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Oil level question when first checked???

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Oil level question when first checked???

Postby Arkie » Fri Sep 18, 2020 10:45 am

What causes the oil on the dipstick to not seek normal level on the dipstick as a small engine cools after several hours???
Why does some small engines dip stick oil level read several inches higher after the engine has cooled off first time checked cold. For example when Onan B43/B48, and some Kohler CV730 engines the dipstick oil level will be several inches high (almost to the top of the dipstick) the first time when checked cold, wipe off the dip stick and next check level is normal.
:oops: :bricks: :?:
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Re: Oil level question when first checked???

Postby 90+ret-d » Fri Sep 18, 2020 11:54 am

I have a mower with a Brigg's engine and I found the same the same thing loosen the cap it reads correctly. I think that the bottom oft the oil fill tube is slightly below the full oil mark and as the things cool down the expanded air in the tube pulls enough vacuum to pull the oil up a small ways. If I just slightly loosen oil the cap while hot the level will be correct after it cools down, just my observation.
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Re: Oil level question when first checked???

Postby bgsengine » Fri Sep 18, 2020 12:13 pm

90+ret-d wrote:I have a mower with a Brigg's engine and I found the same the same thing loosen the cap it reads correctly. I think that the bottom oft the oil fill tube is slightly below the full oil mark and as the things cool down the expanded air in the tube pulls enough vacuum to pull the oil up a small ways. If I just slightly loosen oil the cap while hot the level will be correct after it cools down, just my observation.

Absolutely correct - dipstick tube end below oil level, as engine cools, it draws oil up into the tube further (Surely y'all have done that science class experiment in grade school with a candle in a pan of water and a glass over top of it..? the one that covers several basic scientific theories including atmospheric pressure/vacuum, oxygen content and thermal expansion..?)
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
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Re: Oil level question when first checked???

Postby 38racing » Fri Sep 18, 2020 8:37 pm

Aircraft mechanic used the term dipstick creep. I've got a Briggs vtwin with synthetic oil in it and when I first check it after days it's right on full on first pull out and same after wipe insert remove. Others it's way up the stick.
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