8.1 Overheated, Motor Died, Now just “Clicks”

[Rcg917]

8.1 Overheated, Motor Died, Now just “Clicks”

Put a new impeller in. Motor reached eng temp 160 and kept slowly climbing. I thought maybe I had lubed to new impeller too much so I throttled up to force water into the impeller housing and hoping to start cooling it down. The motor died after I barely got on plane. It never started again. Tried it this morning with the garden hose feed. All it does is “click” like it can’t turn the motor over. Freshly charged batteries so that’s not it. I feel like it must be seized up. Any ideas? Any way to turn the crankshaft manually to free it up? Thanks!

[jhnmdahl]

How high did the temperature climb? Seized up seems unlikely, but a code scanner might be a good next step.

[bruceb58]

Pull the plugs. Then see if you can put a breaker bar on the alternator to turn the motor. Can't use crankshaft bolt since the raw pump is there.

What temp did it get up to?

[Rcg917]

I want to say the temp was above the 175 mark but not pegged for sure. When I opened the hatch it didn’t make any pinging sounds like a typical overheated motor.

I’ll try the plug pull and alternator turn this week.

I do have a Fox Marine Gateway hooked up to it. I wonder if it can give me any insight or “codes”?

[jwill323]

crazy I had just watched this video. This may be the problem. Hydrolocked engine maybe, Check your oil for water.



Also if you have the fox on the 8.1 is it the 555PCM on your engine? I also have the fox on an 8.1 merc and if you have the App it will give you the codes. I believe it is only on the 555PCM/ECM that will allow yo to view and clear codes.

[billk2632]

There is a good chance that motor is hydrolocked - don't try to start it OR turn it over with a breaker bar until you pull the plugs -- all of them. Get them out ASAP, if you find water spray something (oil, marvel mystery oil, fogging oil - anything) into the cylinders to keep rust at bay until you can get it running again. Water in a cylinder does not compress like fuel, trying to start or turn over a hydrolocked engine usually leads to something bent or broken.

[bruceb58]

Yep...I was also thinking hydrolocked which is why I suggested pulling the plugs. All it takes is a quick "dieseling" moment, which can happen if the engine is overheated, to pull in some water.

[Rcg917]

Thanks for the hydrolocked tip. I will for SURE pull the plugs before trying to crank it again. Wish I didn’t have a day job. I’m dying to check it out asap!

[Rcg917]

You guys that brought up “Hydrolocked” are my HEROES!

I’m not out of the weeds yet, BUT, I did take all of the spark plugs out. The very first one I pulled started dripping water out. I said to myself, “Cool! The theory is working!” None of the other 7 looked to drip much but I did not have my face right down there. After all the plugs were out I hit the key into the start position and the motor started blowin’ and goin’ in a good way! I spun it over and over for about 15 seconds. Sounded good. Looked into the engine area and could see obvious water blowout on the floor. Smelled a little like gas too. I sprayed some WD-40 in all the spark plug holes and left it like that for the night. Oil on the dipstick looked real clean. No signs of water that I could tell. Wish me luck with new plugs here in a day or two.

I CAN’T THANK TOU GUYS ENOUGH FOR THR ADVICE!

[jwill323]

I would change the oil and plugs out to be on the safe side but glad it turned over! hopefully that means nothing is bent or broken internally. probably not a bad idea to change the oil again after you run it for a little while too.

[billk2632]

I think you might have dodged a bullet - continuing to try and start it would have eventually broken something - you did the right thing. You probably don't even need new plugs - can't hurt and maybe it's time, but the water didn't hurt them. Oil change is also a good idea - get it running first though. It will probably smoke and carry on a bit when it first starts due to the WD-40, but once it burns through that it should be fine.

[AsLan7]

.
So glad you found us RC.

Yes, nice job not continuing to crank the motor. Glad you got her fixed.

Post a pic or two when you get a chance.

And welcome aboard mate.

.

[jwill323]

Don't forget to figure out what caused the overheat to begin with, if it was an impeller issue or something else. Could be a blockage if the old impeller you replaced had damaged vanes on it. You could use your fox gateway to check the sea pump pressure and block pressure from the fox marine app.

[Jimmy Buoy]

If this is a Merc you likely removed the raw water pump to install a new impeller. Did you ensure that the water feed hose went back to the correct fitting on the pump? If they were reversed (easy to do) your engine will be starved of cooling water.

If you have an 8.1 Volvo - this does not apply! (totally different raw water pump setup)

Here's how it was explained to me...When your engine gets too hot and it is shut down while sitting in the water, the exhaust manifolds, risers, and tubes become quite hot. If you do not restart it until it cools significantly you can find your engine has become hydro-locked. This is due to simple science. Hot gasses in the exhaust system cool after a while, causing the air within the tubes to contract forming a vacuum. This causes the water back inside the outdrive to be drawn in via the Y-pipe, up and over the riser and settles in the bottom of the exhaust manifold. There, the water will discover some exhaust valves open to the cylinders and fill'm up! Next time you try and start, the cylinders with water will not be able to compress. If you're lucky it won't get enough torque to damage connecting rods or bearings. Once discovered it is imperative to get the water out and run the engine up to temps and check the oil for water intrusion.

I had this happen with my last boat (Merc) when a serpentine belt jumped off while underway - triggering a solid NO WATER PRESSURE alarm. Freaked me out, but luckily I had tools on board to remove the plugs when I suspected hydrolock. I only tried the starter once and knew something was very wrong. Luckily, the engine was fine afterwards with no ill effects.