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Stelvio with blown piston&cyl - what else to look for

2manybikes

Just got it firing!
Joined
Aug 28, 2021
Messages
18
Location
Greater Boston, MA, USA
Possibly going to look at a late model Stelvio this weekend with blown RH cyl, piston, valves, etc. Current owner (not sure if he's on this forum) stated it was caused by water in the gas that led to hydrolock.

Supposedly the LH cyl is fine. I won't be able to tear into the engine during a pre-sale look, but what else should I look for, especially if visible from the outside?

Also, could a blown RH piston/valves bend a connecting rod or cause damage in the engine internals? the bike was running at speed during the damage. Unclear yet if he limped home on one cyl or had it towed from the spot.

I've resurrected many dormant bikes, mostly Japanese bikes from the 70's and 80's. I'm decent with a wrench, but none of those past projects had blown engines.

Any guidance or thoughts from the Stelvio experts? Thx
 
Other damage is probable for sure.
I highly doubt an engine would even run with enough water in the gas to cause hydrolock. I believe there is a lot more to this story.
The price better be very low to take a chance on it. I wouldn't.
 
Other damage is probable for sure.
The price better be very low to take a chance on it. I wouldn't.
Agreed, and that's the tricky part. I know the vintage Japanese prices well, but MG's are premium bikes with higher prices even for projects. The price will have to be low enough to be worth taking the risk. Otherwise it just becomes a parts bike.
 
It is IMPOSSIBLE to hydrolock an engine from water in gas. Absolutely impossible.

Hydrolock is when the cylinder fills with a liquid which prevents the piston from being able to move up in the cylinder because the liquids filling it cannot be compressed.

You are being given a huge stinking fish story. My strong advice is RUN, don't walk AWAY. He's lying.

FWIW: I have seen this a few times before when idiots think they can decarbonize the piston crown and cylinder head squish area by attaching a vacuum tube to the intake manifold, then running the engine while quickly dipping the tube into a glass of water, deliberately sucking water into the combustion chamber. The problem is, that this was an old timers trick but you must be extremely careful not to let more than a few drops of water be sucked into the tube at a time. If they just stuck the tube into a glass of water then the piston would have sucked a large enough quantity of water into the combustion chamber which then in turn could not be compressed by the piston on the upstroke, bending the piston rod and probably damaging the crankshaft and/or crank journal as well. This would also explain why it is on one side. More than likely, he did this himself through stupidity.

I tell you again, that it is impossible to hydrolock an engine from water in the fuel.

"HYDROLOCK - the technical name for it is hydrostatic lock. The term has been shortened to hydrolock, but the meaning is the same. Simply stated, it means a fluid is preventing the pistons from reaching the top of their stroke. For an engine to become hydrolocked requires fluid to enter one or more cylinders, and the fluid needs to be more volume than the combustion chamber allows when the piston is at its uppermost travel in the compression stroke. In other words your engine has locked up.

Normally, the piston compresses an air/fuel vapor mixture in the cylinder. Fluid simply doesn’t compress like a gas does. When the piston reaches the fluid, it comes to an abrupt halt. And, when one piston stops, they all do. Your engine shuts down, and you’re left wading through water to get to safety."

carbrain.com/blog/what-does-it-mean-to-hydrolock-your-motor
 
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It is IMPOSSIBLE to hydrolock an engine from water in gas. Absolutely impossible.

Hydrolock is when the cylinder fills with a liquid which prevents the piston from being able to move up in the cylinder because the liquids filling it cannot be compressed.

You are being given a huge stinking fish story. My strong advice is RUN, don't walk AWAY. He's lying.
Thanks Scott. That was my first reaction and my BS detector has been flashing as well. I've worked on a bike with water in the tank and it just causes poor/no running.

I *suspect* he is just reiterating info from his mechanic, who has been mentioned in the email chain.
 
What year bike? Does it have roller rockers?
When did used Guzzi's become premium?
It's a 2017, which I assume is beyond the earlier problems that require rollerization.
Rightly or wrongly, I lump the Euro bikes (BMW, Triumph, Guzzi, Ducati) together as generally being more expensive than thebig 4 Japanese bikes. I can get used vintage J-projects for a few hundred dollars, although more for Honda's.
 
FWIW: I have seen this a few times before when idiots think they can decarbonize the piston crown and cylinder head squish area by attaching a vacuum tube to the intake manifold, then running the engine while quickly dipping the tube into a glass of water, deliberately sucking water into the combustion chamber. The problem is, that this was an old timers trick but you must be extremely careful not to let more than a few drops of water be sucked into the tube at a time. If they just stuck the tube into a glass of water then the piston would have sucked a large enough quantity of water into the combustion chamber which then in turn could not be compressed by the piston on the upstroke, bending the piston rod and probably damaging the crankshaft and/or crank journal as well. This would also explain why it is on one side. More than likely, he did this himself through stupidity.

I tell you again, that it is impossible to hydrolock an engine from water in the fuel.

Thanks for adding this bit after the fact. Does sound like a possible explanation.
 
With the little we know here, if you can’t “Crank it over “ turning the back wheel with the plugs out - price it like it needs a new engine !
EBay + labour 3,000$ ( ok maybe WAY more - 8k - IF you can find one... )

if the assembly will still rotate maybe it’s not Fubar?
See if he will take the plugs out & valve covers off...
 
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With the little we know here, if you can’t “Crank it over “ turning the back wheel with the plugs out - price it like it needs a new engine !
EBay + labour 3,000$ ( ok maybe WAY more - 8k - IF you can find one... )

if the assembly will still rotate maybe it’s not Fubar?
See if he will take the plugs out & valve covers off...
Thanks. I'll see if that's possible. The RH cyl is already off and I'll bring tools to see of the LH plug&valve cover can come off.
 
FWIW: I have seen this a few times before when idiots think they can decarbonize the piston crown and cylinder head squish area by attaching a vacuum tube to the intake manifold, then running the engine while quickly dipping the tube into a glass of water, deliberately sucking water into the combustion chamber. The problem is, that this was an old timers trick but you must be extremely careful not to let more than a few drops of water be sucked into the tube at a time. If they just stuck the tube into a glass of water then the piston would have sucked a large enough quantity of water into the combustion chamber which then in turn could not be compressed by the piston on the upstroke, bending the piston rod and probably damaging the crankshaft and/or crank journal as well. This would also explain why it is on one side. More than likely, he did this himself through stupidity.

I realize this a somewhat of a rhetorical question - but how could someone be stupid enough to Blow up a 3 / 4 year old bike like that !

I always thought the best way to clean it out was to take it for a good TEAR and not get busted and sent to Jail !
Or that spray in stuff ? Spray it in till it stalls - then Pray it runs again ??
 
I haven't yet "ran away" from this potential project, but haven't bought into it either. Given that. there are two more questions if I may indulge the forum ...

1. Could hydrolock also cause damage to the transmission, drive shaft, and final drive? or would the clutch isolate those parts from potential damage?

2. When looking for spare parts, can the '17 Stelvio use parts from other rollerized 1200 8V engines of the same era (Norge, Griso)? I would avoid any pre-2012 top ends.
 
I haven't yet "ran away" from this potential project, but haven't bought into it either. Given that. there are two more questions if I may indulge the forum ...

1. Could hydrolock also cause damage to the transmission, drive shaft, and final drive? or would the clutch isolate those parts from potential damage?

2. When looking for spare parts, can the '17 Stelvio use parts from other rollerized 1200 8V engines of the same era (Norge, Griso)? I would avoid any pre-2012 top ends.


1. Unlikely.

2. Again, unlikely. There might be a few things that are the same part number but they are different series engines.
 
So I assume that magically finding a complete replacement engine from a Norge or Griso is not an option.

I don’t believe so.

Let me cut to the chase here…

I own a 2012 Stelvio NTX (since new). The average trade vale of a Stelvio is 5k USD.

A Stelvio with a blown motor is worth 2k to me and I am a professional mechanic. You have NO IDEA what else is screwed on this bike and truthfully, the seller has already lied sbout the proximate cause of the initial hydrolock. You would clearly be buying the motorcycle “AS IS, WHERE IS”.

So I guess I’m trying to save you grief and $$$.

At 2k, I would take a chance but only because I can repair it myself. That’s what it’s really worth, 2k. It’s not a lowball, but rather a sound business judgement based upon worse case scenario.

That leaves me $3,000 for parts which in Moto Guzzi land, doesn’t buy a whole lot. Ever priced a ECU before?

So if repairs started to look ugly, I could reverse directions and dismantle and sell off the parts and recoup my initial investment.

Ok, that’s all I have to say. Good Luck!
 
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I don’t believe so.

Let me cut to the chase here…

I own a 2012 Stelvio NTX (since new). The average trade vale of a Stelvio is 5k USD.

A Stelvio with a blown motor is worth 2k to me and I am a professional mechanic. You have NO IDEA what else is screwed on this bike and truthfully, the seller has already lied sbout the proximate cause of the initial hydrolock. You would clearly be buying the motorcycle “AS IS, WHERE IS”.

So I guess I’m trying to save you grief and $$$.

At 2k, I would take a chance but only because I can repair it myself. That’s what it’s really worth, 2k. It’s not a lowball, but rather a sound business judgement based upon worse case scenario.

That leaves me $3,000 for parts which in Moto Guzzi land, doesn’t buy a whole lot. Ever priced a ECU before?

So if repairs started to look ugly, I could reverse directions and dismantle and sell off the parts and recoup my initial investment.

Ok, that’s all I have to say. Good Luck!
Your time and input is very much appreciated. I'm a decent mechanic, but not a pro and my experience is vintage Japanese bikes, not modern Guzzi's.

$1500-$2000 is about what I was thinking as well, assuming I'm willing to take the risk.

BTW - Part of my interest in this bike is to help out a budget conscious friend who would like a large Adv bike. I also enjoy rescue projects, but they are usually lighter lifting than this one.
 
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$1500-$2000 is about what I was thinking as well, assuming I'm willing to take the risk.
BTW - Part of my interest in this bike is to help out a budget conscious friend who would like a large Adv bike. I also enjoy rescue projects, but they are usually lighter lifting than this one.
Blown engine rebuilds as a hobbyist will bite you. It's a quite complex task, even for Guzzi-experienced engine builders. Plan on a strip to the cases and hot-tank endeavor to start, and also peruse the parts PDF to see crank & rod color-dot notes to start (all motors are factory balanced). My recommendation is to only take it on if you can source a complete (well documented) engine to do the swap. Complete eBay engines are, 95% of the time, parts only lumps. Too many people think this isn't the case. If the motor has taken any impact, it's likely parts only.
 
Blown engine rebuilds as a hobbyist will bite you. It's a quite complex task, even for Guzzi-experienced engine builders. Plan on a strip to the cases and hot-tank endeavor to start, and also peruse the parts PDF to see crank & rod color-dot notes to start (all motors are factory balanced). My recommendation is to only take it on if you can source a complete (well documented) engine to do the swap. Complete eBay engines are 95% of the time parts only lumps. Too many people think this isn't the case. If the motor has taken any impact, it's likely parts only.

So .... you're saying this isn't something I could do over a weekend? Hold my beer ...
 
So .... you're saying this isn't something I could do over a weekend? Hold my beer ...
Are we talking from Friday to Monday ( 96 hours ) with a team of machinists and mechanics supporting the effort ?
I have used a ball peen hammer to make gaskets out of paper shopping bags - in 1974 ?
I can bring my own hammer - but you’ll have to supply the gasket “Quality” shopping bags !
 
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