Pressure test for rotory gear chamber.

[Black67tb]

Hello. Put the cases together with a new crankshaft on my 787. Did a 5 psi pressure check at the rotory valve chamber. But l don't know the rate (or timing) of bleed off on the pressure. Would appreciate some feedback.
Thanks.

 

[coreygmart]

I am not too sure on the 787, but for the 580/650/720 you should be able to hold 6-8 psi for 10 minutes without any lose.

 

[Black67tb]

will the pressure gradually decrease to zero.?

 

[tobytd]

Get out your soapy water.

 

[mikidymac]

No pressure should not drop at all. You should really be pressure testing the engine by blocking off the intake and exhaust and pressurizing through the pulse line, not the rotary chamber.

 

[Black67tb]

No pressure should not drop at all. You should really be pressure testing the engine by blocking off the intake and exhaust and pressurizing through the pulse line, not the rotary chamber.

Yes, l will do the complete engine test as you described. I just wanted to test the rotory valve chamber before i continued with the rest of the build.

 

[Black67tb]

kinda disappointed. Got a new crank, rebuilt rotory valve shaft with seal, assembled the case with Threebond, and i see this leak.

 

[Black67tb]

No pressure should not drop at all. You should really be pressure testing the engine by blocking off the intake and exhaust and pressurizing through the pulse line, not the rotary chamber.

So, the leakage in the rotory chamber l see is not a issue until l complete the engine assembly?.

 

[DanSquires]

So, the leakage in the rotory chamber l see is not a issue until l complete the engine assembly?.

If your cases are assembled and your RV shaft is installed, you should be able to test the RV chamber.
On a fresh build I pressurize those at 8lbs and they typically hold all 8lbs overnight.

 

[etemplet]

Pressure testing the rotary chamber is quick and easy. Stick a hose on the outlet line and clamp it... pressure test the inlet line. Done. This one was leaking at the casing seam inside the rotary valve. I was able to stop the lead without disassembly. Good Luck.

 

[Black67tb]

I assembled this case with a new rotory shaft seal and a new crankshaft including new center seals. Then i used Threebond on the case halves. I plugged the oil outlet and pumped air at the inlet. Leaks down within minutes. So l took it apart and tried sealing the case with loctite 518. Let it sit for 4 days. Tried pressure testing again. Still leaks. Also used soapy water on all the seams and at the rotory shaft seal. What am i missing? The cylinders, pistons, and cylinder head have not been installed yet. Do they need to be?

 

[etemplet]

Did you put any sealant on the outside of the crankshaft inner seals?? I didn't do that on the first 787 I built and that engine has leak on the inner seals. I believe both sides. I installed a valve to shut off the oil when we are no running the ski so it works fine. My point is that NOW, I always put sealant on the outside of the inner seals. Not a lot but enough.

 

[Black67tb]

Yes i put sealant on the inner seals both times. The only thing l can think of is l purchased a set of used cases because the balance shaft broke in half and cracked my original case in 3 places. Maybe these used cases are not straight? Wonder if anyone seen this before.