Running an engine on muffs dangerous temperature

Hello all, sorry to be long winded, but I need some help with my 2000 210 Sea Ray Sundeck with a 5.0L Mercruiser Alpha One Gen II. This is my second boating season. We got the boat into the water after a late start this year. The boat was winterized last year and recommissioned this season with all the info and help here. The boat was in the water for a week and ran flawlessly with no issues, alarms, great power despite alot of people, or overheating.
Sorry I am sure my terminology is incorrect , but when I pulled the boat and went to flush the engine on muffs I could not see any water coming out around the bell housing of the transom and the temp reached 170 degrees and I shut it down. I think the engine was drawing up water since the water leaking around the muffs seemed to decrease when the engine started. I tried three times, letting the engine cool down, but got the same results, mind you it was getting late and darker and had to leave so I was not able to really analyze the situation well. I will not be back to the boat until this weekend.

So my questions are :

How long does it take once you start the engine on muffs should we see water coming from the bell housing and what temp should it happen ?

At what temperature can engine damage be done if the boat is not drawing up water?

Is there a thermostat involve and can I be shutting it down before the thermostat opens up?

What should I look for, diagnose or do when I get back to the boat this Saturday?

For those who will ask, the impeller was changed out last June by the previous owner (I have the original so I know it was changed out).

Any advise/info would be greatly appreciated. again engine ran well, good power, no overheating or alarms. I ran the boat on muffs all last year and just before putting it into the water with no issues.

Thanks Ike

Re: Running an engine on muffs dangerous temperature

Make sure the muffs are on right and the hose is fully on.

170 is not overheating.

Relax and enjoy the boat

Re: Running an engine on muffs dangerous temperature

Popeye, agreed that 170 degrees is probably operating temperature, but how high can I let it go if the motor is not drawing up coolling water before a concern of engine damage/ overheating starts to be a concern!!!

Thanks Ike

Re: Running an engine on muffs dangerous temperature

may be sucked up weeds when boating, pull the drive, inspect water passage and intake hose from bell hsg to transom, then check the water lines and coolers all the way to the thermostat hsg

Re: Running an engine on muffs dangerous temperature

There is no concern for engine damage at 170*, however, if there is no water circulatingm the rubber parts of your exhaust will not last long. Remember, your exhaust temp is HOT as soon as your start the engine.

Re: Running an engine on muffs dangerous temperature

So, how do I verify that I have water circulating by the muffs? I was thinking of pulling the distributor so that the engine would not start and pulling the water feed tube from the thermostat housing to see if I the impeller is pushing water up, but with just the starter circulating the engine would I see much water even if it is functioning properly?

Does anyone have any other tests that I can run to see if I am getting water circulating?? I would appreciate any advise !!!! Thanks ike

Re: Running an engine on muffs dangerous temperature

yeah, you can run the engine and pull the inlet hose to the t-stat hsg, do not need to ground coil wire. with motor running you should see water coming from feed hose in a matter of seconds. running the motor with no water is fine if it is under a minute. like i said earlier, check for weeds, or muck, or anything in the water inlet hose and coolers

Re: Running an engine on muffs dangerous temperature

Well all, I will do just that to see that I have good water flow at least to the T-stat housing and no depri in the hose. Hopefully it will run fine and then take it from there!!! Thanks again all Ike

Re: Running an engine on muffs dangerous temperature

i would not run water thru it without engine running as i did that and put water in cyl. Exhaust pressure keeps water out especialy in elbow area where water and exhast mix. Merc bulletin said that.