If compression and oil pressure are good…,

[alk]

Some may remember the motor in my bowrider, it’s a 1999 454 bravo, used to be mpi, but a couple years back the rusty mpi was acting up and after two shops couldn’t straighten it out, I retrofitted a carb and DUI ignition. I probably should have just repowered at the time - but the compression was perfect, oil pressure right at spec, and I did get a couple good seasons. However, it’s still a 26 year old raw water motor, used in saltwater its entire life.

Which brings me to this year. Boat ran fine first few days this season, but yesterday bilge pump came on ten minutes from the ramp. Water was pouring out side of motor, right above the starter, and deep enough that it was getting thrown all over the motor and accessories. Turns out the freeze plug was no longer in the block. Found the brass ( bronze?) plug in the bilge. It looked fine, but had some ‘motor’ stuck to it. I was able to reinstall it ( way too easily I suspect) with some permatex to hopefully hold it in ( jb weld might have been better). Boat started right up, and ran it about three hours, not a drop leaked out. But it wasn’t running great; at cruising speed and above ran 100%, but at idle and no wake speed it was running rough. Shut it off to dry some things out, then it wouldn’t crank. looks like I killed the starter with salt water, because battery was close to 13 volts.

I know this motor is about done, when the freeze plug was out I was reaching inside and pulling out scoops of rusted metal. But this is not the ideal time of year for a repower. Thinking about throwing a new starter in this evening, re-testing the compression, confirming the oil still looks good, and trying to make it another two months.

Anything else I can check, before or after starter replacement, to better predict the hours left on this old block? Has anyone ever brought back a dead starter / solenoid after a salt water soaking?

Still wondering why the plug came out in the first place. There is no pressure on the raw mater cooling. I really don’t think I botched the winterization. Mainly because I had run the boat 10+ hours this year before it gave way. There have been some years where I’ve been in a rush, and didn’t pull the thermostat when winterizing; but this wasn’t one of those years. Only thing I am wondering is if all of the rust I scooped out was clogging up the motor and not letting antifreeze to that section. But since it wasn’t out right away, still thinking that is unlikely.

 

[Bruce Herrington]

While I can't answer your questions, I can sympathize with you about freeze plug blowing out and ruining a good day of boating.

The plugs blew out on my single inboard with 318 raw water cooled engine. No damage to anything..

 

[alk]

While I can't answer your questions, I can sympathize with you about freeze plug blowing out and ruining a good day of boating.

The plugs blew out on my single inboard with 318 raw water cooled engine. No damage to anything..

Did they blow out because of freezing, or did they just end up in the bilge one random day?

I saw a bunch of YouTube’s where people had to put their plugs into a freezer to get them to contract enough to install. I wedged mine back in with a pry bar and socket extension - so worried that the journals are now oversized, hence the easy installation. Did yours fall out a second time, or once reinstalled all was well?

 

[Phillbo]

Typically I'd say run it until it eats itself but being on a boat that adds a risk.

 

[Bruce Herrington]

First use after winter; I did not winterize at all, just kept a heater on and cranked it up a few times each week.

Mechanic re-installed the plugs and never had another issue with freeze plugs.

 

[DeeVee]

Alk. see if you can turn the engine by hand first before replacing starter. Just a thought.

 

[alk]

Alk. see if you can turn the engine by hand first before replacing starter. Just a thought.

I am 99% sure that the salt water spilling down on the starter killed it. Reason I am thinking this - the first time I ran it after putting the plug back in, fired right up, and ran ok ( not great, but not like there was a hydrolocked cylinder). A few hours later turned the key three or four times and only got the dreaded ‘click’, then on the next try turned over and started right up. And a few hours after that, half a dozen clicks, but never spun.

Pulled the old starter off this evening, and picked up a replacement. My parts may be thinking along the same lines as you. He told me to pull all of the plugs and spin the motor before I install, and if I see any water bring back the starter for a refund, cause I need a new motor!

 

[Bob Ware]

Even though there generally is not much pressure on the raw water, what may have happened is due to all the rust some of the ports were blocked and built up just enough pressure to pop the plug. If there was no serious rust in the plug opening you may want to consider removing the old one and inserting a new one since you said it went back in fairly easy.

 

[alk]

Man I HATE everything about Mercruiser right now. Motor was running ok for past couple weekends, but then today was stalling at low rpm. Probably wouldn’t have been a huge problem, but these geniuses designed a cone clutch that will only shift when the motor is running. How do they sell junk like this? And wtf was I thinking when I bought it in 1999?

When it stalls in forward, even worse in reverse, it takes a lot of force to get it back to neutral. The smart thing to do would have probably been to jump the neutral safety switch and just start the stupid thing in gear. But I tried to muscle it back to neutral.

The good news is that even with my advancing age and sedentary lifestyle apparently I still have some arm strength. The bad news is that the way merc decided to attach the shifter plate to the side of the exhaust riser has less strength, so it tore off. which gave the lower shift cable enough slack to wrap itself around the coupler and fray since I could then start the motor.

So now, assuming I haven’t given up on this boat, I need at a minimum an exhaust riser, and a shift cable. And the drive has to come off to install the cable. And then troubleshoot the stalling issue ( with a bypassed neutral safety switch!). I should have listened to the boatyard, and converted this thing to an outboard two years ago. Or just bought a different boat. What are you supposed to do if the motor shuts off in gear? Call a tow and remove the drive?