96 mariner 115 exhaust only from tell tale

[pinellas50]

The boat ran fine last season. I fired it up for the first time yesterday since October. After a time I realized there was not water coming out of the tell tale. I confirmed the muffs were on and so was the hose/water. The only thing coming out of the tell tale was exhaust. When I shut the motor down it did shoot a small amount of water out as the engine came to a stop. I started the motor up again and still no water from the tell tale. Normally, the motor will start pushing water out just seconds after start up when it is on the hose.

I just pulled the lower unit and everything appears in good shape. I still have to pull the water pump housing off and replace the impeller which I had planned to do anyway. I also planned on putting in new thermostats.

Is there anything else that could be causing this.............anything else I should look for while I'm in there?

 

[carholme]

Re: 96 mariner 115 exhaust only from tell tale

The easy thing is to shove a length of lawn trimmer line up the ptube to make sure mud daubers or the like have not clogged it, which they will.

Gerry

 

[pinellas50]

Re: 96 mariner 115 exhaust only from tell tale

A blockage in the tell tale line is what I first thought too. Until it put out a small but steady stream of water when I turned the motor off.

I'll still check the line as suggested.

Is it normal for exhaust to come out of the tell tale? I have never seen that before because there is normally water coming out.

 

[M0nhegaN]

Re: 96 mariner 115 exhaust only from tell tale

A blockage in the tell tale line is what I first thought too. Until it put out a small but steady stream of water when I turned the motor off.

I'll still check the line as suggested.

Is it normal for exhaust to come out of the tell tale? I have never seen that before because there is normally water coming out.

If you are not getting water pressure to fill the block, the exhaust will back up through the cooling water exits.
If you have a motor with thermostat and or pressure diaphram, something else can happen to make exhaust back-up into the cooling passages, see the last paragraph of this message.
Are you sure it's exhaust and not steam?

If the boat was stored, and you have the gearcase off, use a flashlight and look up the exhaust tube. My neighbor has a 90 hp 4cycle merc, and field mice built nests up in there and clogged it up. It acted a little like you describe.

 

[quicktach]

Re: 96 mariner 115 exhaust only from tell tale

Perhaps it's steam coming out the ptube and not exhaust. Despite the small steady stream of water the passages could still be badly restricted. If you're opening up the t-stat housings, look carefully and try compressed air to see if it comes out down below ...after the t-stat is out. If you run the engine primarily in salt water you may have salt deposits built up. Try compressed air up into the block through the tube that the water pump discharge connects to. Check the water intake screens. You can also keep the t-stats out, put the covers on and then try compressed air into the ptube. For using compressed air, get a hose nozzle with the neoprene tip so you get a seal.
It will be interesting to hear the state of the water pump.

 

[pinellas50]

Re: 96 mariner 115 exhaust only from tell tale

The water pump impeller still looked to be in great shape. I replaced it anyway.

I pulled the thermostat and poppet valve out, put their cover back on, and then put the garden hose to the water pump discharge pipe so water would go to the motor. Water came out everywhere it should with no issues what so ever. I have all the new parts on now but ran out of time to put the lower unit back on and test the water flow. I'll be back if there are any issues from here......if not, thanks to those who responded.

 

[Bosunsmate]

Re: 96 mariner 115 exhaust only from tell tale

If it doesnt work now and you are sure on the LU impeller being ok suspect a leak into the cooling jacket- exhaust gasket etc pressurising the cooling system.
If it doesnt work, try running it with the hose onto the water intake pipe LU removed and see if the lack of back pressure fixes it.