1983 Mariner 75 hp, question

[rstibbetts]

I have a 1983 Mariner 4 cylinder, 75 hp engine. The motor is tough to start, kills frequently at low RPM, but runs fine at top speed. To start it requires choking at nearly full throttle, even when the engine is warm. The engine runs pretty well when in the backyard, but not under load on the lake.<br /><br />We have checked the obvious like fuel lines/tank plugged carburetor jets and blocked fuel pump. Everything checks out. We have not done a compression test and I am concerned that this could be the problem. Would this type of problem be consistent with bad compression? And if this is the problem, is the motor shot? Hope not, as I just bought the darn thing.

 

[dilligafda]

Re: 1983 Mariner 75 hp, question

Well I wouldn't say the motor is "shot" but it sounds to me like it will need some serious repairs. The condition you describe is very similar to an engine I worked on not long ago that had the crankshaft seals out of it. The seals (called labtyrinth seals) were worn out and needed to be replaced. unfortunately, the engine needs to be disassembled to accomplish this task. Have it checked out by a qualified mechanic for a thorough diagnosis and good luck!

 

[jenny's dirtwater]

Re: 1983 Mariner 75 hp, question

Hey rs.Recently had similar symtoms on a 93 Mariner 115.Turned out to be a weak stator.You need manual,some diagnostic tools to rule it out though.

 

[rstibbetts]

Re: 1983 Mariner 75 hp, question

Thanks for the info. I had heard about crankshaft seals going out...certainly would be consistent with the age of the motor, though it has been well taken care of. Is there any way to diagnose this short of taking the entire engine apart? I know it is labor intensive.