cooling system on blackmax 150 not working right???

[crazyhunter]

hi everybody i have a 1984 blackmax 150 2.0l. we took it camping with us to a place where you could only run idle speed and on our second trip out i notice the pee stream was coming and going to i killed the motor and trolled back. well when we got back from the trip i replaced the whole waterpump tested on the hose and was doing perfect so i figured i was good to go so went to the lake and ran WOT for about 2 min the looked back and it was doing it again. it will pump good then stop pumping. i can stop and rev the motor in nuetral and it will start shooting out steam then a weak stream but not enough to cool the motor. i can turn the motor off for 5 min or so and fire it back and it pumps fine for a couple of min. then it happens agian. what can cause this. what do i need to do to fix this. could it be a thermostat or do they even have a thermostat???

 

[Laddies]

Re: cooling system on blackmax 150 not working right???

That's caused by the thermostat opening and closing in cool water

 

[aussieflash]

Re: cooling system on blackmax 150 not working right???

Its normal,as laddies said.
You can still check Tstats to make sure they open and shut at the right time.Also clear pee hole with wire or similar as they often get crud inside.

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

i check the pee hole but the motor is running extremely hot like hot enough to melt wires. i replaced alot of the wires from the power pack due to them melting. where is the tstat located on the motor i will check that maybe it could be going bad??? also i forgot to mention i cant get it to do this when hhoked up to the hose

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

ok so i went on youtube and found where the tstats are will it hurt anything if i take the out??

 

[Laddies]

Re: cooling system on blackmax 150 not working right???

It needs the thermostats to work properly, if Mercury could have done without them they never would have spent the money to install them in the first place.

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

ok well i geuss i will replace them and see what happens from there thanks for the help

 

[Chris1956]

Re: cooling system on blackmax 150 not working right???

Likely makes sense to rebuild poppit valve as well.

 

[CharlieB]

Re: cooling system on blackmax 150 not working right???

Likely makes sense to rebuild poppit valve as well.

T-stats really only control temp at lower engine speeds. At higher engine speed, load causes the motor to produce much more heat, the rising water pressure with engine speeds opens the poppit valve allowing maximum engine cooling.

A sticking poppit will cause the engine to run hot enough to melt wiring.

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

thanks chirs/charlie i will check that i check where the tstat was suppose to be but they were not there. i also ran the motor on the hose for 10 min or so and noticed the warmer the motor got the weaker the pee stream. could that be caused by a failing poppit valve?

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

i can not seem to find the poppit valve on this motor. ive looked at diagrams and pictures of other motors but cannot find one of mine can anybody tell me exactly where it is. ive read its on the bottom starbored side of the motor and it looks like an 8 but i couldnt find it?

 

[carholme]

Re: cooling system on blackmax 150 not working right???

From the parts list which I sent you previously:

Mercury, Mercruiser, Force, etc. - EXHAUST MANIFOLD AND EXHAUST PLATE - 150 H.P. XR-2 MARATHON MAGNUM (V-6) (1978-1985 COMBINED BOOK)

See item 15.

Gerry

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

thanks

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

i checked the valve and it looks good everything is clean and looks almost new

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

got any other ideas???

 

[CharlieB]

Re: cooling system on blackmax 150 not working right???

If the stats are missing, order new ones and install them. Operating without stats can lead to a cold-seize and destroy piston/cyl's.

Double check that the poppit valve is ablel to smoothly move open/closed and that the 'seat' remains firmly in place in the block.

Check compression, a leaky head gasket under heavier load can allow combustion gases to entire the cooling system, overcoming cooling water pressure, displacing water and causing over-heating. Unfortunately, cyl pressure at cranking speed is nowhere near as high as under full load running, and I would seriously consider replacing the head gaskets. Get the part # from the link previous given, them compare prices with iBoats and other suppliers to find your best price.

PM sent.

 

[crazyhunter]

Re: cooling system on blackmax 150 not working right???

ok thanks for the info i work at a car shop in the afternoons after school so getting a good compresion tester shouldnt be hard. i will try and get some tstats for it also i would hate to kill my motor over a 10$ part