1996 mercury force 15hp getting hot

[poida]

Hi all
Neighbour dropped off his outboard with an overheating issue.
Plenty of water comming out of the exhaust port at all times, head headed up to 180 plus farenheight where i shut it down.
The head got hot very quickly, side of block/jackets were at 100.
I have no experiance on these motor's.
Should i order a thermostat and impellor and try again?

Cheers

 

[poida]

Any thoughts fellas?

 

[Mohawkmtrs]

Exhaust port or tell-tale?

Drop the gear case and inspect the water pump, impeller, etc.

Remove the thermostat and test.

Inspect before ordering parts.

 

[Sea Rider]

Being such an oldie and if used constantly in salt water it's a candidate to disassembly the cylinder head, exhaust cover and make a spot on work mechanically cleaning all water paths. Will need to install new cylinder head, exhaust covers and lower pan gasket. Torque all bolts to factory specs and will have an OB working as if just taken it out of the box..

Just in case will be good to install a new water pump or just the impeller itself if the liner is found in excellent state along a new thermo and volila!!

Happy Boating

 

[poida]

Outboard has exhaust port only

Any drama's dropping the lower pad to get the exhaust covers off? I've done this on jonny's and you have to remove the motor with the pan, its a pain in the arse.

I'll report back soon

 

[Sea Rider]

The isues with engines that doesn't cout with a removable cylinder head is that will be virtually impossible to clean to perfection salt layer deposits, crusts already built up in that area. Once exhaust cover is removed will know how much salt contents has already built up there.

If removing the powerhead along the exhaust cover, must install new gasket as the old ones might already be dried, cracked, burnt out. Slight grease with marine grease all bolts prior torquing them tight with wrench.

Happy Boating

 

[poida]

Do I have to remove power head?
Or can I drop the pan and remove exhaust cover?

 

[Sea Rider]

Know that outboard model, but not so well as to answer your questions. Assume that model has a side exhaust cover, if so will depend on how easy or hard are the exhaust cover bolts to work on them as probably the lower pan won't have a suitable availble space to remove lower bolts with a wrench ? If all bolts are of easy access, don't remove powerhead.

If removing the powerhead off pan take advantage to remove all the carbon build ups on both exhaust ports located under powerhead...

Happy Boating

 

[poida]

Plot thickens
Undid the 2 flat head screws where the water/exhaust exits the motor and there is NO thermostat.
Why did the PO remove it??? Must have been an overheating issue.
Is i possible that NO thermostat can cause overheating??? Can this cause a lack of water into the head?
or is the thermostat after the head?

 

[poida]

Hi all, sorry been busy with work and life.
The missing thermostat Spring is no longer available.
does any one know it's purpose?

 

[jerryjerry05]

Don't do anything until the water pumps been replaced.
The removal of the head, exhaust chest and powerhead is not needed until you replace the pump.

This motor was made without a thermostat for YEARS!!
The thermo regulates the temp, the motor runs better at a certain temp, gets better fuel economy.

The spring keeps the thermo in place and is needed.
You can use this spring.
https://www.ebay.com/itm/338174-NEW...=item33fff07e3d:g:AHMAAOSwg5FcRhIQ:rk:24:pf:0

 

[Sea Rider]

If with new thermo, impeller or complete water pump installed and engine keeps overheating you know what to do, read again the previous posts and be ready to do a DIY cleaning work.

Install the appropiate spark plugs gapped to the manufacturer's specification.

Happy Boating

 

[The Force power]

Very good suggestions/instructions mentioned above, if I may add my advise/experience on this particular motor.

first verify if the lower-unit sits far enough into the water, remember a water pump is not designed to pick up water but to transfer! With that I mean the water level should be as far up as where the water pump is situated in the lower unit.

pull the LU and check the Impeller/ water-pump housing. to eliminate that portion.

then I would slide a garden hose onto the copper P/U-tube and pressurize with house hold water(you me have to clamp the garden hose)

open tap and see what happens....the majority of water should come out the bottom (tell tail is only a bypass)
however if there's no water coming out of the tell tail check for blockage

it would not hurt to remove the water-jacket (try to keep the gasket in one piece I paid $30 for them)

inspect the smaller drain-hols and inlet-holes run water through to verify (you may get wet doing this)
I hope this was of any help

 

[Faztbullet]

You can use a S/S washer with a 1/4 hole as a t-stat..you want to slow the water flow thru motor just enough that the water take the heat with it.

 

[poida]

HI all
Parts finally arrived and fitted last night.
The engine got up and ran in a tank well, Having a thermostat and not just a gaping hole for water to run out of will hopefully be the end of the problem. However with this motor being cooked to seizing point once already (and amazingly has good compression 120/pot) i don't want it to happen a 2nd time.
The thermostat package reads 105 deg, i am unsure if this is celcius or Fh? The package is USA so i assume its FH
I will give it a run in the tank and see what the head heats up to at idle, then fast idle.
I'll assume that it can get a bit hotter than 105dg Fh as the thermostat will open at this point but hoping it wont go near the 180dg Fh again.
2nd question having a look at the tilt. The motor has a tilt run lever on the front which locks it in the down position incase you want to reverse. We do alot of shallow running and often tilt the motor (johno's) to do the final run in. The johnson/evenrud's automatically kick out the metal tang so you can pull the motor towards you then it drops back on a 30dg angle or so.
This motor has that feature but i can only get it to work if i pull it forward with my hand. Should it automatically drop down when you pull the motor towards you or is this how it is meant to function.
Thanks for all the help and advice thus far

 

[poida]

Just gave it a run and the top pot went up to 200dh fh pretty quick, shut it down.
thats 93dg C so if the thermostat is in Celsius then I might be ok
Any firm ideas on the temp I should be getting to?

 

[poida]

Have been told that the thermostat is in FH so its running hot.
Pulled the lower unit and blew up the pipe, little to no restriction.
Pulled the power head, fell off real easy like the PO had taken it off (yep gasket is like new)
Cylinderhead did not seem tight and was clean with a new gasket
Exhaust cover was clean and fell off, metal plate was a bit warped.
New thermostat, impellor, head and exhaust ports are clean,
Out of idea's here, a small hole in the block around the cylinder's might have been blocked, puffed it clean.
The flow out the thermostat is huge, like its totally bypassing the head.
Possible incorrect head? Has a hole blocked off that leads to the water exit hole.

 

[jerryjerry05]

105d is the thermo.
200 way too hot.

 

[poida]

Power head is off and sitting on my bench
exhaust covers were are clean
head is clean
rubber grommet under head is good
could a possible leak from the head to a water jacket cause it to overheat
welch plug missing
its obviously been fully stripped and rebuilt and the problem was not fixed or it created the overheat situation
Anyone know the head torque???

 

[jerryjerry05]

225 in#
Pics of the plug/area?

Leak from the head to the water jacket?
That would show with water in the cyl.

You test the thermo?