aussie merc
Well-known member
can anyone tell me the oil height in the sump or how far the oil level is from the sump rail as sticks and tubes are notoriously inaccurate
oil height
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Flathead Fever
Well-known member
I might be able to answer the question I have some different pans with dipsticks as long as the sticks haven't been mixed up. What year pan is it? If you know how many quarts it takes four or five, fill the pan with quarts of water and see where it is on the dipstick.
Make sure that crankshaft counterweights are not hitting the oil unless it does not have an oil pump and uses dipper rods. Then the rods better be dipping into the oil.
An engine with an overfilled crankcase can start out with good oil pressure that eventually goes to zero. The crank hitting the oil turns it into aerated froth and the oil pump does not pump froth. That uses to be a question on the old automotive ASE tests. What causes an engine to lose oil pressure after driving it for a while? The answer was an overfilled crankcase.
Make sure that crankshaft counterweights are not hitting the oil unless it does not have an oil pump and uses dipper rods. Then the rods better be dipping into the oil.
An engine with an overfilled crankcase can start out with good oil pressure that eventually goes to zero. The crank hitting the oil turns it into aerated froth and the oil pump does not pump froth. That uses to be a question on the old automotive ASE tests. What causes an engine to lose oil pressure after driving it for a while? The answer was an overfilled crankcase.
aussie merc
Well-known member
exactly where im coming from regardless of sump size shape and capacity oil height is critical, what i have is a 59A 239ci in a 39 mercury eng is not original but as far as i can work out sump is correct for model and year. Supposedly should be 5 US quarts or 4.7 liter how ever this only shows about 1/3 on safe range hence the dilemma and the questions . Years of swinging spanners in the heavies [road trains] has taught me [DONT TRUST WHAT YOU DONT KNOW FOR SURE] so since the stick tube and sump are the unknowns this leaves oil height so an answer would be appreciated
Ramjet47
Member
I have the sump removed from my 1937 21 stud 221” at the moment. I took these photographs to show the relationship between the dip stick full mark and the cutout at the rear of the sump which is sealed by the cork strip. This strip sits in a groove in the cap of the rear main bearing. There is no positive rear seal on this engine, just a slinger. Hope these photos are of some use.
Attachments
5" from the top of the oil pan. Which is 1/2" below the radius part of the pan.
It is 2 1/8" from the underside of the pan to the top rivet on my dipstick casting and the FULL mark is 4 7/8" below the casting with tube removed (remember it is at 45deg.).
Measure the outside of the tube (screwed in) and add 4 7/8".
It is 2 1/8" from the underside of the pan to the top rivet on my dipstick casting and the FULL mark is 4 7/8" below the casting with tube removed (remember it is at 45deg.).
Measure the outside of the tube (screwed in) and add 4 7/8".
Mart
Well-known member
Height is irrelevant.
Decide what quantity you want. Normally somewhere between 4 and 5 quarts. Pick a number.
Put your chosen quantity in and mark the stick to suit.
If the level drops after running, due to filling the remote filter, add some more to get to the mark you put on the stick.
I had one motor with mismatched stick and tube and was habitually running lower than I should have been until I checked everything and remarked the stick.
Mart.
Decide what quantity you want. Normally somewhere between 4 and 5 quarts. Pick a number.
Put your chosen quantity in and mark the stick to suit.
If the level drops after running, due to filling the remote filter, add some more to get to the mark you put on the stick.
I had one motor with mismatched stick and tube and was habitually running lower than I should have been until I checked everything and remarked the stick.
Mart.
aussie merc
Well-known member
Mart i would argue with you on this height! is everything an engine will run happily if the oil is below that height but when its above DRAMAS come out of the woodwork like no tomorrow , ive seen poor oil pressure /blown rear and front main seals / destroyed cranks and run bearings that have all come down to high oil levels and nothing causes oil leaks and oil consumption like oil levels being to high . .
aussie merc
Well-known member
yes i agree but as Im dealing with unknown's . If it was close with what is listed as the correct amount i wouldn't worry to much about it but its not so any information could be helpfull ie tube length and dipstick length and distance from the top stop to the mark but the most acuate would be the distance from the panrail to the oil
aussie merc
Well-known member
thanks must have missed it
quik
Member
I’m swapping a center sump for a rear sump pan on an 8BA for clearance purposes. I measured 5.25” from the top of the oil pan to the full mark on the dipstick. Is that 1/4” worth worrying about?
Also, I’m guessing the most critical aspect of the oil level is to ensure the oil pickup is covered. Is that correct?
The rear sump pan is 1” shorter and will probably hold less oil, again is that an issue?
aussie merc
Well-known member
again don't just dump 5 quarts in and hope for the best there are several documents in the service notes in regards to sump capacities /oil height and pickup clearance and they state that pickups must be correct to the sump. Pickup to low or close to the pan bottom will induce oil starvation by starving the pickup of oil and to high will result in it sucking in foam and suffering from oil surge . Oil capacity will control the change intervals .If i can find these docs will post here may take a few days .
quik
Member
Thanks man. That’s the info I was hoping to find.