I am ready to purchase a 1999 35 fountain w/500 hps-NO waterpumps just a by-pass(ss)pipe-is this ok? what reasons for taking off pumps? future issues?

There's no such thing as an engine with no water pumps. Those engines have raw water pumps located on the lower left of the engine as you face the front of them belt driven. The cross overs (by-pass) are very common on performance big blocks. There's no need to double up on water pumps unless you're trying to control water flow for some reason. (automotive type pumps will slow flow). All that being said it might be good to have a marine mechanic check it out before you buy.

Cross overs can create more problems than they are worth. The circulating pumps are trouble free sytems. Do you want to turn key or turn wrench?

impellers? is that the pump you are saying

The impellor is part of the sea (raw) water pump, which is the belt driven pump Sunshadow mentioned. The circulating pump is your regular automotive looking pump on the front of the motor. Which in this case has been replaced by the cross over setup. You still need the sea water pump regardless.

Talking about 2 different things here guys. The crossover replaces the circulator pump, often refered to as the water pump on cars. You need the raw water pump, which is the impeller pump sucking in the water to cool the engine. You don't need the circulator pump because the Bravo raw water pump has enough pressure to circulate the water also.

mercruiser only comes w/circulating pump correct? w/o circ. pump does it add more hp? or just better cooling?

One reason that some people change to a crossover is that it is a lot cheaper than the circulator pump ... go to mercruiserparts online and you will see what merc charges for that black paint! Also, the crossover won't need replaced again. Some say that you gain a couple hp not turning the circulator pump, so you might gain 0.2 or 0.3 mph. If the outdrive has low water pickups only, you might run into high water pressure problems with a crossover, too. Many end up drilling bypass holes in the thermostat to help relieve some of the pressure problems, so, if/when you change the thermostat, make sure to check for any "relief holes" that may need to be re-drilled. For a stock HP500, you should have no overheating issues with the circulator pump, so gaining aditional cooling is not really a factor.

Best to find a certified Merc tech and have him check it out for you.

My question is, if the pumps were removed, what other things have been modified on the motors??


Get it checked out before buying.

i have a pair of hp-500's with cross overs and have never had any issues. i run a 160 thermostat with two 1/8 holes drilled in flat area. water temp is a solid 150 when engines are at operating temp.