mariner 50 3 cyl, clamshell 1989

Hello to all and thanks in advance for any help,
I have a mariner 50 3 cyl, 1989(I think) serial no. 9560228.

I replaced the impeller end of last season and was readying the boat for the water last weekend. Started fine but I noticed very quickly there is only a trickle of water coming from the tell tale.

Removed the bottom leg (blew the system thru with a compressor, no probs) and attached a hosepipe under v/low pressure to the pipe that carries water from the impeller.

Water is peeing quite happily thru the tell tale but also water is coming back down inside the leg and some from the exhaust holes?? I'm not familiar with the workings up there but it seems likely there must be a bad seal/grommet at the top end of the pipe. Does this make sense? Any diagrams, advice or experience with this? Just hope I dont have to remove the powerhead
Cheers, Jochen

Oh, I also found the overheat alarm wire tucked away(brown/white), when I ground it with the ignition on it beeps but where should it be connected to the engine?

Re: mariner 50 3 cyl, clamshell 1989

I have a similar engine,mine 1989 60hp merc. The top of your water tube is held in place by a rubber sleeve which in turn is located in the i.d. of a housing.the housing is held in with 2 screws with a paper gasket between it and the exhaust plate.My motor had one of those 2 screws vibrated out,allowing the housing and tube to rotate around so it was no longer pumping all the water into the powerhead.As far as the water you see coming down the leg,the majority of your cooling water comes back down thru a hole in the exhaust plate and fills the leg,after it goes thru the powerhead of course.As far as the overtemp warning system,the switch is mounted into the engine block just to the right of the #1 (top) cylinder.Runs about 5 inches to a terminal block,where the main harness picks up the signal and takes it up to the control box where the actual alarm is. Hope this helps.

Re: mariner 50 3 cyl, clamshell 1989

thanks for the rundown,
Sorted the stray wire, just afew questions tho as I'm abit slow sometimes.
How did you end up getting to the screw to replace it? And can I access the rubber by removing the exhaust plate? Just feel like I should "get right in there" to check things thoroghly. Cheers pal

Re: mariner 50 3 cyl, clamshell 1989

I changed the upper seal and housing thru the leg from the bottom,with about 2 feet of extensions on my ratchet,not easy.Take a look up the leg with a light,or is it a torch over there in the uk.at least you can check on the torque easy enough,they are 10-32 screws with 5/16 heads.If the water tube feels snug up top your problem may lie elsewhere.with the lower unit removed i would take a peek at that recently replaced impeller.by the way the rubber seal and nylon washer used for the water tube in the upper housing for the impeller are the same items up top on the bottom of the exhaust plate.Need some sleep now,midnight shift is killing me! Best of luck

Re: mariner 50 3 cyl, clamshell 1989

Can't believe it mate, the "new impeller" has crumbled to bits. Perished rubber or something I guess.:redface:
Still good to check out the upper end of the water tube, and all was just fine. Will do the necessary and let ya know how she goes.. Thanks again bud

Re: mariner 50 3 cyl, clamshell 1989

I was happy to be of help,as others here have helped me. Best of luck.