Takes a long time for oil to drain back to oil pan 140hp

Alumarine

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Feb 22, 2005
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Just picked up a 1980 Sylvan 18' aluminum with a mercuiser 140hp serial 566xxxx.
Last week I changed the oil and filter (short filter) and put in 3.8 liters (approx 4 us quarts).
I checked it after 5 minutes and it was low.
I checked it an hour later and it was at the full mark.

Today I ran it for about 20 minutes on muffs, shut it down and checked it after 20 minutes.
It showed I was down about 2/3 of a quart.
I checked it after sitting for 40 minutes and it was right up to the full mark.

I've never had this issue with any motor before.
I put a level on the valve cover and have been checking it when it shows level if that helps.

Any idea what's going on?
Runs great btw. Compression is 150-152 on all 4.

thanks
 

Silvertip

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Remove the valve cover and check the oil drain back holes in the head. If the cover and valve area is all sludged up, oil cannot drain back as fast as it is being pumped up top so you could possibly run the oil pump dry. Rare event but it can happen. If everything is clean up top, then consider the situation normal. You check the oil sitting at the dock with just you in the boat. If you check it at that attitude all the time you get a true reading of oil level. Is the dipstick tube mounted solidly. If it is moving around, so will the oil level reading on the stick.
 

Alumarine

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Great, thanks for that.
I'll remove the valve cover and check things out before I run it today.
Dipstick is mounted solid I believe but I'll double check.
 

Alumarine

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Just got the valve cover off (with some help from my sawzall to remove some boat structure).
Looks like brand new in there. Galleys are free, no crud at all.
Mystery continues...
 

Howard Sterndrive

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It's October. In MB, and you are using 30WT, 20W40 or similar recommended oil, it's probably about as runny as corn syrup this time of year. On muffs the oil is probably just never really getting hot enough to thin out.
 
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fishrdan

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Today I ran it for about 20 minutes on muffs, shut it down and checked it after 20 minutes.
It showed I was down about 2/3 of a quart.
I checked it after sitting for 40 minutes and it was right up to the full mark.

My guess..... The oil filter is draining and emptying back into the pan., thus getting another 2/3 qt of oil in 20-40 minutes.

I'd start the engine, run it up to temp, shut off, check oil level, then fill as needed to bring it up the full mark.

..... Actually, I'd confirm the filter was leaking and draining back into the pan,, then replace the filter, no need to starve the engine for oil at each cold start up.

What brand of oil filter is this? I use WIX oil filters on my 140HP and haven't seen this issue. (Use Wix on most everything.)
 

Alumarine

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My guess..... The oil filter is draining and emptying back into the pan., thus getting another 2/3 qt of oil in 20-40 minutes.

I'd start the engine, run it up to temp, shut off, check oil level, then fill as needed to bring it up the full mark.

..... Actually, I'd confirm the filter was leaking and draining back into the pan,, then replace the filter, no need to starve the engine for oil at each cold start up.

What brand of oil filter is this? I use WIX oil filters on my 140HP and haven't seen this issue. (Use Wix on most everything.)

You might be on to something. I have a PH30 on there now.
Just picked up a Napa Gold 1069 and will put it on tomorrow. Hope that's the right one and hope they are WIX in Canada.
Will report back tomorrow, thanks.
 

Alumarine

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It's October. In MB, and you are using 30WT, 20W40 or similar recommended oil, it's probably about as runny as corn syrup this time of year. On muffs the oil is probably just never really getting hot enough to thin out.

I'm using 15W40 but letting it run long enough for the oil to at least get warm.
I've been doing this every fall for 40 years and this is the first time I've had this problem. Strange.
 

Grub54891

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The dipstick tube goes right to the bottom of the pan. Maby the oil takes a bit to work up the tube, try pulling the stick out a bit to let the airlock out,and wait a few min.
 

Alumarine

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The dipstick tube goes right to the bottom of the pan. Maby the oil takes a bit to work up the tube, try pulling the stick out a bit to let the airlock out,and wait a few min.

That's an interesting idea. I'll check that out as well. Thanks.
 

Alumarine

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My guess..... The oil filter is draining and emptying back into the pan., thus getting another 2/3 qt of oil in 20-40 minutes.

I'd start the engine, run it up to temp, shut off, check oil level, then fill as needed to bring it up the full mark.

..... Actually, I'd confirm the filter was leaking and draining back into the pan,, then replace the filter, no need to starve the engine for oil at each cold start up.

What brand of oil filter is this? I use WIX oil filters on my 140HP and haven't seen this issue. (Use Wix on most everything.)

No luck. Swapped out the PH30 with a Napa Gold 1069 and added 1/2 quart of oil.
Ran it till it was warm, shut it off and checked the level 5 minutes later.
The level was at the add mark. I checked it after 10 minutes - same thing.
40 minutes later the level was almost up to the full mark,
 

Alumarine

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The dipstick tube goes right to the bottom of the pan. Maby the oil takes a bit to work up the tube, try pulling the stick out a bit to let the airlock out,and wait a few min.

No luck with this either. I pulled the dipstick out a bit and that did not quicken the time it took for the dipstick to register full.
 

DaveG55

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Does sound like clogged oil passages. I've had good luck in cars with stuck lifters by running a full can of Marvel Mystery Oil in the oil for a couple hundred miles then doing an oil/filter change. Perhaps something like that might get you better flow.
 

fishrdan

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Ran it till it was warm, shut it off and checked the level 5 minutes later.
The level was at the add mark. I checked it after 10 minutes - same thing.
40 minutes later the level was almost up to the full mark

Pull the filter to see if it drained, sounds like it has to me.
 

NHGuy

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If the filter draining isn't your issue I would run some seafoam in the oil for half an hour then do an oil change and check it.
 

frank246

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I had a similar thing with my ford 302..the dipstick was reading odd levels.
I twisted the section with the marks on it so pulling the stick it woudnt touch the tube..that cleared the issue in my case.
 

Alumarine

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Pull the filter to see if it drained, sounds like it has to me.

I pulled the Napa filter and it seemed ok, although I'm not sure how to tell if the oil has drained out.
It's certainly as heavy as any used filter I've changed before. For that matter so was the PH30 I had on before.
I can't imagine having 2 filters in a row that somehow drained back.
But I don't know. I'm stumped.
 

Alumarine

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As others have said I'm beginning to think it has something to do with the dipstick tube.
I inserted the dipstick from my chevy car (which is a lot narrower, but much too long) into the tube and got a reading right away.

Is the tube just pressed in? if so I was going to insert something into the tube to support it and twist it back and forth with channel locks to get it out.
 

Alumarine

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Ok, i took the dipstick tube out. Looks fine but it is bent and angles towards the crankshaft.
Is it supposed to be straight or does it matter?
 
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