See full version: Yamaha 25hp 2 stroke emulsified oil in exhaust
Hello. My name is Jason and I am at wits end. I have a 1993 25 hp Yamaha 2 stroke. I recently purchased this engine on craigslist knowing it needed some TLC, though NOT knowing what is needed to safely operate. I am mechanically inclined, however, this problem has me clueness. Here's the low down:
After cranking entine I noticed no water coming out of tell tale. I dropped gearcase to inspect water pump. It looks good. New impeller. I even took the water pump (impeller, housing, gaskets, etc) to west marine and they said it looked good. Here are the steps I've taken to fix/diagnose:
*inspect water intake on gear case. good
*clean out tell tale. good
*clean out rubber tube connecting crank case to tell tale. good
*pumped water up through the water tube (mid section). good
*pumped water down through thermastat out of tell tale and water tube. good
(By the way, intial inspection of thermstat revealed lots of corrosion. Previous owner said engine had sat in his yard for 4-6 months).
*flushed Salt-X down thermastat housing followed by a power flush with garden hose. This solution (blue color) was seen coming out of tell tale, water hose, and exhaust.
*lowered gearcase (again) to make sure impellar turned correctly with drive shaft. good here
A mechanic i met thinks I need to remove crank case head (cover) to clean water veins that surround head. I agree this needs to be done since the thermastat is so corroded (i also replaced thermastat and gasket). I noticed that in order to remove crank case cover it looks like the apron to the lower cowling has to be removed to access the 2 bottom crank case bolts. Seems like a big job. Also, I've run engine for no more than 1 minute. I was taught at a young age that if the engine isn't pissing, shut down immediately. However, I recently read that it's necessary to run engine for 5 minutes in order to bring engine to operating temperature BEFORE going through process of opening powerhead. This is counterintuitive to me. Is this safe!! [links]
Re: 25 Hp 2 vs 4 stroke comparison?
Because (and only because) of the proliferation of "green" laws that are banning 2 strokes from more and more waters I would still go for a 4 stroke and probably look for one with EFI, which gives better economy than carbs. more
Are you saying they will ban existing 2 strokes?
Worst case scenario, the waterlogged cylinder walls, piston rings and precision roller bearings may have rusted. Another possible problem, when an engine is running and ingests a great quantity of water, incompressible liquid may bend the connecting rods. It's not a pretty sight. Diagnosis of bent rods requires nothing more sophisticated than cranking the engines through a couple of crankshaft revolutions. It is not a good sign if either the flywheel doesn't move at all, or the crankspin has rough spots.
As soon an outboard is out of the water give it a bath with freshwater. This is even more important with an outboard that sank in saltwater. Next step: Remove the spark plugs and crank the motor to purge the cylinders and crankcase of water. On a four-stroke, drain the crankcase. Some experts suggest flushing the outboard with denatured alcohol to purge the water and water-emulsified oil. Squirt, pour or spit an ounce or so of oil into the cylinders and crank again the engine to spread it out within. more
It was probably your own fault for not making sure the clamp screws were snugged down tightly enough. To make a long story short, the outboard motor took a flying leap off the transom and then unceremoniously sank in about eight-feet of water. You were able to estimate the submerged outboard's depth thanks to the length of the fuel hose buoyed by the floating fuel tank leading down to the submerged motor. So now your question is what to do before running the motor again?
Losing an outboard motor overboard is just like being thrown from a horse. You've got to climb right back on and ride, immediately. Only in the case of an outboard motor the reason isn't a matter of self-confidence, but instead damage to the vital machined surfaces. Namely, rust on the cylinder walls and piston rings. So if you can't run the engine right away, pickle it. Fill the cylinders with oil, or even leave the outboard motor submerged until you can fix it.
Remove the carburetor and disassemble it. Flush every passage and jet with carburetor clean. On small outboard motors with integral tanks, or portable tanks, drain whatever's inside and take it to a recycling center. Do not dump it on the ground. Flush the tank with denatured alcohol and completely drain it. Best practice requires pulling the flywheel and flushing the area where corrosion would otherwise take hold. more
Start the engine and idle it for a few minutes to warm it up. On a four-stroke, after a few minutes change the crankcase oil. You will be surprised to see how much water is in the oil, a white, frothy mess.
Aytek Aytekin – May 28, 2020
Good service great sound room great outboard shop
Model Enduro 25 Short Shaft 2-Stroke. Specifications: Cylinders: 2. Compression ratio: 2.08. Shaft (S) 16″. Prop shaft hp: 25 hp @ 5000 rpm. Weight: 120 lb. Control: Gear – fwrd, neutral and reverse. Features: Manual trim & tilt method, loop-charged scavenging creates a circular flow for efficient removal of exhaust gas and even distribution of air-fuel mixture, a lanyard clips to clothing or around the wrist, stopping the engine immediately if the operator leaves the helm, shallow water drive, start-in-gear prevention, extremely durable crankshaft, long life piston/piston ring, sturdy gears and gear case. more
Dean Evans – May 3, 2020 more
Aytek Aytekin – May 28, 2020 here
This is a Triumph dealer they have outboard motors, parts and accessories. I chatted with them for awhile and they seem pretty Triumph knowledgeable. I made an order and it was delivered right to my doorstep. They are legit.