Cold Start Valve

[AMM]

Good afternoon.

Have a rich running situation. Likely from leaking csv. First 3 cylinder plugs very black,the ones closer to the Csv.

Split linkage test shows rich at idle.

I've taken the electric solenoid out and can see the piston of the Csv. Ignition on I can see fuel seeping through. Under vacuum this would probably suck a lot of fuel into the intake.

Csv disassembled and piston polished / lapped with autosol Polish. Still see fuel seeping through. Pic attached to show what I mean.

Taking the small 7mm nut off shows dampness through the hole as well which is expected if I can see the fuel seeping the other side of the piston.

Question is should the shut off be complete with no fuel allowed through?

Can get a replacement piston from either Neimoller in Germany. Will a new piston solve my issue?

Thanks in advance.

[ctaylor738]

The definitive test for a leaking cold start valve is to remove it, turn it around, reconnect the fuel line, turn the ignition on, and observe the nozzles. You can also connect the electrical if you want to test that along with the spray pattern as well.

You should have a gasket on hand before removing the valve.

Cheers,

CT

[ja17]

Depends on cost? Some vendors of IPs also offer a reconditioning service on the CSV. You can also verify your diagnosis by blocking the fuel line to your CSV to see if the rich situation goes away.

[AMM]

Thanks for replies.

How would I block off fuel line? Any idea on bolt / nut size and how to plug the flared connection from fuel line to valve?

[ctaylor738]

You can block the line by screwing a bolt into one end of a 3" piece of fuel hose.  Slip the other end over the feed line and secure it with a hose clamp.

CT

[Lorsar]

I was able to fix my leaking csv after taking it all apart and cleaning it, then I gently stretched the spring a bit which allowed for the needle valve to close tighter.

https://www.sl113.org/wiki/Engine/ColdStartValve#toc-1

[AMM]

Thanks.

What did you clean with?

I used autosol polish, Stretched the spring a bit but made no difference.

The new piston is around £30. Concern is if the other side is worn. Probably worth trying for the price of the piston.

BW

[Lorsar]

I soaked everything in carb cleaner.

[ja17]

It is common practice to use a steel ball to block a fitting. Don't choose a size too small. Probably something like a 5mm or 6mm diameter steel ball. Just use a little grease and stick it in the fitting and gently snug the fuel line nut. a lot of pressure is not needed.

[AMM]

It is common practice to use a steel ball to block a fitting. Don't choose a size too small. Probably something like a 5mm or 6mm diameter steel ball. Just use a little grease and stick it in the fitting and gently snug the fuel line nut. a lot of pressure is not needed.

Amazing tip. Thanks for sharing.