Help! Overheating 3.0, not impeller or circulation pump

[Vetal]

Hey everyone, really need some help with this one. 3.0 started overheating to 220F where the needle stops.
Inlet hose has water flow in it. Hose to exhaust 4 times out of 5 has no water coming out of thermostat housing, to be more specific: while engine was still barely warm, removed water hose to manifold and saw good flow. Restarted the engine in 1 minute and no water flow anymore, tried couple of times again - no flow.
Removed circulation pump, no cracks, no play, turbine spins with the shaft.
At this point I am completely lost, please help

 

[alldodge]

Welcome
No water flow is the pump housing, impeller or connection from pump to thermostat housing.

You say not the impeller, why? If you just replaced it, there could be a problem with the install.

Get a short piece of clear hose, hose clamps and barbed fitting from the hardware store. Place clear in between the drive hose and thermostat housing. Start motor and look for air bubbles

 

[Scott Danforth]

Overheat is lack of water flow.

Either no flow in....or no flow out

Is there flow from the raw water pump thru the hose to the thermostat housing?

 

[Vetal]

Like I said, I have decent (visually) amount of flow from inlet hose, when I remove it from thermostat housing. But no water flow out of the housing to the exhaust

 

[alldodge]

Remove the elbow to exhaust pipe boot. Look down inside to see if exhaust shutters broke up and are blocking the exit

 

[Vetal]

Remove the elbow to exhaust pipe boot. Look down inside to see if exhaust shutters broke up and are blocking the exit

Pls explain why it would matter, if there is no water out of thermostat housing? I'm confused

 

[Scott Danforth]

Pull the thermostat assembly and remove what ever is blocking it. If you have water coming from the raw water pump to the thermostat housing, you should have water to the exhaust as that is a straight shot unless there is a blockage or there is no flow from the raw water pump

Running your motor without the cooling water, your rubber exhaust bits are now burned up. Flappers and hose should be inspected and replaced as needed

 

[Vetal]

Pull the thermostat assembly and remove what ever is blocking it. If you have water coming from the raw water pump to the thermostat housing, you should have water to the exhaust as that is a straight shot unless there is a blockage or there is no flow from the raw water pump

Running your motor without the cooling water, your rubber exhaust bits are now burned up. Flappers and hose should be inspected and replaced as needed

I wanted to put circ. pump back on and measure raw water flow. Does it even makes sense to measure raw water flow if there is zero flow out of the thermostat housing?

 

[Scott Danforth]

Yes. Should fill a 5 gallon bucket in 15-19 seconds with motor at 1000 RPM. Should shoot a good 8"+ up when holding the hose vertical

However before proceeding since you stated you have water flowing from the raw water pump. Pull the thermostat housing apart and clean the blockage

 

[alldodge]

Pls explain why it would matter, if there is no water out of thermostat housing? I'm confused

How do you know there is no flow?
and no flow meaning it's going to the Stat but not leaving the Stat

 

[Vetal]

Yes. Should fill a 5 gallon bucket in 15-19 seconds with motor at 1000 RPM. Should shoot a good 8"+ up when holding the hose vertical

However before proceeding since you stated you have water flowing from the raw water pump. Pull the thermostat housing apart and clean the blockage

Awesome response!

 

[Vetal]

Just wanted to update you guys. Problem hopefully found - intake water hose today when started engine shoot like a liter of water into the bucket and then nothing after So impeller/surroundings are probably shot, and were intermittently working yesterday, messing up diagnostics

 

[charliedaubitz1]

Just wanted to update you guys. Problem hopefully found - intake water hose today when started engine shoot like a liter of water into the bucket and then nothing after So impeller/surroundings are probably shot, and were intermittently working yesterday, messing up diagnostics

on the top of the impeller housing are the black plastic oringed sleeve with a white plastic sleeve that's a guide for a plastic tube that transfers the water up the I/o to the transom , check that tube for a hole in it, ( it just pulls out). Also are you able to drain you manifold. Mine was totally plugged and there is a hose from the water pipe about the position of the side of the carb that connects where the manifold drain is and it provides water to the manifold all the time. mine was plugged by rust in the bottom of the manifold.

 

[Vetal]

on the top of the impeller housing are the black plastic oringed sleeve with a white plastic sleeve that's a guide for a plastic tube that transfers the water up the I/o to the transom , check that tube for a hole in it, ( it just pulls out). Also are you able to drain you manifold. Mine was totally plugged and there is a hose from the water pipe about the position of the side of the carb that connects where the manifold drain is and it provides water to the manifold all the time. mine was plugged by rust in the bottom of the manifold.

Sorry I don't understand what is this water pipe to manifold (except the one from the thermostat housing)

 

[Bondo]

Sorry I don't understand what is this water pipe to manifold (except the one from the thermostat housing)

Ayuh,...... That's two of us,.....

 

[charliedaubitz1]

at the manifold drain there are 2 hoses that snap on, follow the one that's NOT the drain hose.

 

[alldodge]

at the manifold drain there are 2 hoses that snap on, follow the one that's NOT the drain hose.

You got us all scratching are heads, I thought your first post was talking about items 29 thru 31 in link, but right now I have no clue

Lower drive

 

[charliedaubitz1]

You got us all scratching are heads, I thought your first post was talking about items 29 thru 31 in link, but right now I have no clue

Lower drive

https://www.amazon.com/Quicksilver-860235A04-ASSY-EXH-MERCRUISER-END-RISE/dp/B002IQYGEU

it's a hose that's connecting to the manifold drain that's screwed into the manifold bottom. not part of the lower unit. it goes to the hose going to the tstat housing. it's a 1/4" hose with a fitting like the speedometer fitting
on the front of the lower unit. It feeds water into the bottom of the manifold.

 

[charliedaubitz1]

https://www.amazon.com/Quicksilver-860235A04-ASSY-EXH-MERCRUISER-END-RISE/dp/B002IQYGEU

it's a hose that's connecting to the manifold drain that's screwed into the manifold bottom. not part of the i/o unit. it goes to the hose going to the tstat housing. it's a 1/4" hose with a fitting like the speedometer fitting on the front of the lower unit. It feeds water into the bottom of the manifold. located right under the manifold where the riser bolts on.

 

[alldodge]

Think I figured it out, your talking about the newer single point drain system. It's mentioned in manual 26

While we don't know what year the OP's motor is, I don't think it's that new