the rockers could be attributed to the fact that they may be cooler in front from oncoming airflow. Are you seeing more deterioration of the tappets on the exhaust side verses intake? And should I consider removing my fuel tank and cleaning out the blow by system? This is really pissing me off!

[Chuck in Indiana]

From the pics it appears Guzzi still persist with lubricating the cam lobes via the splash and hope methodology like the Daytona engine, pls correct me if i'm wrong.
What I do know is as my Daytona engine goes back together with new cams, rockers and lifters it will also have 1mm lubricating holes located just before the opening ramp on all the lobes.
Why you wouldnt put the oil directly where its needed is beyond me. I could wear it if these engines had bullit proof lifters but they dont.
Not saying its going to be the answer but it sure as hell will be an improvement.
Ciao   

IIRC, Megacycle did that with the Lario cams, but it didn't help.

[Chuck in Indiana]

I am also wondering if the mayo only being on the forward half of the rockers could be attributed to the fact that they may be cooler in front from oncoming airflow. Are you seeing more deterioration of the tappets on the exhaust side verses intake?

That's an interesting finding.. what about it, Pete?

[Chicago Mark]

Pete,

     I no longer have my beautiful pearl white 2009 Griso 8v, or any Moto Guzzi for that matter. I continue to see what's happening on wildguzzi because I know that some day I'll very likely have another Moto Guzzi. I know I'm not alone in wanting to thank you for your many years of dedication to the Moto Guzzi brand, to helping countless people improve their motorcycles and for your tireless investigation into the 8v cam failures. Plus for the many pther things you do for the Moto Guzzi community.
     Thank you sir, you're a good man. I greatly enjoy reading your posts and learning from what you do and share with us.

[Wayne Orwig]

Removed the rocker covers to find both, half covered in yellow smooze. Interestingly  they were only coated on the forward half of the cover, as if the vent at the rear seems only to work on the rear half of the compartment.

The front half of the valve cover is going to run cooler because it is in the wind. Plus, the rear half is mostly covered by the black plastic decorative cover.
It doesn't matter how well the vent system is working if the cover is too cool to cook off the moisture. We need a hat for the valve cover.  ~;

[twhitaker]

We need a hat for the valve cover. 

Maybe something along the lines of what Bill Blake came up with 40some years ago.

[lucian]

Pic of 1/2 shmoozed valve cover, is this typical? I can't help but think that the rear location of the vent is only servicing the rear half of the space within the cover.







https://dl.dropboxusercontent.com/u/46509859/griso/IMG_0133.JPG

[Viker]

Thanks for the pics and info Pete. Much appreciated!

[kevdog3019]

Pic of 1/2 shmoozed valve cover, is this typical? I can't help but think that the rear location of the vent is only servicing the rear half of the space within the cover.







https://dl.dropboxusercontent.com/u/46509859/griso/IMG_0133.JPG

I can see there are going to be some lights on in the Guzzi garages tonight!  That can't be good and seems to speak to what Pete has been saying is the problem.  Aargh!

[Wayne Orwig]

Pic of 1/2 shmoozed valve cover, is this typical?https://dl.dropboxusercontent.com/u/46509859/griso/IMG_0133.JPG

Yes. And my 2 valve EV it is the entire cover gooed up, since the back half of it is not insulated.