Sq4 MkI - what now?!?

[Gui.dorey]

Many thanks Paul. I’ll turn a piece on the lathe and try it out.

What I still don’t understand is if the release valve is faulty and basically remains open letting the oil flow through it, why do I have a lot of pressure when cold? The gauge needle always went to the stops after starting and only started slowly coming down after 5 miles or so. With so much pressure when cold, I would have thought the relief valve would open then and not when warm and the oil is more fluid. Or am I thinking this completely wrong?

[Gui.dorey]

Take the timing side end cap off the front crank, remove the oil pressure relief valve and test that to see what pressure it blows off at. If need be I can PM you my design of a simple test rig for this purpose. If the oil pressure relief valve wasn't working, oil pressure wouldv drop to zero as the oil warms up and all oil would flow straight into the sump, rather than to the big ends.

It wouldn't leave all the oil in the sump though, would it?

Simes, I could be wrong, but what I think happens is that the relief valve allows a much larger oil flow through it than through the passages to the big ends. As the Morgo pumps a huge amount if the relief valve is open the oil just flows freely through into the cases filling them up. It takes the path of least resistance and thus the big ends are starved. But again, I am not sure if I fully understand how the whole system works.

[simon.holyfield]

I think you are right - the resistance to flow through the relief valve will certainly be lower. My oil pressure drops with engine temperature, to maybe 25 psi (idling) after about 15 miles riding. Never lower though.

[Gui.dorey]

Paul (Jameson),

I’ve built my own high tech relief valve testing device and it could be I found the problem.

I used my equally high tech bicycle pump which has a gauge and at first I was happy seeing the pressure go up very fast with the first two pumps. However as soon as I stopped, the pressure came steadily down to zero. Also tested in a bowl of water to make sure there were no other leaks somewhere.

It seems my pressure valve opens straight away and doesn’t close/seal again. The ball isn’t sealing properly. All three parts - housing, ball and spring - are new. I can’t see anything wrong with it, even hit the ball on its seat, but to no avail. It doesn’t seal.

So I suppose part of my wet sumping comes from the incontinent valve and as the oil became more fluid with temperature, it just flowed through the valve and didn’t hold up pressure and flow to the big ends. Sounds about right?

If that is indeed the fault, I’m glad I found the cause, but still don’t know what the problem with the valve itself is. Bad machining on the housing? A wrong or bad ball? Maybe this is a test Draganfly should do before delivering new relief valves to customers.

[paul.jameson]

That sounds exactly like the faulty valve which I had, although mine was a genuine Ariel original. Like you, I changed spring and ball, hit the ball onto the seat then fitted a new ball, etc. all to no avail. Like you, I could see absolutely nothing wrong with the seat. I test all these valves before fitting now.

[Gui.dorey]

For such a critical component, it seems to be a faulty design, if several don’t work for no apparent reason.

So, who has a good working valve body they would be willing to part with?

Cheers,
Gui

[daveleek]

Gui , Acme stainless have them 2151-50 for 14 quid

[simon.holyfield]

Does the spring foul somewhere when the ball is moved off its seat?

[rschurr]

As I understood, you installed a Morgo oil pump. A pressure relief valve is installed in this. So you don't need a pressure relief valve in the crankshaft. You can simply replace the end of the shaft with a short matching screw. This is how I did it.
Cheers Rudy

[Gui.dorey]

As I understood, you installed a Morgo oil pump. A pressure relief valve is installed in this. So you don't need a pressure relief valve in the crankshaft. You can simply replace the end of the shaft with a short matching screw. This is how I did it.
Cheers Rudy

Are you sure? I don’t think the Morgo for the MkI has a relief valve. If I remember correctly that only comes in the version for the MkII.