Inactive engine, pull plugs, hit starter until oil pressure?

Domenick

Domenick

Pattern Altitude
PoA Supporter
Joined
Sep 11, 2019
Messages
2,126
Display Name
Display name:
Domenick
In the winter I'll not fly for up to a month. I've always cringed at first startup, imagining the wear that is occurring. I don't remember where I saw this suggestion, but I did archive it, and I'm putting it out here for comment:

Remove the top plugs and squirt some penetrating oil in the cylinders, then turn the prop by hand to feel for any surprise restrictions. If there are none I'd leave the plugs out and crank the engine until it registers oil pressure, then install the plugs and fire it up.
Click to expand...
 
Won't hurt anything, but seems a little overkill for 30 days or less.
 
A month? That ain’t nothin’. Let it be with Camguard.
 
My practice is lower plugs out and spray UP.

Gravity sucks so cylinder walls get coated rather than just the bottom.

I wouldn’t do it for 1 month though.
 
Domenick said:
I'm putting it out here for comment:
Click to expand...
Have you compared it to what Lycoming/TCM recommend? My recommendation is to always follow those instructions. That said most instructions start at the 30 day level. I believe the recommendation is that for engines flying at least one full hour within a 30 day period you're good to go. Each OEM has a bulletin on this. Post what engine and I'll find them if you want.
 
I’ve always questioned how much benefit there is from using the starter to build oil pressure prior to starting an engine that has already ran at some point prior. The cam and lifters are always the biggest concern (but not the only one) due to their high failure rate and since they’re not pressure lubed I can’t see cranking to build oil pressure helping that interface.

If anything, I think there’s potential to hurt the cam and lifters due to extended cranking with little lube oil on the cam and lifters. Some of the oil additives, such as Camguard and LW16702 are supposed to generate a protective, sacrificial layer on surfaces and that would be getting wiped off while cranking.
 
Thanks all, and I am a thinker--often over.
I do use CamGuard with Phillips X/C 20W50.
 
The procedure for intalling a new or overhauled engine is to fill it with oil, remove the plugs, and crank it until the oil pressure comes up. That gets the system all primed so that everything is lubed immediately on the first start, as opposed to just starting it and having combustion loads on everything before the oil gets there. Not good.

An engine that sits long enough will be in a similar oilless state.
 
Oil runs from the “top” of the barrel and accumulates at the bottom.

Engines sitting for extended periods may show rust and pits when

viewed through the LOWER plug hole.

The resultant Dry Start may result in chipped or broken rings.

Spraying “ bottom up” should provide lube for the upper surface

at start-up.
 
I presume when doing this that starter duty cycles still apply?
 
No plugs- use starter to build oil pressure is SOP prior to initial start of a field overhauled engine. It works fine. Worth doing after 30 days? Nobody has any evidence one way or the other. If you choose to do it? It certainly won’t hurt anything.
 
.
bflynn said:
I presume when doing this that starter duty cycles still apply?
Click to expand...
Sort of, though the load is far less and the starter spins faster, offering more inductive reactance that limits current flow and the heating from it. Shouldn't have to spin it for more than 15 seconds or so anyway.
 
Stewartb said:
No plugs- use starter to build oil pressure is SOP prior to initial start of a field overhauled engine. It works fine. Worth doing after 30 days? Nobody has any evidence one way or the other. If you choose to do it? It certainly won’t hurt anything.
Click to expand...
I wouldn't bother at 30 days. Six months, maybe.
 
My TCM IO-520 has sat six months and I just start it and never any damage. Oil pressure is not even necessary for full film lubrication. The old, reliable Chevy sixes only had oil pressure to the main bearings, the rod bearings just had scoops. A spinning bearing can self pressurise due to rotation.

I have had my airport car sit two years and I would just start it (a battery jump might be necessary).
 
the 20w50 and camguard is the perfect winter combination. 1 month is nothing. I cranked mine a few days on a trip at freezing with 50w. That hurt. It started but I cried. I guess the good thing is it had set only overnight but still hurt.
 
My imagination and assigning human emotions to bearings and journals is as bad as y’all’s’. Happy Thanksgiving to you and your engines.
 
You must log in or register to reply here.
Back
Top