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A bit more of a heads up on the 8V grenade issue.

Penis Rotor

GT Godfather!
Joined
Oct 28, 2008
Messages
2,833
Location
Bungendore, NSW Australia
I went to Sydney today and discussed this and looked at lots of pics. I'm pretty sure i can tell you what happened, what I can't tell you is why?

Later, gotta cook tea.

Pete
 
Re:A bit more of a heads up on the 8V grenade issu

Well, I'm waiting to find out what, even if I can't be told why. :huh:
 
Re:A bit more of a heads up on the 8V grenade issu

OK, first up a warning. Just like they give before TV programes here in Oz.

Any message by me may contain bad language and jokes of questionable taste. Don't like it? Stop reading now, OK. I'm an Aussie mechanic, not a bloody saint so if you're easily offended quit while you're ahead.

OK. Yesterday I had to go up to Sydney and took the opportunity to drop in the the importer to a,) pick up some warranty bits for a couple of jobs, b.) have a gurn at the Stelvio as I still hadn't laid eyes on one and c.) have a bit of a natter and see what I could find out about the alleged top end problems on the 8V motor. Interestingly Ken had a whole host of pics of the damage that has occured to something like five 8V Grisos here in Oz, I have no idea what that is as a percentage of ones sold.

These stated to me, as clear as the nose on my face what had happened. One or more tappets had stopped rotating. The cam had then scallopped out the tappet until it tore the foot off which then, in the most extreme cases, jammed the cam, snapped the cam chain and shattered the cam sprocket. It wasn't pretty.

The question is what caused it? well I don't think its a lubrication problem as the cams run direct in the head and are clamped down by the 'Scaffolding' that carries the tappets and rocker gear which is also made of alluminium alloy. None of the aluminium bearing surfaces showed any damage. If lubrication supply had been interupted anything more than momentarily the cam journals would of ripped the bearing surfaces to shreds, that hasn't happened. There is little or no 'Blueing' or other signs of damage to the cam journals and surprisingly the cams themselves on the whole look unremarkable given the damage to the tappets!

So *something* has caused the tappets to stop spinning. The question is what? The tappets themselves run in holes bored in the 'Scaffolding' The Scaffolding is alloy, the tappets are, I pressume, chilled cast iron therefore the scaffolding should expand more than the tappets as things warm up. THat being the case as long as the tappets are able to rotate on installation they shouldn't *grow* to the point they seize. I'd like to think we can rule that one out. Next possibility is that the tappets are poorly radiused or the cams ground poorly. To the best of my knowledge one of the things that the factory got in the recent 'Upgrades' was a brand, spanking new cam grinder and the heat treatment oven was fully refurbished so poor heat treatment is also unlikely, (But by no means impossible.).

One other possibility is quite simply dirt! I know everybody thinks the Factory is a wonderful place steeped in history but it is also a filthy, grubby, crumbling tween-wars fascist edifice. Trying to assembl;e precision manufactured componentry in such an environment must be a nightmare. The tappets do have to run a tight clearance in the 'Scaffolding'. Perhaps its just some of them got microscopic bits of grit stuck in the assembley lube and that jammed the tappets? It's probably no more far fetched than any other hypothesis!

I would like to get my hands on one of the damaged cams and a couple of tappets though. I can take things to the Mint in Canberra and get them analysed and hardness tested which would at least allow me to rule out metalurgical problems.

At the end of the day it is not an 'Endemic' problem. it is something that seems to be effecting a few machines but their IS a consistency in the failure that shows that on SOME of them something is wrong. One thing I do find fairly incredible is that some of these machines got to the point of catastrophic failure. They must oif been making an appalling racket for some time before they failed! Were all their owners deaf? Were the dealers who sold them so lacking in care and responsibility that they simply said "Nah Mate! She'll be right. They all do that!" The long and the short of it is if the top end starts to rattle, (Rather than the light ticking the valve lash usually makes before it is fully warm.) stop riding IMMEDIATELY and get the top end examined. This will only require pulling a rocker cover for a looksee, any undue wear of damage will be easily detectable and it'll take but a few minutes.

As I've mentioned before the top ends of these machines DO seem to do a lot of 'Settling in' during the first few thousand Km. My valve gaps on mine closed up drastically during the first 5,000 Km. Could it possibly be that the tappet wear is the result of the tappet 'Riding' the cam as a result of the loss of all the clearance? I dunno but sure as shit ain't sugar I'd recommend frequent valve clearance checks during the first 10,000Kms.

There you have it, that's as much as I know. It certainly wouldn't put me off buying a Griso or Stelvio but it would be something I'd be glad to know about so I could keep a close ear on it for the first few thousand Kms. My guess is that it will be one of those things that will either happen very early in the piece or it won't happen at all.

Oh, for those Aussies waiting for the Stelvio and V7S the ADR compliance has gone through on the Stelvio and they should be in the shops in a couple of weeks. First consignment of V7S's *should* be landing next week if I understood correctly.

Pete
 
Hey Pete, tea must have been good - 15 hours and 38 minutes - or were you seconded to do the washing up as well as cook a four course banquet and then just fell asleep on the couch - common affliction in this house, but it's worth quite a few brownie points. B)


Anyway great info, question is I suppose what is the factory's response, obviously they would fix any affected bike under warranty, but without trying to find a cause they might end up with an ongoing random ticking bomb in every new bike with the 8V engine.

Was there any comment or ideas in that regard?
 
Sounds just like the first 8v Griso's in the UK a while back, ......oh and My Stelvio .oh and the other UK stelvio's. but hey, we aint got an issue here have we.
 
Kudos for reading up to here, Gary! :p You're right, no issue, just a consistency in the failure showing that something's wrong on some bikes. Which I presume means, even in the words of an Aussy Mechanic (what would the latin name of that species be? :silly:), that there's something wrong somewhere in the chain that turns out those bikes (for instance the factory not being clean enough, or Luigi using the remains of his lunch to grease the tappets :silly:).
 
I don't have any engine drawings at hand at the moment, so this may be way of the rocker: doesn't the 2V engine also have tappets that turn (run) in holes bored in a similar 'scaffolding'? Whether or not, how come the corresponding components in the 2V engine aren't affected by being assembled in a factory that's the opposite of a white-room, if that's indeed the explanation?
 
Gary wrote:
Sounds just like the first 8v Griso's in the UK a while back, ......oh and My Stelvio .oh and the other UK stelvio's. but hey, we aint got an issue here have we.

With the design? No. With the overall attitude to maintenance and just *maybe* with production or assembley there is a possibility.

My conviction remains that the failures are most likely related to the fact that the running in process in the top end of the motor leads to the valve clearances closing up appreciably during the first few thousand Kms. The factory may well of recognised this which was why when I checked my clearanced prior to putting my bike into service I found them very, very loose. Perhaps this was deliberate to allow for the closing up without the tappet riding the cam? My suspicion is that bikes that are suffering this sort of damage aren't having their clearances checked at the first, 500mile, service. Maybe the service isn't being carried out soon enough? Maybe the clearances just need checking more frequently during the innitial 10,000km/6,000miles? It's not as if it is a difficult, time consuming, task.

What can the factory *do* about it? Well if it is a maintenance issue then they can suggest more frequent clearance checks during that period. If though the bikes in question are suffering failure simply because maintenance isn't being carried iut???? Well, there isn't really anything much the factory can do about that is there? If the dealer who sells the bike is unwilling to stick to the listed maintenance schedule then suggesting changes to that schedule isn't going to make a ha'porth of difference. Here again owners, if they are concerned that maybe the work isn't being carried out satisfactorily, could always take matters into their own hands and check the clearances themselves but it's so much easier to diss the manufacturer and shriek like a great big girlie frock about how they are the 'Victim' of some sort wicked conspiracy:laugh: .

Rene, my suggestions re. cleanliness etc were really simply grasping at straws and trying to cover all bases. The pushrod motor's tappets rotate in the crankcase and are of a different design.

Pete
 
Re:A bit more of a heads up on the 8V grenade issu

Early-life maintenance so critical that if it's not carried out properly could lead to serious failure later on, I'm not really sure what to think of that in terms of design. It seems a radical departure from the earlier engine design at the least, as far as I've understood it.

Another thing ... does this mean that somewhere those components are actually quite fragile, and what would that mean for long-term reliability (or maintenance costs)?
 
Re:A bit more of a heads up on the 8V grenade issu

RJVB wrote:
Early-life maintenance so critical that if it's not carried out properly could lead to serious failure later on, I'm not really sure what to think of that in terms of design. It seems a radical departure from the earlier engine design at the least, as far as I've understood it.

Another thing ... does this mean that somewhere those components are actually quite fragile, and what would that mean for long-term reliability (or maintenance costs)?

Early life maintenance has always been critical with designs like this. It was equally important with the pushrod motors but failure to carry it out usually manifested itself in other ways.

As for fragility? Yes, any component is fragile if it is abused. Run a bearing without oil? It will fail. Run a tappet without clearance? it will fail. Run a tyre without air in? It will fail. Is an inability to take abuse a design flaw? I think not.

Pete
 
Re:A bit more of a heads up on the 8V grenade issu

Manifested in what kind of ways?

I'd thought of your counter-examples, of course. As far as I can see, the difference there is that it is probably easier to check for the condition that could provoke failure: oil-checks, tyre pressure checks. The sort of thing we learn to do regularly. Tappets ... I just don't know. You do it when the facture says to do it, to the best of your ability (which would often mean having it done I guess :) ), and then? Is it inevitable that if one or more fail one has to strip or change the whole engine?
 
Re:A bit more of a heads up on the 8V grenade issu

RJVB wrote:
Manifested in what kind of ways?

I'd thought of your counter-examples, of course. As far as I can see, the difference there is that it is probably easier to check for the condition that could provoke failure: oil-checks, tyre pressure checks. The sort of thing we learn to do regularly. Tappets ... I just don't know. You do it when the facture says to do it, to the best of your ability (which would often mean having it done I guess :) ), and then? Is it inevitable that if one or more fail one has to strip or change the whole engine?

Burnt exhaust valves usually.

Checking the valve lash is a 15 minute task, perhaps on a Norge a bit longer if you need to remove a panel or two but the principle is the same. It takes longer for me to drain the oil thoroughly on my 8V than it does to check the valve clearances! My instructions I posted up show exactly how easy it is to check the valve clearances. If the owner feels that this is beyond them that's fine, and if that is the case perhaps they have made a mistake purchasing the first edition model of a new design but it was their choice. Can't cope with that? Buy something else.

I'll keep saying it until I'm blue in the tits. I don't think there is a design problem with the 8V. I also think it is oodles of fun. I'd love to get my hands on some of the parts from a blown up one but since mine obstinately refuses to do ANYTHING wrong 'm a bit stuck aren't I??? Once again, for the record. It is my belief that the most likely cause of the failure is that the valves bed in, the gaps close up and the tappet rides the cam, overhears, deforms, stops rotating, gets scalloped out by the cam and, if left eventually fails catastrophically but this wouldn't happen instantly you'd get a LOT of warning. If that warning sound is ignored catastrophic failure is going to be the result. Once the wear starts it can't be halted, the only way to cure it is to replace the damaged parts. Therefore the logical way to deal with the problem is to treat it BEFORE it occurs. It's called 'Preventative Maintenance' it's cheap and it works. Whining and snivelling achieves nothing but for some it seems like a far more satisfying way of getting through life:S

Pete
 
Re:A bit more of a heads up on the 8V grenade issu

pete roper wrote:
If the owner feels that this is beyond them that's fine, and if that is the case perhaps they have made a mistake purchasing the first edition model of a new design but it was their choice. Can't cope with that? Buy something else.

Shit mate I'm not sure about that one? For me personally, I will just be checking mine every couple of hundred, as I have both the tools, the inclination and the ability, and in the end it's a motorcylce not a Holden Barina girly car, so from that prespective I agree.

But, these bikes are an expensive bit of kit and do you not think that it is fair enough for an average purchaser to assume that he or indeed she would not need to dismantle the bike to check mechanical things that it could be argued are the province of the dealer? If MG can't get dealers to service their machines in a way that prevents breakdwon, then seems to me that small a design alteration to make a system that is more robust and can cope with poor servicing would be a good idea.

I suppose the problem with that is that if the current system is a good design from a performance point of view a change might be an issue.
 
Re:A bit more of a heads up on the 8V grenade issu

Pete,

Very good, very detailed presentation of the possibilities. Thank you for taking the time to write it up for us!
 
Re:A bit more of a heads up on the 8V grenade issu

I've always said that one ought to be aware of the odds when buying a version 1.0.0 design of just about anything! I tend to avoid that.

I'm perfectly willing to believe that checking the clearances isn't rocket science. But it still is something different than checking air or oil levels - and probably not something you'd want to do regardless of where you are. And adventure bike where you have to check the engine's internals "every couple of hundreds"? Hmmm, let's hope the 'dusty factory' hypothesis turns out wrong! ;)

Fully agree with you, Mike. But maybe Pete was hinting at the fact that if this "issue" (or however to call it) warrants and can be addresses with a small design alteration, it might be among the first "upgrades" MG will apply to the engine!
 
Sounds just like the first 8v Griso's in the UK a while back, ......oh and My Stelvio .oh and the other UK stelvio's. but hey, we aint got an issue here have we.
 
Just got in and rebooted the internet connection and it seems to have reposted this mornings post, soz chaps.
Anyway back to the plot. The dirty factory.........dont think so really eh ?
Low mileage bikes getting the problem ok, mine had 9400miles on it. Let's look alittle closer, 500 miles had 1st service , 3400 miles, oil and filter, 6250 miles service. Getting to 9500 was going to have another oil and filter. Saturday morning, left home at 4 am for a 180 mile trip, no noises at all strange. Full power no worrys down the motorway. Stopped for fuel after 120 miles, engine sounds the same as normal returned to the motorway, 80/90 cruising for 50 miles, had to slow to 50 for contraflow road works, wind noisw dies and is replaced by the tiny pitter patter of what sounds like a few nuts and bolts being shaken in a cake tin.
Yea that quick..........my trade is a paper machine engineer, I specialize in PPM planned preventative maintenance, I listen for dodgy bearings daily,

RJVB with regard to the ' upgrades',. The Uk bikes also have a dodgy side stand, it bends. The US spec bikes have an updated stand which is 50mm longer. Guess what, I extended mine 50mm 5 months ago. Have MG replaced any UK stands, no. I'm trying to buy one but they're not on the parts list yet.

Stelvio is still a great ride though.
 
Re:A bit more of a heads up on the 8V grenade issu

Mike.C wrote:
pete roper wrote:

But, these bikes are an expensive bit of kit and do you not think that it is fair enough for an average purchaser to assume that he or indeed she would not need to dismantle the bike to check mechanical things that it could be argued are the province of the dealer? If MG can't get dealers to service their machines in a way that prevents breakdwon, then seems to me that small a design alteration to make a system that is more robust and can cope with poor servicing would be a good idea.

I suppose the problem with that is that if the current system is a good design from a performance point of view a change might be an issue.

Mike, checking the tappets is scarcely 'Dismantling', to be honest at my age I actually find checking the tappets easier than checking the tyre pressures at a servo:laugh:

If, as I strongly suspect, my guess for the cause is correct it is something that may be fairly easily addressed by changing something simple. What? I don't know. I'm NOT an engineer, I'm a mechanic, I have to know the how and the why, its an engineers job to know the 'What'.

There is also the issue of testing. While I don't doubt for a minute that extensive testing was carried out prior to the engine being launched there is no comparison between bench testing and real world conditions. Honda have found this out time and again. Remember the CX500 debacle when it was launched???? Perhaps you're too young? But it happens all the time with virtually all manufacturers.

I am being very careful to check, double check and triple check stuff on my 8V because, as I've previously said large and important parts of it are new. I'm also more than happy to share any information I glean or at least I will be as long as I'm not misquoted or have any observations I make used as a bludgeon to diss Moto Guzzi. If I think that's happening I'll simply pull the thread. No skin off my, or my customer's, noses but since nobody else seems to be willing to post their experiences it might be construed as a bit of a loss to others who might be running the risk of suffering problems. Not suggesting my input is invaluable or even important, just that it is out there for people to independently assess.

Pete
 
Re:A bit more of a heads up on the 8V grenade issu

Well said, Pete, & thanks. Oh, and I do remember the Honda CX500, but never did hear about any debacles re same. I always thought they were stone cold relaible, albeit grossly ugly. Please, tell us...

Also agree on the ease of tappet clearance check/adjust. If you can't do that, you are truly helpless-esp on the old 2 valve heads.
 
Re:A bit more of a heads up on the 8V grenade issu

pete roper wrote Mike, checking the tappets is scarcely 'Dismantling', to be honest at my age I actually find checking the tappets easier than checking the tyre pressures at a servo
For my part I leave checking the tyre pressure to The Minister - her penance for me looking after her bike's mechanicals so checking the tappets on my bike will definitely be a lot less costly than the time taken working on her bike to accrue enough brownie points for her to agree to check my tyre pressures :)

pete roper wrote There is also the issue of testing. While I don't doubt for a minute that extensive testing was carried out prior to the engine being launched there is no comparison between bench testing and real world conditions. Honda have found this out time and again. Remember the CX500 debacle when it was launched???? Perhaps you're too young? But it happens all the time with virtually all manufacturers.
Um well actually without giving too much away the ugly duckling was in the bike mags when I was hooning around on my 750 four, but only just - by the time I came on the scene the CX was old hat - I never heard of the inbred problems with it, but that was probably because I didn't care - I was having too much fun with the Four!

I have consistently tried to suggest to the doomsayers that these 8V problems are a transient thing in the life of the 8V motor - and from all the info available to date, I am still sure that that will turn out to be the case, doesn't make those with failures any happier though - I for one don't give a rats about it, as long as I am aware of any issues so I am able to take any preventative measures and if MG are prepared to back the product which IMO they have done very well with all warranty claims that I have read about so far and seem to be trying hard with any problems (lack of parts availability asside).

That's where your expertise comes in - not that I want to piss in your pocket, but I have no way of finding out or interpreting this type of info, so keep it coming for better or worse!

Problem might be that bad news travels fast, and issues like these can be blown out of all proportion on the internet, which for a small brand like MG is a problem.
 
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