K series inlet manifold

[Derek Clement]

Does anyone know if a jiggle valve [non return valve] is incorporated in the inlet manifold.It would be where the small pipe connects manifold to expansion tank.

[revilla]

Yes there should be a small captive ball that performs the function you describe.

[Derek Clement]

Is the ball metal or plastic, I understand it is designed to release air from manifold but not allow air to be drawn from expansion tank when engine running.It seems the only way to tell if it is jammed is to dismantle the manifold from the head. Some Rover forums suggest removing ball and fitting a restrictor in the hose,I note there is a restictor in the hose connection at the expansion tank.

[revilla]

Not sure what it is made of but pretty sure it is hollow and floats. The valve definitely closes when the flow is out of the head to the tank and opens when the flow is from the tank to the head though, which is slightly different to what you describe. I think the idea is that when there is air behind it the ball drops down and allows the air to flow out. When there is water behind it it floats and blocks any significant outward flow of water, buy allows water to return on cooling.

[Derek Clement]

thanks for your thoughts. I am going to have to bite the bullet and dismantle the inlet maniold to have a closer look.

Cheers Derek

[Richard Price]

I've known a few to stick. Removing the hose and poking a small screwdriver or allen key until you feel resistance, then a light tap normally frees the ball from the seat. If you press too hard and actually push the ball out completely, then its not the the end of the world. Most cars with TB's simply have a nipple and run with a constant return back to the header tank.

[Wrightpayne]

My inlet manifold was off recently and its a metal ball bearing - if I squeeze the bottom hose hard repetitively you can hear it clicking as it moves too and fro and water is pushed up into the expansion tank.

I'd be inclined to remove the hose and have a gentle poke around first.

Ian

[Derek Clement]

Update on problem with cooling system,the problem I had was expansion cap releasing coolant. Tried new cap Rover [E bay] no better, started thinking head gasket. Fitted a pressure gauge to hose near heater matrix, cap releasing pressure about 0.6 bar. Was new cap faulty?  Made a test rig as suggested on a rover forum, Old expansion tank from scrap yard , cannibalize cycle inner tube and connect to small tank connection [bits of hose jubilee clips etc] more jubilee clips pressure gauge on larger tank connection. Fit cap to tank pump up pressure with a foot pump till cap releases pressure.

This confirmed new cap faulty, ordered cap from Redline [ the release valves in new cap are different, has the cap been modified] ? Problem solved !

Cheers Derek

[Jonathan Kay]

Well done. And a nice test routine.

Jonathan