Awakening 1997 Mercruiser 4.3 LX

[FBCoach]

Been rebuilding a ski boat. Just finished putting the motor back in and cleaning it up. It has sat for over a year. New fluids. New fuel pump etc. Hooked the muffs to it and it started right up. Noticed no water is coming from the exhaust only a lot of smoke. Scared me and i quickly cut it off. Is this normal? Is it burning off the old crud or could there be larger issues? I attached motor information and a pic.

 

[alldodge]

Noticed no water is coming from the exhaust only a lot of smoke

Depends on how long there was no water.
If muffs were on and water has normal pressure, and its on full force, it still takes a little bit to fill the block and mans before it shows up.

How long did you wait?

 

[FBCoach]

Startedbon the first turn of the key. Took it 15 seconds or so to wake up. Ran it about 30 seconds in neutral and noticed a water leak at the thermostat. I had forgot to tighten the hose clamps when i put in the new thermostat and fuel pump today. Cut it off and tightened the clamps. Started right back up and immediately choked down. I gave a min and it stared again. Smoke immediately came out. Scared me so i cut it off. 15 seconds this time. Never engaged the throttle.

 

[alldodge]

New motor, figured new impeller

Pull a plug on the block and see if water comes out.

Was exhaust mans to elbow gaskets replaced?
If so did you use the ones with slot holes?

 

[FBCoach]

Gaskets were replaced. Had the holes for the intake and exhaust. Just pulled a plug. It looked really good and clean. No water.
Could the smoke have been from squirting the carb with seafoam a few days ago?

 

[alldodge]

Just pulled a plug. It looked really good and clean. No water.

Ahhh there is a restriction or the impeller is not working

Could the smoke have been from squirting the carb with seafoam a few days ago?

No, its from lack of water

 

[nola mike]

Is op talking about drain plug or spark plugs and that he pulled?

 

[FBCoach]

First, thanks so much for your help. This means a lot.

The motor has been in storage for over a year while i rebuilt the stringers and transom. I just put it back in yesterday and today so it is was bone dry before i added new fluids.

Few Questions:
1. Being i saw the water leaking at the thermostat housing, after 20-30 seconds, would this mean the water pump is sending water?

2. Did it choke down because it ran the initials seafoam and fuel out before the fuel pump got new fuel to the carb? The fuel lines were replace as well as the fuel pump.

3. Did i let it run long enough to get water through the system? It smoked immediately and i know there was no water in it to begin with. Just don’t know if i let run long enough to make it back to the prop.

Thanks again.

 

[FBCoach]

I pulled a spark plug from the block. Did i need to check a winterizing plug? If so, I’m feeling stupid...

 

[QBhoy]

Hi
before all panic sets in...jeez I’m always very weary about the muffs some folk use and think are good without even thinking this is an issue. Without sounding harsh....there are definitely muffs that work and muffs that don’t.
Really hard to tell without being there or a video but generally you need reallt right fitting muffs that are meant for an alpha 1 and or the big 4 3/4 (I think) big gear case merc V6 outboards. The circular ones that fits flat and snug without too much leakage even with the engine not running but hose and water on.
The square bulbous cheap muffs you get just don’t work sometimes.
Years ago I had a full on similar panic with muffs I bought off eBay and though the same thing. Quickly resolved by getting a proper pair of tight fitting circular and proper ones.
Regardless...you’ll still need to wait a good 15-30 secs at least for a full flow to come out through the exhaust and prop. Never a nice thing in any case or circumstance

 

[FBCoach]

Got you. I have both pairs of muffs. Used the rectangles today. I’ll try the circular tomorrow. I just checked the drain plug leads into the starboard manifold. Fresh water came out.

 

[alldodge]

Got you. I have both pairs of muffs. Used the rectangles today. I’ll try the circular tomorrow. I just checked the drain plug leads into the starboard manifold. Fresh water came out.

Having water in the manifold means its ready to come out the exhaust.

1. Being i saw the water leaking at the thermostat housing, after 20-30 seconds, would this mean the water pump is sending water?

2. Did it choke down because it ran the initials seafoam and fuel out before the fuel pump got new fuel to the carb? The fuel lines were replace as well as the fuel pump.

3. Did i let it run long enough to get water through the system? It smoked immediately and i know there was no water in it to begin with. Just don’t know if i let run long enough to make it back to the prop.

1. yes
2. unknown, but seafoam doesn't burn very well
3. That is the question I have

 

[FBCoach]

Would it hurt to unhook the main input hose at the thermostat housing and fill the system with water from a garden hose? If this is ok to do, would water eventually come out the prop?

 

[nola mike]

Yes, but... Rereading your post. Did any water come out of the back of the boat at all, but just not out of the prop? Either way, with a few seconds of running I doubt you did any damage. The water was on with the muffs, so your impeller is fine. Sounds like there's water in the block now, and esp the exhaust manifold, which should mean that you're getting cooling to the rubber bits. I'd just give it another shot.

 

[Boater31]

I would agree with Mike that it sounds seconds away from water coming out. It does look like you have the old "bat wing" manifolds. You can do your own reading but they seem to be know as engine killers, almost took out mine and was the source of water in cylinders and oil. They sell kits to convert them. If you go that route you will have the exhaust shutters exposed and could tell if they melted or not.

 

[FBCoach]

Tried again. The good and the bad...
Good: No Smoke. Water coming out - see pics.

Bad: Purred real smooth for about 3-4 mins at about 1200 RPMs. Water coming out the whole time. Then choked down.

Carburetor?

 

[alldodge]

Cool sorry to hear

 

[BudL1te]

I am not as seasoned as others on this site but just my 2 cents worth.

Sea foam, especially straight will cause a lot of smoke. AllDodge mentions that.

An engine really won't smoke when first started unless it has oil sitting in the cylinders. Being stored for a year I would expect none really to be there. *Edit Fuel Mixture can cause smoke if too lean or too rich, sorry.*

Did the engine run fine before?

If so, I would suspect that the sea foam is the issue. If I was worried I would put a couple squirts of oil in the cylinders and run it to check that oil was making it to the top of the head but if your oil pressure is good then that really should not be an issue although technically I suppose something could be blocked but that is an entirely different problem then what you are experiencing.

Smokey exhaust = combustion chamber contaminants.

I would blame the sea foam as the culprit based on what you have shared.

As AllDodge also said, Sea foam does not burn well so that can also be the reason for the erratic RPM.

 

[FBCoach]

Rebuilt the carb today. It wouldn’t crank until i disengaged the drive and opened the fuel up. Ran well for about 10 mins at roughly 1100 rpms. As soon as i shifted back to neutral she cut off. Let sit for a few minutes. She wouldn’t crank in neutral. When i disengaged the drive and gave her more fuel she fired back up. Any help on adjusting the carb so it will crank and idle in neutral? I turned the idle mixture adjustment back roughly two turns on the install.

 

[Rick Stephens]

How old is the fuel in the tank? Any chance it is too contaminated?