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V8 wet sump pan level

V8 wet sump pan level

V8 wet sump pan level

(OP)
On a car enthusiast forum, a recent discussion on the dipstick indication got me to thinking about “How is the sump level designed”. I had no luck with Google and from discussions on other forums it appears there is a lot of myth intermixed with reasoning.
For example, my illustration shows where someone measured to their dipstick FULL mark (with the pan off) and was 5.5” below the crank centerline. Thus with that as FULL, the shown advertised 9 quart pan would only need less than 5.5 quarts to show full.
So does anyone know if there is any design criteria the industry uses to set FULL on the dipstick.
https://res.cloudinary.com/engineering-com/image/upload/v1495827643/tips/oil_pan_qh42vp.bmp

RE: V8 wet sump pan level

Designers select an oil volume for the engine, give the lubrication, cooling, and drain back time, today this is usually 4-5qt.
Then they select an oil pan depth based on space available, crank clearance, and some amount of slosh freeboard.
The fact that the gross capacity of the pan is 9qt and it reads full at 5.5 sounds perfectly sensible.

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P.E. Metallurgy, Plymouth Tube

RE: V8 wet sump pan level

If the vehicle goes around corners or accelerates with vigor, there may be a horizontal baffle between crank and static oil level, sometimes with trapdoors.

The one thing you want to avoid is having something moving at crank speed contact the oil pool.

... except for engines without oil pumps, which may have 'dippers' on the rod caps, or other oddities intended to splash oil where it needs to go.



Mike Halloran
Pembroke Pines, FL, USA

RE: V8 wet sump pan level

The [stationary] air compressors in one station where I worked had twin sump oil level gauges, one running [the lower of the two] and one standing [the upper]; the quantity of oil in circulation when running was known and the lower glass had been correctly calibrated for this. As a result there was no need to shut compressors down to check their oil level, and it was not only completely acceptable but quite expected of us operators to top up the lube oil as required with the compressor running. We took considerable pains to tell the trainees to use the correct glass for the status when topping up, the penalty being not only the privilege of cleaning up all the spilt oil if one got it wrong, but also suffering the ridicule of those passing by - and the word that it had happened always seemed to spread like wildfire.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: V8 wet sump pan level

So why don't they do something like that for the trans fluid? Gotta check it running, everything else cold. PTA :(

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: V8 wet sump pan level

Well, most automatics have a torque converter and probably lots of other places where oil normally lives.
All of those have varying and unknown drainback times. So, the only way to know how much is really in there is to have all the drainable things kept full, by having it actually running and pumping.
Most automotive engines have a pretty quick and predictable drainback time. For them it makes sense to check with engine off.
Maybe the biggest reason is - engines throw oil around when running - pull the dipstick with your motor running sometime! There will not be a visible "oil level".

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: V8 wet sump pan level

My Volvo was a pia about oil level.
5.5 qt, and long drainback time.
It was always being overfilled because mechanics couldn't wait another 10 min to actually check the oil level.

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P.E. Metallurgy, Plymouth Tube

RE: V8 wet sump pan level

My dry sump Corvette is also very particular about the oil checking procedure. If you wait too long it will drain back and then you will overfill it and probably hydraulic the motor the next time you start it.

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