Weak water flow through pee hole (Merc 1979/85hp)

rdreskai

Cadet
Joined
Jun 17, 2007
Messages
10
Hello,

I just picked up an old 1979 850 (85hp) Merc, it ran great at the test ride (10 minute run). Before taking it out again, I've changed the impeller, gear lube and prop - Engine seemed like it was well cared for, screws came off easily and the lower unit came off no problem. Took it out again today for another 10 minutes. It ran great, but I noticed not too much flow through the pee hole (heh, you can tell I'm a total newbie by the lingo I use). I'm a little worried it's not getting all the cooling it needs. I've got a couple of questions:

1. When we were changing the impeller, I wasn't sure how much tightening I should do on the impeller housing. Should it be really tight or not too much? Does it matter? Should I replace the gasket as well (we didn't do it)?

2. Is there supposed to be a gasket or a "sealer" between the lower unit and the leg? I've notced some water inside the lower unit. Is it supposed to be sealed or just screwed in? Also noticed some water was escaping through that area as well. Should we seal that or just tighted the screws more?

3. What would be the next thing to do to check if the water cooling is ok?

4. Is it the water pump? How can I check (guy said the water pump is fine).

Motor Details:
- Merc 850 serial number 7033158 (this may be a Canadian serial, part express site doesn't recognize it)
- Beginning Serial 4590512 & UP
- Mercury 85HP
- 4 Cylinders
- 2 Stroke

Thanks for your help!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,275
Re: Weak water flow through pee hole (Merc 1979/85hp)

Most of the cooling water will come out the grating above the Antiventilation plate above the prop. You cannot see this water discharge while on the water, hence the need for the tell-tale outlet. If you pull off the cowling, you can find the rubber hose that feeds the telltale. It is on the head, between the spark plugs. Sometimes the tell tale gets clogged. Stick a wire up it to clean it out, or suck the dirt into your mouth using the supply hose.

There is not supposed to be any sealer between the midsection and LU. Also, the water pump cover bolts and screw should be snug only. Too tight and the cover will crack.
 

rdreskai

Cadet
Joined
Jun 17, 2007
Messages
10
Re: Weak water flow through pee hole (Merc 1979/85hp)

Thanks! I'll be working on it tomorrow and have a look if there is any blockages.

Cheers!
 

rdreskai

Cadet
Joined
Jun 17, 2007
Messages
10
Re: Weak water flow through pee hole (Merc 1979/85hp)

So, here are the new findings: I've checked the rubber hose that feeds the telltale hole and it was clean. Then, I've taken the lower unit off again and taken a hose to the motor and it's "peeing" much better, as it should really. So, I take this as good news that there is not much corrosion/salt buildup in the motor. But rather it's the problem with the water pump/impeller. I've opened it up and taken a look at the gaskets - one is torn near the middle and the metal plate is slightly bent. So, I'll be replacing those parts and see how things work out.

If that doesn't fix it, I'm afraid it may be the water pump lower unit/housing. There is the 3 bolts that keep the top part screwed in and a 4th screw that I'm not sure what it does. If you keep turning it, it keeps turning (it never stops). I've checked the manual and from what I understand, it's suppsed to be that way and used to detach the lower water pump housing. Am I correct in saying that? Or is it not behaving as it should? Does anybody know?

Thanks again for your help.

-robert
 

rdreskai

Cadet
Joined
Jun 17, 2007
Messages
10
Re: Weak water flow through pee hole (Merc 1979/85hp)

Well, after changing the gaskets and the metal plate - it's peeing like be after 12 beers!! She's good to go.

Thanks for your help!
 

diaric

Chief Petty Officer
Joined
Jul 8, 2006
Messages
532
Re: Weak water flow through pee hole (Merc 1979/85hp)

thats good to hear. if its cooling properly , motor should be warm to touch. if your still getting water in the lower unit then most likely the water pump base. there's o rings and seals there. the base can be a pain to get out.
 

rdreskai

Cadet
Joined
Jun 17, 2007
Messages
10
Re: Weak water flow through pee hole (Merc 1979/85hp)

By the looks of it, base of the water pump is sealed quite well. I haven't noticed any water coming out through there anymore, so I think it's good. I'll try to take it for a spin this weekend.
 
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