8V Failure info.

[Brian UK]

Owner now says that since the oil pump change it's running "noticably" cooler on the LH pot. Don't know whether he's clutching at straws here though. From your description of the oil system I can't see how this can happen, both pumps failing the LH pot.
But this is what he was told, for what it's worth.
Apparently the oil pressure is sent first to the bottom end, then the r/h cylinder head and last to the left cylinder head. Of course he might have totally misunderstood what was said to him. I'm fairly sure it's total Bo****ks.

 

[Penis Rotor]

Look in the valley. Both heads are fed by a 'Y' pipe

Unless there is a physical blockage in one arm of the 'Y' 0r the gallery in the head.........

As you can see, the top end lubrication also comes direct from the "Low pressure, High volume" circuit via the cooler. It DOESN'T go through the bottom end first. That is how the OLD pushrod motors doo it but as zi said, the new motor is a very different fish altogether!

Pete

 

[Brian UK]

Looking at the Stelvio parts list, the pipe does indeed go to the RH head then to the LH head, not a Y pipe. Indeed the Stelvio pipe is a different part no to the Griso one. However, I am splitting hairs here.

 

[Penis Rotor]

Not so. If that is the case I was wrong. I didn't realize the difference. Having said that the delivery origin has to be the same basically so unless the right to left pipe is blocked delivery should be the same.

Same basic shit.

Pete

 

[Penis Rotor]

The other thing is that the tappets are not pressure fed. The cams rotate in a 'Bath' in the cambox and splosh oil around. The oil arrives in the top end in large quantities. If there was insufficient delivery the pressure would have to be so low that the mains and big ends would of shat themselves long before damage would of occured to the tappets. Sorry, once again it sound like a diagnosis by a 'Mechanic' who doesn't know their trade and that being the case I'll bet a bus full of beehives they are using sone cheapshit lubricant becaue it's 'Only a Guzzi'.

As long as Piaggio UK continues to use clowns like this their reputation will remain in the gutter!! :roll:

Pete

It should also be noted that the above statement is also wrong because the top end is fed by a different pump to the bottom end. I suppose it is concievable that the high volume rotor could of been stuffed and the low volume one not but if that was the case you'd still expect both heads to be starved of oil not just one of them.

Pete

 

[Penis Rotor]

Also Brian? have you any idea how many miles these machines had done? Had they had their first service? And if so was a high quality oil f the right specification used? I know that Silkolene is popular in the UK and while I have no experience of it in Guzzis I had an oil change done at a shop in Denver on my Mana GT. That shop used Silkolene and the bike that had prviously used no oil at all promptly started using it at a steady and slightly worrying rate! It gradually got 'Diluted' as I added more, better, oil and it slowly ceased to use it again.

Is that relevnt? No idea, but it didn't impress me as to the lubricants ability to seal!!!!! If a similar, inferior quality, oil was used its asking for problems as Dan said!!!!

Pete

 

[Brian UK]

This particular bike has been dealer serviced for its whole life, by a very reputable place formarly of Colliers Wood in London, now in west Surrey, who use Rock Oil. Can't tell you the total mileage, it's done 1600 since the repair.

Am I right in assuming, from your description, that the camshaft bearings are lubricated by the low pressure pump and the cam followers and cam lobes from splash lubrication from what comes out of those bearings?
Remember this dryness was seen on first start up, cold new oil. The pump was then changed, nothing else touched, and oil then was seen on the LH head.

 

[Penis Rotor]

Looking at the Rock Oil website they do make a 10/60 weight. Also interesting is that although Penrite suggest their oil (Sin 10) is not compatible with wet clutches Rock says theirs is.

Be intersting to know if the oil being used is the Rock 'Synthesis' 10/60 or whether they are using one of the other blends? I remain convinced that most of the problems associated with the 8V are related to either incorrect part installation or ignorance of the cooling function demanded of the oil.

I am NOT claiming I'm right, simply comparing MYexperiences with those of others. It's up to everybody else to make their own decisions and assesments of the worth of my ramblings but as I keep saying, I have seen NO failures on bikes that have been serviced as 'Per Book' after the correct bits have been put in correctly. Surely I can't be the ONLY dealer or service agent to have this experience?

Pete

 

[Brian UK]

What bothers my small brain is that if the cam bearings are fed from the low pressure pump, which is also supplying the cooling galleries in the head, is there really enough pressure to reliably lubricate a plain bearing? In the recent case, new cold oil was not arriving at the LH head, but after a change of pump, it did.
This suggests to me that the system pressure may be teetering on the edge of being inadequate.

 

[Penis Rotor]

I don't think so Brian. Perhaps you aren't old enough to remember Kawasaki Z1's and GSX Suzukis? These machines were basically un-burstable but they had rolling element cranks which need high volume, low pressure delivery and plain bearing camshafts which theoretically need the exact opposite! The cams are also running at half crank speed which would mean their ability to wedge would, (From memory?) be reduced.

Certainly if delivery was inadequate or pressure was critical you would expect the bearings in the camboxes to show signs of galling and poor clearance issues long before the cam lobes and tappets became starved of oil to the point where the sort of damage we are seeing in these 'Failed' motors occurs.

Sorry, I just can't swallow it. If there were constant reminders of seemingly "Structural' or 'Engineered' problems they would presumably be occuring in places where the stresses imposed on the engine in a 'Holistic' way were most extreme. They aren't! We aren't hearing of rashes of failures in Oz and Arizona and Texas in high summer! We're hearing about failures in the UK and to a lesser extent the Iberian peninsular and while Spain especially can get hot reported 'Failures' are happening in the Northern WINTER. The UK, even with the hotter summers it is now experiencing compared to those of my childhood is still a meek and gentle climate compared to Texas or NSW in high summer. An oil/ air cooled motor will cope easily with that sort of environment as long as the metalurgy is right and it is recognised that exhaust valve seats get BLOODY HOT and that any coolant used to remove heat from them will have to be pretty bloody special!

Look, at the end of the day I don't know any more than you do, but I can add two and two together and join the dots to come to what seems to me to be a logical explanation for why something is happening in one place but not making itself widely apparent in a larger environment. YOMV.

Pete

 

[Brian UK]

Old enough? most certainly. :lol:

Agreed there have been no reports of cam bearing failure which I would have expected too in the case of oil starvation. Must check on what grade of Rock oil they use there. Last time I used their services it was 15W50 Synthesis 40 racing oil.
Wish I had been able to look at the "faulty" pump. It does sound that for some reason, that one was not producing enough pressure though.
I have heard some alarming stories on which oils some dealers use here, though whether they are doing better on the new 8 valve engines I don't know.

By the way, this bike was not the subject of a recall, but the LH cam follower went TU.
Do you know when Guzzi started fitting the new cam follower into production engines? (ie. when they stopped the recall).

 

[Mi_ka]

Is the oil fed to the heads first passed through the oil filter?
Maybe a lower pressure than needed filter bypass valve could delay pumping pressure built up when the oil is thick on cold weather starting and cause less flow towards the heads and subsequently, tappets damaging them on these first rotations if thick oil is used?

 

[Brian UK]

An interesting point, as the low pressure oil feed is not filtered at all.

 

[Mi_ka]

No filter in the flow means no filter bypass valve opening prematurely when oil is cold and thick but what about
a possible pumps bypass valve? Ah , I think I have been wrong - the filter bypass valve just bypasses the filter and does not return the oil to the sump as the pump bypass valve does (ain't it?).

Or what about this scenario:
You stop the warm engine after a ride, the warm thin oil form the pipes escapes through the pump back to the sump so the head feed pipes become empty.
Next day you start the bike but the cold thick oil is slow on filling the head feed pipes as the pump's bypass valve opens due to over pressure so the heads are starved until enough oil comes through the narrow pipes.

 

[Phang]

The point of failure is at the tappet flat surface.

As Pete mentioned earlier, the cam lobes are lubed by dipping into an oil bath (circled in red) in the cam box. It will get lubed as soon as the engine starts spinning.

IMHO, the delayed oil feed during start up is unlikely affecting the lubrication need of the cam lobes and tappets.

 

[Mi_ka]

Thanks for the graph! I see. This bath holds oil when the engine is stopped so no problem when starting up, right?
To completely kill my oil starvation theory:
Are the reported failures happening at the same rate for LH and RH cylinders?
If yes then no connection to side stand tilt and possible bath going empty.
So only the oil quality along with low winter temps can be blamed.
Low quality cheapo or wrong spec oil goes butter when cold. And goes custard when hot.
This is where the expensive oil shines out.
All that Pete has been whining about so long it seems, given the fact that he has even tested the tappet hardness! (Just saw this, kudos Pete!)

 

[Penis Rotor]

Last of the bikes eligible for the recall were early 2009's I believe with a build date up to about mid 2008 but I may be wrong.

Look, it may well be that there was another batch of poor quality components or some incorrectly assembled bikes. I really don't know. I will continue to say though that I see no fundamental problem with the 8V and tend to think the 'Problems' are being inflicted on it from external sources.

Pete

 

[Brian UK]

Maybe someone just couldn't bring themselves to throw all the remaining faulty ones away, and they found their way back into the parts bins. :twisted:
However, all the Stelvios I have heard of recently have failed on the left side. Harpers of Cambridge have three in the workshop at the moment. Don't know the age of all of them though, the only one I know is a 2010 model which does not date back to late 2008. The oil pump on that has been checked and declared OK.

 

[Mi_ka]

However, all the Stelvios I have heard of recently have failed on the left side. Harpers of Cambridge have three in the workshop at the moment.

Hmm, maybe has something to do with the not-Y feed pipe, maybe a bunch of bad pipes?

 

[draidt]

Maybe someone just couldn't bring themselves to throw all the remaining faulty ones away, and they found their way back into the parts bins. :twisted:
However, all the Stelvios I have heard of recently have failed on the left side. Harpers of Cambridge have three in the workshop at the moment. Don't know the age of all of them though, the only one I know is a 2010 model which does not date back to late 2008. The oil pump on that has been checked and declared OK.

Well Hells bell man no wonder they failed on the "Left" side you blokes drive on the Left ( Wrong ) side of the road. Seriously, I go back to my original post was the Factory recommended oil used ? Tiny oil orifices blocked because of "Cooked " oil ?