Mercruiser 165 overheating question

[i_build]

Alpha 1 outdrive. I been running upwards of 190* which I know is high. She is a new purchase. I disconnected the feed hose from the outdrive to the t engine and connected a freshwater hose and she ran cool for a half hour. The hose leading from the outdrive wasn't pumping any water till I sucked on the line and ended up with a mouth full of saltwater. After a half hour on the fresh water hose and temps staying below 150* I shut her off and reconnected the hose from the outdrive and she crept up on temp and I noticed while on the lift she didn't have the constant stream of water coming out of the exhaust bellows. Seemed like it would pulse water and wait 10 seconds and pulse again out of the exhaust bellows. The hose from the outdrive after I primed it seemed to have a steady flow but I don't know if using the freshwater hose compensated for a faulty circulation pump or whether the outdrive wasn't supplying sufficient water. Not sure what to fix? Should the feed line from the drive been as forceful as my freshwater hose? Or is my circulation pump not working and the hose compensated for it? Please advise. Thank you in advance.

 

[Scott Danforth]

You need a new impeller. May as well get a complete raw water pump.

 

[QBhoy]

Yeah...sounds like an impeller issue...for all it costs in time and cost...just do it.
Always hard to diagnose such an issue, unless she is in the water.

 

[Faztbullet]

Is this a Gen 1 or 2 drive as water pumps flow different??? Is it on the original transom plate?

 

[Bondo]

Ayuh,.... Merc 165,..?? is this an I-6, or I-4,..?? I'm guessin an I-4, the 470, if it's an Alpha 1 drive,....
The 165 I-6 went away durin' the MC-1 days,...

Ain't been any 165s with the A1, Gen.IIs,....

Anyways, start by rebuildin' the raw water pump,...
That's always the 1st place to start in 'bout any overheat situation,....

 

[i_build]

It's an inline 6. She is a 1966 Anacapri. Was told it was an alpha 1.

 

[i_build]

Here's a YouTube video of the flow. The boat is a work in progress so please be gentle. Engine has a bit over 100 hours. https://youtu.be/c9GkRtalojs

 

[Bondo]

Was told it was an alpha 1.

Ayuh,... Got any pictures of the drive, or a serial number,....

Alpha 1 didn't come out til 'bout '83,....

'n yes, it needs a eaw water pump rebuild,....

 

[i_build]

The box for the lower unit from sterndrive engineering said se 106 lower sn# 123018 also had numbers 90-106-02

 

[Bt Doctur]

SE106 is the Alpha 1 replacement from SEI , identical to the merc Alpha1 , uses the same impeller in the lower unit.
And just replacing the lower unit would not work anyway because of the spline difference. You have a complete se 106 drive

 

[i_build]

Just wanted to close the loop on this... It was 100% the pump in the lower unit. Replaced the pump & impeller and she cools perfectly.