What does the steel ball inside the oil filter do?

I was changing the oil on my bike as part of a clutch replacement and I noticed that it was missing the small steel ball in the center bolt. I have no idea how long it has been missing although I can assume it was probably during my last oil change. As far as I can tell there have been no ill effects on my bike. Could someone please tell me what it does and whether I should be concerned or if I can let it wait until my next oil change? I would assume it has something to do with controlling the flow of oil within the filter element but I'm not sure for what purpose. Any advice would be greatly appreciated.

 

without looking at a parts fiche (i'm just pulling this outta my ass here) I'd say it's part of a checkvalve.

 

And, what exactly is a checkvalve?

 

I believe it a relief valve.
When the filter plugs and reduces oil flow, the relief opens and allows the engine to stay lubricated. You don't want to shut off oil flow to the engine.

No oil pumping is a BAD thing. (it's worse than pumping dirty oil since you didn't change the filter)

OH...and a check valve will allow liquid (or gas) to flow in one direction, but not flow in the opposite direction.

 

I'm leaning towards relief valve... mostly, because I change my oil regularly and would love for this to be something simple.

 

It's the bypass valve. If the oil filter becomes clogged the ball moves and allows the oil to bypass the filter. No ball=bypass open=oil doesn't get filtered.

I don't believe the ball is a separate piece, it comes as part of the bolt assembly. Time to send some wampum to Chacal.

 

Hmm... that would seem important. I imagine I could just replace it with a ball bearing of the appropriate size though, rather than replace the entire bolt.

 

best to replace the complete bolt assembly as a unit. you don't want to be stuffing around trying to find the right size ball and correct tension spring and hoping that it stays together when for a few dollars you can get the genuine article and have the lubrication system running the way the good folk at yamaha designed

 

Really.

From chacal's catalog: HCP270 Aftermarket oil filter PRESSURE RELIEF BYPASS VALVE & COVER MOUNTING BOLT, bright plated finish, large 17mm head, fits all XJ550, XJ650, XJ700, XJ750, and XJ900RK models. NOTE: All Midnight Maxim and XJ900RK models used this bolt, but it had a black finish on the head. $14.95

You definitely need to get that replaced now.

While we're on the subject, you do have the spring and thin flat washer that go ON the bolt and hold the filter against the motor, right?

 

As far as I could tell all that was missing was the ball... everything else was there. And, I would imagine $15.00 would be a whole lot cheaper than a new engine. Although, I could just take this opportunity to install the spin on oil filter.

 

yep yep. Some pumps need stay primed (your heart for example can't pump blood with air in it) I thought it might be to keep oil draining down from the OHC's from back flushing the system. Yer right though, it's a relief valve like an air regulator. (which incidentally don't allow back flow either since they're basically check valves with a certain amount of force holding them shut)

 

Carl is correct; your oil hasn't been flowing through the filter is all (well, some of it maybe since the filter isn't clogged) but the bypass is open without the ball.