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Small Engine & Correct Oil Fill?

My old neighbor was getting rid of a push mower that "wouldn't run" so I took it to see what I could see.

He had put so much oil in it that the plug was saturated.

I managed to get everything cleaned up enough to get the it started - it smoked like crazy for a while - and it ran just fine.
 
Last oil change on one of my cars I managed to get almost a quart overfilled, not exactly sure how but it almost had to be that not enough got drained out. Did it in a different place and in a hurry, and guessing I didn't account for the slope vs. drain plug orientation.

Anyway, no harm seems to have come from it, but I won't be purposely adding an extra quart just because nothing seems to have happened.
 
prww said:
This is my understanding of proper oil level. The proper oil fill keeps the level below the crankshaft throws. Too much oil, and the crankshaft throws will pass through the oil in the pan, frothing the oil. Oil with air bubbles affects pressure, and does not lube rod and crankshaft bearings properly. I never did overfill an engine to see if this is true. Paul.
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Modern engines all have "windage trays" to separate the crankshaft from the oil pan to prevent this. Even old 60's Mopar high performance engines came with them.
 
krautmaster said:
Modern engines all have "windage trays" to separate the crankshaft from the oil pan to prevent this. Even old 60's Mopar high performance engines came with them.
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That will work with a normal amount of oil but the motor could still be overfilled by the hamfisted..
Plus hard acceleration - as in drag racing - or hard braking and cornering - as in road racing - can cause the oil to slosh around enough to overcome the windage tray.
This is why "real" race cars have a dry sump system.
 
I have a couple of gear boxes on a single piece of equipment that are strange. One box is proven to be happier with an extra quart or two for reaching the upper gears. The other box calls for a revised underfill or you will have a seal leak. You need to make your own dipstick for this one or use a bent hex key to judge the proper fill. I would think that a manufacturer would just provide a corrected dipstick or change the casting fill hole, but sometimes nooo. These things happen.
 
Mr Boochie said:
I keep tools that need oil and my air compressor at a sight level, or maybe a tad less than topped off.

But, if you aren't getting blown O-rings or gaskets, I wouldn't worry about it.

Car engines should not be filled too high. I know some ppl put in an extra quart. I don't know why, as I feel this only invites problems.
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Adding extra oil to a car/truck engine, can sometimes even REDUCE oil pressure under high-speed conditions. Aeration and foaming of the oil, due to the churning up of the extra oil by the crankshaft, isn't a good thing, if it happens.

I'd doubt a typical 4-stroke small engine (lawn mower, tiller, pressure washer and such) ever turns enough RPM to cause any issue with that.

Regards,
Gordon.
 
most small engines use splash lube anyway, so aeration is pretty much a given. Not a problem there, but air compresses and thats bad news in a pressure lube system. If the oil film between crank and bearings becomes an oil/air foam, suddenly parts touch that should not and thats not good.
 
Small engines are designed to run on foamy oil, no pump or passages. Some have a little scooper on the bottom of the rod end, others a little "dipper" to splash the oil around making it somewhat critical to maintain the correct oil level. Not enough and nothing gets splashed, too much (like way too much) overloads the rings and upsets your neighbors with all the smoke.

There's a Honda horizontal shaft OHC motor that uses a rubber internal timing belt to drive the plastic camshaft on the top and it's the timing belt that carries the oil up, these engines usually don't last long enough to require an oil change.
 
Because the engine came with an extra 1/2" on the dipstick, I've had no noticeable problems or oil burning, and the opinions offered, why change what's been working? That conclusion may have been obvious to some but I wondered if others had run into this and if there was a general consensus.
 
ARC Tech-109 said:
There's a Honda horizontal shaft OHC motor that uses a rubber internal timing belt to drive the plastic camshaft on the top and it's the timing belt that carries the oil up, these engines usually don't last long enough to require an oil change.
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did Ford steal their wet belt idea from Honda, or vise-versa? Seems like its not working out terribly well for either.
 
Don't know but this seems to be a trend, the inline-6 DirtyMax diesel has a similar arrangement driving the oil pump with a rubber composite belt and it's located on the backside of the engine meaning trans, flywheel pan and big ugly cover has to come off to replace this piece of junk.

People often ask me why I continue to drive a 2005 Impala-SS and 1981 Yamaha motorcycle... go figure.
 
I generally dislike things with critical engine bits driven by rubber parts. I do own a single OHC belt drive engine but changing it is not difficult. Installing the valve cover is honestly the hardest part of the process, purely because its fiddly to get the cover in place without moving the gasket. The engine doesn't really belong in that engine bay so part of the cowl and the heater hoses get in the way. In the BMW it belongs in, you just lift the thing straight up.

Everything else is chain drive with the cam in the block where it belongs.

the problems I tend to have are just drying up / exhausted sources of parts.
 
gadget73 said:
I generally dislike things with critical engine bits driven by rubber parts. I do own a single OHC belt drive engine but changing it is not difficult. Installing the valve cover is honestly the hardest part of the process, purely because its fiddly to get the cover in place without moving the gasket. The engine doesn't really belong in that engine bay so part of the cowl and the heater hoses get in the way. In the BMW it belongs in, you just lift the thing straight up.

Everything else is chain drive with the cam in the block where it belongs.

the problems I tend to have are just drying up / exhausted sources of parts.
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As long as a camshaft belt is in a non-interference engine (and I think both of mine are non-interference), I don't have any issue with it.

I've never dealt with a broken cam belt, in any case except an engine where someone else neglected it terribly, in any case. As long as you're changing them in less than 10 years/ less than 60K miles, I can't see where there's any real danger.

Regards,
Gordon.
 
GordonW said:
I've never dealt with a broken cam belt, in any case except an engine where someone else neglected it terribly, in any case. As long as you're changing them in less than 10 years/ less than 60K miles, I can't see where there's any real danger.
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I believe that Ferrari V8 and V12 engines often have rubber timing belts (and I'm pretty sure they are interference engines).

You need to drop the engine to replace the belts, and it had to be on schedule. Like an $8-10K job every 30K miles.
 
Mr Boochie said:
I believe that Ferrari V8 and V12 engines often have rubber timing belts (and I'm pretty sure they are interference engines).

You need to drop the engine to replace the belts, and it had to be on schedule. Like an $8-10K job every 30K miles.
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I have a friend who has had a series of Ferraris. And he was, and is FANATICAL about doing the belt service on time. I could definitely see why!

His wife has a Lusso, that she's put, IIRC, close to 100K miles on, so far. With no particularly serious problems, AFAIK. Still looks, runs and drives great. But, it does get every service, on time, EVERY time.

Regards,
Gordon.
 
GordonW said:
I have a friend who has had a series of Ferraris. And he was, and is FANATICAL about doing the belt service on time. I could definitely see why!

His wife has a Lusso, that she's put, IIRC, close to 100K miles on, so far. With no particularly serious problems, AFAIK. Still looks, runs and drives great. But, it does get every service, on time, EVERY time.

Regards,
Gordon.
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I'm a big fan of chain-driven DOHC. Change the oil, keep the chain tensioner happy, and you are good to go. Bikes and cars.

:thumbsup:
 
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