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4T, Impeller, Water Pump, Engine


bigbird2
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My 2009 300 4t has suffered it's 2nd major engine failure. I'm looking for help advice on how to not have a 3rd! -----

I bought the bike used and it always seemed to overheat. I finally partially solved this problem by changing to Evans coolant which has a much higher boiling point than any other coolant. This seemed to work for a while - probably because the ambient temperatures were low and I didn't generally run the bike hard or for a real long period of time. ------

Eventually I started hearing a loud knocking noise and the bike started running badly. I tore it down and found that the red fiber cam chain tensioners had melted and pieces of them were all over the right side of the engine, etc. Thus the knocking noise was the cam chain flailing around and the poor running was the bad cam timing and/or the engine temperature. The coolant was also low. -------

Farther investigation showed that there was NO IMPELLER on the water pump!!! My assumption at that point was that the prior owner had done some engine work on the bike and just forgot to install the impeller. SO I cleaned out the engine, replaced the melted cam chain tensioners and installed a new water pump impeller. I also did some other things like changed the cam chain and the water pump shaft and seals and some gaskets, etc. to try to make it as good as possible. When I reassembled it the engine seemed to still have good compression and ran fine. ------

After a few hours of low stress use all seemed OK. I then lent the bike to a friend to use to help a beginner learn to ride and after several hours the motor stopped. It appeared to be seized (kick starter wouldn't move when trying to kick it over). I pulled the clutch cover and found big pieces of the fiber cam chain tensioner in the right side clutch and drive area. Once I had the clutch off the crank would turn - SO apparently it was just locked up from a piece of the cam chain tensioner getting jammed in the primary gears. I then tore the engine down to investigate and replace what was damaged. I figured maybe I'd over stressed one of the tensioners when I replaced them because I remember having to force them some to get them in. HOWEVER upon farther investigation I found that THE WATER PUMP IMPELLER WAS AGAIN MISSING - TOTALLY GONE !!! ------

I KNOW I put a new one in there last time. Although I had thought the 1st failure was due to the prior owner failing to put in a impeller (because I couldn't imagine that it would totally disappear) I now know that these impellers can TOTALLY DISSAPPEAR!!! ------

SO now I don't know what is causing this OR what to do to prevent this from recurring? I think I remember reading about an aluminum impeller replacement? IS THAT THE FIX??? HELP! ------

Unfortunately I also found that the piston is scored and there is piston material on the cylinder wall. I haven't done any analysis of how badly the cylinder is damaged but that is next and I will obviously need a new piston and a cylinder hone or bore or replacement depending on how bad it is. Any advice on this would also be appreciated. -----

THANKS for any help!

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I have a 2011 Evo 300 4t that I bought used over a year ago. Had a similar thing happen. It was leaking oil from the cylinder and head gaskets. Found out there was no impeller blade, which may have caused it to run hot, pushing a pin hole leak in the top rockerbox cover, which only uses a sealant, not a gasket.

Long story short, replaced all of the gaskets, selants and had te vales adjusted, replaced the plastic impeller blade and run Engine Ice for coolant. Have run this set up for over a year now, no issues. I took the water pump cover cover off to check on the impeller blade, yep, still there, in good shape.

Sounds like your engine may have been running too hot for a while causing the cam tensioners to melt. Are all of the cam bearing good or worn out? May want to check your fan and sensors too, make sure it is kicking in to help cycle the coolant. You could of had a air pocket keeping the water from not circulating and just staying hot. Jitsie does make an aluminum impeller blade, larger with an adaptor for the cover to handle the larger blade...may push more fluid to keep the bike cool.

I have heard other Beta owners complain about this issue, even with the 2Ts.

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