I have a 1998 7.4L 310hp efi. I am accumulating about 2 gallons of water in the bilge after a day on the lake. I can see some water spraying up from behind the raw water pump pulley, but can't see where it's actually coming from.

When I bring the boat home and hook it to the garden hose, I don't get any water leakage. Is this because of the lack of pressure in the pump system while at idle? I've reconnected the hoses and tightened down the cable hoses thinking it might be that, but no change.

Also, when I'm in salt water, the leak seems to go away, figure the salt is clogging the problem area.

Anyone seen these kind of symptoms?

I've taken a water pump off an older big block before which didn't have the single belt, but rather it had the multiple belts for all the pulleys... Is this setup the same with the fuel pump attached? It's a real ***** to even get close to looking at the pump in this boat....

Thanks for listening!!! I'd appreciate any insight you might have as to how I should attack this... I'm thinking of ordering in a new raw water pump assembly.....

I put a mirror on the bottom of the bilge and I can see that it doesn't have the fuel pump assembly attached to this raw water pump... I don't see any cracks in the hoses or the pump itself, from the view I had from underneath.... when the water is leaking it seems to be hitting something that is spinning, because it shoots a water spray upward from what seems to be right behind the pulley.... I have 116hrs on the engine and had the pump replaced under warranty about two years ago. At that time, they said they replaced the old unit which had a plastic pulley with one of metal... I see that this one has a pressed on pulley.... possible it's leaking throught the pump drive shaft???

Check the lower weep hole, on the underside of the pump. Its probably dripping onto the crank pulley and spraying.

From what I tell, it appears that the water might be coming from under the engine water pump and dripping through the weep hole onto the harmonic balancer... does this sound correct? Can't see the weep hole itself, so I'm assuming that's where it's coming from. Now, when I remove the water pump from the front of the engine, it appears that the pulley is bolted on with 4 bolts, will the pulley come right off or will I need a puller? I think it will come right off, just want to be sure I'm ready with the right tools if needed. When I order the new water pump, does it come with the two gaskets that I'll need when I mount it? Is the blue gasket sealer all I'll need to put on the gaskets or do you have any recomendations? Thanks for all your help!!!

Hi B,

The pulley should come right off, if it doesn't, there is rust around that little alignment dowel in the front there, hit it with a little WD40 and that should free it up. The gaskets usually come with it, just check inside the box. I prefer the high temp black silicone over the blue.

Talk to you later,

If this helps, a friend of mine has 2 mercruiser raw water pumps for sale way below list. It has the fuel pump attachment and they are brand new never used. I posted an ad in "parts for sale" thread.