3.0 mercruiser, need help. I recently bought a used starter and it seemed to work fine, but.....

Question

my exhaust gasket went out and caused water to get in my oil. I replaced the gasket and drained the old oil, but when i tried to crank the motor, it would turn over a few times and then it would sound like a backfire and lock up. after doing this several times, i did get the engine started, but killed the motor and tried to restart. the starter went completely out and i bought a new one. the guy at the shop told me to that is should have removed my plugs to get any water out of the cylinder, so i did that once replacing the new starter, but the same problem. engine turns over and then locks up, sounds like a small backfire. please help me. i went through 2 starters in 2 days.

Answer 1

take the plugs out and turn it over, if it still locks up the problem is farther down.

Answer 2

identify the cylinder positions find the firing order and one by one see if you have the spark plug wires going to the right cylinders it only takes one backfire to break a starter

Answer 3

Sounds to me like the head gaskets are at fault not the exhaust gasket you still have quite some work in front of you if your atre going to repair your vehicle. P.S. the 3.0 has a common problem to bloow out head gaskets and leak coolant into the cylinders