First crank - oil pressure and RPM?

[Bryan Cotton]

Hey all,
We just cranked our Aerovee over for the first time, no fuel yet. Our goal was to see some oil pressure and RPM on the instrument. We saw neither. Is this surprising or would you not expect pressure and RPM to show at that low RPM? Otherwise the first crank was good. Video to follow.

[Murray Parr]

Hi Bryan,
You should see oil pressure usually within 10 seconds (time it, as it probably seems like you are cranking a long time). Take one of the plugs out of each cylinder so it has no compression which will be a bit easier on things and it will also spin the engine quicker. Not sure if there's a procedure out there to prime part of the oil system on an aerovee but if it hasn't ran in a long time the oil pump gears might be a bit dry to be able to prime itself. Others might have more info but that could be a starting point.

Hope this helps

Murray

[Bryan Cotton]

Thanks Murray. We cranked it 3 times. Video:

[sonex1374]

Bryan,

If you are getting visible oil into the heads after cranking then it might simply be a sensor problem. If you can't see oil in the heads, then you might not actually be pumping oil thru the engine like you should. This could be due to the oil pump not getting or holding a prime and not actually drawing up oil from the sump to distribute to the galleys. Another potential problem could be the oil pressure relief plunger is stuck open and bypassing all the oil from the pump back into the sump.

An alternative to pre-oiling via cranking the engine is to build a pressure-pot pre-oiler. This is super easy using a small garden sprayer (E.G. https://www.homedepot.com/p/HDX-2-Gal-P ... /307766539). You'll cut off the spray wand from the flexible tubing and then connect the hose to a barb fitting temporarily installed into the oil pressure sender port (example: http://sonex604.com/misc/pre_oil.jpg). You then fill the sprayer with a 5-qt jug of 30-weight oil (the normal 20W-50 is a bit too thick to work well in the pot), pump up the pressure (which is what the sprayer is designed to do anyway), and then transfer the oil in a pressurized stream into the engine. Do this for about 20 minutes, draining and recapturing the oil into the pot if needed (or until you're satisfied with the oil reaching the heads). After it's all pre-oiled, drain the old oil, install your run oil, and crank again to check for pressure readings.

It's personal preference, but I like to do the first start with the 10W-30 oil (same oil used for pre-oiling). It starts a bit easier, being thinner distributes better through a tight engine, and you're not going to run the engine hard the first start anyway. After the first start or two and 5-10 minutes of running, drain that oil and dispose of it - it has served to flush any debris that may have been created or knocked loose from the initial run. This gets any of that stuff out of the engine right away and makes the pre-oil serve double-duty as flushing oil.

The AeroVee uses the alternator output for RPM readings. If you aren't getting RPM displayed, check the wiring from alternator to voltage regulator and see if something is amiss.

Jeff

[Area 51%]

A $10 Home Depot pressure gauge screwed into the port will tell you what you need to know.

I used a drill operated pump to deliver oil directly from the sump drain to the pressure port for priming.

[Bryan Cotton]

I did check my transducer earlier. I adapted it to an air collet so I could connect it to a spare tire. My MFD oil pressure reading fell in between two of my tire pressure gauges.

I do have an oil filter. My pump has an inlet and outlet on the cover. IIUC the oil goes from the sump to the filter and then to the engine. Could it just be a matter of filling the lines and filter?

[Area 51%]

I do have an oil filter. My pump has an inlet and outlet on the cover. IIUC the oil goes from the sump to the filter and then to the engine. Could it just be a matter of filling the lines and filter?

Entirely possible. But remember you're cranking a "dry" engine while doing so. Take Jeff's advise. At the very least, remove the filter and check for oil.

[Bryan Cotton]

Very good, I think I'll start at the oil filter.

[Bryan Cotton]

News flash: AN fittings don't self tighten even given a couple of years. We discovered a puddle of oil under the filter. Its fittings were loose. Seems promising though.

[Sonex1517]

One thing Joe Norris told me to do (and it worked) was to pack my oil pump with white lithium grease.