Dipstick level wrong?

Ryland3210

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Jul 21, 2015
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I pumped all the oil out of my Mercruiser 5.7 liter EFI engine, changed the filter and added 4.7 quarts. The dipstick shows about one quart too high after running the engine to fill the filter and build pressure for a couple minutes.

This is my first time with this engine in my boat, but I have changed oil countless times on Chevy 350's and others. Always took about 5 quarts with a filter change. I realized this is the short version filter, but it still has me scratching my head with such a high level indication.

Is the end of the dipstick tube that far above the bottom of the oil pan so a quart was still left in the sump after pumping it out? Is the dipstick calibrated wrong?(Don't laugh. I have seen that before!) Some thing else?

Can I safely run the engine with one quart above the full mark?

Thanks,
Ryland
 

nickmo

Petty Officer 2nd Class
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Apr 2, 2010
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I have a 5.0 and it's been that way since new. I use the long filter so it should take 5 quarts, but always reads above full. I used to think I wasn't getting all the oil out, but I don't think that's it either.
 

alldodge

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pumped all the oil out of my Mercruiser 5.7

You probably didn't get it all out. How did you pump it out, connect suction hose direct to dipstick or put smaller tube down the dipstick tube?
Was the boat sitting level?
 

alldodge

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Thanks! Unfortunately, I can't reach the drain plug to find out for sure.

I understand that, and removing oil from a marine engine is removed via the dipstick (less chance of leak later and is easier). What method did you use thru the dipstick and was the boat level?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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That's why I have added an oil drain hose when I had my motor out last
 

Ryland3210

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Jul 21, 2015
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I used a vacuum suction device directly on the dipstick tube. It continued working until I heard it breaking suction. The boat was level on jackstands.
 

Ryland3210

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Jul 21, 2015
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PS I did attempt to force plastic tubing down first, thinking I could make sure it reached the bottom of the sump, but it got stuck only part way down.
 

alldodge

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Guess your dip stick is a bit short then. Normally there is no issue putting the tube down the dip stick, must have some damage. I suck it straight from the dip stick and wind up leaving about a little.
 

Lou C

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If you have the garden hose threads at the top of your dip stick tube and fab up a hose fitting to work with your oil pump it will work better than shoving the little tube down the dip stick tube. You might not be getting it all out. My 4.3 does not take as much oil as the book says to read full on the stick. Make sure to pull the stick out and let the level in the dip stick tube stabilize before checking because I have found:
After running it will read low; it takes a while for the oil to climb back up that tube...
After sitting the air in the tube coold off contracts and pulls more oil out of the pan. This causes it to read high. So.... Pull the stick out; leave it out for a few minutes and then check it several times. There is a small relief hole at the top of the tube for this reason but you still get this effect even so..
 

JustJason

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Throw a small level on the spark arrestor or valve cover.... Is the engine close to level? If it's not, that will effect your reading.
 

64osby

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Did you measure the amount of oil you removed? If not maybe try doing that next time.
 

Ryland3210

Seaman
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Jul 21, 2015
Messages
60
The dipstick tube does have the garden hose thread. That's what I used, and it appeared to have no leaks.

I did not measure what came out. Didn't think I would have any problem, but sure will next time. I spoke to the old timer that sold me the vacuum system. He was surprised the tubing would not go down the dipstick tube. Perhaps there is some damage, although I can get the dipstick down without trouble. Having said that the tube was bent when the boat was delivered such that there was a risk of shorting out to the alternator terminal. I bent it straight. I'll take a close look at it.

A local Mercruiser mechanic immediately told me I didn't get all the oil out. He sees this a lot. Advised me not to run like this because the oil will be agitated and aerated, resulting in low oil pressure. In my '67 Barracuda, Chrysler installed "windage trays" between the sump and crankshaft to prevent this on their high performance 383's. I doubt GM does this on Mercruiser engines, based on what the mechanic said. So I guess I will try again with the vacuum pump, measure what comes out, and also see if I can get the tubing that comes with it all the way down.
 

alldodge

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Windage trays are to help keep the splash down and foam, and Merc (GM) does this also. To high an oil level allows the crack shaft to splash into the oil and cause foam, a windage tray being present will not change the fact if oil is over full.

Note: I don't use the threaded fitting, I use a hard line hose clamped to the end of the dip stick tube it self. This method will not change the amount of oil removed, just the way I do it
 
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