Mariner 8 Outboard 677 S Manual
Save big on 8 HP Mercury outboard motor parts that fall in the serial range. Mercury 8HP Outboard Parts Serial Range 677-057507 & Up. Catalog Mercury Mercury & Mariner Outboard Parts By HP & Liter 8HP; 677-057507 & Up.
QUOTE QUOTE If in doubt remove it / QUOTE Don't remove it and run without it. The engine is designed to operate at the temperature determined by the thermostat. If you leave it out, all other things performing normally, the cylinder will be over cooled although the piston and possibly the rings will still just about reach their normal temperature which means that the piston to bore clearance will be less than designed to be. Scuffing or even seizure could be the final result! / QUOTE My 9.9 Mercury ran perfectly alright for 5/6 years with the thermostat not working at all but jammed open.If it had jammed closed the conditions you highlight would certainly have occurred. The thermostats only role seems to be to control the water supply for a few seconds at start up & since we don't live in Antarctica you have got to question it's real value. I have got a new thermostat fitted now at the cost of thirty quid & I am starting to suspect that the damn thing is restricting the water supply during normal running because the 'tell tail' seems to be running hot & not as strongly as before.I may yet remove it altogether rather than risk a seizure.
I'm not familiar with the layout of the Mercury cooling system but the purpose of the thermostat in any engine is to control its temperature to the level at which it is designed to operate. If the flow from the tell tale is reduced and hotter than normal I would suspect the water pump impeller may be due for replacement especially if its much more than 3 or 4 years old. Although of course the system could be obstructed, by scale and corrosion perhaps. For just reduced telltale flow blockage of the telltale is the first thing to investigate.
However the thermostat is easily accessible so an obvious thing to check before tackling the more complex job of servicing the water pump. I completely overhauled the water pump replacing the impeller before finding the faulty thermostat & not only was it seized partially or fully open & bunged up with a fair amount of debrie but I then realized upon fitting a new one that it had never worked during my ownership. All in all it looks like a damned liability & I note that it was not fitted to earlier models of at least the 6/8 HP according to my manual. I might take it out & see if that improves the flow because to much water has got to be better than to little.
Hi Guys Recently acquired a mariner 8 hp 2 cyl 2 cycle engine of around 1982 vintage that is virtually identical to the yamaha 8b engine of the same vintage and I have an irksome problem. This engine will start and run for about 30 secs then it dies and refuses to start.
I have checked the points and timing and they are ok in that there is a nice fat spark white in colour so I know that the charging coil is working. I have also cleaned all the wire connections and earthing points for the coils and isolated the kill switch so I am pretty sure its not the ignition system thats the culprit but I am more than willing to listen to any suggestions on the ignition system as there may be something I have overlooked. I have also removed and cleaned the carburetor and there is fuel present in the bowl and the jets seemed clean to me in that after removal I could see clearly through the jets apertures. The fuel bulb primes as it should so I am at a loss as to why this motor will only run for 30 secs. Compression is also excellent in both cylinders. Can condensers cause this type of fault? Or is this a fueling problem?
8 Hp Mariner Outboard
All suggestions are appreciated guys LLB Engine serial number 8M 677-370218. Re: Mariner/yamaha 8b 1982 Righty ho nada zilch the big goose egg aint going to get this motor working chappies. Been at this motor again today have stripped the carb totally and cleaned it with carb cleaner including all jets and orifices in the carb body. I have checked the fuel diaphragms and both of these are showing no sign of any damage.the primer bulb goes hard once it has fueled the engine as it should and does not loose pressure. I connected a inline spark tester and proceeded to crank the engine. The tester is glowing as it should indicating that the spark voltage is being delivered to the plugs. As the motor still refused to start I noticed on here about spraying a petrol oil mix straight into the carb venturi.
When I do this the engine will start for about 10-20 secs and then cut out again so leading my to believe this is a fuel problem. What has me perplexed is that I know that fuel is getting from the fuel can via the primer bulb to the fuel filter on the side of the engine and then on to the carb fuel bowl. I know this as the bowl was full of fuel when I removed the carb for cleaning today. So it looks to me as though for some reason unknown to me the fuel is not getting from the main jet to the engine. The reeds defo work as spraying fuel/oil mix straight into the throat of the carb gets the engine going for 20 secs or so. When started the engine will respond to the throttle but then as I have said previous it just dies a death and will then refuse to start. Is there some system of vacuum that pulls the fuel through the main jet on these motors that could be causing this problem?
For the mods attention this engine is just a rebadged yamaha 8B so this may be relevant to the yamaha forum as well. Some help or suggestions would be very much appreciated guys. Re: Mariner/yamaha 8b 1982 LLB; Go here for the manual: User ID is marshall Passwrod is public When you have logged in, select Small Engine Repair Then, select Marine/Boat Motors Then, select Mariner Then, select OUTBOARD 2-220 HP, 1976-1989 (INCLUDES ELECTRIC MOTORS Then select the sub categories as needed. Note that when selecting the sub categories, depending on the size of the file, you may have to wait 20/30 secs for the page to load. You can then download the various sections to your computer as needed.