Yamaha TRX850 Enthusiasts Forum

Ok, bit of a strange one...

Last night I got the engine swap done, fired it up after a lot of coaxing & a little bit of swearing, & I thought all was going well.

I had oil pressure from the bolt on the head, so I figured I would take it around the block, that went well, came back, tightened up a few things I had missed, namely the brake calipers & took it get some tea.

I got about two block away, stopped at the lights, then there was a huge bang!

I looked down, saw oil everywhere & said a few very brief & succinct swear words, then pulled into a servo around the corner to have a look.

I couldn't believe my eyes, I just stood there looking at it for a minute or two. The whole sight glass where it presses into the oil tank is gone.

Any way, there was still oil in the bike & it was still flowing, so I rode it the two blocks or so home & gave up for the night.

Anyone have any idea how this could have happened? I put bit less than 4 litres of oil in it, maybe 3.5... but it should hold 3.9, right?

I was thinking it might have been either too much oil (is this possible?) or a blockage further down from the oil tank, I'm about to go & see if there's still oil pressure & if I can drain from the tank, I'll report back.

Thanks in advance!

Oh, & damn yamaha to hell for not putting in a oil pressure light!

Whoo, i´d have to change underwear after that...

For sure must be a blockage so the pumps pushed all the oil up in tank creating pressure and pop!?
Mine take´s just over 4L when also doing filter change...

Oh boy, I'm now living in fear of having my right leg shot off from the impact of a sight-glass travelling at sub-sonic speed........ that's a bit of a mystery you have and I couldnt help give it some thought......... how's this for a daft suggestion?.... if your replacement engine still had old oil left in the crankcase, ie. it hadn't been drained, and you then filled the reservoir tank with fresh oil, the scavanger pump would then transfer the old oil from the crankcase up to the reservoir, and do so faster than the lube pump could remove oil from the tank back to the engine (scavanger pumps have a greater flow rate). The situation would end up being that after a short time the tank would completely fill, and "hydraulic". Probably the first thing to give out would be the sight-glass, to relieve the pressure.........please keep us informed on how things are going ...... I'm really interested in what caused this.....Good luck

Never heard of that happening before

And you can bet it's not a service item

Orright, I've sorted out the problem, lets just say it was operator error & leave it at that hey?

No, I'll post up a pic of the fault when I get home tonight, you may get a laugh out of it!

Never heard of that happening before

And you can bet it's not a service item

Sure isn't, yamaha want $360 of my hard earned australian dollars for a new oil tank top, lucky my wrecker had one for $85!

Okay, you got me curious. Now come on with that pic, just for education and entertainment!

waiting for a pic and explanation

Spot the Error for 20 points!

why is there a black dot and a silver dot like something sealed on the inside of the tank on that dooverlacky part bout third of the way down from the top left.. Had a spark plug shoot me in the leg off my old triumph bonne when I blew that out coming across the story bridge ...thank god it was only at 60kmh just chuggin along...Lucky I saved the plug(and shooting someone else ) ...the lead kept it from goin too far.

I see it - unlucky

Not quite sure, glad you could get a cheaper option from the wreckers though! What a bugger of a thing to happen...

You'll notice one more hole in the gasket on the left, the new one I made!

Guess where the hole leads? That's right, into the crankcase, it's the breather for the oil tank!

Oh well, a lesson learned. The new engine is getting better by the mile (klm?), time for an Italian tune up I think!

Good to see alls well again , usually with gaskets it's too much goo

Thanks for the insight......I was baffled as to how the tank was vented. I hadn't noticed when I had my tank off last, which is a bit worrying that I wasnt that observant. ....great find