Yet Another Sucky First Outing - Please Advise

I apologize for the long post but bear with me. So I backed the trailer in the water, and immediately water was shooting through the pictured brass fitting. obviously, the shaft needs to be repacked, but my question is, does the shaft configuration look normal? Or rigged? Also, is repacking something that can be done myself? Additionally, does anyone have an idea of how much it will cost? My other issue is, overheating. So we let it idle while still on the ramp, an it shot up to where the warning buzzer came on. Afteinspection of the thermostat, it was hung in the open position. My buddy, who is a former Mercruiser machanic said it would be OK to remove the hung thermostat to troubleshoot the problem. After removal, heated up quickly, so it is probably the impellar. Could it be the water pump? the former owner claimed to have changed the impellar last year, but I wonder? Anyway, pulled the boat out of the water to make sure no air pockets were in the water intake lines, backed in and heated up again. Could anyone tell me where the impellar is located? Is it on the housing attached to the bottom pully wheel on the right side? (Mercruiser 350 Mag motor) Thanks again for anyone's advise. It really is a succky start to the season. I want to get it fixed ASAP.

Not sure about the exact motor but the impeller is in the water pump. There should be a plate that you remove with 4 or so screws. remove this and you should be able to see the impeller. If there is no plate you may have to remove the whole pump. If the impeller is ripped to shreds you may have pieces of it throughout the cooling system. Try to get as many pieces out as possible. When you put the new one back in coat it and the housing with some vasoline. I can't really help you with the shaft packing though. When you say shooting what exactly do you mean? Maybe you just have to tighten the nut on the shaft packing tighter???

Thanks for your response. In the picture, where the stainless shaft enters the brass nut, water is literally pissing out of the joint. If you look closely, you can still see moisture on the bottom side of the nut. this is where it was shooting out. Anyway, are you saying I can tighten something there to maybe fix it? Also, where is the water pump located? I really appreciate you help. I am a vdrive noob here.

yeah, just tighten the packing nut. it's adjustable- loosen the narrow nut that locks it into place and cinch down the big one. Do this when its on the water because you still want approximately 1 drop per minute or so (if I have the # of drops per minute wrong, sorry)

Thanks dan, I will give it a shot.

looking for a drop or two every ten seconds, and if your impeller is good and youre not running a thermostat and still are overheating id lean towards the possibility of a blown head gasket or pieces of the old impeller are caught and restricting the line somewhere

oh yeah thats one to two drops every ten seconds with the boat in gear.

Could it also be a shot water pump? (not the raw water pump)

could be if it was improperly winterized usually if the water pumps shot it will crap out nasty brownish black water

I would at least like to open the raw water pump and check out the impellar condition. Could you guide me to where the raw water pump on a Mercruiser 350 Mag is located?

find general location of intake grate on bottom of boat and then from inside boat, locate same location on bilge floor and follow that intake hose coming in from the grate to lead you right to the pump housing where your impellar lives..

Packing is relatively easy to replace if the old stuff is worn/thin. I had a problem with continuous leaking a while back so I went with a graphite packing I purchased from Skidim. Since then things have been great/dry. Removing the old packing can be bothersome however I used a jigsaw blade (without the saw) to pick it loose then pulled it out by hand. You want to be sure not to scratch your shaft when you work at getting the packing loose otherwise it may cause leakage. When you repack you also have to consider which way your shaft turns.

Thanks again, love this site! ManFox, found that location, followed it, looks like the serpentine belt actuates the pump by a wheel pully?

That is correct, i have a mercruiser as well and to get to the impeller i had to take the entire impeller housing out of the boat. It's still not that hard, It probably took 5 minutes to take off.

Cool, suppose I need to loosen the tensioner to get slack on the serpentine, remove the hoses and three or four bolts to snatch the housing? What brand impeller are you using on your Merc?

mine was on an 89 sunsetter, depending on the year of your boat one of these will do.
http://www.skidim.com/prodinfo.asp?number=SIE18-3237
http://www.skidim.com/prodinfo.asp?number=SIE18-3087K

Thanks for the links, I'm going to try to tackle that bad boy myself.