restrictor is TOO restrictive

[frankh]

For a while now I have been starting my Mattituck and waiting for 6 or 7 seconds to see ANY oil pressure.

Made me very nervous.

After some testing it turns out that the oil line contains air not oil and this acts like a big spring and on start up the oil has to flow that little tiny hole and compress the air before it shows pressure.

Over night of course the air gradually forces what little oil there is in the line back through the restrictor.

I took my restrictor out and bingo...Instant pressure on cranking.

Now one could argue that removing the restrictor is a bad idea in case the oil line failed but if your worried about that then you would never install the oil cooler.

The Dynon has plenty of signal dampening by itself apparently. The other option is to make sure the line is full of oil.

One sqwark down a couple more to go.

Frank
7a

[Mel]

Frank,
Might I suggest that you drill the restricter one size larger and try it again. That restricter really needs to be there. I have a pretty small hole in mine and the gauge responds immediately.

[airguy]

You could also replace the current line with 1/8" stainless to minimize the internal volume. Come to think of it, with 1/8" instrumentation line, you wouldn't really even need the restrictor in the first place!

[frankh]

Originally Posted by Mel

Frank,
Might I suggest that you drill the restricter one size larger and try it again. That restricter really needs to be there. I have a pretty small hole in mine and the gauge responds immediately.

I mean I can see why the restrictor is a good idea in case the line broke but it is no more vulnerable than the oil cooler oses and they certainly have no restrictor.

So I guess I don't see what the need is?

Can you explain?

Frank

[pierre smith]

Frank,
On my PT6 engine, they WANT air in the line in order to stop the pointer from jiggling left and right as the gears in the oil pump put out pulsating oil pressure bursts. The air in the line is a damper, smoothing out the pulses for a very steady gage. Whenever my needle starts skittering back and forth, vibrating, I purge the oil line completely.

Don't be concerned with the slow pressure indication......you know it's there. I agree with the need for the restrictor though.
Regards,

[frankh]

Originally Posted by pierre smith

Frank,
On my PT6 engine, they WANT air in the line in order to stop the pointer from jiggling left and right as the gears in the oil pump put out pulsating oil pressure bursts. The air in the line is a damper, smoothing out the pulses for a very steady gage. Whenever my needle starts skittering back and forth, vibrating, I purge the oil line completely.

Don't be concerned with the slow pressure indication......you know it's there. I agree with the need for the restrictor though.
Regards,

There are two "Needs" I see here. The first is to provide signal dampening. With the electronic engine monitor the signal is already damped....

The other is if the line breaks it slows the oil loss down....But this line is at no more risk than an oil cooler line.

So am I missing something?

Frank

[rvbuilder2002]

...to bleed all of the air out of the line (after reinstalling the restrictor fitting).
Remove the top plugs from the engine.
Slightly loosen the hose at the oil pressure sensor.
Crank the engine with the starter until the loose fitting leaks a small amount of oil.
Tighten the hose and reinstall the spark plugs.

No more time delay caused by air in the hose needing to be pressurized before you get an oil pressure reading.

[frankh]

Next time I have the cowl off I will install a straight restrictor (not the 45) that I will make by brazing up the end of a 2 dollar steel fitting and drill a #40 hole in it.

At least that way I can install it with a deep socket cus getting the 45 on and off is a real bear!

Thanks for your thoughts

Frank