clear pvc fuel/oil lines

General forum on engines, transmissions, gearing and modifications to each

Moderator: rztom

Message
Author
silverstrom
- - - - -
- - - - -
Posts: 3236
Joined: Sat Feb 04, 2012 7:36 am

Re: clear pvc fuel/oil lines

#16 Post by silverstrom » Wed Aug 30, 2017 7:47 pm

The check valves are outside the pump and easy to see. They can be removed, but are a non-serviceable part, meaning you can't take them apart to clean them. Inside the check valve is a spring and a small steel ball. The spring presses the ball against the valve opening and seals it closed when the engine isn't running. When you start the engine pump pressure overcomes spring pressure and oil flows. Problems arise when the spring doesn't fully seal the ball when the engine is off. That lets oil migrate past the check valve and with the oil tank being much higher than the check valves that oil takes the path of least resistance and ends up at the carb manifold and then into the cylinder. It's a common problem and not unique to Yamaha. If you remove the valves you can shoot parts cleaner through them, which does help remove dirt and crud, but if the springs are weak you have a problem. There is a solution, as you can see in my photo below.

If you do attempt to remove the check valves be VERY careful. They are fragile and it is VERY easy the snap the threads off.

http://www.rzrd500.com/500phpBB3/viewto ... =3&t=14145" onclick="window.open(this.href);return false;

Image

Image

trix
- - - - -
- - - - -
Posts: 371
Joined: Mon Feb 25, 2008 11:44 am
Location: Northern Ireland

Re: clear pvc fuel/oil lines

#17 Post by trix » Thu Aug 31, 2017 7:13 am

It's $90 (£70) for 4 of the valves shipped to me in the UK from boats.net.
Then I'd need another 8 of the clips; $32 (£25) so $122 all in!

User avatar
jackson.40
*****
*****
Posts: 2328
Joined: Fri Dec 30, 2005 7:01 pm
Location: Cambridge,UK

Re: clear pvc fuel/oil lines

#18 Post by jackson.40 » Thu Aug 31, 2017 5:54 pm

From the old newsletters...................

Image

Image
Last edited by jackson.40 on Sat Apr 21, 2018 3:30 pm, edited 1 time in total.

trix
- - - - -
- - - - -
Posts: 371
Joined: Mon Feb 25, 2008 11:44 am
Location: Northern Ireland

Re: clear pvc fuel/oil lines

#19 Post by trix » Fri Sep 01, 2017 6:27 pm

this is great thanks jackson. Though it seems to be very risky to take the nozzles out to inspect them as suggested. Might be safer to put the outlet pipes into 4 separate containers and see if any oil leaks out over a day or two??. Adding an additional check valve in the line wouldn't help the problem he mentions of there being not enough oil in one line..

trix
- - - - -
- - - - -
Posts: 371
Joined: Mon Feb 25, 2008 11:44 am
Location: Northern Ireland

Re: clear pvc fuel/oil lines

#20 Post by trix » Sun Sep 03, 2017 10:46 am

wonder if the cracking pressure is too low on these;

http://www.ebay.co.uk/itm/NEW-Sullivan- ... XQNOZRCD11

Post Reply