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Blackmax low speed oyerheat

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XS POWER

Regular Contributor
Hi 93 150 blackmax on a 21 ft, my bro just purchased this rig so we went through it comp is 120 + on all 6 new impeller,base plate, thermos, poppit diaphragm, spring, the impeller kit did not come with housing, the alarm comes on at bout 8 knots taco not working but runs cool at 20 knots and above any ideas before I pull heads and divider,gaskets are 2 weeks wait min thanks

Dave
 
XS POWER said:
Alright mate is that something I have done,not done, not cleaned ? I will revisit
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Pull the cowlings and remove the pop-it (bypass) cover, Remove the valve and spring. The black plastic seat needs to be flush or just below the surface. When the grommet comes out a little the popit cannot open at low speed and you get a low speed over heat. Usually around 1800rpm

Do you have a serial number?
 
Thanks chris,0d254619 I purchased a new grommet yesterday every tech here said it's something they don't change but I figured if I am in there might as well do it
 
XS POWER said:
Thanks chris,0d254619 I purchased a new grommet yesterday every tech here said it's something they don't change but I figured if I am in there might as well do it
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They are correct.. I don't change them either... That does not mean that it has not moved... When you pull the cover you can feel the edge of the grommet... it has to be flush with the aluminum housing or just below the surface... If it is above the surface a mm it will cause an over heat.

If you find yours has moved, drive it back in with the back end of an appropriate sized socket with an extension and a hammer.
 
We just reassembled, the carrier was flush I tried to give a belt was bit worried to how much ti give it.going for water test now but not confident will keep posted
 
XS POWER said:
No change will get a bigger hammer and beat it like a redheaded stepchild will keep updated
Click to expand...

Flush is fine.... Just as long as it is not above the housing where it is pressed in.

The cooling system temps is on these engines is controlled by the t-stats below 1800-2000rpm and the popit above that RPM range. If the grommet is in its correct place, it is time to check the water flow out of the t-stats at low RPM. You can run the engine with the cover off, remove the hoses from the t-stat covers , install a longer hose on the covers and watch the water flow.

Make sure the popit valve stack up is correct. If the valve cannot seat at low RPM all cooling water will go out of the adapter... Nothing to the block.
 
Thanks for spending the time Chris,going to replace pump housing tomorrow to eliminate that,I get the checking the water out of thermos bit but you have lost me on the make sure poppit valve stack up is correct as i don't know what is stack up, cheers mate
Dave
 
Thanks for your direction chris learnt 2 things the workings of the bypass valve and don't cheap out on a impeller kit get the whole pump, Peace
 
Didn't sea trail just took comps and checked oil the leg was suspect so swapped it out with spare I had the housing looked serviceable so put in impeller kit,should have known better than trust unknown hour housing
 
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