Mercruiser 5.7 Locked up?

[sjayjock]

Engine Type: 350 MAG MPI SKI (GEN+) GM 350 V-8 1999

Went out and took off from dock, engine overheated and started smoking at 30mph. Not sure of exact location of smoke but it smelled sweet. I noticed that the serpentine belt was snapped. Luckily I was right near the dock so I let the engine cool down, and started it back up and went back in.

Today I inspected the pullies and found that one of the stationary pullies (meaning one that does not run a mechanical part and is just bolted to a frame was not turning) I removed the pully and cleaned out all corrosion and added some grease to help it turn. I re-installed the pully and it turns now. I bought a new serpentine belt from Advanced Auto 13/16" X 88 and installed as shown in the manual and tightend.

Attempted to start the boat to go for a test run to make sure that everything was working and the boat would not start. It would not even crank. Tested the batteries and had them re-charged and they are 100%.

This season I have replaced the starter, starter selunoid, distributor, ignistion sensor, and impeller.

I have trouble shot electrical issues before concerning my starter and this seems to be something more. When attempting to start the engine, it begins A crank and locks up. It does not continue cranking. It just starts A crank and siezes. I tried about 4 times to listen for something... but that is the best that I can explain.

 

[achris]

Re: Mercruiser 5.7 Locked up?

Try turning the engine by hand (take the plugs out first)... If you can't turn it... it may be siezed...

Depending on just how hot it got, you could have water in the engine (hence the sieze.

Chris...........

 

[TilliamWe]

Re: Mercruiser 5.7 Locked up?

If you were in salt water and the cylinders have water in them and it's been more than a day, your engine is junk. If you were in fresh water and your cylinders have water in them and it's been a few days, your motor might be junk!

 

[sjayjock]

Re: Mercruiser 5.7 Locked up?

The boat was in Fresh water. It did get hot enough to start smoking I was standing up driving and was not looking at the guages so I didnt notice the heat until I smelled it.

That being said you have mentioned that I may have water in the engine? How does it get in and how do I get it out??

This happened on Sat. at 5:00pm. Please advise why you think the engine is junk. No way to repair and no other reason that it will not crank?

please say it aint so...

 

[chiefalen]

Re: Mercruiser 5.7 Locked up?

pull the plugs quick and try to turn it over. Water coming out the plug holes?

 

[chiefalen]

Re: Mercruiser 5.7 Locked up?

Don't put no water to the oudrive. it's toast already i bet the impeller. Quick,quick go pull the spark plugs. Try to start it. crank all the water out.

 

[sjayjock]

Re: Mercruiser 5.7 Locked up?

Okay, so everyone thinks that water is in the engine? How would that happen with the belt broken and the impeller not spinning? I will not be able to go out to my boat until tomorrow afternoon.

If I pull the spark plugs and try and turn the key why would it even crank or do anything different than it is now, (not cranking) This removes the water? I am just trying to understand what is going on and how it happened?

 

[Silvertip]

Re: Mercruiser 5.7 Locked up?

The idler pulley being seized should have been replaced. You cannot lubricate a sealed bearing and have it last more than 10 minutes after it has seized. The first check for water is to pull the dipstick. Then pull the plugs and see if water is expelled from the plug holes. If there is. Get out your wallet. And by all means, install a new idler pulley on the rebuilt/new engine.

 

[TilliamWe]

Re: Mercruiser 5.7 Locked up?

Removing the spark plugs and cranking the engine over will blow out any water that may (or may not) be in the cylinders. You HAVE TO do this first, or water sitting in your nicely machined cylinders will rust and pit them and they will be ruined. Junk!

Now, if the spark plugs are removed, and you can't turn it over with the starter or with a wrench, then the motor is SEIZED up due to metal to metal contact and will have to be torn apart and rebuilt.

Water gets into marine engines via the exhaust manifolds and risers. And on a 9 year old boat, one or both of them could have internal cracks. Especially if they got HOT.

Important question, is this an Alpha or a Bravo? If it was an Alpha, the manifolds and risers should have not been starved for water, since the impeller in the outdrive kept turning. If it's a Bravo, then they were run dry and got HOT, since when the belt snapped the impeller pump on the motor quit turning too.

 

[TilliamWe]

Re: Mercruiser 5.7 Locked up?

Oh and silvertip is right on, that idler is junk and needs to be replaced. Once they seize up, they are junk.

 

[sjayjock]

Re: Mercruiser 5.7 Locked up?

I have a V-Drive Transmission... Is there any way that I could tell if I have a Alpha or Bravo by looking at the engine or is it something that I will have to research. I agree that it was overheating because the belt was not moving the impeller and cooling the engine. After the initial overheat, I did let it cool and pull out the broken belt. I crept to the dock keeping the boat at low temps and it ran without the belt... Does it take time to seize? Why would it have not been seized when I overheated and why was I able to ride back to the dock?

I picked up a new idler pully and am going out to the boat tomorrow afternoon to install. I will check the oil and transmission fluids for signs of water. How do I remove the spark Plugs are they easily accessable? I know that the starter will not crank because I tried to start today and it wouldnt turn over... Just a loud click and short half crank and it stops. Where would I go about cranking the engine by hand? How is it done? I want to do as much as I can before I turn it over to my mechanic.

 

[sjayjock]

Re: Mercruiser 5.7 Locked up?

Any guidance on this matter would be greatly appreciated. Thank you.

 

[captmello]

Re: Mercruiser 5.7 Locked up?

You've got no alpha or bravo. Your motor probably overheated and popped the head gasket or cracked an exhaust manifold allowing water into a few cylinders. Pull the plugs and dry out your block before it rusts. Your still looking at a couple head gaskets or manifolds

Good luck

 

[sjayjock]

Re: Mercruiser 5.7 Locked up?

What tools do I need? Any special tools required?

 

[captmello]

Re: Mercruiser 5.7 Locked up?

spark plug wrench, like everyone said. Let us know what happens.

 

[TilliamWe]

Re: Mercruiser 5.7 Locked up?

I have a V-Drive Transmission... Is there any way that I could tell if I have a Alpha or Bravo by looking at the engine or is it something that I will have to research. I agree that it was overheating because the belt was not moving the impeller and cooling the engine. After the initial overheat, I did let it cool and pull out the broken belt. I crept to the dock keeping the boat at low temps and it ran without the belt... Does it take time to seize? Why would it have not been seized when I overheated and why was I able to ride back to the dock?

You have neither an Alpha or a Bravo, but you have an engine mounted belt driven raw water impeller pump. So when the belt broke, you lost all cooling to your motor/exhaust manifolds/risers. That means your exhaust manifolds/riser got HOT! Probably hot enough to crack them. The remaining water in the exhaust seeped through the (probably) now cracked exhaust manifolds and into the cylinders. Not enough had leaked in during your cool down to keep it from starting back up. And you are right if the engine was seized up due to the over heat, it would have stayed that way and you wouldn't have gotten it started after the initial cool down.
But then you hooked up the water hose to it after you replaced the belt, and forced water through the cracks and now have water in some cylinders. Get those spark plugs out and get that motor turned over, pronto. Oh, and don't be surprised if your starter is or does break. Trying to start a hydrolocked engine is not something they are designed to do, and they can/will break a plastic gear off the bendix.

 

[TilliamWe]

Re: Mercruiser 5.7 Locked up?

You've got no alpha or bravo. Your motor probably overheated and popped the head gasket or cracked an exhaust manifold allowing water into a few cylinders. Pull the plugs and dry out your block before it rusts. Your still looking at a couple head gaskets or manifolds

Good luck

Probably don't need the headgaskets. Manifolds and risers are the #1, #2, #3,and #4 source of water in a marine engine. Especially a small block chevy. They can withstand quite a bit of heat before they blow a headgasket. Very common to trash an impeller in a SBC, get it hot, let it cool, then change the impeller and have no problems with the headgaskets.

 

[BLinindoll]

Re: Mercruiser 5.7 Locked up?

Uhm... stop trying to start your engine without pulling the spark plugs. Water doesn't compress and you risk bending your rods. Just do what everyone here already has told you 10 times atleast... pull the plugs and turn it over with the starter. watch for water... but again STOP TRYING TO TURN YOUR MOTOR OVER BEFORE YOU PULL THE PLUGS!

 

[Windykid]

Re: Mercruiser 5.7 Locked up?

I agree with everyone else, however if something seized enough to break a belt and then you installed a new one the engine may not turn. Try removing the belt and see if the motor will turn. It also depends on how hot you got it. U may just need to change the idler, but thereis also the alternative.

 

[egldvrbags]

Re: Mercruiser 5.7 Locked up?

Uhm... stop trying to start your engine without pulling the spark plugs. Water doesn't compress and you risk bending your rods

This is so true. Look at the pix on this thread. This was an expensive lesson!!

http://forums.iboats.com/showthread.php?t=236728

Dave