I have the factory installed fresh water kit with garden hose attachment installed on my engines. I connected a separate garden hose to each flush connector, wide open water flow, and ran engines for 2 minutes.

Stbd engine had lots of water flow, headers were cold, so all good. The hose was fully off the reel and free of kinks. Engine temp never above 120 degrees.
Port engine didnt seem to have too much if any flow from exhaust, Stbd header was warm, and Port header was hot. Engine temp never above 120 degrees. No alarms sounded. This hose is a 100' hose and 60' or so of hit was still wound up on the storage reel.

Not happy with this, I drove down to the boat ramp and started boat with drives fully in water. Ran both engines, Stbd was now pumping plenty of water and both headers cold. Normal operating temps, both engines. Headers cold on both engines, etc. I have SmartCraft, but didnt think to look at the water pressure. So all good I think.

Moral of my story and question is:

M: I think what must of happened was the garden hose that was still wound up tight on the reel was restricting max water flow and seapump suction exceeded garden hose flow ability, hence lack of water flow. Agree?
Q: Do you think I did any damage to impeller or headers? They didnt blue at all, and again, water was being flowed directly into water pump.

I'm probably being more of a worry wort, but thanks in advance....

IGM

A garden hose simply does not supply anywhere near the amount of water , that the sea pump can while in the lake, even at idle.

I don't think you would have damaged the headers, but if it were me personally, I would change the impeller just for a piece of mind. It doesn't take much to burn them up.

I have seen the hose sucked flat after running for some time..

Change the impellers for peace of mind.
But here is my thought on the situation.
The water pump impeller needs water to pump and cool it as it spins. So if your providing it with any water that is better than nothing. I am assuming that when you were running the boat it was running at idle.
If you engine temp was over 120 then you had water in it. You have to remember that marine headers will still get cooling even on the garden hose. What goes in must come out. Possible reason your port header was hot is because you impeller was already going bad.

I've had the same thing as ezstriper happen when it sucks the hose flat. Now I use a heavy duty rubber garden hose, not the vinyl kind from HD. I have a Y connection to run two garden hoses into my strainer that I will connect when I was running the engine at high rpm, other wise I would just hook up one hose to the strainer.

For the 2 minutes they were running, only bumped the throttle to 1500 rpm twice, a quick bump and back down. While I watched temps on SmartCraft and gauges, never over 120, Port motor (the one in question here) actually ran cooler than Stbd engine by a few degrees. When I see the boat again, I plan to fire her up again in the lake and look at water pressure read outs, feel headers for coolness.

I know best peace of mind is to replace it, do you guys replace just the impeller or the whole housing too? My impellers and housing were changed out new 1 year ago, 27 hours run time since.

Thanks,

I normally replace the housing also. You could pull the old housing off and inspect it but you are looking at roughly $30 for just the impeller vs. $70 for the complete kit. For the extra $40 it's all new and nothing to worry about then.

Thanks all, I plan to run it again on lake water and assess all the temps and pressures etc. Sounds like it should be ok. of note its fresh water obviously, I don't run aground, no silt sucked in, and easy boating. Mostly 3000 rpms and below...

Do you have extremely high water pressure at your house or where ever you had the two hoses hooked up? (I.e. 75-100psi? Typical household PSI is 35-50psi.)
I'd never consider doing this. In the future, only do one at a time.