95' 175 EFI power head rebuild or replace.

[nate1220]

I just purchased a 1995 ski ray with a mercury 175 EFI hanging off the back. When looking at the boat we performed a compression test on the motor. All six cylinders had 120 psi of compression. We changed the impeller after getting it home and headed to the lake. After cruising around for about five minutes the engine bogged down and died. I pulled the spark plugs susPecting a fouled plug. But instead of fouled plugs I got a nice surprise, the end of one of the plugs looked like it was covered in never seize. I got the boat home and did a compression test. #1 0psi #2 5psi #3 110psi #4 120psi #5 120 psi #6 120psi. I'm guessing I have a hole in #1 piston and a scored cylinder or hole in #2 piston. Should I attempt to rebuild the power head myself and if so how difficult would it be or should I pay $4000 for a new power head?

 

[casey228]

Re: 95' 175 EFI power head rebuild or replace.

I just purchased a 1995 ski ray with a mercury 175 EFI hanging off the back. When looking at the boat we performed a compression test on the motor. All six cylinders had 120 psi of compression. We changed the impeller after getting it home and headed to the lake. After cruising around for about five minutes the engine bogged down and died. I pulled the spark plugs susPecting a fouled plug. But instead of fouled plugs I got a nice surprise, the end of one of the plugs looked like it was covered in never seize. I got the boat home and did a compression test. #1 0psi #2 5psi #3 110psi #4 120psi #5 120 psi #6 120psi. I'm guessing I have a hole in #1 piston and a scored cylinder or hole in #2 piston. Should I attempt to rebuild the power head myself and if so how difficult would it be or should I pay $4000 for a new power head?

I too just bought a 1999 Mercury 175 ......it also has a detonated piston in one of the cylinders....after tearing down engine I found that the piston ring glands have broken apart leaving melted Alum in the cylinder........I stripped it down and sent off to have a new sleeve done......cost Approx $250..still have to buy gaskets, new piston and bearings....But should be back together for less than $800...the rest of my engine looked mint
It all depends how mech inclined you are, It was not difficult at all, but finding the cause as to why it failed is another thing....Lean condition?.......timing off?......
Good luck with what ever you decide!

 

[Faztbullet]

Re: 95' 175 EFI power head rebuild or replace.

If you dont have the injectors and ECU tested it may meltdown again!!!!!

 

[nate1220]

Re: 95' 175 EFI power head rebuild or replace.

I have rebuilt my fair share of legend motors (old mercs, e-rudes and johnsons) but the EFI motors are all new to me. I spoke with the marine restoration place I bought the boat from and they are willing to rebuild or replace the power head at cost. They said they would try to help me out the best they could. I just hope they aren't blowing smoke.