Bottom end failure - 2018 EC300

[Gasser Nate]

Has been drowned during my time, around 70 hours ago.

Tipped up side down, spark plug out and water pumped out - started it up and rode the rest of the day. Drained gearbox oil and didn't think anything else of it.

Unless it had been drowed before my ownership within the 5 hours of use from the previous owner, but seems unlikely.

Unless it was drowned in a spotlessly clean creek that will be a big reason for its early demise. It is just pretty much impossible to clean all that sand silt and crap out of the bearings/piston/rings bore with out disassembly.

 

[swazi_matt]

Has been drowned during my time, around 70 hours ago.

Tipped up side down, spark plug out and water pumped out - started it up and rode the rest of the day. Drained gearbox oil and didn't think anything else of it.

Unless it had been drowed before my ownership within the 5 hours of use from the previous owner, but seems unlikely.

Shouldn't be that then. I have done the same numerous times and my bottom end was still perfect when i replaced it at about 300 hours. Normally see problems (like rust) when people don't know what to do an load the bike up full of water and take it home for a few days and then off to the bike shop for repairs. drown, fix and run should burn out any moisture.

Normally the air filter prevents any sand getting through to the engine.

Maybe your buddy need gas, used it and replaced it without knowing it was supposed to be premixed

 

[Stoby]

drowned

Ive drowned my 200 and 300 and many many hours / years later still good

 

[Doc Brown]

As said on thumper talk, that bike has been left sitting with water in the engine, maybe by a previous owner. The corrosion in the case where the main bearing sits is severe.
Such a corrosion will not happen in a day or two, not even in a few weeks.

 

[swazi_matt]

As said on thumper talk, that bike has been left sitting with water in the engine, maybe by a previous owner. The corrosion in the case where the main bearing sits is severe.
Such a corrosion will not happen in a day or two, not even in a few weeks.

makes sense, why else would anyone sell a 2018 gasgas with only 5 hours!?!?
if you've ridden the bike for 5 hours you will know what an awesome bike it is, but if you are a noob and drown it in those 5 hours and don't know what to do (as mentioned above) you may get into panick sell mode LOL

 

[Jakobi]

Shouldn't be that then. I have done the same numerous times and my bottom end was still perfect when i replaced it at about 300 hours. Normally see problems (like rust) when people don't know what to do an load the bike up full of water and take it home for a few days and then off to the bike shop for repairs. drown, fix and run should burn out any moisture.

Normally the air filter prevents any sand getting through to the engine.

Maybe your buddy need gas, used it and replaced it without knowing it was supposed to be premixed

I've drowned numerous bikes and got away with it.

I've also seen a few pumpkins take a lung full of slop through the filter and fail to finish the ride. One on pull down had worn the rings so far out of spec they wouldn't even hold themselves in the cylinder anymore.

Lots of variables involved.

 

[Booki]

Hmmm it is interesting - I too thought that a drown wasn't a big deal - Pumped the water out, started it up and continued on.

Drained the gearbox oil and refilled it, did that till it was clean, checked down the intake boot for any debris and it was clean.

I suspect maybe something happened early on in its 5 hours of use before mine, as Doc has said this doesn't happen over night.

I wouldn't be surprised if someone had tampered with my petrol, it was left there for a while.


Funnily enough as well - the ring end gaps on the piston rings are still within spec, one being actually a little tighter than it should be, so that tells me there wasn't a whole lot of debris going into the combustion chamber, so I feel like I can rule out dirt as a cause. The piston however was a bit undersized, another member mentioned that perhaps an undersized piston could cause some combustion to get past the rings and have some detonation on the underside of the piston (like mini combustion events happening below near the bearings) perhaps thats why they were quite dry in there?
I would have thought the rings would stop it but perhaps it can happen?

As the underside of my piston had quite a bit of burnt oil - then again all this could have just been caused by lack of oil in my gas, though if that was the case, wouldn't the top end seize up ? Surely I would have had some pretty severe scoring on the cylinder if that was the case.

Sometimes I would hear a little bit of "pipe bang" when the bike was cold and warming up, I probably should have paid a bit more attention to it.

 

[maxfli11]

The 2018, possibly other models also had main bearings that have plastic cages. They do fail in the 100 hour range consistently. Don't know why GG would do this other than to save a dollar. They were going through a financial crunch around that time. I've got a friend with one that just got his back together. Get the metal cage bearings to replace with.

 

[5valve]

Same issue, main bearing fail, 65 hrs...2 hrs after new piston, which is useless now. Once apart, will do the conrod also while at it, since this is how freshly honed cylinder looks like now.

 

[Zman]

It is very important that after drowning a bike you need to get the water out and get it running ASAP!! Change trans trans oil ASAP too.

 

[Gasser Nate]

The 2018, possibly other models also had main bearings that have plastic cages. They do fail in the 100 hour range consistently. Don't know why GG would do this other than to save a dollar. They were going through a financial crunch around that time. I've got a friend with one that just got his back together. Get the metal cage bearings to replace with.

Whilst I also prefer the metal caged bearings, they are not a cause for failure. Plenty of manufacturers use them and I have personally seen them do a lot more than 100 hours. People forget that water is never spotless and carries a massive amount of abrasives that are never fully removed unless a tear down is done.

 

[Doc Brown]

We had a 2018 engine on the bench and its bearings had no plastic cages. It was the first time the engine was opened. Unfortunately I had not taken any pics but couldn't know that this will be a point of discussion in the future.

 

[gg3]

My bottom end just failed at 145hrs.Very disappointed.

 

[Doc Brown]

That sucks! What bike and model year if I may ask?

 

[gg3]

2018 xc300.
Bought it at 52hrs. It hasn't been drowned since I've had it,so very surprised it failed.Will open it up next week & see what state it is in.

 

[Doc Brown]

Oh man, that's no fun. I am currently at 52 hours too

 

[5valve]

Had a talk with a tuning pro, plastic cage bearings provide better RPM limit, but must be installed with utmost precision, pressure and heat wise,
so having failed bearing at certain hrs goes back to the person, who was assembling the engine.

It is not to save a buck, since plastic cage bearing is more expensive, but more of a hurry, corporate pressure and expertise of engine assemblers.

Remove, install steel cage bearing and avoid further damage.

https://www.youtube.com/watch?v=5RSTnhQcNtw

 

[gg3]

UPDATE. One main bearing rusty & completely failed. Other main bearing rusty.
Have never dropped this bike into a river or even had it in water up to the bottom of the airbox. Always run it after washing to help dry it off. I did buy it at 52hrs & now at 145hrs.Don't know how it got moisture in there?

 

[Booki]

UPDATE. One main bearing rusty & completely failed. Other main bearing rusty.
Have never dropped this bike into a river or even had it in water up to the bottom of the airbox. Always run it after washing to help dry it off. I did buy it at 52hrs & now at 145hrs.Don't know how it got moisture in there?

Did it look like my bottom end?

Perhaps previous owner took her for a swim.... hard to know when you haven't had the bike 100% from brand new.

 

[5valve]

My case exactly, bought at 62 hrs, replaced top end, at 65 bottom fail, found rusty and failed bearings and crank inside. Crankcase chamber and transfer ports had darkish discoloration which looked like burned antifreeze deposits. Cleaned off with some chemicals. Piston was black underneath, indicating heat, even though sparkplug was richish.

Could be crankcase porosity, warped head, wrong head oring, previous owner neglection (drowning, pressure cleaning), failing plastic cage bearing, cylinder base gasket leak.
Many options.

Kind of not in a hurry to assemble the engine, since Im not sure if it could be a repeatory behaviour untill true culpit is found.

Even worse case was documented on YT, but dont know if he resolved the exact cause.