Belt broke / hard to start

[SoCalFisher]

I just recently replaced the alternator on my mid 80s gm 350 inboard. Took the boat out this morning and was cruising to the island. Heard an unfamiliar noise and noticed that the the belt broke and was spraying coolant throughout the engine bay. Luckily I always carry 2 of them as well as most common replaced items. After the engine cooled down about an hour later we were able to put the new belt on.

After the we got everything back together we tried firing her up. It was not the normal 2 cranks and she starts. We notice when we were attempting to turn her over small puffs of steam were coming from the spark arrestor. After the 3rd attempt we were able to get the engine to turn over but only at 2500rpms. No puffs and sounded good. Once we back off the throttle the engine dies.

The previous trip none of the issues were here except the 20yr old alternator. Changed oil last week. No signs of milky oil. Was a bit darker then usual but was clean. Cleaned the spark arrestor during oil change.

Any ideas?


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[Jaegerboy]

What was your engine temp when you noticed the problem?

 

[SoCalFisher]

Literally when we heard the belt broke the temp went up to 160 (but seemed a bit higher when we stopped)

 

[Jaegerboy]

Well, bad overheat with a potentially cracked block. That would potentially explain the white smoke and dying at low rpms. Are you losing coolant as well?

 

[SoCalFisher]

Yes coolant went straight to the overflow. When we removed the engine cover it pulled the hose off the overflow hose and sprayed the interior of the engine compartment.

I would like to clarify that the puffs of steam are not continuous. Only intermittent. When we were towed back to the ramp, we were able to get the boat to the clean out station and fire her up with no issues. I wanted to make sure the saltwater was removed before the drive home.

I was able to take some time to assess the motor a bit more last night. I will post images in a following post.

 

[SoCalFisher]

I have to adjust photos to fit since most smartphones take HD photos and forums limit the size


Edit: added link to photos

http://s108.photobucket.com/user/ups420/library/Mobile Uploads

 

[Grub54891]

What does the oil look like now? Take a sample in a clear jar and show us.

 

[Bt Doctur]

Heard an unfamiliar noise and noticed that the the belt broke and was spraying coolant throughout the engine bay. Luckily I always carry 2 of

aside from the rust, the auto fuel pump , the auto dist the vanes of the impeller are shot . You have a crank mounted raw water pump so losing the belt affected the circulation pump and caused a overheat condition

 

[SoCalFisher]

Pulled the dipstick and looks clean and fresh. What would pulling a jar of oil out determine? I also pulled one of the spark plugs out.

 

[Grub54891]

Pulled the dipstick and looks clean and fresh. What would pulling a jar of oil out determine? I also pulled one of the spark plugs out.

The dipstick may show good clean oil, pulling sample in a clear jar will show us if any water is in the motor. Oil floats on top of water.

 

[SoCalFisher]

The dipstick may show good clean oil, pulling sample in a clear jar will show us if any water is in the motor. Oil floats on top of water.

Ah gotcha. When I get home from work tomorrow I will pull some out.

As some have said that I might have a blown head gasket, how would I check that?

 

[SoCalFisher]

I would like to say that the coolant levels are still at almost full and loss was at a minimal. Im starting to think that the puffs of steam from the carb was just due to the engine attempting to start or starting to get flooded.

Would there be another reason that the engine stalls at low RPMs? There was no other noise when I had the RPMs over 2000. It just seemed that the engine wasnt getting enough oxygen. There is no white smoke from the exhaust and have plenty of water flow.

 

[fishrdan]

Belt driving the circulation pump broke, coolant boiling over, white puffs out of carb, won't idle under 2500rpm...

I'm thinking blown head gasket(s) too. Run a compression test and see what it shows.

 

[Grub54891]

On one of my vehicles, it would overheat, but the coolant would remain steady. It was the head gasket. Sometimes they don't leak much but enough to cause issues.