89 Mercury 115 cooling issue

[PTSTL]

89 Mercury 115 2 stoke. Boat got beached and I think I ingested small rocks and dirt. In the water the engine seems to pee but not like it use to out of the water on muffs the water will not pee where in the past it did. I replaced the Impeller and there were some small pebbles around the housing, could there be a small enough blockage that could result in this condition?
Also is there a way to flush the cooling system? serial number is 0c162046 not sure if there is a thermostat.. But in the past it would pee just a few seconds after starting with the muffs.
There seems to be some water leaking at the top of the drive shaft housing, where the motor housing connect, this may have always happened, but now I am more sensitive to water leaks a such.

Thanks in advance..

 

[CharlieB]

Re: 89 Mercury 115 cooling issue

Merc part will show you everything in your motor

http://www.mercruiserparts.com/Show...9&bnbr=100&bdesc=Cylinder+Block+And+Crankcase

You need to re-inspect the water pump, the SS cup and lower plate for scoring, if there is a line worn in either/both parts, a circle just larger than the center hole, then order a pump rebuild kit and replace those SS parts. The body of the impeller has this raised line as a seal against these parts, wearing a matching line and losing the good seal necessary for proper water pressre/flow.

While you have the LU off, remove the T-stat housing on the top of the rear of the motor, use a garden hose and back flush the motor to try to remove as much sand as possible.

Worse case, the exhaust cover may need to be removed to flush clear the lower passages. I'd wait on this one until I could test in the water, feel the exhaust side once warmed up, it should always stay cool. If any heating then pull the cover and clean the water passages. Running on the hose can be misleading as the hose pressure 'assists' the water flow, also without load of turning the prop at throttle the motor doesn't' produce much heat.

 

[PTSTL]

Re: 89 Mercury 115 cooling issue

I will try these suggestions tonight. Thank you,

Merc part will show you everything in your motor

http://www.mercruiserparts.com/Show...9&bnbr=100&bdesc=Cylinder+Block+And+Crankcase

You need to re-inspect the water pump, the SS cup and lower plate for scoring, if there is a line worn in either/both parts, a circle just larger than the center hole, then order a pump rebuild kit and replace those SS parts. The body of the impeller has this raised line as a seal against these parts, wearing a matching line and losing the good seal necessary for proper water pressre/flow.

While you have the LU off, remove the T-stat housing on the top of the rear of the motor, use a garden hose and back flush the motor to try to remove as much sand as possible.

Worse case, the exhaust cover may need to be removed to flush clear the lower passages. I'd wait on this one until I could test in the water, feel the exhaust side once warmed up, it should always stay cool. If any heating then pull the cover and clean the water passages. Running on the hose can be misleading as the hose pressure 'assists' the water flow, also without load of turning the prop at throttle the motor doesn't' produce much heat.

 

[PTSTL]

Re: 89 Mercury 115 cooling issue

Okay, so I pulled the lower unit and pulled the t-state, also tested the t-stat in hot water and it opens. So I flushed the motor with water in the t-stat hole with the poppit plugged with a rag, lots of water and just a little bit of debris came out. Ran compressed air up the tube for the pee hole and the air comes out the open t-state housing. So no block there.

The thing I notice, as you implied, is there is a groove in the pressure plate and the impeller housing about 3/16 to a 1/4 from the hole where the shaft comes through and turns the impellor. It isn't there on the new pressure plate. So I guess I'll buy a new housing and replace that as well.
Do I need a new impeller as well? Since I ran the motor with the grooved parts? I guess I will anyway since that is the cheapest of the parts.

I'll put it back together and test it. I hope that makes it work with the muffs on. I'm be heading out to Mark Twain lake Friday and hope to see it run well in water as well.

Wonder if I should replace the t-state while its out anyway?

Thanks for your continued advice, I'll report back with results.

Hate to have to pull the exhaust cover seems like a lot of bolts.

 

[CharlieB]

Re: 89 Mercury 115 cooling issue

Mark Twain, as in up Hwy 19, Missouri?

If there is short time on your impeller it will be fine. A new pump kit should come with a new impeller, save either one of the two for next year.

Some owners change impellers every year for the insurance.

Some install a water pressure gauge and change when the pressure begins to droop.

 

[PTSTL]

Re: 89 Mercury 115 cooling issue

Yes Mark Twain lake by Hannibal Mo