Water pouring from harmonic balancer area on muffs

[Blentz17]

Alright guys I need help confirming my motor in my project boat is toast.

Mercruiser 488 3.7 with closed cooling system

Been working on this boat for a while now, but I think I'm to the point where the motor is toast. When I got the boat the electrical system was a mess and the trim wasn't working. Rewired the boat, installed new ignition switch ( the boat had no key when bought) fixed the trim and finally started digging into the motor. Normally I would check the motor first on a project but I had to get power to it first

When looking at the motor it looked good on the outside, but I have ran into rust and corrosion on the inside. The first time I attempted to turn the motor the starter clicked, figured it was bad cables, put new cables and battery on and had the same thing. The starter was pretty rusty so pulled it and bench tested it, the solenoid engaged but the bindix didn’t rise oiled it and same issue, pulled the plugs, they had a good bit of rust of the bolts but the bottom of the plugs looked clean, filled the cylinders with mystery oil and let it set for a week. Came back took old started off it was so corroded that the ground post broke off when removing, checked fly wheel it wouldn’t budge (frozen I think) soaked it with PB BLASTER, and got it to turn some via ignition switch after installing new starter without plugs

After installing plugs I attempted to start again this time on muffs, same thing new started turned the motor a little quicker but still slow. After attempting to get it to turn a few more times, water began to poor out of the front of the engine to the left of the harmonic balancer. When attempting to see exactly where the water was coming from I stuck my fingers behind the balancer and felt a bunch of large metal pieces. When I pulled them out they were magnetic….

I’m 100% sure this motor is toast but wanted some opinions on what happened and what the shavings may be.

Edit: the metal pieces were more like chunks with shavings sticking to them, but it was all magnetic

 

[04fxdwgi25]

Bought a dead car long ago and it did the same thing. Head casting busted when it froze. When filling the radiator, water came running out of the front crank seal. Game over. Block crack will do same thing

 

[Scott06]

The 488/3.7 engines were a redhead step child . A lot of mechanical shortcomings in the design. If the boat is worth the effort swap in a3.0 or 4.3

 

[ScottinAZ]

ok, not real up on the 488 motors, but this sticks out from what I do know..... first off, you have fresh water leaking on muffs. The 488 is a closed system, so its something on the raw water side. By definition, it cannot be the block or the engine, however it CAN be a hose, pump connection, system drain or engine exhaust manifold leaking. That "stuff" behind the harmonic balancer IIRC is the stator, which is the functional equivalent of the alternator on your engine. There of course would be magnetic parts there, as permanent magnets are used to generate the power (same as on a motorcycle or a 2 smoker).

If your engine has rust in the cylinders, you have more than one issue.

One is water intrusion into the engine, either from sitting badly and it just naturally getting in, you have a leak in the closed cooling system (pressure test this) or you have a cracked wet exhaust, and the water is getting in through the exhaust valves.

Second is the leaking on muffs on the raw water side, which I addressed above.

I wish you good luck in finding your issues. The 488 as stated is a bit of a red-headed step child and not well liked due to lack of parts, inherent design issues and being pretty much obsolete. You need to balance what it would cost time/labor to revive the engine vs. what a repower would cost with a more modern and serviceable engine, such as a 4.3 in your power range. A 3.0 would be easier, but you would lose a significant amount of power by doing so.

 

[nola mike]

yeah, there are magnets glued to the inside of the rotor there, likely what you're feeling. as mentioned, closed cooling and can't think of what would be leaking back there. you're sure it's fresh water and not coolant? show a pic...
other thought would be if you have a leak in the HX that would allow fresh water into the coolant side, then maybe a leak from the weep hole on the circulating pump right above there. Dunno that it would be pouring out though

 

[stresspoint]

The 488/3.7 engines were a redhead step child . A lot of mechanical shortcomings in the design. If the boat is worth the effort swap in a3.0 or 4.3

red head step child """ thank you that made me spit my tea at the keyboard"""

 

[Blentz17]

yeah, there are magnets glued to the inside of the rotor there, likely what you're feeling. as mentioned, closed cooling and can't think of what would be leaking back there. you're sure it's fresh water and not coolant? show a pic...
other thought would be if you have a leak in the HX that would allow fresh water into the coolant side, then maybe a leak from the weep hole on the circulating pump right above there. Dunno that it would be pouring out though

I thought it was water it’s def coolant

 

[ScottinAZ]

I thought it was water it’s def coolant

so, it was green coolant that was leaking on muffs, and not raw water? not to get too specific, but these are two different and separated systems that only come into contact through the heat exchanger. Unless someone put fresh water in the closed system it should have your normal "green" automotive type antifreeze in it which "should" prevent that part of the system from freezing. If someone put fresh water in the closed system, then all bets are off......

 

[nola mike]

I thought it was water it’s def coolant

In that case, you're either dealing with the weep hole in the circulating pump, or just a run of the mill leak. Post a pic. Neither this nor the magnets = dead engine. What the cylinders look like who knows. Did you check compression yet?

 

[Scott06]

red head step child """ thank you that made me spit my tea at the keyboard"""

No reason we can't have fun here...