Why do we fog an engine?

[Cup of Joe]

I have been doing it for years and the question is why?

I recently pulled the head off an old lawn mower engine that had not been fogged and has been sitting in my garage for a few years now. There was no rust of any kind, just carbon deposits. I have to ask myself, why am I bothering to pull the plugs on some of these engines and fogging them in the 1st place.

 

[Bluestream]

Its for insurance against rust formation.

You live a charmed life, and were just lucky I guess...

 

[Panzerman]

Its to keep the rings and cylinders from rusting, most engines wont rust up inside, especially two strokes, but it does prevent the cylinders and rings haveing to dry scrape. I have had small engines sieze up and just hose down the spark plug holes and they would free up. Rust on the rings and cylindrs make everything tighter.Healthy for them, probably not, will they still run, probably. Fogging a enhine just helps protect the motor, koop the cylinder smooth, so everythig works like it should,

 

[boraticus]

"I have been doing it for years and the question is why?"

Good question.

Some people do it because that's what they're told to do and have all the time in the world to dote over one or two engines.

When I was young and naive, I used to do it. As I got older and accumulated numerous small engines, the task was just too onerous. I have 60+ cylinders that I would need to oil/fog. So around fifteen or twenty years ago, I stopped doing it. The results? Absolutely no difference. Everything starts and runs well and I've yet to have an engine cause me any type of problems caused by absence of oil in the cylinder. No oil consumption in all but my snow blower engine which has done that since new and has an aluminum bore. Compression is good on all of them and some are 30+ years old.

Here's something to think about...

If the engine isn't showing any rust on the outside, what are the chances of rust happening inside.

Another thing to think about...

Do people pull the fuel injectors on diesel engines to pour oil into or fog the cylinders for storage?

I've come to the conclusion that unless you keep the engine in a very moist and salty environment, it's a total waste of time.

If Tater is living a charmed life, I must have the protection of an invisible force shield of invincibility over my stuff! Maybe even an invisible pyramid!

OCD can invoke some strange beliefs and behaviour.

Sometimes a little common sense can save a person a great deal of unnecessary work.

 

[xxch4osxx]

I have never fogged any engine I have put into storage. With lawn mowers, when I bring them out again in the spring, I pull the sparkplug out and pull the cord a few times to get the oil splashed around so it isn't a dry start. Never had a problem doing it that way.

 

[The motor guy]

The metal on the outside isn't the same as the metal on the inside. They usually have something special done to the outside. I forgot what its called. Think carburetors how the outside is kind of rough and the inside is bare metal and shiny and smooth. Most small engines are completely aluminum except for the bolts that hold it together and sometimes the flywheel but on a lawnmower I think even that is aluminum since it has the blade as a flywheel too. so you're not really going to get rust. Maybe some corrosion.

 

[boraticus]

Originally Posted By: motor_oil_madman
The metal on the outside isn't the same as the metal on the inside. They usually have something special done to the outside. I forgot what its called. Think carburetors how the outside is kind of rough and the inside is bare metal and shiny and smooth. Most small engines are completely aluminum except for the bolts that hold it together and sometimes the flywheel but on a lawnmower I think even that is aluminum since it has the blade as a flywheel too. so you're not really going to get rust. Maybe some corrosion.


Rust/corrosion, same idea. If it's not happening outside, you can rest assured it isn't happening inside either.

 

[Brons2]

Originally Posted By: boraticus
Do people pull the fuel injectors on diesel engines to pour oil into or fog the cylinders for storage?


Seems like it would be near impossible to fog a diesel, the engine would use the fogging oil like a fuel.

Could there even be the danger of a runaway if you used too much?

 

[Quest]

Fogging is still a good practice to keep an engine that goes into storage to be "ready" when needed.

Different folks may have different experience on this subject but a good way to product the engine innards (machined parts like cylinder walls, etc.) from rusting or suffering from dry starts.

Q.

 

[Bluestream]

Originally Posted By: boraticus
"I have been doing it for years and the question is why?"

Good question.

Some people do it because that's what they're told to do and have all the time in the world to dote over one or two engines.

When I was young and naive, I used to do it. As I got older and accumulated numerous small engines, the task was just too onerous. I have 60+ cylinders that I would need to oil/fog. So around fifteen or twenty years ago, I stopped doing it. The results? Absolutely no difference. Everything starts and runs well and I've yet to have an engine cause me any type of problems caused by absence of oil in the cylinder. No oil consumption in all but my snow blower engine which has done that since new and has an aluminum bore. Compression is good on all of them and some are 30+ years old.


4-stroke engines are less susceptible to crankcase rusting than 2-strokes, as they have a full oil bath. They can get rust forming on the valve face and seat if stored with one valve open. I always pull the cord to get to the compression stroke, then I know both valves are closed. 2-strokes that are oil injected, can be very susceptible to rusting as the cranks and bearing are "dry".

Originally Posted By: boraticus
Here's something to think about...

If the engine isn't showing any rust on the outside, what are the chances of rust happening inside.

Another thing to think about...


The inside has a bare metal cylinder wall, that is more susceptible to rust than the outside of the engine

Originally Posted By: boraticus
Do people pull the fuel injectors on diesel engines to pour oil into or fog the cylinders for storage?


This one is easy...Diesel fuel unlike gasoline, is actually a thin oil and is coats the cylinders to protect them

Originally Posted By: boraticus
I've come to the conclusion that unless you keep the engine in a very moist and salty environment, it's a total waste of time.


I live in the lee of the great lakes, and the air here is full of moisture. I parked my Ford explorer last summer, and it spend 4 months sitting in my garage. In the fall, the metal belt tensioner pulley was covered in rust, but only the side that was exposed to the air. The side against the rubber belt was still shiney as the belt kept the air away from the steel. Same as oil does for metal...

 

[Pablo]

I only fog my tiller because it's basically in long term storage in a shed where moisture is a problem (6 plus years now). But OPE used at some point in any given year, it's not worth hassle. I do use oils with rust preventatives.

The answer is it depends on where you live and how long an engine will be in storage. I live on a hillside rain forest. We have some large temperature swings and a LOT of moisture. Stuff rusts.

 

[Artem]

Originally Posted By: xxch4osxx
I have never fogged any engine I have put into storage. With lawn mowers, when I bring them out again in the spring, I pull the sparkplug out and pull the cord a few times to get the oil splashed around so it isn't a dry start. Never had a problem doing it that way.


I just tilt the lawnmower side to side to get up and about and fire it up. My Toro is like 8 years old now, stored outside in the backyard with just a plastic bag covering the block. Starts from the first pull each and every time.

 

[Bluestream]

Read this entire thread on Sea-Doo Engine fogging. (start at the bottom of post 3, and ignore info on carbon seals)

Note posts by "Mr.Bill" He is a Tech who owns a repair shop. He is also a factoy race team member. He fogs engine after each use

Fogging Info

 

[ARCOgraphite]

For Seasonal storage of small engines, I cant see why it would be required. Longer storage of classic engines, partially tore-down engines and marine IB/OBM would be another story. Cast iron and Al will rust if not lubed if the valve is open and the carb is even partially open to the atmosphere and there is no good polar napthenic oil film clinging to the surface. Yes I just said between the lines: no 80% base PAO

 

[crw]

Here in the desert, I've never fogged an engine. Quite frankly, I've hardly ever heard about it either.

 

[boraticus]

Considering the imminent and absolute dissolving of the engine internals if not oiled or fogged, I'd like to ask the proponents of engine oiling/fogging a few of questions:

Have you ever disassembled an engine?

When was the last time you took an engine apart that had been stored without fogging? What condition were the internals?

When was the last time you took an engine apart that had been fogged? What did you see there?

Far too often, we have proponents of unnecessary procedures who have virtually NO mechanical experience yet they're dead convinced that their advice cannot be ignored.

You can rest assured that most "hands on" mechanics don't do much of what the inexperienced deem necessary.

 

[boraticus]

Originally Posted By: Brons2
Originally Posted By: boraticus
Do people pull the fuel injectors on diesel engines to pour oil into or fog the cylinders for storage?


Seems like it would be near impossible to fog a diesel, the engine would use the fogging oil like a fuel.

Could there even be the danger of a runaway if you used too much?


Therein lies the quandary.....

If fogging is so essential, how do we save our diesel engines from imminent destruction?

Oh, wait..... Maybe it isn't all that necessary.

 

[Bluestream]

Originally Posted By: boraticus
Originally Posted By: Brons2
Originally Posted By: boraticus
Do people pull the fuel injectors on diesel engines to pour oil into or fog the cylinders for storage?


Seems like it would be near impossible to fog a diesel, the engine would use the fogging oil like a fuel.

Could there even be the danger of a runaway if you used too much?


Therein lies the quandary.....

If fogging is so essential, how do we save our diesel engines from imminent destruction?

Oh, wait..... Maybe it isn't all that necessary.


As I mentioned, diesel fuel is a light oil, (AKS diesel oil, or home heating oil) so its does the protection of a diesel engine that fogging would do for a gas engine. In fact you could protect a gas engine with diesel if you wanted to...

 

[Bluestream]

Originally Posted By: boraticus
Considering the imminent and absolute dissolving of the engine internals if not oiled or fogged, I'd like to ask the proponents of engine oiling/fogging a few of questions:

Have you ever disassembled an engine?

When was the last time you took an engine apart that had been stored without fogging? What condition were the internals?

When was the last time you took an engine apart that had been fogged? What did you see there?

Far too often, we have proponents of unnecessary procedures who have virtually NO mechanical experience yet they're dead convinced that their advice cannot be ignored.

You can rest assured that most "hands on" mechanics don't do much of what the inexperienced deem necessary.



I don't have the patients to type paragraphs here, but I have had many engines apart, and seen rusted engines many many times. We saw snowmobiles come in the shop every fall that had not been stored properly with rusty crank bearings. Top end was good as the owner would put oil in the plugs only and not fog the engine. Moisture in the air would go up the exhaust and into an open post...

 

[boraticus]

I bought five 1970's Yamaha two cycle motorcycles that had spent ten or fifteen years in an old unheated barn in North Dakota. My objective was to restore them. I picked them up in January and put them in an unheated shed. Each year I pulled a bike into the garage and pretty much rebuilt them from the ground up including rebuilding the the engines. Of the five bikes, I've rebuilt four of them so far. Call me lucky but I didn't see any of the dreaded rust inside the crank cases.

Actually, I was pleasantly surprised how healthy the engines were after so many years being left unattended. One engine was a bit flogged but had plenty of material left in the bores to make room for larger pistons and rings. Crank bearings were fine but the seals were shot. The lateral play in the connecting rods was beyond spec too so, I rebuilt the entire bottom end.

These aren't the only engines I've rebuilt. I've worked on quite a few including outboards and OPE. The crankcase rust issue is waaaaay overblown.

If an engine is showing signs of rust inside of it, I'd suspect that water was ingested likely through the carbs and highly unlikely via condensation.

Regardless, people can do what they want with their engines. However, as always, we need to temper the hysteria somewhat and recognize the insignificance if one decides not fog their engine(s).