2000 7.4 Litre MPI

M

McNally260DA

New Member
Jul 30, 2010
25
Ogdensburg
Boat Info
260 Sundancer 2000
Engines
7.4L Mercruiser w/Bravo III Drive
Went to start my 260 Sundancer today and the engine would not turn over. The motor acted seized up. I removed the serpentine belt and found the bottom left pulley on the front of the 7.4 litre MPI engine seized solid. Is this the fuel pump/cooler unit? I had no problems with it prior to this.Thanks
 
Thanks for the quick reply. Thats correct. Looking at the front of the motor, its bottom left down near the motor mount.
 
Your sea water pump can feel almost frozen if it's dry try rotating it clockwise looking from front of engine it might free up the veins even if it's frozen the engine should still turn over and start with a frozen sea water pump it would really squeal. Need more info than it won't turn over like does it click or no sound at all when you turn the key to start it.
 
the motor eventually started but serpentine belt was sgueeling and smoking badly. shut the motor down immediately and found after removing the belt that the bottom pulley cant be turned even by hand with the belt off. This is the very bottom left pulley.
 
Sounds like your going to need to rebuild the sea water pump be sure and put a new serpentine belt on it or it will squeal now.
 
I just went through this same engine same problem. I ordered the pump off of ebay. Oem from mercruiser . 330$ appose to almost 600$ from local marine supply. A rebuild was out due to frozen bearings not just badIbadImpeller. Swapped out pumps and belt and everything is great. If your boat is in the water and the hoses are below water line when you disconnect the hoses you will take on a little water until you raise the house above the water line. Have zip ties and a rag to plug the hose until you reinstall the me pump.
 
Michigan Mortz has them with bracket and pulley for $219.00 new.
 
If this is true WOW but make sure your not ordering the circulating pump. Lookls like an regular water pump on a car. You need the raw water pump and not a rebuild kit, the whole pump.
 
Thanks everyone for the help. I took the boat out of the water and will be repairing it in the driveway. It seems that there are two ways to approach this. One is to remove the whole unit with the bracket and rebuild the pump on the bench. The other is to just remove the housing from the back of the pump leaving everything else in place and rebuild and install. The unit is fairly easy to get to although not real easy to see if you were rebuilding the pump in place. If anyone has done this could you please advise? It's a 2000 7.4 litre 260 Sundancer.
 
Take it out and do it on the bench. We're quite lucky (with our model) to have very good access all around the engine. But, even so, it's just that much easier on the bench.
 
Thanks Lazy Daze. Thats the way I'll do it. This is a maintanence item so I want to learn to do it myself. I boat about 75 Hours a year in the St. Lawrence River. Should I do this every year? The river is like bottled water but I don't want neglect preventive maintanance.
 
Nah, I wouldn't do it every year. You can't go wrong by doing it, but it's likely overkill. In fresh water, with minimal silt/sand, you should be good for about 3 years. I absolutely wouldn't recommend this, but we get boats in all the time (from local lakes) that haven't had the impeller changed in 6-7 years + and they're still flowing good water. I can even remember a few times when I've asked customers (owned their boat for about 10 years at the time) "when was the last time you changed the impeller". Their response... "What's an impeller"?

Jabsco makes a better pump, if you're interested. It's a bit pricey, but it's rebuildable and made from bronze, not plastic.
 
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A couple tips when you install the impeller into the housing use dish soap as a lube don't use any oil products on the impeller it will cause it to swell and seize up I did this last year. Also it's a lot easier to remove the whole bracket assembly and don't forget to mark which hose is intake and exhaust. I also use Loctite 242 threadlocker on the bracket bolts. There's a lot of videos on the web to show how to do it.
 
One last thing; Your engine is newer than mine so this may not apply, but... IF the pulley itself is plastic, replace it with a metal one while its on the bench. My plastic pulley, (again 1998), failed, leaving me dead in the water. Its an easy & cheap enough job on the bench.
 
Thanks for the tips. The pump housing is plastic but I think the pulley is metal. I don't think the bearings are seized up it feels more like the impeller is preventing the pulley from turning. When you try and turn the pulley by hand it feels spongy like a rubber impeller might be twisted up in the housing. Hope so anyway the rebuild kit is alot cheaper than a new unit.
 
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