oil pump bleeder bolt and bubbles in lines

[CJF]

Does anyone know if there should be a washer under the air bleeder bolt on the T500 oil pump? I'm trying to problem solve air bubbles in my oil lines and have not been able to fix it yet. I have added stato seal washers in place of the aluminum crush washers hoping that would take care of the bubbles, but that has not fixed it. The parts diagram for the T500 doesn't show a washer under the air bleeder, but mine has one. Anyone know?

[CJF]

Ok, thanks for the info. I was thinking there might be a potential that there was air coming through the bleeder bolt, but probably not likely. Must be some other issue. Based on other posts, it may be the check valves stuck open. Guess I'll have the pull the lines off and see if cleaning them out will fix the problem.

[tz375]

On my 750 I was able to remove the pump and pinch off the feed pipe. Then I filled each line with oil and left the bike for what the GPS calls "for quite a while".

I cam back and some lines were still full and others were partially drained. That only reveals a forwards leak. Yours may be sealing that the forward direction but leaking from a weak spring. It might be worth trying.

[CJF]

I can see a constant stream of real tiny bubbles on both sets of lines coming out of the pump. If the check valves are stuck open, would that cause air to pass through the lines starting from the pump? It is worth a try to flush the lines and check the valves, but i am still trying to understand why I would see bubbles coming from start of the lines at the pump if the check valves on the other end of the lines is stuck open. Isn't the valve supposed to stay open when the engine and pump are on? If yes, then I'm wondering why a valve stuck open would cause air to leak into the lines the way mine are? I'm probably missing something basic...just wondering how this things works.

[tz375]

Good questions.

Think of the check valves this way. Each time the pump rotates it ejects one shot or pulse of oil into the line. That pulse of oil will be followed by another etc and the pressure of each pulse open the valve for a moment to allow that oil to pass and then closes behind it. The valves or not so much open all the time as opening and closing continuously.

On the other side of the check valve, every time the crank descends the gas pressure will try to push back into the check valve and will force it to close.

So that's the check valve side of things. The other question is how could an oil pump be pumping air bubbles. That could be an air leak at the bleeder or a torn gasket below the top cover or it could be an air lean between the pump and oil distribution manifold or maybe even a small crack in the feed pipe from the oil tank or an air leak where the feed pipe connects to the pump.

I like to start with the easy things:
Check valves - do they leak/weep/drain down?
Is the bleed screw leaking? Fit a fiber washer or statOseal or nylon washer and test it.
Oil feed pipe is there a washer on the banjo and does it leak?
Is there a leak in the feed pipe from the tank? test it
Are the O rings between the pump and distribution in good condition?
And then look at the pump if teh problem isn't solved

[CJF]

Thanks for explaining Richard...I get it now. I'll start with cleaning out the oil lines and checking the valves. BTW...how do you check to see if there is a leak in the bleed screw?

[tz375]

On mine, if I crack the bleed screw open, oil seeps out and when I close it the oil stops. Since I don't have bubbles, and it doesn't leak, I assume it's fine.

That isn't a very satisfactory answer I know, but I don't have an issue, so I didn't try to test it. I would expect that in general, if air can get in, oil can probably get out, unless the oil tank breather is blocked......

It may be possible for the pump to draw air in through a slight leak in the bleed screw if the breather is blocked. I have not tested that hypothesis, but I guess it may be possible. Worth checking at least.

[CJF]

I pulled the lines yesterday and let them sit over night standing upright...with cylinder sides facing down. The left side line did leak some oil to the point a small amount pooled under the line. The right side lines had a small amount sitting in the banjo, but nothing pooled underneath. I guess this also explains why my left side exhaust is always real smoky on start up after it has been sitting for a while.

I purchased a small oil bottle from harbor freight with pointed tip ($3 ), but not yet sure how to flush the lines with alcohol given the small opening. Will have to try a few more times to see if i can get them cleaned out and eventually working properly. It seems NOS oil lines are basically not available even on ebay, so this better work.

[tz375]

The 750 is easy in that the octopus has a large flat surface and it's easy to use a stock O ring to seal against the oil can. The 500 has separate lines with the banjo open on both sides. Can you devise a set up with say a flat plate drilled and tapped to take a banjo bolt and then bolt a line with a banjo bolt and then pump oil into the banjo bolt to get it into the lines?

Looking at the 500 set up, it seems that either a blockage in the oil tank breather (in the cap) and/or a slightest air leak in the feed pipe banjo could result in air getting into the pump. Try a couple of Stat O Seals or new nylon washers either side of the banjo on the feed pipe and see if that seals it.

Have you checked the filler cap to be 110% sure that air can get in easily to replace the oil? It's like a fuel tank in that there has to be a tiny air bleed in the cap or else it doesn't work properly.

[CJF]

I figured out how to do it. I put the bolt back in the pump side with 2 washers and a nut and tightened it down. This allowed me to get a good seal against the end of the bolt and pump alcohol in that end. I have flushed both lines 7 or 8 times now. The right line is working well and I am unable to blow air back through from the cylinder side (using my mouth and spitting a lot...its a wonder what you will do to keep these things on the road!). The left side is now working, but not all the time. Sometimes it holds and sometimes not. I will keep at it in hopes it will eventually start working 100%.

Funny you mention the oil tank breather. This summer I put a small pneumatic brass screw in screen vent (6MM size hole) in my tank cap where there was already a small drilled breather hole. I did this because there was some oil splashing out onto my paint when the tank was on the full side. I just went out and tried to blow air through the breather from the top of the cap and it was a little restricted. I just took it off and air flows much better, hopefully that will help solve part of the problem.

[CJF]

I have a slightly different setup from stock . My oil is behind my arss.

[diamondj]

I have a slightly different setup from stock . My oil is behind my arss.

Not to be the little devil on your shoulder but AHRMA is going to run a round at NJMP next year in early August. They have a race school for all of their rounds (except Daytona) so this would be a great opportunity to get your competition license. You did originally build your T500 as a race bike after all.

Jim

[CJF]

Thanks Bloop.

Hey Jim, not sure if racing is in the cards...but you never know. That little devil could change my mind.

[CJF]

I can't get my left line to work, so I stole another line off my project build in the works and flushed it to see if the check valves are working. That line had a stuck valve as well. I am beginning to think everyone is riding around on these things with stuck check valves not knowing it!!

I flushed this one a few times and then tried a few different things. I pulled the metal band off of the banjo where it attaches to the plastic line and tried heating up the banjo bolt a little in hopes this might free up the ball/spring components that make up the check valve. To my surprise, it actually worked and the valve now opens and closes. Not sure if this was just dumb luck or this might work for others.

I'm going to try the same with my original line to see if I can get the same result.

[CJF]

It was just plain dumb and no luck involved. Turns out the check valve I thought I fixed isn't fixed. I did the old fill with oil and let stand upright test....half the oil leaked out within 2 days. Should I expect some leakage like this or is that too much for a working check valve to leak?

I have now resorted to playing Russian roulette with used oil lines off Ebay. This could get expensive.