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Air in lines or sucking out oil question?

Posted: Sun May 11, 2025 7:01 pm
by Repeater
I recently had my 73 T500 engine rebuilt. Crank, pistons, and some mild porting with 34mm flat sides. I have been having what appears to be the oil being sucked out of the lines on the left (clutch) lines. I primed the lines with my spare pump. I let them sit over night with the check valves facing down with no leaking. I don't have anything to check the break pressure of the check valves at this time. What have you folks used for checking?

The lines stay filled up to the junction but appear either be sucking in air or are having the oil sucked out by the engine. Not sure which.

I'm getting pretty frustrated. I'm guessing its the one junction, but wanted to know if there could be anything from the rebuild that could cause something to create to much of a vacuum that would open the check valves and suck in the oil? All new aluminum oil seals. right side no issues. And I also primed the pump.

The engine when I let it run sounds amazing.

Any suggestions for DIY line solutions would be helpful. I've done my searching. What tubing and interconnections besides the OEM junction have been used by folks.

Thanks

Re: Air in lines or sucking out oil question?

Posted: Mon May 12, 2025 1:36 am
by joethebike
On my T350 there was a problem with air bubbles in the lines that was traced to a crack in the plastic line hiding under the metal collar securing the plastic line to the pump end banjo fitting.
This is not the same as your draining problem but you never know.

Re: Air in lines or sucking out oil question?

Posted: Mon May 12, 2025 2:05 pm
by karl pa
The junction is a common place for air leak, some coat the junction with clear epoxy or sealer, this will verify the problem is there. Some have made new lines, a search on here may find results.

Re: Air in lines or sucking out oil question?

Posted: Tue May 13, 2025 10:30 pm
by Repeater
Found this post.
http://www.suzuki2strokes.com/forum/vie ... p?p=177240

And these check valves. I'm hoping they will ship here.


https://www.cmsnl.com/products/valveoil ... 671094502/


Has anyone tried these valves? Any update from the OG maker?

Thanks,

D

Re: Air in lines or sucking out oil question?

Posted: Wed May 14, 2025 11:53 pm
by Repeater
It's the lines stupid.

I took apart a couple of lines to get two good check valves. Grabbed a 1/8" 3 way drip system splitter and some 1/8" clear tubing that was pretty hard from age. Stuck it all together and Bingo no air.

Now I want to get some spare check valves. Not sure if I should get the Ebay ones from the UK or the one in the link above that kall399 used. And thanks kall399 for replying to my PM.