OMC Cobra 5.7 Oil change

7

79Rude115

Petty Officer 2nd Class
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Aug 23, 2006
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122
When I winterized my boat last September I had a real pain with the oil change and I want to make sure I get it all right before I put it in the water this year.

For reference the boat is a 90 Four Winns Horizon 200 with a 5.7 OMC Cobra

The previous owner gave me a top side oil removal pump (it may be an OMC pump); you stick a hose down the dip stick tube and attach the pump to a drill. When I did the oil change I ran the engine for about 10 minutes, got it fairly warm but not too hot to work around. I had real trouble getting the pump primed then once it was primed the oil came out very slowly, it took 40 minutes or more to get about 5 quarts out then it just quit?.so I assumed it was empty.

I then changed the filter and added 4.5 quarts of oil back in. I fired it up and let the oil psi come back up. When I checked the oil, it was over filled by about a quart so I must not have come close to getting it empty. I used the pump to pull another quart or so back out to get the oil back down to the correct level.

What is the trick to these pumps? I am very concerned I am not getting old oil and sludge out ? I would feel much more comfortable if I could pull the drain plug and make certain it?s empty.

Has anyone tried a funnel and hose setup, draining the oil through the plug?
 
fat fanny

fat fanny

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Feb 9, 2006
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1,935
Re: OMC Cobra 5.7 Oil change

I drain mine out through the bilge just pull the oil pan plug out and let it flow into drain pan through the transom it just requires a little clean up of the bilge when complete Dawn and warm water work great. I don't trust dip stik pumps for the reason you posted. All the above works if you can actually access your oil pan drain plug I have a 3.0LX inline 4 so it's relativly easy.
 
a70eliminator

a70eliminator

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Re: OMC Cobra 5.7 Oil change

My 90 OMC 5.8 doesn't have an oil pan plug the oil must be pulled out through the dipstick, there is a male hose adapter affixed to the end of the dipstick that the hand pump's hose attaches to, the dip tube can be removed from the fitting in the pan for bilge draining if desired but I don't feel it's necesary for the tube goes right to the bottom of the pan, my pump does a pretty good job, I usually get close to six quarts out and changed often enough that sludge isn't an issue. I have noticed that the oil level mark on the stick will vary from ADD to OVERFULL depending on how level the boat trailer and engine is.
 
havasuboatman

havasuboatman

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Re: OMC Cobra 5.7 Oil change

I got tired of all the hand and drill pumps so I bought a Jabsco pump (with the rubber impeller) mounted it on top of a 5 gal. bucket. Drains my 5.0L in 3 minutes. It's real easy to tell when it's empty, sounds like someone is sucking air through a real big straw.
 
R

Rupp

Petty Officer 2nd Class
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Jul 15, 2007
Messages
110
Re: OMC Cobra 5.7 Oil change

Which pump did you buy? Do you have a part number or link?
 
7

79Rude115

Petty Officer 2nd Class
Joined
Aug 23, 2006
Messages
122
Re: OMC Cobra 5.7 Oil change

On further inspection the dip stick tube actually connects to the drain plug on the bottom of the oil pan. I would imagine my trouble with getting the pump primed and the oil out quick would have something to do with sludge, the hose that is put down the dip stick tube is fairly small in diameter. Is it necessary to put oil in the tube to get it primed?

I think I am going to try to change the oil out of the drain plug this time, it is going to be a knuckle buster but at least i will know i have clean oil and no sludge in the pan.

havasuboatman - would like to know what pump you got too
 
bruceb58

bruceb58

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Mar 5, 2006
Messages
30,581
Re: OMC Cobra 5.7 Oil change

Buy a pump that threads onto the fitting in the top of the dip stick tube. Using the pump that has the tube going down the dipstick tube makes it tougher to suck since the diameter is so small. I just use a Jabsco hand pump and only takes a few minutes.

Those drill pumps suck...and not in a good way!
 
Mkos1980

Mkos1980

Chief Petty Officer
Joined
Oct 25, 2007
Messages
640
Re: OMC Cobra 5.7 Oil change

I double up 2 heavy duty garbage bags and pull the plug on the pan and let the oil go into the bag. I then slide it all out. Not one drop. Just dont get that bag hung up on anything.
 
havasuboatman

havasuboatman

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Re: OMC Cobra 5.7 Oil change

The pump model number has long since been worn off the sticker of my pump, but I am pretty sure I saw a similar set-up in either a west marine, or Sierra parts catalog. It came with the bucket and everything and probably cost a lot less then what I paid piecing mine together. The pump was kinda' pricey, but worth every penny. I have used it literally thousands of times (I'm a Mercruiser tech) and only replaced the impeller twice in 7 years.
 
redone4x4

redone4x4

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Re: OMC Cobra 5.7 Oil change

Mkos1980 said:
I double up 2 heavy duty garbage bags and pull the plug on the pan and let the oil go into the bag. I then slide it all out. Not one drop. Just dont get that bag hung up on anything.
Click to expand...

I am really tempted to try this method...
 
a70eliminator

a70eliminator

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Re: OMC Cobra 5.7 Oil change

79Rude115 said:
On further inspection the dip stick tube actually connects to the drain plug on the bottom of the oil pan. I would imagine my trouble with getting the pump primed and the oil out quick would have something to do with sludge, the hose that is put down the dip stick tube is fairly small in diameter. Is it necessary to put oil in the tube to get it primed?

I think I am going to try to change the oil out of the drain plug this time, it is going to be a knuckle buster but at least i will know i have clean oil and no sludge in the pan.

havasuboatman - would like to know what pump you got too
Click to expand...

It would be better to force the tube over the dipstick tube rather than down into it, even if you have to adapt another hose, you can drain it by pulling the bolt off down below if you want but be carefull you don't strip the thread out and it's easy to do.
 
ScottRogers

ScottRogers

Cadet
Joined
Apr 3, 2009
Messages
24
Re: OMC Cobra 5.7 Oil change

Forgetting one of the most important things here......you must get that motor up to operating temp. Oil is very thick, even though the engine feels warm, the oil is still thick, so give it a few mins. past full operating temp. and you will see how much faster the oil will drain.
 
flargin

flargin

Chief Petty Officer
Joined
Aug 13, 2008
Messages
540
Re: OMC Cobra 5.7 Oil change

If you think you may have sludge, you can throw a quart of "oil cleaner" and run it for a few minutes.... I just use a quart of Diesel.

I used to do this if needed to clean out gunk...
 
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