787 RFI Leakdown Test

[mattrourke]

I'm sorry if this has been covered but I've been searching and haven't found a write-up for doing the EFI Leakdown test. This is completely new to me so I'm not at all sure how to set this up. I found info for the carbuerated engines but not for the RFI.

My understanding is I need to block off the exhaust and the intake somehow and provide air pressure to the pulse line and then install a gauge somewhere to monitor the leak down.

First off... Which is the pulse line? I believe I can just hose clamp a valve from an inner tube onto there and use a bike pump to create 10psi... Where do I then install the gauge to monitor it or can I just watch the bike pump gauge?

Second... The engine is still in the machine and we are trying to find out where I'm losing power so I would like to keep the engine mostly installed until the problem is diagnosed... Can I unbolt the exhaust and the intake and create a rubber block off plate from an inner tube or something and bolt them back up to create a rubber barrier? Or do I need to create an aluminum or steel solid plate?

Is there something else I'm missing completely?

 

[mikidymac]

You can use rubber between the manifolds and pipe/intake to seal them off. that is what I do.

The pulse line is for the carb skis so you will have to find another port to get air into the engine once blocked off.

 

[mattrourke]

You can use rubber between the manifolds and pipe/intake to seal them off. that is what I do.

The pulse line is for the carb skis so you will have to find another port to get air into the engine once blocked off.

Thank you for the reply. I know we were speaking about this already in my other post but thought this info specifically might be helpful to someone else one day. Can i pressurize through the spark plug hole or do i need to find an access in the bottom end? Sorry for all the questions i just want to make sure i get this figured out properly.

 

[mikidymac]

If you can make and adaptor that will hold air pressure to go in the sparkplug hole then absolutely yes.

 

[mattrourke]

Perfect. Thank you! At least now I have something to try that doesn't involve a trip to the lake for a 5 minute test. 10 trips to the lake in the last 10 days is getting old real fast.

 

[mattrourke]

I'm attempting to get this leak down test done. I've blocked off the intake and the exhaust with rubber. I plugged the vent on the exhaust manifold. Is there anything else I need to block off? I'm applying pressure through the spark plug hole but it never seems to build pressure. Im using a bike pump and it is hard to pump but continually and steadily drops down to zero. I'm just wondering if this is the final result of my leak down test or if I simply forgot to plug or block off something else.

Thanks!

 

[mikidymac]

You need to block off between the manifold and the throttle body, not the air cleaner base.