Overheating on vacation

[NicksterFL]

Hey guys, here's the deal.
Mercruiser 3.0
Pre alpha drive
We are on vacation at a rental with our boat in a canal. Been out almost everyday and has been running fine. Last 10 trips no issues. Yesterday I noticed the engine was running a little hot. Seemed to cool off as I slowed down. This AM we are prepping the boat for a day out again and as I start the boat and idle it begins to get too hot again. I shut her down.

Checked the outdrive for any plastic bags or something around the intake ports and it's clean.

I also disconnect the hose from the outdrive to the thermostat housing to see if it's getting water and it's getting an inconsistent flow. Kinda gurgles.

Thinking it's clogged with sand or grass I connect a garden hose to the hose leading to the outdrive to back flush it. Doesn't seem too pressurized. Some pressure but not alot.

My impeller was replaced last august or september.

Here's a video. Notice I have a house going into the thermostat housing to keep it cool while I run with it disconnected.

https://youtu.be/P-FuJgXB-6Y

Would love to resolve this as we are due to checkout tomorrow otherwise it's a seatow ride back to the high and dry.

 

[Bondo]

My impeller was replaced last

Ayuh,.... The raw water pump is the 1st place to start,.....

 

[NicksterFL]

I realize that but I'm at a dock at a rental house. Anyway to differentiate between a shot impeller and an obstruction (shell, grass etc)?

If I connect a garden hose to the thermostat housing input ( where the hose from the drive would connect) engine runs at correct operating Temps.

 

[NicksterFL]

Any tips on back flushing?
If I blow in the hose to the outdrive I cannot blow through to where bubbles would come out of the drive intake ports.
If I connect a hose I can hear some rattling and a little water barely coming out of the drive input holes

 

[Bondo]

If I connect a hose I can hear some rattling and a little water barely coming out of the drive input holes

Ayuh,.... The impeller is probably blockin' the flow,....

I take it, it's outa the water, so drop the lower unit, then back-flush it with a garden hose,..

 

[NicksterFL]

It's not out of the water. It's at a dock in the water at a vacation rental house until tomorrow. I'm trying to back flush it to remove any clog there may be (if that's the problem) or otherwise tomorrow it's a seatow ride back to the high and dry.

If in water should I be able to blow in the hose to the drive and blow bubbles out the intake? I have to blow very very hard and barely any bubbles come out.

Is it blocked or my impeller is shot?
Or are you saying the impeller is blocking it and to only back flush with the drive off?

 

[GA_Boater]

I don't think you can blow hard enough to dislodge anything, even blowing until you're blue in the face..

Without tearing it down, you won't know if it's a blockage or bad impeller and it sounds like you aren't in a good place to remove the drive.

What you could try is use the water hose to back flush and tap the motor over with the starter to possibly allow a path for water to exit the lower unit. Only tap, don't try to start.

 

[NicksterFL]

Thanks I tried back flushing while just bumping the engine to turn the drive. No luck. Its looking like a seatow ride back to high and dry tomorrow. Ugh.

I must have picked up somethin on the suction side of the impeller. When I disconnect the hose after back flushing, and start the engine the water pumps out fine and strong. Then runs dry.

 

[GA_Boater]

One more thing to try is using a coat hanger or heavy wire with a hook on the end and probe the water inlets on both sides. If something is in there, might dislodge it.

 

[NicksterFL]

One more thing to try is using a coat hanger or heavy wire with a hook on the end and probe the water inlets on both sides. If something is in there, might dislodge it.

Tried that