1994 Black Max 175

[Shore_core]

We are having over heat at idle and on plane. Confirmed by mounted temperature sensor and thermal heat gun. It is on both sides of block with reasonable similar temps everywhere but cooling as you get in to centre of block as expected. New poppet valve kit, water pump rebuild, impeller and all housing, cooling hoses, both thermostats and all are mercury parts. Ran on pre mixed day tank to confirm proper oil ratio. Compression test is good. Happens at idle with thermostats removed. Good flow out of thermostats at idle and rpm. Motor does cool when above 2000 rpm in neutral… What am I missing?

 

[QBhoy]

Is this on the trailer or in the water ?

 

[Dukedog]

water pressure gauge???

 

[Shore_core]

No pressure gauge and the boat was in the water. There is a delay in telltail until water comes out. 20 seconds.

 

[Shore_core]

only place I could put a pressure gauge is in the out of the thermostats inline on this motor.

 

[Dukedog]

goes in to a "T" you add in tha hose going down to tha poppet at tha "top of tha block"............... tha "T" has ta close to tha top as possible......

 

[dubs283]

Blockage between sea water pickup and water pump

Or

Blockage in water passage tube between water pump and powerhead

 

[Chris1956]

Sometimes debris gets under the waterpump base, interrupting flow to the waterpump. The other choice is a head gasket leak. You could put a torque wrench on the head bolts and see if they are tight.

 

[Shore_core]

While water pump has been removed inspected now to seal in the leg and rebuilt.

 

[Shore_core]

Ok so… Where the 2 hoses off of the thermostats and tee off to the tell tail and a nipple the seems to go to the above water water and leg exhaust. Remove that hose to exhaust an let it free flow in to the water and engine cools a lot better. There is a fair amount of pressure that is coming out of the exhaust nipple that the waste water goes to. Are they fighting each other for some reason?