water stream intermittent

[Dougan]

Mariner 25hp long shaft 1996 2 stroke tiller. This model is the same as the '96 Mercury of the same specification.

When I run this, the water stream is very intermittent. I'll run it, and it will just barely sputter any water out of the pee hole. It will open up and fully pee water for about 5-10 seconds, and then stop and sputter for 5-10 seconds, and then go back. Not sure how the impeller could break in a way that behaved like this ,but figured that was the problem.

I always thought that the motor should always be spraying water strongly. But after research, it sounds like the thermostat could potentially be turning off the cooling system when it cools down enough. Am I making a whole big deal over nothing? Is this how this outboard is supposed to behave?

I will probably replace the impeller no matter what, just because I don't know when it was done last. But how do I know that my thermostat is working right without overheating and finding out "the hard way?" I don't really even know what the thermostat does.

Thanks,
Scott

 

[Micahhaase]

Re: water stream intermittent

Im assuming the theromstat works like a cars... When you first start your motor it doesnt want the water coming through because its cold as soon as your motor gets to a certain temp the thermostat senses this and pops open so that the water will run through the motor cooling it. I have a 1995 mariner 90 hp that is kinda doing the same thing. At first it will shoot out a strong stream and then get smaller and smaller until it dribbles out. I shut the motor off for a bit and it does it again strong then dribbles...this weekend im going to replace the impeller and the thermostat to see if that fixes it right up

 

[Dougan]

Re: water stream intermittent

How do you replace the thermostat? I don't even know where to start. The manual makes it look tough.

 

[Dougan]

Re: water stream intermittent

Just to put the epilogue on the thread in case someone stumbles upon it, I replaced the impeller, which was not the worst impeller job in the world, and also replaced the thermostat, which was simple, and now everything runs very well.

If I had to guess at my problem, the old impeller had half of the "arms" of the impeller pointing the wrong direction (not sure why). This was probably the problem. The impeller itself looked in decent condition, but since I had it apart, I put the brand new guy in there anyway.

 

[Micahhaase]

Re: water stream intermittent

How hard was it as im going to change mine out this weekend...Im hoping to find the manual locally somewhere if not ill have to order it

 

[Dougan]

Re: water stream intermittent

I downloaded the manual from the manual sticky in this forum. "achris" posted a bunch of factory manuals on rapidshare in there. The link is http://rapidshare.com/files/213240335/20jet-20-25.rar . PM me if you can't get it and I can email the manual to you.

The thermostat was simple. Took maybe five minutes tops.

The impeller was about average as far as impellers go. There wasn't really anything abnormal or unusually complicated about it. Took about two hours and that was with me taking my time. The manual basically says everything you need to know. Find the section about dropping the lower unit (including removing the shift linkage). Then find the section about replacing impeller. Chapter 6 I believe.

One thing that was not mentioned, but I read somewhere on here-- if you have electric start, which I did, you have to remove the starter to get at the shift linkage. This was tough for me to get at with a socket wrench (don't have a metric crescent wrench set-- 10mm crescent would be useful here) so I had to take off the manual rope start to get at the starter. But anyway, just remove the battery, remove the two screws that hold the starter on, and remember where any wires that you got rid of were. Then you should be able to get to the shift linkage. Easiest to deal with if you shift into Forward.

There's a washer that the manual talks about not losing. It's tough to get at, and I had to think for a bit-- but a pair of locking fishing hemostat pliers came in handy there. Not sure what this washer does, or why it's so important, but whatever.

Otherwise there's really nothing I got that the manual didn't have... good luck!

 

[Micahhaase]

Re: water stream intermittent

I wonder what is different on your 25hp and my 90hp??? I've never changed an impeller but thank god im mechanically inclined and have at least some patience... I was talking to my dad..he knows even less than I do and he said he heard the worse part of changing the impeller is getting the shaft lined back up to where it will go in forward and reverse the same as it used to.

 

[Dougan]

Re: water stream intermittent

Oh, I forgot you had a 90 and not a 25. So that manual isn't the same, my bad.

I think that the manual for the 90 is there at that link though.

I've only taken the lower unit off of smaller motors-- this 25 is the biggest I've done. Aside from disconnecting the shift shaft from the engine, they're all the same. Getting the lower unit back in is harder than just sticking it back in, but was only about 2-5 minutes of frustration each time. I could see how that could be compounded by a bigger, heavier lower unit, though. Might help to have a buddy for leverage. A flashlight is a must so you can see inside and line things up. It's a bit frustrating at times, but I've never had a "problem". Different motors have different shift linkages so maybe your dad had a bad experience-- the couple I've done were not difficult in that regard at all.

I think a normal impeller job would be something on par with someone who has "average" technical knowledge so if you consider yourself technically inclined, I'd bet you could do it without getting stuck.

 

[davey33jay]

Re: water stream intermittent

When removing and reinstalling the lower unit, make sure the transmission is in Forward. I agree with 'Dad' - the shift linkage is the most difficult to align during the reinstallation process. Took me about 15 minutes of 'fooling' with the gear shift to align the spline.