135 HP poor water flow

[circle hook]

I have a 1990 135HP Blackmax and just replaced the water impeller and (2) thermostats and at idle I get almost no water flow, but at 1,500 or higher RPM a stream shoots out, if the system was clogged you wouldn't get that stream, and its in a bucket not ear muffs so that tells the impeller is working what could be next Thanks Bob & Happy New Year

 

[Dukedog]

Re: 135 HP poor water flow

Low rpm/idle you might not get much till tha t-stats open. Just has small by-pass holes/slots on 'em. You NEED a pressure guage ta really moniter tha water system. Is it gettin' hot at idle? Do you have a water supply feedin' tha bucket?.............

 

[circle hook]

Re: 135 HP poor water flow

the bucket has a feed and enough water and it wasnt running hot but no tell tail stream a idle raise the rpm, and a good stream is there where would you test it with a gauge, Thanks Bob

 

[circle hook]

Re: 135 HP poor water flow

if I pull the thermostats should that open the flow at cold idle in order to elimate a posiable blockage. Thanks Bob

 

[Dukedog]

Re: 135 HP poor water flow

Doubt ya got any blockage. Not gettin' hot. Just no discharge at idle. You may have worn and/or damaged stuff in tha pump. ie: base gaskets, ride plate, housing. These parts can "LOOK" fine but can actually be worn out or torn (gaskets) and not be noticed. Best ta ALWAYS install a complete water pump kit. Symptoms like this is just another reason why a water pressure guage is important ta have. But a weak stream at idle (where a guage would come in handy) is pretty much normal at idle till tha motor is warmed up ta operating temp.............JMO

 

[1nebel0]

Re: 135 HP poor water flow

Most Mercury motors just don't pee a lot at idle. I have 6 motors of different h.p. and they all take almost a minute after being started before water comes out.. Johnsons just pump the water out..My larger h.p. motors with my gauge on dash are 1-2 pounds at idle and 12-15 at full throttle... My 90 really puts out a large volume at idle however it uses the large, less vanes impeller like the Johnson;s. I have a lazer heat gun and you can measure at the thermostat housing how hot the motor is running.. You can also aim it at the water coming out.. Given the fact that most outboards are using 143 therms the water will be around that to 150...hope this helps...

 

[circle hook]

Re: 135 HP poor water flow

well the gaskets top & bottom & impeller were replaced only the steel plate was not I will invest in a thermo gun and let the engine warm up more and see what happens then I may even hook up a pressure gauge, does any one know where the gauge hooks up to the block on a 1990 135HP black max Thanks Bob

 

[CharlieB]

Re: 135 HP poor water flow

You have to look very closely at the SS plate and cup in the water pump. If there is a groove worn that looks like a small circle around the center hole of either metal piece, replace it, that line, groove was worn by the raise ridge around the side of the impeller hub and is supposed to seal the sides to the metal parts. This worn area will not allow the impeller to seal and pump full volume and pressure at low rpm.

 

[circle hook]

Re: 135 HP poor water flow

I am going to replace the water pump completly, and also I would like to install a pressure gauge but where on the engine would you mount this, my 225HP has a port on the stearn of the engine block, but I do not see the same set up on the 135HP. Thanks Bob

 

[Chris1956]

Re: 135 HP poor water flow

I installed a tee in the hose that ran from the top of the block to the base of the block. I do not get much/any flow at idle in my Merc 135HPV6, but the gauge shows some waterpressure at all times.

 

[circle hook]

Re: 135 HP poor water flow

I ran the engine this morning in a bucket and removed the starbord thermostat and had a nice volume of water come out of the block, so I replaced the thermostat and let the engine run for 15 min. and the barrel of water started to get warm and the flow of water from the tell tale hose started to flow better at idle and much warmer, I guess that I just didn't run it long enought to open the thermostats, I do still need to install a pressure gauge is there a port on the block to attach a gauge instead of in line with the hose Thanks Bob

 

[Dukedog]

Re: 135 HP poor water flow

I installed a tee in the hose that ran from the top of the block to the base of the block. I do not get much/any flow at idle in my Merc 135HPV6, but the gauge shows some waterpressure at all times.

This is it. There is a hose coming from a fitting on top, right behind tha flywheel. It goes down to tha poppet right below tha switch boxes. Simply put tha "t" fitting like he says at tha top of tha motor. You may have ta spend some time at tha hardware store for tha right fitting combination depending on tha type hose tha guage uses (there's a couple different kinds)................

 

[circle hook]

Re: 135 HP poor water flow

thanks for all the info I will put the "T" in line with that hose spoke about I am really happy it was only the cold water not opening the thermostats fast like in summer time and it turned out not being a big job Thanks to all and a safe and happy new year Bob