Bottom end failure - 2018 EC300

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Originally Posted by 5valve

Did you measure original head inner oring. Mine was 1.9mm, instead of 1.78mm (from new), which caused coolant blowby over time into gearbox and maybe into crank.

Also, did you have your crankshaft measured for alignment. Mine was at the top of allowable free play, at 0.05mm. I've corrected it to 0.02mm.

Were your cylinder trasfer ports discoloured, darker. (check attachment) They should be aluminum light colour. I'm assuming it could be from antifreeze leak.

Next thing I noticed, was original piston rings having half the allowable minimum ring end gap, 0.25mm instead 0.5mm, So it might have added some extra binding heat to equasion. More heat, more expansion for possible leak. It also made vertical lines on cylinder wall.

What torque did you use on the crankcase bolts 0.8 kg or 1kg? There could also be a crank leak of coolant, in small amounts, but enough to corrode the insides over time. While you think that topping up small amout of coolant after few rides is normal, but it is not, if there is no boil over.

Perdona No entiendo, te refieres a la hendidura del cilindro donde van las juntas toricas?

La alineacion del crankshaft no lo he medido,pero ahora cuando he cambiado los rodamientos otra vez he cambiado tambien la biela y lo han equilibrado.

Si no recuerdo mal los puertos de transferencia del cilindro tenian ese color que dices.

Los anillos del piston tienen tolerancia correcta,y el cilindro estaba en perfecto estado.

Los pernos del carter los he apretado sin llave dinamometrica, pero 1kg-1'5kg deben tener. En caso de haber una fuga de anticongelante, la compresion del motor se iria al circuito se refrigeracion y en ese caso deber?a haber mas presion de la normal en el circuito no?

Adjunto fotos de como estaba el carter y rodamientos con 2000km, el crankshaft estaba igual.

[5valve]

I was thinking of head oring, it has two, bigger and smaller, both should be 1.78mm thick. If it is thicker, there is a compression blowby into gearbox, mixing coolant and gear oil. It could also push coolant into crank area, if there is a crack or bad seal between the cases. There could be only small coolant leak but in a longer timespan, this damage could happen. It is chronic, not acute occurance.

if bike is not flooded and is pressure cleaned correctly, there is no way, water could enter and corrode the bearings and crankshaft in just one instance.
I've cleaned other bikes numerous times without being extremely cautious, and nothing happened in years time.

This corrosion, on the other hand, has some deeper meaning. Same is happening to beta 300RR and xtrainer from 2015 till today. They even say 5-10% are affected. Its like enduro virus.

Beta's original response was: a bad batch of bearings, then changed to factory wrong bearing installation and again switched to bad bearing theory.
Beta uses NTN stock, so they say NTN is faulty. GG uses SKF explorer. And we are having SKFs fail...

I went for SNR and NTN combo, C3 & C4, but I think bearings are not to blame. Bad bearings fail in just couple of hrs.
Somewhere somehow there is a small leak into crank area, which in year or two kills the innards.

My engine is now apart for the first time, but you are having a 3rd occurence, therefore water entering somehow is the only thing I can think of.

Unless you are purposefully flooding the bike through carb and exhaust, not running it after washing and leaving it for weeks at a time, full of water....there's sth going on.

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En mi caso no hay agua en la caja de cambios,pero de todos modos es muy raro que los rodamientos se estropeen en poco tiempo. Por lavar la motocicleta no es,eso seguro. Como la compre usada y ya tenia los rodamientos en mal estado(y todo oxidado),pense que la motocicleta caeria en algun rio con el anterior propietario. Pero parece que el problema es otro. Investigando tambien vi el caso de Beta, que como dices le echaban la culpa a los rodamientos o instalacion de estos,el caso es que los rodamientos aparecian con oxido igual que las GG. Tambien se,como dato curioso, que todas las GG que han dado problemas de rodamientos de crankshaft son 300cc (algunas han agrandado el alojamiento del rodamiento en el carter,que hace que no ajuste)y 2018, las 250cc 2018 no conozco ningun caso.

[5valve]

Yes. Bearing will destroy the case if bearing cage fails due to corrosion or other factors. Balls from bearing then accumulate together untill it locks and starts rotating outer bearing race in its seat.
It could be faulty bearing if it fails after first few running hrs, or due to water or coolant constant leak if it fails in 1000-2000km range.

I would certainly rule out water in fuel or 2t oil, since not all bikes are affected.

Cracked cylinder water channel would not leak into crank during riding, but could leak down while stopped.

Casting inperfections on the cases, where water channels pass the crank area closely could also leak water inside.
Maybe not much during riding, but when cooling and not in use.
Pressure test of the cooling system should reveal a leak, but some sort of marking fluid, just like testing aircon system leak, should be used, to pinpoint location.

We're talking small amount of water at a constant rate. Not enough to disrupt compression, but enough, that slowly in 1-2 years or few months rust the bottom end, even though it is
covered in oil and somewhat protected.
I dont know how antifreeze/water mix reacts with oil covered steel, but it doesnt seem to do good.
Maybe even antifreeze type is to be consider, red, pink being more aggressive than blue.

Maybe AndreaGG from enduropuro.it has some clues, if they did any warranty replacements, like beta did.

Last picture shows old bearing prior to removal from my previous bike, how it should look like.

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Ojala descubramos el problema, son motocicletas muy buenas y no me gustaria tener que cambiarla. Como ya sabras, el motor de las 250cc y 300cc es identico excepto cilindro,cylinder head y piston,y como dije en la anterior respuesta no conozco ningun caso de 250cc con este problema,todas son 300cc. Lo que me hace pensar que el problema quizas lo tengamos en el cilindro. Desde luego esta claro que si hay oxido es porque de alguna manera entra agua,como entra ya veremos si lo averiguamos. AndreaGG no esta en este foro?

[5valve]

Either 300 cylinder fault or a certain batch of porous cases, that coincidentaly got used on 300's.
Maybe assembling the engine cases with cylinder, without gearbox, crank, piston, and connecting cooling system, pressurizing it and observing.

Andrea is on forum, but is not very active, I've sent him email.

[5valve]

Copy paste from TT

If you are using pump gas and there is any ethanol in your fuel you can expect moisture in your crankcase and corrosion from condensation. Ethanol is the enemy of a 2 stroke. When that rust starts falling off the crank your rod bearings will pay the price.

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Puede ser otro motivo,pero en mi caso lo descarto. Siempre uso el mismo combustible en todas las motocicletas que he tenido y nunca he tenido este problema. Habr? que seguir investigando y haciendo pruebas a ver si lo averiguamos

[5valve]

So far so bad.

First try was using only air, then coolant. When pressurized coolant, pressure drop was slower, but nontheless should be nonexistent. Starting point at 180 Kpa or 1.8 bar, as per cap blow off value. It held even 1.9 pressure.

https://www.youtube.com/watch?v=cZ-ImSU6yyQ

Next job is submerging whole engine, using air only in cooling system and observing bubbles.

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Interesante prueba,muchas gracias por compartir. Por lo que veo y entiendo,si no se mantiene la presion es porque hay alguna fuga en algun punto.

Yo por mi parte,he dejado la motocicleta parada mas de 1 semana para ver si el nivel de anticongelante bajaba(y no ha sido asi)y ademas he probado a arrancarla ,pararla a los pocos segundos y quitar la bujia para ver si habia restos de agua. En el cilindro-piston(por la tobera de escape) tambien e echado un vistazo y no hay nada de agua,la cabeza del piston negra. De haber quemado anticongelante tendria color claro.

Espero tus avances con las pruebas que estas haciendo, ojala averiguar donde esta el problema.

Edito: al haber usado refrigerante presurizado,no se visualiza donde esta la fuga?