old 5.5hp outboard.....revs low under load.....transmission oil in the gas???? what do you think???<<<<<<<<<<

Question

hi, i have an old 64? mercury 5.5hp outboard. I think thats what it is. But i took it out early this summer and after warming up a little bit after being away since last year it ran great.

it was really fast and worked fine.
but later that day when id start it up it seemed to just go a litle slower that it did earlier. and even just a little slower yet the next time i would start it.

i took the boat out a few more times in the summer and each time i ran it, it progressively got slower.

it would rev just fine in neutral and sound good. but as soon as i put it under load it would rev really low, the last time i took it off we could barely move and it was kind of difficult to keep it running out of neutral.

Anyway....... someone told me to put 1/4-1/2 Cup of transmission oil into the gas and run it for 5 minutes or so.

I guess its an old trick that the old timers used to do with small engines to clean them out. Anybody know of this? Is this the right ammount?? Thanks

Answer 1

I not make a promise.
I have seen people use Transmission Fluid in their cars for an injector cleaner. They say it works good. I not know. I not see it would hurt as the engine use oil in the fuel anyway. I would think it may have a clogged fuel jet and may require removing the carburetor to clean. Also, it may be some carbon. When I suspect carbon I try "Seafoam" as it seems to work well and would also remove moisture.
http://www.seafoamsales.com/
Most auto-parts store sell it. Also, be sure to check your fuel tank, that it clean and the vent screw is open on the cap.

Answer 2

Don't put transmission fluid in your engine. If the carburetor needs cleaning, take it off and clean it. Are you sure that the engine is pumping water? If it isn't it will run hot and seem slow. It sounds like the main jets are clogged and under a load it is starving for fuel. Disassembe the carb, soak it in a good cleaner and put it back together with a rebuild kit. Don't do stuff like using transmission fluid. You will be looking for a different motor.

Answer 3

"Transmission Fluid" is just motor oil that did not meet "S.A.E." requirements, it has a red dye added to it so if it leaks in the drive way, you know where it's coming from.