9.8 Merc cooling headache.

[Col Coates]

Bought my motor new in 1985 Mod.No 109OU Ser. No 6518543.
Just reconditioned W/Pump again due to no circulation. Still can't get water through. Manual says motors S/N 8069595 and above don't have thermostats. By that I guess my motor has one. Could this be my trouble,thermo stuck shut. The manual does not show where it is or how to replace them. Havent had any busted impellers and motor has hardly any corrosion.
Any help would be appreciated.

Your forum is great, Ive learnt a lot.
Thanks. Col Coates.

 

[Alumarine]

Re: 9.8 Merc cooling headache.

Hi there and welcome.

You should try posting this in the Mercury Outboard forum.

You posted this in the Problems using Website forum by mistake.

 

[Col Coates]

Re: 9.8 Merc cooling headache.

Thanks Marc C

Taken your advice and re-entered. Hope its right this time. All this is new to me.
Col Coates.

 

[emckelvy]

Re: 9.8 Merc cooling headache.

Col, if your motor had a thermostat, the housing for it would be built into the side of the exhaust manifold cover at the top. If your cover is relatively flat without the big 'bump' of a thermostat housing, then you don't have one.


Steps to find the blockage/issue:

1. Pull lower unit, force air or water up the copper supply tube, check for air/water dumping out the center of the exhaust tower (center section) and/or telltale.

2. If no circulation found, run a wire up the tube to see if you can find any kind of blockage.

3. If still no luck, pull the cyl block water jacket cover (the one over the spark plug holes, no it's not a head!). Check for silt/trash in the block; clean out anything you find; then see if you can then blow air up into the block from the water tube.

4. Still no luck, pull the powerhead because the water tube rubber grommet and/or plastic washer are squeezed shut and restricting flow of water.

Note the parts to fix this are pretty cheap, just the labor involved.

Caution don't force any bolts, if they don't come with normal "hand tool" force you need to use a combination of heat (propane or MAPP torch) and penetrant (PB Blaster is the best).

One last thought, if you do get flow thru the motor, there's likely some issue with the impeller installation, pump housing, or water supply passages in the lower unit.

Anyway, hope that gets you down the road to sucessfully diagnosing and repairing your cooling problem.

G'luck and keep us posted.........ed

 

[Harker]

Re: 9.8 Merc cooling headache.

Have you checked your tell tale hose/tube for bugs/dirt ? When you run it, does water spritz out of the relief holes on the back of the exaust housing?

 

[8075mercury]

Re: 9.8 Merc cooling headache.

One other thought, after checking all of the above out and you still do not have flow, I would put the lower unit in a bucket of water and chuck up the drive shaft to a drill and spin at about 600rpm and make sure you have good water flow out of the impeller discharge. Be careful not to damage your drive shaft splines doing this.

Good luck.

 

[Col Coates]

Re: 9.8 Merc cooling headache.

One other thought, after checking all of the above out and you still do not have flow, I would put the lower unit in a bucket of water and chuck up the drive shaft to a drill and spin at about 600rpm and make sure you have good water flow out of the impeller discharge. Be careful not to damage your drive shaft splines doing this.

Good luck.

Hi 8075mercury

Many thanks, if previous info does'nt fix will certainly give it a go.
Much appreciated. Will let you guys know how I go.

Col Coates

 

[Col Coates]

Re: 9.8 Merc cooling headache.

Hi Guys,

Thanks for all the info. Will let you know how I go. Boat is up north from here,
Might be a while but will let you know.

Working on the motor is the easy part, this computer stuff is for the birds, taken me ages to get through.
Much appreciated. Col Coates.