‘84 Evinrude 15 water pump issue

[andrewss]

Come into my possession is an ‘84 15hp Evinrude. Fires up and idles great. But it has intermittent water issues.
From water pump to tell-tale is clear. I can hook a hose direct to the copper water inlet tube and run it through no problems.
I replace the complete water pump. Impeller shim is good. Though there is no gasket between the metal plate and the LU as well from between the metal plate and the plastic impeller housing.
I am forgoing muffs and garden hose and have it sitting in a 50gal barrel for testing.

Sometimes it spits water out the tell tale when idling, sometime when under throttle. And sometimes not.
I disassembled the water pump after a test and it looked like exhaust residue was inside the impeller housing. And when I blew low pressure air through the copper inlet tube I could hear slight water gurgling from the midsection exhaust shaft/chamber.

If the water cover gasket is blown (where the thermostat is) could exhaust be getting into the water system and pushing the water out of the motor instead of allow it to cycle? Or the head gasket?
I haven’t pulled the water/thermostat cover off yet as I don’t want to need to buy a new gasket unless that’s where diagnostic takes me. A readily available gasket is $40 so I’m trying to avoid throwing money at the wall.

 

[kbait]

I had a similar issue eith a 15 this year, ended up being blocked water passage under exhaust plate. Piece of broken impeller fin lodged there. Tough to diagnose as I’ve never seen that

 

[racerone]

Thermostat cover gasket is listed online for $4.01

 

[saltchuckmatt]

Careful, those bolts can be hard to get off without breaking them.

 

[andrewss]

Thermostat cover gasket is listed online for $4.01

Readily available in Canada is $40 with shipping

 

[andrewss]

I had a similar issue eith a 15 this year, ended up being blocked water passage under exhaust plate. Piece of broken impeller fin lodged there. Tough to diagnose as I’ve never seen that

I'll keep digging and cleaning!

 

[oldboat1]

So I gather the issue is a problem with the tell tale, not with overheating. Check operating temp at the top of the head (160F is overheating, or too hot to touch). Run a piece of weedwhacker line way up the tell tale to clear clogging.

 

[racerone]

Andrews----try----evinrudeparts.ca----About $6.39 + likely $10 or less shipping !!!

 

[andrewss]

Andrews----try----evinrudeparts.ca----About $6.39 + likely $10 or less shipping !!!

thanks a million!

 

[andrewss]

So I gather the issue is a problem with the tell tale, not with overheating. Check operating temp at the top of the head (160F is overheating, or too hot to touch). Run a piece of weedwhacker line way up the tell tale to clear clogging.

ran the weed whacker line in both ends. came out black and oily like partially burnt fuel on a spark plug.
ran it in the 50gal drum with the waterline about 2-3" above where the impellor housing is. it only spit water in neutral, soon as i clicked into gear with or without throttle there was zero water out the tell tale. it also needs about half throttle, even in N, to get water pumping out. i havent had an issue running outboards in this barrel before, from 9.9 to 60 but maybe the prop is disrupting flow to the water pump inlet. so i'll bust out the dual flow muffs later. but it was doing this, or similar, in the lake too.

edit: even with water running through it in N it got up to 200 then i shut it off. i think I'll pull the water cover to see what the T-stat and channel ways look like

 

[andrewss]

T-stat and two ports were gunked up. I think I may as well do a top down cleaning of the cooling system. So what is the best way to access the upper water tube grommets? Does it require pulling the power unit (would prefer not to)?

 

[oldboat1]

I don't think the grommets are a first priority (and yes, would need to remove the power head).

Remove the cylinder head with thermostat cover in place -- leave the lower head bolts backed out of the threads in the p.head, but still in the cylinder head. Lift the head vertically to remove. (Work on the thermostat cover on your workbench.) Clean out the water passages in the powerhead with a thin piece of metal or small screwdriver (hacksaw blade works well). Look for broken pieces of impeller fins.

 

[andrewss]

Well final recap. Replaced the thermostat and did a combo of weed wacker line and purple degreaser through the water system and that has solved it. The inlet and outlet port the thermostat we very gunked up. Its peeing with optimal pressure now and block stay low temp.

This year of 'Rude has the thermostat at the bottom, which is tricky to removed the water cover due to the spring and tight spacing with the lower housing and the latch for the upper housing, and even trickier to put back on. Youtube folks seemed to pull the entire power head and/or cylinder head to do this. I compressed the spring inside the water cover using 2 zipties, then slide the plate into place, started 2 of the bolts then cut the zipties and pulled them out nice and simple. 3 minutes.

Thanks everyone for the help. This motor will be going on an old 14ft princecraft

 

[909]

I have this year of motor in the 15 version as well and hate the thermostat position.