zrad

WR400 No Oil to Head

4 posts in this topic

Just wanted to take a minute and share a oil pump failure experience I had on my 98 Wr400. I picked up the bike in non running condition and it turned out to have a roasted head. I rebuilt the top end and was having a head oiling issue and it turned that one of the steel ball bearings dislodged from the pump only allowing the oil to flow back into the crankcase and not through the filter and up into the head. I assume this caused the original failure and I ended pressing the ball back in and it's working fine. Should I worry about it dislodging again? It's kinda got me scared and I was wondering if anyone has experienced a similar situation. I assume it would take some serious pressure to initially force the ball out in the first place and I'm now wondering why the heck they would use a couple balls to seal the ends anyway. Any thoughts?

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Tough to give much confidence to an 18 year old motor that is already shown to be capable of creating catisrophic failure.....

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Yes, you should worry about it.  If it pressed out in the first place and you only pressed it back in, the bore has been worn twice.  You need to stake it in and I would have put some retaining compound on there before you pressed it, but that ship's sailed...

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I will be replacing this faulty pump. Does anyone know what kind of pressure the oil pump runs at?

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