Yamaha TRX850 Enthusiasts Forum

OK, the subject title says it all really - I know I've got the correct amount of oil in the
motor but recently I've noticed on a number of occasions that there's none visible in
the sightglass.
This can happen when the motor is stone cold, after warming up or even after a ride.
Has anyone else had this happen? I've read on here that the TRX has two oil pumps -
I guess one is for returning oil to the dry sump - is it possible that this pump can only
work intermittantly - sometimes there IS oil visible in the sightglass.

I would imagine there`s an oil return valve check valve (don`t have time to check the pdf ). If there is then it`s allowing your returned oil (in the tank) to run back past the oil return pump down into the sump.
Whatever it needs some investigation although if you`re CERTAIN she`s not excessively using oil and there`s plenty in there it`s not urgent that you do it immediately.
How much oil is in the tank as soon as you turn the bike off after it`s been up to operating temperature?
If the level in the sight glass is right you can be sure you`re ok to run it.

monitor your tailpipe or tailpipes too. You know your oils there,you'll soon know if your burning it.

this sounds a bit daft, but also check theres not too much oil i.e. The siteglass is full of clean oil so theres no oil line to see.

Mincehead wrote:I would imagine there`s an oil return valve check valve (don`t have time to check the pdf ). If there is then it`s allowing your returned oil (in the tank) to run back past the oil return pump down into the sump.
Whatever it needs some investigation although if you`re CERTAIN she`s not excessively using oil and there`s plenty in there it`s not urgent that you do it immediately.
.

where does the oil pump that sends oil to the crank source its oil from? if its from both oil tank and crankcase then its not so bad, but if its only from the oil tank then you run the risk of burning out the crank bearings due to lack of oil, no?
sounds like the scavenging oil pump is on its way out?

iirc from reading other threads there is more than pump and they have nylon gears

Thanks guys - couple of answers for YOUR questions: since doing the rings & stem seals in 2009 mine
doesn't seem to use oil & I know it's got the correct amount in it, exhaust tailpipes are not oily, it's not
a case of the oil being so clean that it's not visible either. As I said before, sometimes you can see the
oil in the sightglass as per normal.

Hi pbear62!

It is most probably as Mincehead already supposed:
There is a valve for keeping the oil in the oiltank to let it only be conveyed by the oil pump.
If this valve does not do its job anymore the oil follows the laws of gravity and the sightglass is empty.

Lightweight greetings from Munich!

OK, as Mince & Holer have suggested, there is a relief valve in the system (it's shown in the workshop
manual - lubrication section) - but I've looked right through the whole manual & it doesn't mention
anything about removing or checking it. Anyone else had a problem with this valve?

The relief valve is not the non return valve that Mince mentioned. The non return valve would be between the oil tank outlet and the pressure pump and as far as I know the TRX doesnt have one.