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1986 Mercury 25hp Outboard leaking water.......

C

ccruiser91

New member
Good morning;

I have an 86 Mercury 25hp outboard, s/n 0b172098, on a 2006 Cobra R208 River Boat.

Here are some details about my engine:

It is in very good shape. The gentleman who owned it before me did everything right. It was winterized properly and looks and has run great.

I wasn't able to use the boat last year and am hoping to use it soon. I decided to replace the impeller and even though my motor didn't have a thermostat, according to the s/n, it was supposed to, so, last week I added the thermostat, gasket and impeller and those procedures went well. I blew out the hose running from the thermostat to the tell-tale and from the thermostat housing through the block and met no restrictions. I put the motor in a barrel, added enough water to cover the cavitation plate and fired it up. Water wasn't "shooting" out of the tell-tale, but, it was coming out in a steady stream. The volume increased once the thermostat opened, but, once again, it wasn't shooting out like I thought it would.

It was then I noticed water coming out of the seam where the lower unit butts up against the drive shaft housing (the four bolts that attach the lower unit to the shaft housing were torqued to 25ft/lbs, per the Seloc manual instructions, after the impeller change). I immediately figured I must have misaligned the copper water tube that runs from the impeller up to the block. I took the motor out of the water, drained and removed the lower unit and dried up the water that had collected around the impeller. I looked up the drive shaft housing to see if I might have knocked a fitting/bushing loose where the copper tube fits into the head and everything looked ok. As I reinstalled the lower unit, being extra cautious, using an extra pair of hands (my wife's) along with a good flashlight, I made sure everything was perfectly aligned this time, and it was. I bolted everything back together, filled the lower unit, put it back into the "test tank", fired it up again and had the exact same results as before.

I removed the lower unit again and had the idea to remove the copper water tube from the impeller, then install it back up into the head and blow through the hose from the tell-tale, to see if I could feel any air coming through the copper tube and felt nothing. In fact, removing my finger from the end of the copper tube and replacing it, like one would do keep a liquid in a straw, didn't even change the sound of the air I was blowing through the tell-tale tube. I'm thinking I need to replace the parts listed as #3 and #4 in the attached diagram, or could it be indicative of something else? I really want to fix this motor and cannot afford to replace the whole thing at this time so any advice is appreciated. Thank you in advance for your assistance.

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The stream being weaker with the thermostat in is normal. I don't understand the problem you are having you don't mention overheating at all. The water does two things in the motor first it cools the power head second it cools the exhaust in the exhaust housing. After the water leaves the powerhead it freefalls through the exhaust housing to the prop or wherever else it can get out. So when you blow air through the thermostat it's just going down the exhaust leg path of least resistance. When you say water leaks out between between the lower and the exhaust housing how did you see that in a test tank. The water has to be above the waterpump in a tank which puts it above the seam. One thing you might have going on is the lower unit drains are plugged
 
The "P" stream will be a heavy steady flow and will not "shoot" out under pressure due to impeller design and its normal for water to leak from lower unit mating surfaces...
 
fatzbullet and flyingscott; [FONT=Helvetica, Arial, Verdana, sans-serif]the powerhead was just warm to the touch while it ran it for 30 minutes or so the first time I started it up after installing the thermostat, gasket and impeller. The water coming out of the tell-tale was warmer than I expected it to be, but, figured out it would be since the thermostat doesn't open until it reaches a higher temperature. Also, the seam between the lower unit housing and drive shaft housing was an inch or so above the water level in the barrel and the water was above the water pump inlets. So, if I'm understanding you correctly, even when this motor was brand-spanking new, air being blown back through the tell-tale, through the engine, would not come out of the copper water tube exclusively, but would also come out the exhaust leg? If that's the case, I should be good to go! I've read every page in the Seloc manual and couldn't find anything about the excess water that was pumped up to the head that doesn't leave the tell-tale exiting through the exhaust leg. Whew! [/FONT]

[FONT=Helvetica, Arial, Verdana, sans-serif]One other thing I want you both to know, this last week was a rough one for me, on about seventeen different levels and I was feeling pretty down. When I ran into what I thought might be an irreparable problem with this motor, I just couldn't believe it. But, with both of your quick responses, taking time from your busy schedules to help me out, you really have brightened things up and I sincerely appreciate your words of wisdom. Thanks again![/FONT]
 
So, if I'm understanding you correctly, even when this motor was brand-spanking new, air being blown back through the tell-tale, through the engine, would not come out of the copper water tube exclusively, but would also come out the exhaust leg?
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That is correct as there are many smaller passageways in block for cooling including the exhaust cover and for water wall to cool exhaust tube/housing.
If that's the case, I should be good to go!
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yep...
I've read every page in the Seloc manual and couldn't find anything about the excess water that was pumped up to the head that doesn't leave the tell-tale exiting through the exhaust leg. Whew!
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Note: Good Words...Get rid of the Selco manual and get a factory one.
 
fatzbullet, I now have another issue. This evening, 09/10, I put everything back together and started the motor for the first time since we chatted about my first issue in this post and the motor is now not pumping water. As before, I put the motor in a barrel and filled it with fresh water above the cavitation plate. It was running pretty smooth, but, never pumped a drop of water. I never shifted it out of neutral. I put my hand under the tell-tale fitting and could feel air coming out of the hole, but nothing else. After about 30 seconds, I shut the motor off. I blew air back through the tell-tale and met no resistance. As I mentioned in the very first post, I just changed the impeller and it was pumping water. Do you have any thoughts as to what it might be before I drop the lower unit again? Thanks for your help........
 
What did you have apart as it was determined there was nothing wrong with your motor. If you took the lower unit off make sure you got the water tube lined up in the pump or did you forget to put the key in the impeller that will do it every time.
 
flyingscott, thanks again for responding. I've not had the impeller housing apart since installing the new impeller at the beginning of this journey, so, I must have misaligned the copper water tube when putting the lower unit back in. Lol! All the times I thought something was wrong as described in my first post I was able to line up that water tube with the fitting in the power head, to now, with nothing being wrong, I misaligned it. In my meager "defense", it's tough (at least for me) verifying it's lined up right because when it's close, I can't see up the housing to guarantee it's seated properly. Well, we'll drop the lower unit again this evening and try again.
 
Trust me if that's the problem you are not the first or last to do it no shame in doing that at all. If you run the motor on muffs it's easier to tell if you misaligned the tube because a bunch of water will run out the prop
 
flyingscott and faztbullet; Well, I put everything back together and now can't get the motor to start. After reassembling everything, I could not get the motor to fire. I could smell gas, as I repeatedly pulled the rope starter, but, it would not fire. The kill switch was in the "ON" position. I checked for spark with my tester and found cylinder #1 wasn't getting any spark. Thinking it might be the coil, I reversed the position of the two coils and then #2 wasn't getting any spark, which I thought confirmed my idea of a bad coil. I think the coils are the originals. I purchased a new Sierra coil and it arrived today. When I finally got home, I couldn't wait to install it! I took out the coil for #1 cylinder and replaced it with the new one and it wouldn't start. Cylinder #1 now has a great spark and #2, which was the one getting a good spark last week, is now getting no spark. I moved the coils around again, then #2 had spark and #1 didn't. Is it just an extreme coincidence that the other one is now bad? I checked the spark plug wires and they are reading zero ohms, which is believe is good. Should I just order another new coil, which will give me a matching set of two new ones or is it possible I'm missing something else?
 
Check the small studs coming out of the coil on the bad cylinder see if they are loose. The problem with those coils is when they get old they don't like to be disturbed so probably when you tightened it you probably spun the stud. It should still want to start and run on one cyl. Get another coil
 
flyingscott and/or faztbullet; I'm not sure what to do next. Last weekend, with one brand new coil, I wound up with good spark from the new coil and nothing from the older coil. I ordered another coil, received it today, installed it and now have no spark at either plug. The kill switch is in the "On" position, all connections are tight and I'm not sure what it could be now. Any thoughts? Anything jump out at either of you? I did nothing to the engine other than cover it up while I waited for the other coil to come in. The Kill switch maybe?
 
I forgot to mention these two bits of information also. The Seloc manual (I will get the factory one eventually) says the resistance between the trigger leads on the Rx100 scale should be 6.5 to 8.5., which it is and the resistance between the stator leads (black/yellow & black/white) should be 3.1 to 3.7 on the Rx1000 scale and that too is correct.
 
Disconnect the kill switch from the switch box black and yellow wires. If it starts it is the kill switch you will need to shut it down with the choke. Do you have the kill switch in the tiller.
 
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