Oil dipstick mystery

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mike37909's picture
mike37909
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Posts: 154
Oil dipstick mystery

I pulled my dipstick and the oil was reading low almost empty.  The rest of the stick up to the full mark was spotless no oil.  

of course everyone knows you wipe it off and stick it back in to read it and magically it is perfectly full.  What the heck this is baffling.

can anyone explain this.  

Catalina 36 MK1
1984 Hull #306

 

Chachere's picture
Chachere
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Posts: 797

Always been that way on ours as well.  Maybe air pressure builds up in the tube and prevents an accurate reading at first?
 

Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

Catboat Willy's picture
Catboat Willy
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Posts: 366

It's a pressure thing, much like holding your finger at the end of a straw and plunging the straw into a glass of water. There is a rubber seal on the dipstick and seals the pressure in the engine. It happens to all of us. Take the dip stick out and let the pressure equalize. Then measure the oil. As a matter of practice, do not measure the oil quantity  too soon after running the engine as there is usually a quart stuck up in the engine (oil filter etc) . Diesels engines do not like to be overfilled with lubricating oil. When changing the oil, measure what you take out and only refill that same amount as it is easy to over fill. I check the engine oil levels in the morning before running the engine. 
Bill

Bill Dolan 1990 Catalina C-36 MKI - Hull #1041  'Williwaw'
Std. Rig, Walk Through, Wing Keel
M35, Oberdorfer Conversion,
Home Waters; Charlotte  Harbor & The Gulf Islands of Florida
'You are never out of work if you own a boat'

 

mike37909's picture
mike37909
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Posts: 154

Thanks all this makes sense. 

Catalina 36 MK1
1984 Hull #306

 

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