mckinney004
Seaman Apprentice
- Joined
- Jan 26, 2016
- Messages
- 46
1993 Mariner 175 Magnum EFI (2 stroke)
I have one cylinder that has very low compression. All other cylinders are testing good and look good through the spark plug hole. The bad cylinder has low compression, but the piston itself appears to be moving properly if I turn the flywheel. The piston head definitely looks "bad" compared to the others that look good. I cant see any holes in it, but it's not pretty like the others. I can't see cylinder walls through the spark plug hole to see if there was any bad scoring of the walls.
YES water pump was pumping
YES the fuel was mixed
I'm looking for advice on what direction to go from here. I'm thinking best case scenario that piston needs rings, worst case (assuming no serious damage to cylinder walls) full rebuild. The 2 local shops don't do rebuilds, and quoted $5-7k to replace with a new powerhead. I'm considering doing this myself, but have concerns. First, I've done a lot of mechanic work on outboards, but nothing this major. I'm also concerned because I don't know what would cause this. The motor was peeing the entire time (I'm obsessed with checking the tell tale) and the fuel was mixed 50:1. The only explanation that I can come up with is the injector for this cylinder quit, giving no lubrication, causing it to get hot and fail. That is entirely speculation. My point is I don't want to take the time and money to rebuild, just to have a repeat failure if I can't diagnose the root cause. If I'm taking the engine apart this much, I might as well replace all cylinders, rings, bearings, etc right? I don't know the difference in parts cost for 1 cylinder vs 6, but I feel like it might as well be done on a 26 year old 2 stroke if it's already torn down to replace 1 cylinder.
What would you do? Anyone have a good used powerhead for this engine for sale? I'm considering just buying another used motor and trying to sell this one. Any suggestions on the cheapest place for the replacement parts? I'm all ears... I'm 27 and been running 2 stroke outboards very frequently my whole life, but never had any internal problems. Always thought mixed fuel and a working water pump would make it nearly impossible for a catastrophic failure like this. Can an ambitious DIYer tackle this job, or is it really out of my hands?
Here's the back story:
I recently bought a lund baron 2100 that had been sitting for 8 years. After getting the vapor separator float unstuck, the motor started up and ran great with a water hose. I disabled the oil injection, and hooked up to an external 6 gallon fuel tank with 50:1 mixed gas and went to the lake for a test run. The motor ran PERFECT! We spent half a day on the water, most of the time with the motor running at all ranges of throttle. Absolutely perfect motor. One week later, I put the boat in, idle around for a few minutes, and take off. A couple minutes later the motor bogs down, dies on plane, and I hear some less than ideal metal noises from the engine. At this point, I assume the worst has happened and troll back to the trailer with the kicker motor.
I have one cylinder that has very low compression. All other cylinders are testing good and look good through the spark plug hole. The bad cylinder has low compression, but the piston itself appears to be moving properly if I turn the flywheel. The piston head definitely looks "bad" compared to the others that look good. I cant see any holes in it, but it's not pretty like the others. I can't see cylinder walls through the spark plug hole to see if there was any bad scoring of the walls.
YES water pump was pumping
YES the fuel was mixed
I'm looking for advice on what direction to go from here. I'm thinking best case scenario that piston needs rings, worst case (assuming no serious damage to cylinder walls) full rebuild. The 2 local shops don't do rebuilds, and quoted $5-7k to replace with a new powerhead. I'm considering doing this myself, but have concerns. First, I've done a lot of mechanic work on outboards, but nothing this major. I'm also concerned because I don't know what would cause this. The motor was peeing the entire time (I'm obsessed with checking the tell tale) and the fuel was mixed 50:1. The only explanation that I can come up with is the injector for this cylinder quit, giving no lubrication, causing it to get hot and fail. That is entirely speculation. My point is I don't want to take the time and money to rebuild, just to have a repeat failure if I can't diagnose the root cause. If I'm taking the engine apart this much, I might as well replace all cylinders, rings, bearings, etc right? I don't know the difference in parts cost for 1 cylinder vs 6, but I feel like it might as well be done on a 26 year old 2 stroke if it's already torn down to replace 1 cylinder.
What would you do? Anyone have a good used powerhead for this engine for sale? I'm considering just buying another used motor and trying to sell this one. Any suggestions on the cheapest place for the replacement parts? I'm all ears... I'm 27 and been running 2 stroke outboards very frequently my whole life, but never had any internal problems. Always thought mixed fuel and a working water pump would make it nearly impossible for a catastrophic failure like this. Can an ambitious DIYer tackle this job, or is it really out of my hands?
Here's the back story:
I recently bought a lund baron 2100 that had been sitting for 8 years. After getting the vapor separator float unstuck, the motor started up and ran great with a water hose. I disabled the oil injection, and hooked up to an external 6 gallon fuel tank with 50:1 mixed gas and went to the lake for a test run. The motor ran PERFECT! We spent half a day on the water, most of the time with the motor running at all ranges of throttle. Absolutely perfect motor. One week later, I put the boat in, idle around for a few minutes, and take off. A couple minutes later the motor bogs down, dies on plane, and I hear some less than ideal metal noises from the engine. At this point, I assume the worst has happened and troll back to the trailer with the kicker motor.
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