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No oil pressure

vmirv8bldr

Well Known Member
Today I prepared the plane for first engine start and after topping off ht oil and removing the bottom plugs, hand propped several rotations, probably 20, then engaged the starter (plugs still out) hoping to see some pressure. None, zilch. I ran the starter for probably 10-15 seconds. I did this cycle a few times with no joy.

The engine came from Barrett and has run before (90 minutes on the dyno.) It was pickled by them a couple of years ago, dessicant plugs and all that. I added about 7qts of oil and the dipstick reads right at 8 at level flight attitude.

Any suggestions?

Thanks,
Bart
 
Sensor wiring to your indicator to include grounding if required. Assume a simple problem first.

What is your indicator? Separate gauge? EFIS?
 
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Had the same problem.

My oil pressure indicator wasn't working. I was fortunate to have one of the local mechanics helping; he happened to have a mechanical oil pressure gauge that we could plug in quickly.
 
Empty oil filter?

I notice that when i change the oil and spin the motor over with the plugs removed it can take about that long before I get any oil pressure indication.

Frank
 
More time needed.

More like 30 seconds the first time you try to get oil pressure.
You really can't hurt that engine spinning it on the starter without plugs installed. I remember I had the same thoughts a couple of month ago.
It took about 3 tries of more than 10 seconds each to finally register oil pressure about 45 psi . It seems a very long time when you are grinding the starter and normally it would be but with the plugs removed you really are not putting any load on the crankshaft or its bearings.
 
It's very common to take a good thirty seconds of cranking (no plugs) to get an indication Bart. Remember that you've got air in the lines from the engine to the oil pressure gauge (or transducer, and you've also got an orifice in the fitting coming out of the engine. Common practice is to disconnect the line at the gauge/transducer, and hold the end in a rag while cranking. Once you get oil to that point, attach it to the gauge, and you'll have pressure.
 
I notice that when i change the oil and spin the motor over with the plugs removed it can take about that long before I get any oil pressure indication.

Frank

Note that it's perfectly OK and good practice to Pre-fill a new oil filter by hand prior to installing it when changing your oil. Obviously, if you have a standard horizontally mounted filter you don't want to fill it so full that the oil spills when you install it, but you can put a surprising amount of oil in. This helps th OP to come up much faster after an oil change.

Skylor
 
I second Paul's suggestion.

I did the same prior to first start, and it took a surprisingly long time before oil came out of the line.

At first, there was a mix beetween oil and air coming out, but after a few sec's, there was steady oil-flow. After hooking up the line, oilpress-indication was there.

Let us know how it goes.
 
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Yep

A friend of mine is fighting that problem with a Conti IO-520 that had to be disassembled after a prop strike.

After that 2 years of sitting, your oil pump has lost its prime and you can refill it by removing the oil filter and using a funnel and a piece of flexible clear plastic tubing, fill the oil pump from the center of the oil filter hole and turn the prop backwards so the pump gears suck the oil in from that end.

Best,
 
The best way to prime the oil system is fill the filter with oil and pressurize the oil galleys via one of the pipe plugs where the cam galleys are drilled in the case. Hopefully the filter your using has a drainback valve. I have a can that I use for this purpose that I fill with oil that has a schrader valve welded to it so I can pressurize it with air. This can is attached via a hose to the pipe plug.
 
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Layman's terms?

Rocketbob, I value you're input, but am lost in the terminology. Can you "dumb this down" for me? Pictures?

Today I removed the oil temp sensor which I believe is positioned at the outlet of the filter. (I assumed this would effectively fill the filter.) I poured about a half quart (slowly) into this opening, until it quit draining. Still no pressure. I also raised the tail to level flight attitude which should run any oil in the filter out of the filter. I also disconnected the oil pressure hose from its sensor as Paul suggested.... nothing comes out when engaging the starter.

Tomorrow I will remove the filter itself and do as Pierre suggested.



Thanks,
Bart
 
First off a only newer oil filters have a drainback valve. This is basically a silicone flap in the filter that prevents oil from draining out when the engine is shut down. If you look at the holes in the filter and see rubber immediately inside your oil filter has a drainback valve in it. These are superior because at shutdown they close off the inlet side of the filter to keep oil in there so that when you start the engine up its not filling up with oil for a period of time. You get oil pressure sooner when starting. You want to fill the oil filter up directly.

Secondly there are two pipe plugs on either side of the crankshaft on the case at the front, next to the most forward pushrod bosses. These plugs cover the long holes drilled by the factory for oil passages. You can remove one of these plugs and with a garden sprayer with the wand cut off or a specific setup like I have, and connect the hose to a barbed fitting that you thread into one of those holes and pump oil into the engine under pressure.
 
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Pressure Pre-oiling

Check post #3 of this thread for how I pre-oiled my O-300. I have yet to work much on Lycs, but I would assume there is similar access to the oil system.
 
oil pressure

At this point I would head down to Auto Zone or whatever and get a cheap mechanical gage. Hook it directly to the oil pressure port and try again.
 
Oil in cooler

Well, after a big mess and still no pressure today, I got to thinking about the oil flow and where the pressure hose connects.

(FYI, I have disconnected the oil pressure hose from the transducer and am cranking to see oil coming from it before trying to read a pressure value, as was suggested by Paul.)

BTW, the filter I have on it now is the type with no valve, and it was full. The temperature probe port is at the outlfow of the filter, and my pouring about a half quart into it filled the filter.

What occurred to me was that the monster SW 10610R oil cooler I have mounted to the firewall, and all the hoses that connect to it are probably dry as a bone. Particularly since it appears that the oil pressure port is at the same location as the oil return line from the cooler. So even if everything works properly, the engine still has to fill the cooler and associated lines before any oil will show up in the pressure line.

After searching a bit online, I found the Lycoming pre-oil service instructions. http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1241C.pdf which says how to do this. I must say though, that this instruction could have been written a little more clearly.

As per Rocketbob's suggestion, I will build a pre-oiler and pressure fill the galleys. I just built a similar thing to fill the brake lines and have scrap from that project I can use, just need to buy some more fittings and a ball valve or two.

I'm also calling Barrett in the morning.

I'll keep everyone posted.
 
OIL!

I called the good folks at Barrett Precision Engines this AM to learn that Allen was already over half way finished reading this thread! He was very comforting and knowledgeable. He agreed I needed to fill the cooler, but also suggested I take the pressure reading off the port adjacent to the right mag and top right mount. (A cursory review of ALL the drawings show this from the beginning, but one drawing somewhat indicates the top left port...which is where I was plugged in.)

As per Allen's suggestion, I relocated the hose and plugged the top left port and filled the cooler. To avoid a mess, I learned quickly to pour about a tablespoon at a time into the lower hose.

Once that was full, I reconnected and torque the hoses and hand propped (plugs out) with the pressure hose hanging into an empty oil can. After each 25 rotations, I checked the hose for signs of oil.

First 25 - nothing
Second 25 - nothing
Third 25 - OIL!!!!!!

Then my phone rang and I had to focus on money MAKING efforts for a while.

I came back and reconnected the pressure hose after changing the fitting on the manifold, torqued it and hit the starter.

I followed the previous advice:
Starter for 30 seconds
wait 2 minutes
Starter for 30 seconds
wait 2 minutes
Starter for 30 seconds
Wait until starter has cooled completely
(This wait was not a problem, three 30-second runs on the starter (plugs out) will completely drain a PC680!) A&P at the field says rule of thumb is if the starter is too hot to touch, then it needs to cool. Mine got warm, but never hot.)

Still no indication of pressure on the instrument, but at least I do know oil is flowing. After speaking with an A&P with RV experience, this is not uncommon, and I should expect to run through as many as 15 or so 20-30 second starter cycles to see the pressure.

Tomorrow I will hook up the jumper cables to keep from having to wait the six hours required to recharge the 680!

Thanks for everyone's assistance.
 
I am confused. Are you now using a mechanical oil pressure gauge in addition to the panel mounted indicator? If so, still no indicated pressure?
 
After speaking with an A&P with RV experience, this is not uncommon, and I should expect to run through as many as 15 or so 20-30 second starter cycles to see the pressure.

This is flat out wrong and will cause bearing and/or crankshaft damage! Never have I overhauled an engine that the pressure didn't come up in 3-5 seconds after the first start.
 
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I agree 100% with Bob on this - I get worried if I don't "see" oil in (2) 30-second cranking cycles, and go looking for what I did wrong. No oil pressure on the gauge in (4) cycles? I've got a gauge problem, or haven't purged the line.

I's be seriously worried about my starter's and battery's health after much more than that.

Paul
 
This may seem improbable, but it has happened. If you have an oil filter adapter and the gasket was installed backwards, it blocks the oil passage and if you continue to crank the engine for any length of time, it will rupture your oil cooler or oil filter. :eek:
 
I have oil pressure, finally!

Got the oil pressure to show up late today.

Thanks for everyone's suggestions and help, both on and off the thread. Allen Barrett wins the prize and the beer, whenever I see him.

Allen and I spoke several times today and eventually determined there was a blockage somewhere. Off came the governor to verify the gasket was installed correctly and no ports were plugged. It was installed correctly, and nothing was plugged. There was oil in the governer, but not much. I hot the starter for about ten seconds to see if oil appeared out of the governor ports. Nothing.

Then Allen asked the magic question:

Allen: Hey Bart, is this an AE engine?
Me: Yes, but I'm going to wait until first annual to install the Christen System.
Allen: I think I know what the problem is. If you're not installing the Christen system, then you need to remove a plug in one of the sump ports. (He named the specific port, I don't recall, but it was the only one with a hex nut on it and about a 6" long screen filter inside.) The plug is all the way inside and has a 10-32 threaded hole in it. You'll need a piece of all-thread or something about 6-8" long to reach in there and get it out. And get something to catch the oil.

The A&P on the field quickly cut the head off a long AN3 bolt and welded it to a piece of rod for me. Then after cursing, cutting myself repeatedly and removing scat tubing to get enough room, I got the plug out and lost about a quart of oil while I replaced the screen filter and plug. I then re-installed the prop governor and other things I had removed in the troubleshooting process. The pressure hose was still detached from the manifold and hanging in a cup. I hand propped it about 25 rotations and then hit the starter (plugs out) and in four seconds oil was (relatively) gushing out of the hose. That was a really, really good feeling right there. I quickly connected the hose to the manifold which was connected to a mechanical indicator ($20 at O'Reilly with all tubes and fittings). I hit the starter again and at about 20 seconds the needle began a steady rise. I stopped it at 25psi. I had seen enough and it was time to go home.

Tomorrow I have a few items that need to be re-safety wired, a few that need to be re-torqued, and I'll put the GRT transducer back on the manifold. After that, I'll remove the plugs and get pressure up, then stick 'em back in and see about fuel pressure and the ignition system. I know the starter works. :) I have already free-flowed the boost pump and am getting about 50gph from either tank.
 
screen

IIRC you will need a new suction screen. The suction screen is shortened to accomodate the Christen plug. They are only about $12.00 so get a new one and compare it to what you have to verify.
 
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