Mercury 9.8 no water out telltale - blockage

[rstier]

Hi,
I'm having an issue with my 84 Mercury 9.8 outboard where water is not coming out the telltale. My impeller shredded and I think a piece got sucked into the block. I took the pickup tube out and it is clear. I tried blowing compressed air up the tube but barely any is coming out. I then took the exhaust port cover and cylinder block cover off (Pic attached) but couldn't see any pieces stuck in there. Tried blowing air through the pickup tube again with the covers off, but again I could barely feel any air coming through. I was hoping someone could point me in the right direction on what to try next? Thanks in advance!
Ron

 

[emckelvy]

Re: Mercury 9.8 no water out telltale - blockage

It's possible the piece could be stuck at the bottom of the powerhead water passages, or in the exhaust plate. Probably gonna have to pull the powerhead for inspection.

You'll need a new powerhead base gasket, and I'd recommend replacing the water tube rubber grommet & washer while it's apart.

A coating of Permatex No. 3 gasket dressing or waterproof grease between the rubber grommet and the exhaust plate will prevent any corrosion around the grommet. A very common condition on these, especially when run in salt water.

Sounds like yours is a fresh-water motor, since the water tube came out easily.

HTH.........ed

 

[rstier]

Re: Mercury 9.8 no water out telltale - blockage

Thanks for the response and yes it is a fresh-water motor. I was afraid I may have to pull the powerhead at this point but wanted to make sure I wasn't missing something stupid. I'll take a closer look in the exhaust port before I head to the bottom passages just to make sure.

Is the powerhead removal difficult? That is one thing that I haven't tackled on a Mercury outboard.

It's possible the piece could be stuck at the bottom of the powerhead water passages, or in the exhaust plate. Probably gonna have to pull the powerhead for inspection.

You'll need a new powerhead base gasket, and I'd recommend replacing the water tube rubber grommet & washer while it's apart.

A coating of Permatex No. 3 gasket dressing or waterproof grease between the rubber grommet and the exhaust plate will prevent any corrosion around the grommet. A very common condition on these, especially when run in salt water.

Sounds like yours is a fresh-water motor, since the water tube came out easily.

HTH.........ed

 

[racerone]

Re: Mercury 9.8 no water out telltale - blockage

These motors have a plastic washer at the top of the water tube.----On severe overheat it melts and blocks water flow to the powerhead.-------Six nuts / kill switch wires / fuel line and the powerhead lifts off.--Not that hard at all.

 

[rstier]

Re: Mercury 9.8 no water out telltale - blockage

Ok, that makes me feel better. It seems like it will be fairly easy to tackle. I'm pretty confident that is where the problem is as I had the exhaust plate off and still no air would come through. If need be, I'll go the route of removing the powerhead. Thanks for the tips!

These motors have a plastic washer at the top of the water tube.----On severe overheat it melts and blocks water flow to the powerhead.-------Six nuts / kill switch wires / fuel line and the powerhead lifts off.--Not that hard at all.

 

[rstier]

Re: Mercury 9.8 no water out telltale - blockage

Ok, got the power head off and the task was as easy as described. It does look like the plastic washer that is on top of the water tube was the culprit. It is melted and I can see where no water could pass through it. I attached a pic of what it looks like in case this will help others. I think I identified it in the parts diagram which I also attached as a pic. If I have the part right, it's called a Nylon Bearing - Water Outlet Tube. I'll also be getting a new power head gasket and rubber seal - water outlet.

Ok, that makes me feel better. It seems like it will be fairly easy to tackle. I'm pretty confident that is where the problem is as I had the exhaust plate off and still no air would come through. If need be, I'll go the route of removing the powerhead. Thanks for the tips!

 

[racerone]

Re: Mercury 9.8 no water out telltale - blockage

Just got 4 of those replacement washers in.-----They are an improved material compared to original !

 

[rstier]

Re: Mercury 9.8 no water out telltale - blockage

Good to know!

One last question. Do I need to use any gasket sealant on the exhaust port, cylinder head or power head gaskets? I assume no but wanted to double-check. With any luck the snow will melt soon and I can start thinking about getting this on the boat and in the water.

Thanks again for the help!

Just got 4 of those replacement washers in.-----They are an improved material compared to original !

 

[emckelvy]

Re: Mercury 9.8 no water out telltale - blockage

Good to know!

One last question. Do I need to use any gasket sealant on the exhaust port, cylinder head or power head gaskets? I assume no but wanted to double-check. With any luck the snow will melt soon and I can start thinking about getting this on the boat and in the water.

Thanks again for the help!

It's not really necessary, but I like to use a gasket dressing on those gaskets, unless they already come with a gasket "glue" pre-applied. If the gaskets are shiny and come in a "crinkly" plastic-protective "sleeve", I wouldn't use a dressing, since it will interfere with the glue. Very likely the exhaust plate gaskets will come pre-applied, but probably not the powerhead base gasket.

Good Ol' Permatex Aviation-Type No. 3 is an excellent gasket dressing and will never harden. It'll prevent any corrosion-products from ever developing between the raw aluminum and the gasket.

If you want to go really hi-tech, pick up a tube of Permatex-518 anaerobic sealer. It forms an excellent flexible seal when assembled. Whatever excess squeezes out when the parts are bolted-up will never cure, and washes/wipes away harmlessly.

A bit more expensive than the old brush-on No. 3 dressing, but 518 does have the advantage of filling pits/voids up to .015". NAPA usually carries both types.

And yeah, Merc upgraded the material on the water tube washer to a type of phenolic-fiber that appears to be more heat-resistant than the old plastic stuff. You should never have a recurrence of that problem.

HTH & have a good Reassembly........ed

 

[rstier]

Re: Mercury 9.8 no water out telltale - blockage

Great info, thanks for the tip.

It's not really necessary, but I like to use a gasket dressing on those gaskets, unless they already come with a gasket "glue" pre-applied. If the gaskets are shiny and come in a "crinkly" plastic-protective "sleeve", I wouldn't use a dressing, since it will interfere with the glue. Very likely the exhaust plate gaskets will come pre-applied, but probably not the powerhead base gasket.

Good Ol' Permatex Aviation-Type No. 3 is an excellent gasket dressing and will never harden. It'll prevent any corrosion-products from ever developing between the raw aluminum and the gasket.

If you want to go really hi-tech, pick up a tube of Permatex-518 anaerobic sealer. It forms an excellent flexible seal when assembled. Whatever excess squeezes out when the parts are bolted-up will never cure, and washes/wipes away harmlessly.

A bit more expensive than the old brush-on No. 3 dressing, but 518 does have the advantage of filling pits/voids up to .015". NAPA usually carries both types.

And yeah, Merc upgraded the material on the water tube washer to a type of phenolic-fiber that appears to be more heat-resistant than the old plastic stuff. You should never have a recurrence of that problem.

HTH & have a good Reassembly........ed