Bass addict
New member
So I have a 1990 Mercury mariner 175 hp motor that's locked up. I have taken off the lower unit and its fine. I pulled the plugs and there's no trace of water anywhere. I than took off the valve covers and exhaust manifold. I couldn't find a failure with the Pistons or cylinder walls. One of the Pistons feels a little loose but other than that everything seems to be ok. You can turn the motor by hand but it stops once you reach a certain position and then u can turn it back so far before it stops again. I'm assuming it's a crank or timing chain problem. I don't feel comfortable tearing down the motor any further and I'm afraid that if I pay a mechanic to finish tearing it down to diagnose it, he might tell me the motors screwed and I'm out a couple hundred dollars. If it's a simple repair should I rebuild anyway? Any advise or thoughts will be appreciated. Hopefully by my description someone can tell me what's wrong. Thanks to all that can help.
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