Hot riser

[damie]

I replaced both flappers in my 98 4.3 mercruiser this week, since then the right hand riser runs quite hot, i can just feel the left is warm to the touch but the other is quite hot on idle both exhaust holes have water coming out from them and new water circulater fitted....any ideas please.

 

[Haut Medoc]

Re: Hot riser

Are you sure you got the flaps installed correctly? Is this raw water or fwc?.....

 

[Don S]

Re: Hot riser

The flaps need to push down to open.<br />Did you remove the riser to replace the flappers?

 

[damie]

Re: Hot riser

Yes i removed the risers to install the flappers,it is a raw water cooled.<br />i have had to take out the thermostat at the moment as it stoped working when i jammed it open a bit the temp was then ok for the engine....would not having a stat in reduce the water pressure to the riser so less water flow?<br />(i will replace the stat when the new one arrives)

 

[milkyway]

Re: Hot riser

Were you testing the riser temperature with the boat on the trailer or on water?

 

[damie]

Re: Hot riser

I was testing on the trailer using the muffs.

 

[hearly]

Re: Hot riser

do not rev above 1500 RPM on the Muffs as pressure is to low and will over heat.

 

[milkyway]

Re: Hot riser

My 5.0L mercruiser's port riser ran hot on the trailer. I always worried. But you know, on the water, it was cold. I don't think about it anymore. Try it on the water at different rpms. The impeller sucks water adequately while totally dunked and dipped and expels more cooling water to the manifold and riser than using a muff. Also check the hose anyway for possible blockage.