No water out transom or exhaust

[toolman4]

Have a 1999 mecrusier 4.3 alpha one . I had the muffs on to do a preseason check and have water up to the manifold on top but nothing out the exhausts. When I squeeze the big hose from the water pump to the manifold on top of motor I here water but nothing is going to the risers. Can it air lock...how long can you run without impeller damage?

 

[wshekar]

The impeller is in the outdrive and it won't get damaged if you have the muffs on correctly and the water running. The only risk you run is overheating the engine.

Air in the system is not your problem. Your problem is probably the impeller in your outdrive. Was it replaced in the off season?

How do you know there is water in the exhaust manifold? Is that water from the previous season?

 

[markhodges78]

Have a 1999 mecrusier 4.3 alpha one . I had the muffs on to do a preseason check and have water up to the manifold on top but nothing out the exhausts. When I squeeze the big hose from the water pump to the manifold on top of motor I here water but nothing is going to the risers. Can it air lock...how long can you run without impeller damage?

You wont have impeller damage if you have water at the impeller..... remove the small hose coming from the transom that is the water from the impeller point it down in the bilge start turn muffs on and start the boat and make sure you have plenty of flow from the impeller...

 

[Scott Danforth]

Start at the impeller and work your way thru the system. And yes, impellers can toast within 20 seconds without flow. Even if you have muffs

 

[toolman4]

Thanks for the replies...so I have water up to the manifold on top of the engine. Does this say anything...I should have water coming out the other hoses if it's up to the top manifold right? The water wouldn't get up there if the impeller wasn't working?

 

[Scott Danforth]

Water from the transom shield hose should spray about 8-10" out the hose at idle

 

[toolman4]

Finally work slowed down and getting back to this. Took the the hose off feeding the manifold at the top of the motor, no water. Checked the impeller and it looked good...no cracks and rubber looks perfect. The fins didn't return straight when I took it out but still had to turn the shaft to make it go back in the housing. The impeller is about 5 years old but the boat was barely used because of work. Still replace? So is this the impeller or circulating pump? When I took that hose off, water stayed sitting in there on the top side of the circulating pump even when I started the boat. I assume it should have cleared if the circulating pump was working. The muffs were on. Should water shoot straight through that circulating pump with muffs on and impeller in good shape? When installing the sterndrive bottom back on...what is the trick to make sure that water tube with o rings is for sure sealed on the impeller housing. Can only see to line it up.

 

[achris]

...The impeller is about 5 years old but the boat was barely used because of work. Still replace?

Absolutely!

It's not USING a boat that kills it, it's NOT using a boat that kills it.

'Barely used' is about as bad as it gets for an impeller. If you used it every day for 5 years, that would be better for it.

So is this the impeller or circulating pump?

If you removed the hose that runs from the transom assembly to the engine and no water was coming out, there's something wrong in the drive. Impeller is most likely, or you could have missed the water tube when you re-assembled it, but a broken shaft or failed coupler shouldn't be ruled out.

...what is the trick to make sure that water tube with o rings is for sure sealed on the impeller housing. Can only see to line it up.

Make sure the guide tube in on the pump, and the water tube is in the upper housing before attempting to put the drive halves back together. A TINY bit of grease on the end of the tube will assist its passage through the o-rings. Watch the water tube into the guide tube and the rest is 'colour by numbers'...

Chris........

 

[toolman4]

Absolutely!

It's not USING a boat that kills it, it's NOT using a boat that kills it.

'Barely used' is about as bad as it gets for an impeller. If you used it every day for 5 years, that would be better for it.

If you removed the hose that runs from the transom assembly to the engine and no water was coming out, there's something wrong in the drive. Impeller is most likely, or you could have missed the water tube when you re-assembled it, but a broken shaft or failed coupler shouldn't be ruled out.

Make sure the guide tube in on the pump, and the water tube is in the upper housing before attempting to put the drive halves back together. A TINY bit of grease on the end of the tube will assist its passage through the o-rings. Watch the water tube into the guide tube and the rest is 'colour

 

[toolman4]

Ok that makes sense...i just took it apart so I will order parts and report back. It's odd the muff pressure doesn't get water to everything even with a worn impeller. Should that circulating pump clear that hose since it's full of water? I would think since the hose is above it water in the pump would be forced out. Maybe with nothing behind it ...it can't.

 

[toolman4]

Just to clarify....does water from the impeller go strait to the circulating pump or does it feed directly into the top manifold and then it goes to the circulating pump? It looks to me it feeds the manifold first. Can I blow backwards with air now that the bottom end of the stern is off.. I also took the hose off from the circulating pump to the manifold. Why would water be sitting in that hose from the manifold to the circulating pump. As soon as I started it, it should have sucked that in.... right?

 

[achris]

... the top manifold ...

What the H is a 'top manifold'?

Just to clarify....does water from the impeller go strait to the circulating pump or does it feed directly into the top manifold and then it goes to the circulating pump?

Water flow diagram... (standard cooling system)

 

[tank1949]

Start at the impeller and work your way thru the system. And yes, impellers can toast within 20 seconds without flow. Even if you have muffs

Been there with impeller toast, while paying attention to complaining wife and not boat/OD.

 

[Scott06]

Ok that makes sense...i just took it apart so I will order parts and report back. It's odd the muff pressure doesn't get water to everything even with a worn impeller. Should that circulating pump clear that hose since it's full of water? I would think since the hose is above it water in the pump would be forced out. Maybe with nothing behind it ...it can't.

I had a blade off the impeller break off years ago , blocked the water outlet passage in the pump body in the drive absolutely zero water from the muffs could get past it

 

[Bondo]

Just to clarify....does water from the impeller go strait to the circulating pump

Nope,..... It goes to the in-comin' water port on the T-stat housin', where it's available to both the circulatin' waterpump, 'n the exhaust manifolds,......

A 5 year old impeller is junk,......

 

[toolman4]

Appreciate the help...got the impeller kit coming. Is it odd with even the muff pressure no water was getting up to thermostat housing with an impeller and housing that looks perfect? How do I know if my circulating pump is working correctly with that water sitting in the hose above it?

 

[wshekar]

Is it odd with even the muff pressure no water was getting up to thermostat housing with an impeller and housing that looks perfect?

No, that is not odd.

How do I know if my circulating pump is working correctly with that water sitting in the hose above it?

You need to work through the system.

First replace the impeller, then verify water is getting to the thermostat housing. Disconnect any hose where the water is coming in from the impeller based on the diagram above. The water should even exit the system if the water pump is not working (what goes in must come out).

The water pump is used to keep the engine cool. Take a look at the water pump. Do you see water stains below the pully where the weep hole is? If so, the pump is on the way out. If the engine is overheating and water is exiting the system then the circulating pump may be garbage (a few other issue on that one).

Be systematic in your approach and fix things as they come up.

 

[toolman4]

K, sounds good...yeah the water pump looks solid with no stains or weeping out the hole. Just don't get why that hose is full of water entering above that circulating pump. I can blow air back through the water line that comes up from the stern right?

 

[achris]

My initial 'watch point' for an impeller is the water spraying out the sides of the muffs. Observe how much is coming out when the engine isn't running, then watch as the engine starts and see if there's a noticeable drop in that volume. That means the impeller is pushing water. It doesn't tell you WHERE it's pushing that water, it just says yep, impeller pumping...

And no, water will never go passed a good impeller when it's not turning. The way an impeller works is the blades act as valves for 6 chambers with a dynamic volume. As the chamber expands the 'inlet' port is exposed and water is drawn in by the lower pressure within the expanding chamber. When the chamber reaches maximum volume, the blade is passed the inlet port and effectively closed and the outlet port is now exposed and the chamber begins getting smaller, pushing the water out, through the outlet port of the impeller housing.. and then the cycle repeats... But when the impeller is stopped, at least 3 of those chambers are between inlet and outlet ports and water would have to push the blades off the sides of the housing to get passed... And that doesn't happen...

Chris.

 

[achris]

... I can blow air back through the water line that comes up from the stern right?

You shouldn't be able to (read description above)...

If you can, and you're not seeing water coming out anywhere it shouldn't, it means one (or more) things. You missed the water tube when reassembling the drive, the o-rings are missing from either or both ends of the water tube, the water tube is missing, the water tube has a hole in it.