Do I have water in the lower unit? Slight leaking under the power head? Pic Attached

[scbasschaser]

I started having idle and ignition problems so I decided to check the oil in the lower unit and came out black with a grey cloudy mixture in it. The oil itself had a strong odor as well. I know I had a small leak in the upper shaft area and only recovered about 6oz of the 9 or 10oz that went back in the foot. Any ideas on where to start to resolve this issue? The picture of the of the engine shows the leaking area just behind the wiring harnessess. Looks like a pretty expensive repair job to fix this.

 

[Texasmark]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

If pic #1 is the oil from the LU then yes you have water intrusion. Intrance points are vent/drain screw gaskets, upper drive shaft seal, immediately beneath the water pump and that seal usually comes as part of a full water pump replacement kit, shift shaft seal in the upper part of the lower unit, adjacent to the water pump where the shift shaft enters the lower unit, and finally the prop shaft seal.

A pressure test with 5 psig roughly and submerging the LU in water can immediately tell you where your culprit is.

Don't know why you have a pic of the powerhead as it has nothing to do with the LU seals.

HTH,

Mark

 

[scbasschaser]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

Texasmark, I think this is going to be very helpful. Could you share more about the psig test. Eventhough this is a 2003, i think Im going to have to do some wear and tear as it seems things are ready for replacement all at once. Not sure of the costs, but might need to just replace each of these areas within reason. Should I try to replace it all together or is there a simple test to check each area. The upper seal is behind the electrical harness is also leaking in the upper cowling. Very nasty issue but still runs fine.

 

[Texasmark]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

If I were to perform the test (other folks may/probably have their own idea) here is how I'd do it: I use the Merc lower unit oil that comes in a quart container with a plastic tube, pump, and adapter that is designed to be placed in the hole where the drain screw is located and normally pumped up till it comes out the top (vent) hole. So this gives me an adapter free of charge and inconvenience.

I would drain the oil, and using just the connector/adapter and hose, insert the connector into the lower unit threaded drain hole. Then submerge the lower unit in water lying on it's side would be ok.

I would then connect a low intensity air source (5 psig is plenty), which is not too much for the plastic hose to sustain, via an air "gun" , spray nozzle or whatever you call it when you use compressed air to blow off/out something and stick the end of it in the end of the tube.

Apply air and bubbles should immediately form to tell you where you are leaking.

In this test, you have removed the drain screw and seal. If that seal were your culprit then you could test for it indirectly in that you would see no bubbles.

Any time you replace the screws (drain and vent) always use new seals unless you have what I have heard to be a new style that is silicon and I believe the info source said it was yellow...I personally haven't seen one but I don't get around much. They used to be (the ones I use) fibrous and light blue and required replacement when disturbed.

HTH,

Mark

 

[Texasmark]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

The upper seal is behind the electrical harness is also leaking in the upper cowling. Very nasty issue but still runs fine.

Is your engine 2 or 4 cycle? If 2 cycle, what "upper Seal" under the wiring harness?

 

[carholme]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

scbasschaser;

If the engine is the 25hp you are referring to in previous posts, here is the parts listing and service manual for it.

Parts listing:

http://www.crowleymarine.com/mercury-outboard/3236.cfm

Service Manual P/N: 90-826883R03

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/826883r2/cover.pdf

You must have Adobe Acrobat reader installed to use this manual. If you scroll down to the lower part of the opening page, you will see the various engine components in red. Click on the one you want and when the first page opens, click on the "Save As" icon at the top LH corner of the page and you can save it to your computer.

Maybe you can use the above to show where the leak is behind the harness. Note the quick check for the leak test in Section 6 of the Service Manual, page 6A1 just under the heading "Specifications"

Gerry

 

[scbasschaser]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

Marak, Thanks for the reply. This will be a great start for me and get the chance to inspect everything. Might find my overheating issue in the waterpump. I was not sure about the drain plug gasket. The vent screw had a small red washer, none on the drain screw. i did notice the rubber gasket stuck to the drain hole look very suspicious especialy after I stuck the oil pump adapter in it. Not leaking any oil at all. Should or could I remove the prop to do the water test? Got a decent service manual free from the Merc web site after following a link on this site. Maybe not a full service manual but I can see where I going at least. I get started and let you know what happened.

 

[scbasschaser]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

Gerry, thanks for the post. Downloaded this yesterday. Very helpful. I`ve got an overheating issue to fix this bigger mess. I`m going try to pinpoint what this are should be.

 

[Texasmark]

Re: Do I have water in the lower unit? Slight leaking under the power head? Pic Attac

Marak, Thanks for the reply. This will be a great start for me and get the chance to inspect everything. Might find my overheating issue in the waterpump. I was not sure about the drain plug gasket. The vent screw had a small red washer, none on the drain screw. i did notice the rubber gasket stuck to the drain hole look very suspicious especialy after I stuck the oil pump adapter in it. Not leaking any oil at all. Should or could I remove the prop to do the water test? Got a decent service manual free from the Merc web site after following a link on this site. Maybe not a full service manual but I can see where I going at least. I get started and let you know what happened.

With what you said here, I wouldn't. Go to your Merc dealer and get some (I get several sets while there) blue washers. Refill the LU with Merc Premium Plus LU fluid....the Quart container at WW has a pump, hose, and adapter. The adapter screws into the lower (drain) hole and, with the top (vent) screw removed, pump it up till fluid with few bubbles....will make a little mess....comes out the vent. Install the vent screw with a new gasket and tighten as hard as you can with a large screwdriver using just your hand for torque.

Remove the fill adapter and quickly install the drain screw with a new gasket and tighten accordingly. You will loose a small amount of fluid but that is ok. The top screw must be replaced first to create a vacuum in the LU which reduces the rate that the oil comes out as you are transitioning from fill to plug.

Go fishing a few times and then let the boat sit up for roughly a week....giving time for the fluid to separate if any water is present. Pull the plug carefully and let a small amount of fluid out. If dark green you are good to go, if some yellowing, it could be residual from the original problem or it could signal that there is another leak. You have to decide what to do next. Might drain some out till the yellow disappears and depending upon how much you let out add new back following the above process.

You need to keep a goodly amount of fluid in there so that it can wick up and lube the upper drive shaft bearing.

HTH,

Mark