force 120 water flow

[firestorm41]

ok heres the deal i have just purchased a 1990 bayliner cobra bass boat with a 120 force from a friend that has never had the boat in the water. he knew that the water pump needed to be replacedamond other things. i replaced the pump housing and impeller. at this point water flows wonderfully throught the two holes about mid way up an the back of the engine when the engine is at idle or low rpm. however when i get passed say 1500 rpm i don't see any water coming out at all. now i have consulted with many techs. on this problem and half of them say that there is a problem that it should be pumping water out those holes all the time and the other half says that once it gets up to speed it shoots all the water out the foot. i need some help deciding whether this thing is working right or not i have not run it enough to get a overheat warning for fear of damamging it. any ideas wuld be greatly appreciated thanks aaron

 

[dmessy]

Re: force 120 water flow

 

[12Footer]

Re: force 120 water flow

Welcome to iboats, firestorm.<br />A firefighter by any chance? Just curious...<br />But you are very smart not to run this engine without making sure it is cooling properly. A pressure gauge installed would ease your mind,and give you the real-time information you need.<br />Anything else, monitoring telltale, heat alarm, temp gauge all give you no time to make a decision before damage occurs.<br />If you have installed a new impeller and thermostat, you should be ok. But until you get that gauge installed, get a "tempurature stick" from an auto store or marina. This is a crayon-like thing that you can draw a line on the head or block with. It is designed to "melt" at pre-determined temps..Get one for 180degrees F.<br /><br />Also, you can look for hot spots with your hand. You should be able to touch the block and head anywhere for three seconds without getting burned or removing it.<br />Of course, be carefull you don't burn yourself , or get too close to the plugs or plug wires

 

[bret walters]

Re: force 120 water flow

checking engine with temp stick but 180 degrees is too high. mercury lists the correct thermostat for this engine at 130. a 160 stick will indicate an overheated condition. stick should not melt for normal good cooling system on this engine. on this engine most cooling water does exit at prop when running on plane. holes in mid section are idle relief ports. <br />ps. the human hand is a very poor judge for an overheated engine, most engines operate at 120 or higher, your house-hold hotwater heater is at 120 or higher so if you can't hold your hand under hot only at the tap then it won't help determine an engine that is normally at that temp or higher. although it is a good way to get burned. temp sticks are good and a infared temp gun is better, many mail order tool supply companys sell them for as little as $20 , and are a very good investment for the boat owners tool box, any do-it yourselfer should have one.

 

[chads15]

Re: force 120 water flow

I would Consider it normal operation. The Force 150 behaved the same way, Cooling is not much different in the 120. Mine would barely spit @ idel. If it is pooring out @ WOT, its working just fine. JB helped me fix that one 2 years ago.

 

[ODDD1]

Re: force 120 water flow

Echo Merctech...what you are seeing is normal operation, once you increase rpm water dumps out the gear housing...

 

[91formula]

Re: force 120 water flow

firestorm41, I have a 92/120 Force, when at idle does yours pump out water almost like a garden hose opened all the way up, thats what mine does, if running WOT almost all my water comes out the gear housing, yours seems normal.