Serpentine belt came off my 5.7 Mercruiser

[robinsbd]

Hello,

I got a new to me boat in June this year. It has a 1997 5.7L Mercruiser with Alpha One drive. It ran good for several outings this summer. During my last outing, I noticed the steering was difficult when turning the wheel towards starboard. Also, the water temp gauge fluctuated a lot. Normally, the temp gauge sits around 170, but on this outing, the gauge fluctuated a lot. Sometimes, the gauge would drop all the way to the lowest temp and other times it would hover in the middle for a bit and then drop again. I think maybe one time it went up around 200, but most of the time it fluctuated between really low and in the middle and sometimes high. It seemed like it bounced around a lot. I never heard any over temp alarms or anything like that (I assume the alarms work, but I am not certain of that).

I drove the boat for about 8 miles back to the dock. Most of the time, I ran at about 2-5 miles per hour. Whenever, I tried to get up to 8-9 miles per hour, it was too difficult to steer to the right.

Anyway, when I was back at the dock, I checked in the engine bay and found the serpentine belt laying in the bilge. The belt was not broken, but some of the ribs were split away from the rest of the belt.

I bought 2 new belts (1 for a spare). I have not installed it yet. Is there anything I should do besides putting the new belt on? Are there other things I should check into? Do you guys think that my engine is damaged now because of running it without the belt on?

I would appreciate your comments on this.

Thanks,
Brian

 

[robinsbd]

The engine serial number is 0K030009.

 

[biggjimm]

Welcome,
I would say it's probably ok (i could be wrong though) beings it never got too hot.Having to go slow because of the steering probably kept you from getting too hot. I suppose at that low of a speed perhaps the impeller in the outdrive is sufficient to keep enough water thru the system to keep the temps from getting too high???
I'd check the pulleys & make sure there's not a bad spot on one (a flat spot or a bent pulley) that could have slipped the belt & also the tensioner if it has one (I'm assuming they run one in boats with a serpentine belt) it could be getting weak. Check that all the pulleys align & have the same # of grooves. Had a truck that kept throwing the belt & someone had changed alternator & it had the wrong pulley & was not aligned with the rest. Good luck. Jim.

 

[Scott Danforth]

check all the accessories for a bad bearing. you may need to change the idler/tensioner

 

[robinsbd]

Thanks for the tips so far. I will inspect the various pulleys / accessories.

Does the Alpha One drive's water pump typically provide adequate water pressure to cool the engine block? I am guessing this is the case since my engine didn't blow up on me.

Thanks,
Brian

 

[Scott Danforth]

the pump is pushing about 19 gpm at about 10 psi

 

[robinsbd]

I checked the accessory pulleys. They seem Ok except the engine circ pump seems like it has some play in it. There is no play in it when trying to push and pull it. However, it does move up and down a little if you grab it and pull it up and down. The whole shaft and pulley together move up and down a little.

I am not sure if this is normal or if there should not be any play at all.

 

[thumpar]

There should be no play.

 

[robinsbd]

Status Update:

Before installing a new belt, I successfully installed a new engine water circ pump. I did a test run of the engine and ran it up to operating temperature. There are no leaks and the engine temp stays under 170.

I gave myself quite a scare during the final stage of the pump install. I carefully tightened all of the bolts down evenly in a diagonal pattern. First, I made them hand tight. Then, I used a standard 3/8 socket wrench to tighten all the bolts evenly. Lastly, I used a torque wrench, and this is where I goofed up. I have an inexpensive Performax torque wrench that has a removable tip with a 3/8" drive on one side and a 1/2" drive on the other side. I didn't realize that the wrench only registers torque settings on one side of the wrench. In other words, you have to remove the tip and flip it around to make sure the 3/8 drive is pointing in the correct direction. Otherwise, only the 1/2" side will register and vice versa. I have never seen anything like this before.

Anyway, I had the 3/8" drive pointing the wrong way, so the wrench never registered any torque (no clicks) while I tightened the bolts. So, I ended up putting the bolts on very tight before realizing the problem with the wrench. The bolts are supposed to be 30 ft/lbs, but I know I went far beyond that. The bolt heads did not break off though and the pump is mounted tightly against the engine block.

My bolts are new Grade 8 bolts (I only reused one of the old bolts that has a stud on the bolt head for mounting the idler pulley bracket).

Should I be concerned about over torquing the bolts? This kind of scared me since I was flying blind with the torque wrench. After fixing the wrench and checking the torque on the bolts, the wrench registers that I am over 40 ft/lbs, and possibly over 50 or more on some of them ( I stopped checking any higher since I was a little sick to my stomach ). Do I need to remove the pump now and install new bolts? Should I not worry about the torque and just use it as is? I am definitely getting a better torque wrench. What do you guys think?

Thanks,
Brian

 

[biggjimm]

You're probably ok. You wouldn't have to replace them though. You could have just loosened them up & then torqued them down correctly once you realized what was up with your torque wrench. Since you didn't break one off I'd leave it be.

 

[Grub54891]

Just have a look at the gaskets, If they look squished out the sides, replace them, But I doubt that is an issue.

 

[robinsbd]

Thanks for the responses guys. Over the weekend, I loosened the bolts on my water pump and re-torqued them to the specified 30 ft/lbs. So far so good with the pump. There is no play at all in the new pump and it seems to work good.

During this project, I installed a new serpentine belt.

I have discovered a new problem. The volt meter on the console stays under 12 volts. I ran the engine for about 30 mintues and the volts seem to get lower. Also, the engine does not throttle up properly. I am suspecting the alternator has a problem. My first course of action was to fully charge the battery with my battery charger. I have not tested the engine yet since I charged the battery. I plan to do that soon.

I have the Thunderbolt V ignition. Does that run in a "limp" mode when the voltage is low? I am trying to understand why I can't really increase the engine throttle. Also, the tachometer is not reading correctly.

 

[alldodge]

The TB-V does not have a limp mode, but you have a Throttle body and it does have a power reduction mode. If your voltage actually is low it will cause to motor to run incorrectly and therefore loose power. Get a hand held voltmeter and measure to voltage when the motor is running. It should read close to 14 volts with the motor running.

 

[Grub54891]

Yeah the alt is probably shot, It'll run crappy without a full battery, and eventually quit. The electronic ignition needs at least 10.5 volts I think. When replacing the alt,I suggest replacing the battery at the same time. I had a couple that wrecked the alt the second time as the battery was not strong enough to keep up and made the alt work to hard.

 

[robinsbd]

Thanks for the info.

I am going to try to test the engine tonight with a fully charged battery. I'll report back the results.

 

[robinsbd]

I tested the engine on a fully charged battery. The engine ran fine and the volt gauge read about 13.8 volts while the engine was running. With the engine off, the volt gauge read about 12.2 volts.

This tells me my alternator is working.

I have a dual battery setup, so I went and bought 2 new batteries since the old batteries were 3 years old. When I pulled one of the batteries, it looked like it had leaked some acid into the battery tray. I installed new matching AGM batteries. The old batts were traditional wet cell and I'm not sure if the previous owner maintained them.

All seems to be well now.

I do have another question about the throttle. To start my engine, I pump the throttle twice in order to prime the carburetor. After I start the engine, I leave it in the first position past neutral (throttle only) for a while and then I pull it back to neutral after the engine starts to warm up. This is how I was told to start the engine. Is this the correct procedure?

Thanks a lot!

 

[Grub54891]

Yup sounds like the correct procedure. Happy boating!

 

[Fleetwin]

IF you have throttle body fuel injection, pumping the throttle does nothing.

 

[robinsbd]

I was wondering about my gas. I bought 50 gallons of gas in June. I have about a 1/2 tank left now in September. Do you think this gas is too old?

I plan on using the boat through October, and I was wondering if adding a gallon or 2 of fresh gas would help boost the existing gas, or is there something else I should do? Thanks for all of your help.

 

[Grub54891]

Your fuel is fine. Use it, enjoy it....