2000 Mercruiser 5.7 EFI looking power over 2000 RP

G

GregR

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33547
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2000 Montery with twin 5.7s Bravo III, 600 hours, heads redone approximaty 40 hours ago. I am the second owner, had the boat for about a year, heads were redone before I purchase a boat. Boat has run strong, reaches wide open throttle.

I tried to put the boat up on plane this weekend, over 2000 RPM port engine would not pick up power and would start to surge. Tried to go to 3000 RPMs, no power. As I increased RPMs the temperature gauge would decrease. I eventually shut down the engine and came back home on the starboard engine. Once back at the dock, I tried to restart the port engine and it would not turn over.
 
What 5.7's? - TBI or MPI? Full or 1/2 RWC ., or full RWC engines?

By "would not turn over", do you mean it will not crank at all as that would indicate? If so , make very sure it is in N and move the gear lever a bit while key is turned to Start in case the neutral safety start switch is misaligned jumper across that switch in case it is bad .
Also check the main button-breaker on the engine.

If you can't move the crankshaft with a long breaker bar on the pulley nut , better pull the sp. plugs and check for water in the cylinders/hydrolock right away.
Did you notice steam in the exhaust when power was being lost?

If you meant it cranks but would not combust, do you have access to a marine scan device for quick basic check for codes or out of range paremters? Or at least a fuel pressure gauge ?
Have you checked the fuel filters , taken a sample to check fuel quality, and inspected the dist cap and rotor for any corrosion?

What temp was the port engine gauge decreasing FROM as RPM increased when still running?
 
5.7 LITRE EFI Digital Ignition full RWC
It tried to turn over, but it was if the battery was dead. I switched to Parallel to use both batteries, same result. It’s as if it could not turn over or was locked.

I did not notice steam, though it’s an outdrive so the exhaust is underwater.

No personal access to marine scan device for quick basic check for codes or out of range parameters, no access to a fuel pressure gauge. I have you checked the fuel filters , taken a sample to check fuel quality, or inspected the dist cap and rotor for any corrosion. We got back to the dock at 11PM, heavy rains, we covered her up and drove home; I live over an hour away.

Port engine temperature gauge decreasing to 0 degrees as RPM increased when still running. When I backed it down to 2000 RPMs the gauge immediately went back to 165.
 
"I have you checked the fuel " should have read "I have not checked the fuel "

Both engines do pull fuel from the same, one fuel tank.
 
Initially sounds like you've spun a prop hub. The temp gauge going to zero and then the no turn-over situation is confusing.
 
I was thinking the same. We bumped into a small log at idle speed the day before, the boat ran fine though afterwards and got on plane with no issues and no wobbling. Boat was on plane for about 10 minutes after that, docked the boat overnight, I left the next day which is when it started acting up.
 
I've never spun a prop hub before. Last 2 boats had V-Drives, previous 2 has outdrives but I never spun a hub. After reading about this last night it sounds like exactly what happened.

I pushed the throttle on that engine to 3000 RPMs for about 2 minutes hoping to get more hull speed as it was getting dark and raining and I needed to get back to the dock. I gained about 2 mphs, though the oil pressure dropped, alarm went off and then I shut down the engine. I tried to restart it back at the dock, about 2 hours later, and it would act like it wanted to turn over, but nothing. I have not been n the boat since.
 
Update: I had the marina mechanic look at the engine. He states the engine went into Guardian Mode because it was overheating, thus why I could only get power up to 2000 RPMs. The engine was overheating because the raw water pump impeller went bad. He states he pulled all of the plugs and there is water in the cylinders, probably a result of me trying to start the motor after I had shut it down hot (it was over 200 degrees on the temp gauge). He said something about it quickly turning backwards and injesting water.

No permanent damage, need a new starter, impeller, plugs and blow out the water and spray oil into the cylinders.
 
I could start a Poll here. My premise being, Greg has a Good Mechanic! Agree? Yes or No?

Good because he found the overheat cause with the impeller.

Really good because he checked the cylinders for water. Engine will ingest water if it "kicks back" and a couple exhaust strokes become intake strokes.

Good on the Starter, too. Along with whatever might be wrong with the starter itself, the bolts can get loosened by cranking against non-compressible water in a cylinder. The bolts actually get stretched.

Good on GREG, too! You didn't dally around while water sat in the engine!!!
 
That's great you seem to be getting it squared away already. I hope the tech is right about the cause of the hydro-lock so you can get past this incident.

Have any idea how old the impeller was? Were all pieces recovered?
 
Yeah, I've been impressed with the mechanic, not cheap compared to others I've used in the past for other boats. I prefer to do the work myself, though I'm a ways from the boat and prefer to not spend my time travelling and repairing.

I'm the 2nd owner of this boat, I don't have much of a mechanical history of the boat other than work done right before I bought it (heads redone and outdrives completely serviced). I was planning to ask the mechanic about the state of the bad raw water impeller. "Kick back" is exactly what he said, I could not remember until I saw you write it, and that's how he described it.

My starboard engine has been running hot, he did a diagnosis on that today, failing fresh water pump, which he will replace today as well.
 
"Greg has a Good Mechanic" Hell yes! Wish mine was as thorough!
 
Engine ran well during a 3 hour cruise 2 weekends ago. Sadly she had to be winterized yesterday...
 
Glad it stood a test of several hours. Wish you weren't out already, but I forget it's November... Glad too, that you can look forward to a better 2018 season, once you get'er thawed out.
 
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