oil pump problems on GT250

[jabcb]

I've had the bike for a few years. In the past I added oil every few hundred miles, so previously the oil pump was delivering a reasonable amount of oil.

Now three of the four oil lines between the oil pump & motor are mostly full of air.
Oil tank has always been at least 1/2 full.
No signs of oil leaking from oil pump.
Tach drive is at the top of oil pump. By using the kick start, I have confirmed that the oil pump shaft turns.

Does this indicate that the pump lost its prime?
Not sure what to check or repair.

[oldjapanesebikes]

If there are no signs of oil leaking anywhere, I suppose it is possible you have a stuck piston in the oil pump. Any air in the lines would be coming back from the check valves. The GT250 pump is similar to the T/GT500 one - I have a photo of one disassembled at this link:

http://www.oldjapanesebikes.com/mraxl_G ... f_Oil_Pump" onclick="window.open(this.href);return false;

You can see the piston on the right. It may also be possible you have a failed check valve or perhaps a leak at the connector where the lines split into two, but on that setup I would have expected to see air in one side and oil in the other. I suppose if you can see oil in the feeder side, but not past the connector that may offer a clue also. See this link:

http://oldjapanesebikes.com/blog/2011/0 ... continues/" onclick="window.open(this.href);return false;

[jabcb]

Oldjapanesebikes, thanks for the input.

Started working on the bike. I have oil in the lines up to where the 1-to-2 joints are. So it looks like the pump is ok.

Am going to take the lines off. Then clean & seal them with clear liquid electrical tape.

Those hollow union bolts look like something an amateur mechanic could easily snap off. (Especially me.)
What should I torque those union bolts to?

[ConnerVT]

3.6 lb ft (50 kg-cm)

Per the T500 Service Manual. I'll assume the GT250 banjo bolts are the same part.

[jabcb]

ConnerVT, thanks for the torque spec. The T500 & GT250 use the same union bolts so 3.6 lb-ft should be good for the GT250 too.

Am working on the right oil line.

Am using several "Squeese It Oil Cans" from harbor Freight:
http://www.harborfreight.com/6-oz-squee ... 96797.html

Flushed line using alcohol from oil pump end & have good flow through both lines. Then flushed using air (used an empty "Squeese It").

Flushing from motor side but did not squeeze very hard:
1) no flow on one line. check valve seems to be working good.
2) easily flows on other line with no apparent resistance from check valve.

Anyone have ideas for what to do? I don't think my skills are up to the task of taking the check valve appart to fix it.

[jabcb]

Update…

Flushed the lines again. Now tests ok & both check valves are working.
Think I have everything figured out now.

[Nomadmax]

Can you post a pic of how you flushed the lines of air from the oil pump side?

[jabcb]

Am just an amateur mechanic, so other forum members are a lot better at this.

Used two "Squeeze It Oil Cans". One is empty & used to flush with air. Filled the other one with alcohol for flushing with alcohol.

The tips don't go all the way through the oil line fitting. So I just press a finger on the other side to force the liquid or air through the line.
When flushing with alcohol, keep the can upright with the oil line above it because it only works right sight up.

Alternated between flushing with alcohol & flushing with air until the lines were clean & the valves worked.
For the T250/T350/GT250/T500/GT500 you need to do this until you have good flow from both lines.

Used a Harbor Freight "Flexible Spout Oil Can" filled with injector oil to prime the lines.
http://www.harborfreight.com/catalogsea ... 20oil%20can

I mostly filled the line with injector oil prior to installing the line.
The tip also doesn't go all the way through the oil line fitting. So I just press a finger on the other side to force the liquid or air through the line.

Then installed the line & banjo bolts feeding the crank & cylinder. Topped the line off with injector oil just prior to installing the oil pump banjo bolt.

A big improvement is to ditch the aluminum crush washers & use stat-o-seal washers.
You shouldn't reuse the crush washers. The stat-o-seal washers work better & are also cheaper.
For info on stat-o-seal washers see: viewtopic.php?f=9&t=6094

Hope this helps.

[Nomadmax]

Come next season I'm gonna have to ride over to SW PA and buy you your favorite beverage! Thanks

[rbond]

Did you check the fitting at the oil tank? I think it is supposed to have a filter of some kind in it, if so, then if clogged up, it could starve the oil pump.

[Nomadmax]

I did not. I will do that before I run it any further. Thank you.

[jabcb]

Problem fixed.

Used stat-o-seal washers & torqued banjo bolts to 30 lb-in (2.5 lb-ft).
Have blue oil in the oil tank (BelRay Si-7). Primed the oil lines with red oil (Amsoil Dominator).
Took the bike out for a several mile ride. Oil lines now filled with blue oil & no air bubbles.