water pump pressure

[olmerc]

My 87 60hp merc (3 cyl, 2 carb)has never had a very strong tell tale stream and after it had been stored for a few years I replaced the impeller and added a water pressure guage (0 to 15 psi). The guage will not even come off the peg at idle and at 2500 to 3000 rpm will come up to 2 or 3 psi. The manual says this engine should develop 3 to 5 psi at 5000 rpm, which just doesn't seem right and there doesn't seem to be a cavity for a thermostat or poppit valve to raise the pressure. Does anyone out there know this engine? and is there any way to raise the water pressure.<br /><br />olmerc

 

[Waterbugtoo]

Re: water pump pressure

How is your sender hose connected to the powerhead? If you do not have it connected to a point with water pressure, you're not going to read anything on the gauge.

 

[wilde1j]

Re: water pump pressure

Two questions:<br />a) Why do you doubt the manual regarding WOT water pressure?<br />b) Since your motor does not appear to be overheating, why do you care at all?

 

[olmerc]

Re: water pump pressure

Hello Waterbugtoo,<br />this guage is connected at the point where the tell tale used to be. If I tee off of this line I get next to no reading at all.<br />thanks for the reply<br /><br />olmerc

 

[olmerc]

Re: water pump pressure

WildeOne, to answer your question, I probably wouldn't have questioned the manual, but after reading a jillion posts on this and other boards, I must have the only engine that operates with near no pressure. Also I just didn't want to make an expensive mistake.<br /><br />Thanks for the reply<br />olmerc

 

[Waterbugtoo]

Re: water pump pressure

If you tee it off that hose, how is it going to get pressure from an unrestricted flow? If you connect it that way, you will have to crimp the pee hose after the tee to provide pressure to the sender hose (usually done with a zip tie). You can crimp it any amount you like until the gauge reads appropriately 3 to 5 psi at idle, and whatever at WOT. Then just use the gauge instead of being totally reliant pee hole for impeller condition. Gauges can be your best friend, but they have to be able to work accurately and consistantly. Connecting the sender hose to the top of the block for instance, will give you very erratic readings due to the steam pocket that builds in the top of the water cavity.

 

[DJ]

Re: water pump pressure

olmerc,<br /><br />Many engines have an orifice where the telltale line exits the cowling. This orifice directed the spray as well as created pressure.<br /><br />Possibly yours is missing?