Engine Noise

Ok Pete just ordered both(green) gaskets. I will let you know what I find in there sir. Thank you

Looking back at the earlier posts in this thread I see they date back to 2015.

A lot of water has flowed under the bridge since then and as time has gone on I've identified various things that are almost systemic, if not universal, failure points. The sump spacer gasket is one of them and although tedious it is easily addressed.

My original motor out of the now yellow bike, (An A5 motored 2008 model.) was, with hindsight, probably the first spacer gasket failure I'd seen and combined with my flat tappets failing at about the same time was sufficient to kill the motor as the combination of low/inadequate oil delivery and DLC particulate contamination eventually did for the front main bearing which, because it is part of the crankcase and not available as a separate part, meant that engine was toast. Although having said that I'm pretty convinced that I can make an earlier front main bearing work by accurate machining of the crankcase. If I can do that it will mean that even seriously damaged engines will be recoverable

So I bought my first GRiSO new, a 13, and put 25,000 miles on it. I joined this group back when I bought it and then one real hot day, my oil light flashed for the first time, and then started coming on somewhat frequently. I ran about another 300 miles after the first sign of the light. I also started to hear a banging from the bottom of the motor that was not there before. I stopped riding it and brought it in. It was now out of warranty. The guy at the shop said he didnt think it was making any non-normal noise and he replaced the oil sensor. He said he also cut open the filter to see if there was any metal in it. The day I picked it up to take home, the oil light (new one) came on again. Anyway, a new 17 came in the shop right at that time and I was not feeling comfortable with the issue I was having so I immediately traded in for the 17. I didn't want to sell it privately if it had an issue. He gave me a good deal on a trade. Not too long after that, he told me the 13 needed motor work and he wasn't sure what had happened to it.

I remember right about this time that Pete was just first diagnosing this sump gasket issue and after I traded in the 13 for the 17, I thought, I bet this is exactly what happened and the dealer didn't know of the sump gasket issue yet. I also know that at that time, there were people who were having problems with the oil sensor light coming on and blaming it on a faulty sensor and that's probably what he thought it was. I don't know what became of the 13, but I have been issue free so far with the 17.

Interesting I also have a 2013 like your original GRiSO. I was wondering if the oil pressure plug fails would it show up on dash? Or just remain dark as if there was no pressure problems. That's one thing I've never seen is my oil pressure light come on except time of key entry into ignition with all the other ones.

Gootzibird13 wrote:

Interesting I also have a 2013 like your original GRiSO. I was wondering if the oil pressure plug fails would it show up on dash? Or just remain dark as if there was no pressure problems. That's one thing I've never seen is my oil pressure light come on except time of key entry into ignition with all the other ones.

Looking at the wiring diagram the oil pressure sensor runs straight to earth so for the light to come on it must be closed circuit.  When the engine develops enough pressure it breaks the circuit by opening the switch and the light goes out.

Crudely speaking a sensor like this can fail in two ways (1) always passing current (closed circuit so the light never goes off) (2) always not passing current (open circuit so the light never comes on).
It can also fail more subtly by opening the circuit at the wrong pressure

That is why it is important that all the lights come on when the ignition is turned on this proves that the sensor can pass current when there is no pressure and if it goes off when the engine pumps oil pressure it is working.
If it comes on later during that ride - you have a problem

And yes it does illuminate along with all the others at ignition sequence. Getting me motivated to start wrenching to see if that gasket has been trying to destroy my motor.

Pete Roper wrote:

Well, I found out what was causing my great chunk of shit to be so noisy.

The RH big end shells are toast. At first I thought it was big end as it was very similar to the noise that Mark S's bike was making but then as I was preparing to rip into the sump I found that the RH exhaust pipe stud on the head had snapped off!

So, getting that fixed I thought 'Maybe it was just the pipe knocking in the head?' Thankfully I took my own councel and persevered. Popped off the rod cap and the bottom shell was OK. Top one fell out of the rod and is toast. Given how little material had to be removed when Mark's rods were closed and ground I'm going to just slip in a new set of shells and hope that cures it. I also found a bit of gasket missing from around the oil pick-up gallery between the spacer and crankcase. Now I've had the sump off before but never the spacer so it must of been missing ex-factory! Grrrrrrrr! Goes to show how bloody tough they are though! 88,750 km of thrashing with the oil pump sucking air and only now the big ends cry 'Uncle'.

They may not build 'em particularly well in Mandello but jeez they make 'em tough! Probably just as well!

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Pete

Heya Pete,

I finally have the time and green gaskets to get into my motor. Excited to see how much damage is done. Riden very few miles since your recommendation to check shells and replace flange gasket. Still very intermittent but the knock is still occuring rarely, seemingly in the right hand side of lower cylinder. I'm no mechanic by any means but am sure I will be replacing shells at a minimum. If in fact that's the case, I will contact you with color code for shells you mentioned you had in stock. Also if available, I need 4 (new) bolts as well. Get back with you tomorrow either way sir.

Thanks Pete

Aj

Gootzibird13 wrote:

Pete Roper wrote:

Well, I found out what was causing my great chunk of shit to be so noisy.

The RH big end shells are toast. At first I thought it was big end as it was very similar to the noise that Mark S's bike was making but then as I was preparing to rip into the sump I found that the RH exhaust pipe stud on the head had snapped off!

So, getting that fixed I thought 'Maybe it was just the pipe knocking in the head?' Thankfully I took my own councel and persevered. Popped off the rod cap and the bottom shell was OK. Top one fell out of the rod and is toast. Given how little material had to be removed when Mark's rods were closed and ground I'm going to just slip in a new set of shells and hope that cures it. I also found a bit of gasket missing from around the oil pick-up gallery between the spacer and crankcase. Now I've had the sump off before but never the spacer so it must of been missing ex-factory! Grrrrrrrr! Goes to show how bloody tough they are though! 88,750 km of thrashing with the oil pump sucking air and only now the big ends cry 'Uncle'.

They may not build 'em particularly well in Mandello but jeez they make 'em tough! Probably just as well!

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Pete

Heya Pete,

I finally have the time and green gaskets to get into my motor. Excited to see how much damage is done. Riden very few miles since your recommendation to check shells and replace flange gasket. Still very intermittent but the knock is still occuring rarely, seemingly in the right hand side of lower cylinder. I'm no mechanic by any means but am sure I will be replacing shells at a minimum. If in fact that's the case, I will contact you with color code for shells you mentioned you had in stock. Also if available, I need 4 (new) bolts as well. Get back with you tomorrow either way sir.

Thanks Pete

Aj

Pete

Wasn't aware in order to get to the fasteners on kickstand mount must remove entire exhaust system. Fasteners of course threaded into flange itself.....so on and so fourth. Saga continues or perhaps time to turn it into yard ornament.

Finally got to it and of course you were right....[You must be registered and logged in to see this image.]

So the getting to the shells for inspection requires a special socket of which I don't own.
Any help out there on type of socket and size please?

What? The big end shells? No, just yer standard 12 point socket. 10mm I think? Or it might be eleven but I think I said 11 last time and was wrong.

On the money Pete as usual. Why I wonder, would a Moto Guzzi Engineer add a spacer riddled with oil galleys Then use a gasket of such shit, shit, shit, quality? I'd sure like to hear someone explain that fubar....hope my big block isn't fucked proper.

No, it won't be, or it's very unlikely. As long as it was running you'll most likely find chucking in a new set of shells will fix it. Just check the crank pin visually and if it isn't scored put new shells in and bolt the caps back up.

Remember to keep the rod caps matched to the rods and make sure the rod and cap surfaces are scrupulously clean and oil free before fitting the new shells then lubricate the face of the shells with assembly lube before bolting the caps back on. Make sure the crank turns freely after the rod bolts are torqued.

Oh and why such a crappy gasket? Because it was CHEAP of course!

Hello sir, here are the outer and inner shells, just a site starting to go it looks like.. Couldn't find any color to determine which size anywhere. You had mentioned you possibly had the shells I need for replacement? I can PM you for details ect. On top of it all I sure owe you a stiff drink to say the least. Thanks for saving my motor Pete.[You must be registered and logged in to see this image.]

Do you know how to use plastiguage?

Negative. All my measuring tools are not digital.

Negative. All my measuring tools are not digital. I don't mind getting one that's accurate. Probably well overdue anyway.

Or I can send them to your shop. I sent you a message from my email. We can handle things from there at this point.

Plastiguage isn't digital. It's a squashable measuring tool that costs pennies.



Just one vid. There are zillions on facetube.

Brilliant. Now I know. What is the torque spec off hand for my four fasteners?

Cool thanks I downloaded work shop manual with all the crankshaft specs and torques. After all the work, exhaust system, kick stand,
and miriad of pan and spacer bolts. Just to get access to the troubled gasket and then to the shells by far the biggest mechanical undertaking of my shady tree career. I am confident that this machine could outlast my riding years upon reassembly. Synthetic oil and being a tractor motor at heart has me sold on the longevity of this big block 8V engine. Most of all the help from Pete and others on this forum giving me the confidence to proceed on project. Thank you