Unfortunately my RV4 project is going to be out of the air for longer than I’d initially hoped, and it’s time to think about inhibiting the engine.
Reading the O320 manual it talks about filling the engine with inhibitor oil, then emptying it after a ground run. It also talks about filling the cylinders with inhibitor oil and also using dessicant spark plugs, and sets of seals to prevent moisture ingress.
I can’t seem to find seals, dessicant plugs or Esso Rust-Ban 626 for sale within the UK – is there anywhere I can buy these things, or equivalents?
It’s an O320 E2C
For the inhibiting oil, one can also use Russian MS-20 – ask Yak owners, they may have some. Officially, it’s a regular aircraft engine oil, but it’s really poor for this purpose. Surprisingly, it’s excellent for corrosion prevention. The boss of the engine shop here at LKBU (where I do work part-time) told me he disassembled a Walter piston engine that had been sitting in storage for over 10 years filled with MS-20, and it was immaculate. Other engineers confirm that as well.
If you fail to find desiccant plugs, they can be easily made – they are simply M18×1.5 bolts (they are used as oil drain plugs in some cars) with a perforated container at the tip that is filled with non-deliquescent desiccant of your choice (silica gel, zeolite, drierite).
This might be of interest 
I would not worry about the plugs. After doing the preservative oil thing, simply remove all the spark plugs and put the engine in a sealed bag, with a few 0.5kg bags of silica gel inside it. See here.
Legend has it that Spitfire engines were stored successfully for 70 years after being totally filled with oil, which is not surprising, but (a) you need a huge amount of oil to fill the crankcase and (b) the seals will probably have to be replaced anyway.
You could make (or buy) one of those devices that blows dry air into the crank case via the oil filler and exhaust. It is usually an aquarium pump, some desiccant, tubing and a humidity meter so you can read the humidity inside the engine. Probably £ 50 of parts from Ebay and that will look after the internals/cam. Then Peter’s idea for the cylinders but if the valves are open the air device should sort the cylinders too.
From memory the target is less than 50% humidity and nothing will rust but a quick Google will confirm.
Edit – I just read Peter’s post after submitting this!!!
Unfortunately 1) it’s not that much of a project, and I’d rather not dismount the engine and 2) I really like the dehumidifier idea but can’t plug anything in.
I’ve put in a big Ebay order for dry silica gel.
Thanks for the suggestions. I wonder whether it would be worth sealing the cowling with lots of gel inside after draining the oil (I get the impression half the trouble is moisture in the oil rather than moisture in the air).
I agree, it is moisture in the oil from combustion products. I think if you changed the oil and put silica gel in the Air filter box (and taped over the input) and the same with the exhausts – ie tubes of gel up the pipes and taped over the ends then that would do a huge amount to protect things.
There is a bit of an issue with damp air as valves will be open or partially open which exposes the cylinders to the outside environment.
Why not make your life easy?
Place the engine in a strong large plastic bag (same as used for cars storage) together with some silica gel bags, pump out all the air and fill with nitrogen.
Much depends on whether the engine is mounted on the aircraft or not.
If not, yes, it is easy to put it in a bag. Otherwise getting a decent seal around the mounting frame is not going to be easy.
KWLF
A quick search of the LAS aerospace website will find inhibiting oil and dehydrator plugs for the cylinders.
So that takes care of the engine. What if you want to store the whole plane ? What precautions need to be taken ? Take the battery out ? Drain the fuel tanks ? What else ? Let’s say you want to store a plane for a couple of years in a non-heated hangar.
