diagnosing engine noise 101

[beauchemin]

I found this interesting site http://remanufactured-engines.com/page4.htm

 

Here is a direct quote: "Rod knocks are loudest at higher speeds (over 2500 RPM) Feathering the gas pedal may result in a distinctive back rattle between 2500 and 3500 RPMs."

 

This is exactly what I'm getting now. At first I was just getting the "loose bolt" rattle while blipping the throttle (above 3000 rpm), but now I'm getting a constant metallic ticking (it is louder than the normal valve train clatter) at all engine speeds above 2500 rpm.

 

I'm going to ride it to the dealer this week.

[pete roper]

I replied to your msg. Having read this I tend to think your problem isn't a big end. Believe me, a shot big end is LOUD and they can't be a 'Little Bit' shot, that's like being a 'Little Bit' dead or a 'Little Bit' pregnant!

 

The noise of a big end gone is a loud clatter, a "Donk-Donk-Donk!"/"Clang-Clang-Clang!" noise, not anything that could remotely be described as a 'Ticking'.

 

Pete

[beauchemin]

I replied to your msg. Having read this I tend to think your problem isn't a big end. Believe me, a shot big end is LOUD and they can't be a 'Little Bit' shot, that's like being a 'Little Bit' dead or a 'Little Bit' pregnant!

 

The noise of a big end gone is a loud clatter, a "Donk-Donk-Donk!"/"Clang-Clang-Clang!" noise, not anything that could remotely be described as a 'Ticking'.

 

Pete

82879[/snapback]

 

Could it be a small-end noise?

[Baldini]

Broken ring?

[Steve G.]

On this list Pete Roper and Todd Haven are the guys to listen to regarding the potential unwanted mechanical noises of a Moto Guzzi engine. My experience with a small end [wrist pin] is with my truck engine, which along with 480,000kms worth of piston skirt slap, I can tell you that a wrist pin is very unlikely, and would be something that would either show it's face very quickly after an inferior assembly, or as a slow progressing thing of years. Piston slap is also unlikely unless it was very badly abused during break-in [and knowing Chris, it's not the case]. A stuck ring? One would think this would show itself dramatically with smoke coming out of the exhaust, if it's an oil ring, or if a compression ring, would show itself with oil vapour showing itself in and around the crankcase ventilation return system [pcv valve] around the airbox.

My experience is limited to my V11, and regular "testing exposure" to some buddies with a 76' Lemans, 79' Lemans, and a couple 850 T-3's. Every one of the things is a thrashy old bugger, including my V11.

Chris, could it be an exhaust leak/crack in one of the headers? Remember Brian Robson had a funny racket starting around one side, and there was a crack in the "bloody cheap" exhaust header, right underneath where you could not see it. The later V11 series with the crossover has had many issues with cracks happening.

Ciao, Steve G.

[beauchemin]

The big-ends were stripped today - both were scored and worn out (left one was making the noise, so I assume it was worse than the other). The sump was clean. I've been religious with my oil changes, and there has never been a speck of metal in the sump, on the screen, or on the magnetic drain plugs. The main bearings seem to be fine (not noisy). The only conclusion is that the big-end shells were faulty or incorrectly installed at the factory.

 

It will get re-assembled tomorrow with new bearing shells in both big-ends, new gasket, new filter, and fresh oil.

[Guest Nogbad]

It isn't easy to see how big end shells can be installed incorrectly without finding the engine is stiff on assembly. It occurs to me that you should investigate the oil pump / relief valve and check that the galleries are clear. Maybe an oil gallery within the crank was machined incorrectly restricting supply. Bearing failure is usually a secondary event that results from insufficient lubrication / overheating etc.

[beauchemin]

It isn't easy to see how big end shells can be installed incorrectly without finding the engine is stiff on assembly. It occurs to me that you should investigate the oil pump / relief valve and check that the galleries are clear. Maybe an oil gallery within the crank was machined incorrectly restricting supply. Bearing failure is usually a secondary event that results from insufficient lubrication / overheating etc.

84183[/snapback]

 

Sorry - I should have been more specific. The service tech said it looks like the shells "picked something up" - he says it mostly likely would have been some metal swarf from the manufacturing process.

 

I assume that the oil pressure is fine since I would expect the main bearings to get noisy and eventually seize if not.

[helicopterjim R.I.P.]

The big-ends were stripped today - both were scored and worn out (left one was making the noise, so I assume it was worse than the other).  The sump was clean.  I've been religious with my oil changes, and there has never been a speck of metal in the sump, on the screen, or on the magnetic drain plugs.  The main bearings seem to be fine (not noisy).  The only conclusion is that the big-end shells were faulty or incorrectly installed at the factory.

 

It will get re-assembled tomorrow with new bearing shells in both big-ends, new gasket, new filter, and fresh oil.

84169[/snapback]

 

Glad you found the problem.

Sorry it won't be cheap.

 

Hope to see you on the road soon!!

 

Jim

[beauchemin]

Glad you found the problem.

Sorry it won't be cheap.

 

Hope to see you on the road soon!!

 

Jim

84250[/snapback]

 

My only expense was transportation to/from the island. It is still on warranty. I will be back on the road by this weekend.

[helicopterjim R.I.P.]

My only expense was transportation to/from the island.  It is still on warranty.  I will be back on the road by this weekend.

84257[/snapback]

 

Great news.

[emry]

It sounds like maybe the tech is being cheap on Guzzi warranty claims process. I have yet seen a big end wear a beaing out and not score the crank. This smells ... odd...

[Greg Field]

I have seen hundreds of shells that were toast without scoring a nitrided crank.

 

I also saw the crank and bearings in question.

 

The crank is fine. The rear bearings most definitely are not fine.

 

Believe me: As horribly as the assholes at Piaggio treat us (MI and the other dealers), we would not screw a valued customer to save the aforementioned assholes a few bucks. The converse is nearer the truth. I'll bet it's the same at MPH or any other reputable Guzzi shop.

[Steve G.]

Gosh Greg,

It kind of makes me sad to hear that Piaggio is frustrating the dealers. I'm getting the same sense of issue from the dealer in Vancouver. Words stronger than assholes were used many times!! I hope it doesn't make you guys give up and start selling Derbi instead!

I'm really glad Chris's bike will be fine. He's too nice a guy to have a new bike go bad. And for some reason I feel responsible. It was me that told Chris to try my V11 out from Ainsworth Hot Springs to New Denver in the B.C. Kootenays. There was a strange smile on his face after that. Soon after he talked to you guys to get a new bike. It's all good.

Ciao, Steve G.

[pete roper]

Believe me: As horribly as the assholes at Piaggio treat us (MI and the other dealers), we would not screw a valued customer to save the aforementioned assholes a few bucks. The converse is nearer the truth. I'll bet it's the same at MPH or any other reputable Guzzi shop.

84301[/snapback]

 

I have to believe that this must be a problem with the US importer? Our mob seem to be pretty good. They have a pallet of 80 CARC drives sitting in Sydney NOW for the recall on that and all of 'em will be fixed within a few weeks as long as owners bring 'em in when the recall notices go out. I can't understand why the US system seems to be so dreadfully inefficient?????

 

To my mind even the idea that dealers like MI or MPH would stiff a customer by cheaping out on parts is insane. These blokes own, ride and love Guzzis, as do many other dealers with good reps like Detroit Eurocycles, Speakers, Harpers, etc. Obviously all of us in the trade are in it to make a living but the reason people like these stick with them has a lot to do with passion as well. They could make lots more money selling 'Ondas and stuff but they stick with Guzzi. Why, well, apart from the fact they're obviously certifiably insane, they obviously reckon they're a bit of all-right.

 

All things man made will have problems occasionally. If they are made by slack-arse Italians in the foothills of the alps chances are there will be more QA issues than with a product built by automata in some thoroughly up-to-date factory elsewhere in the world but that doesn't mean that it's a bad product.

 

Quite often people seem to think that mechanics and service managers have this unique ability to a.) see through metal, and b.) psychically be able to recgnise a problem simply by standing next to a misbehaving piece of equipment. The unfortunate thing is that this isn't the case. Some lucky people are born with a 'Greasy Thumb' which does mean they have a seemingly unerring ability to pick a fault and fix it almost instantly with the minimum of fuss. For most of us though it has to be a process of ellimination as you check off the symptoms against your knowledge and understanding and this can take time.

 

MI are changing out the duff CARC bearings for their early Breva customers pre-emptively, even though not all of the units are going tits. There will also be replacement units supplied and, no doubt, fitted as a warranty thing and at short notice. Given that the dealer 'Cut' on a new Griso f'rinstance in Oz is about $3000AU I'd guess that providing that sort of service to customers in Seattle isn't going to give a huge profit margin on any machine!

 

With a V11 that has torched it's BE's and (?) rear main there will be a warranty payment from the importer but warranty work pays sh*t. OK you can break even on it and maybe even on some jobs turn a profit big enough to justify the time in a fiscal sense but believe me Dave isn't going to be giving Greg a huge pay-rise on the basis of a torched V11 I think that to suggest that dealer or his spannerwacks might be trying to pull a fast one is patently barmy, (Although I'm not saying that was suggested, simply that it's the sort of weirdo-conspiracy-theory-net-nuttiness that goes around!). It'll be fixed, I'm sure that all involved are a bit pissed off and upset that it's occured but life isn't perfect and sometimes sh*t happens. When it's right again and all is good and you're flogging through the Cascades in July all will be forgiven and forgotten I reckon!!!

 

Pete