200 Mariner

[jobu]

I know it's not hull related but I think I need a new impeller in my Mariner and was wondering if anyone had any links for changing it.
Changed the thermostats and it still only pumps water out top at about 2000rpm. Also seems to come out pulsing.
Thanks
Joe

[Blue197320]

its really really easy to do. heres what i do.
i put it in gear and remove all the nuts and bolts holding the lower unit on except the one closest to the transom. that one will hold the LU on for you. get a helper if you need one and loosen that nut. the LU will slide right off. the water pump is very straight forward. replace everything. get the whole kit. it will cost about $50. just when you take off the old piece match them up with the new ones in the kit and put it back the way it was. be careful not to over tighten the bolts holding the pump housing on. when your ready to put the LU back on, get your helper again and line up the shift shaft which should still be in gear and you will have to move the prop a little bit to get the driveshaft to line up with the splines. when it lines up it will slide right back up and put that nut on that you took off last closest to the transom to hold the LU. it probably takes about 20-30 minutes tops.

[Bigshrimpin]

Jobu - you should definitely change the impeller. Also understand that merc thermostats won't open until block temp reaches 143 degrees. There is only a minimal tell tale on those motors until the water temp reaches 143 and the tstats open up. You are also in a cold water area, so the tstats react a little slower.

[jobu]

Well the housing and thermos where covered in corrosion and it looks like the last ones were never cleaned out first so the weren't seated correctly. But what do you think would cause the intermittant pulsing of the water coming out? My guess is a bad blade on impeller. I had it running for a few minutes and the heads were warm to the touch so I am guessing that the thermostats were opening. I will try flushing it all out good again and replacing the hoses too. But I'll also give the impeller a shot too. I was doing this in the driveway with a hose and earmuffs with good pressure(if that matters) and again nothing coming out at top until about 1900-2000 rpm. Thanks Blue too!
joe

[jobu]

Also BigShrimpin....noticed you were local...WTF!!! is up with this rain?

[Blue197320]

the heads should be warm but still cool enough where you can keep your hand on them. i dont have t-stats in mine, i will put them one day but im also going to add another temp gauge so i can see both sides of the motor. the heads fill up with water from the bottom up. do you have a psi gauge on the dash?

[Fr. Frank]

But what do you think would cause the intermittant pulsing of the water coming out? My guess is a bad blade on impeller.

No, it's not a missing impeller blade. Even with two adjacent blades missing, you would be unable to detect any pulsing in the flow of water, as the impeller simply rotates too fast.
Pulsing in the flow of the telltale is either thermostat or poppet valve.

Some think I am overly careful, but I replace my impeller every January, or every 100 hours of use, without fail. I advise all of my friends to do the same. Waiting for your water pressure to fall away to nothing before changing the impeller is like waiting for your oil pressure to fall away to nothing before checking or changing your oil. By the time the pressure falls, damage may already be occurring.

$18 for a new impeller is a cheap insurance policy. I have never lost an engine or powerhead to overheating in 41 years of boating, including over a decade in marina management. On the other hand, I have seen LOTS of outboard failures caused by NOT changing the impeller regularly.

I also have a mechanical water pressure gauge, even though my Optimax Smartcraft system has an alarm if the water pressure falls below 6 lbs.

Bottom line: change the impeller, change the thermostats, change the poppet valves. It's the right thing to do.

[Blue_Heron]

All the above is good advice. I would add just one thing. If you're going to work on your Mariner yourself, buy the FACTORY service manual, not a Seloc or other after market manual. The factory service manual will give you step by step instructions for changing the water pump, cleaning the carbs, pulling the power head, and everything in between. You can usually pick them up on ebay for about 20 bucks.
Dave

[jobu]

Sorry for taking so long to respond but it's been non-stop rain here and the boat has been on the back burner for a while. That said, I changed the thermostats and was still getting similar results. But when I run it with the thermostats out it really flows good (and I have hardly no water pressure at my house)
The poppit valve...is this also called a diaphram?
I bought one from the local Merc dealer and he gave me a schimatic...looks like the lower right bank of block. But there is also an electrical panel there...stupid question but does this have to come off first...and also is this the poppit valve?
Also, thanks to everyone who has responded...I haven't been on in a while and forgot how helpful everyone here is!
Thanks,
Joe

[jobu]

Okay...here's the status.
New stats...same thing...low to no pressure out of top tell tale at idle.
New poppet valve....same thing(there was some seaweed...also I put the round plastic disc that goes between the valve and screw convex side pointing in?).
Drop the LU redo the impeller, gaskets, housing exactly...put key back in...line up LU and reinstall with minimum difficulty...Now I get NO water out of all three...I assume that I didn't line up the water pipe correctly...I try it again and get no water still. Is there a trick to lining up the guide for the copper pipe? Does the pipe attach first to the upper part or to the pump housing first...also if anyone can explain the order this would be great. Also I cant see it but it looked like I got it lined up right so maybe something completely different. If anyone can help it would be greatly appreciated.
Thanks Joe