1987 mercury exhaust question

[Jumbo3905]

60 hp Mercury, on the two exhaust ports just below the powerhead in the mid section should there be water coming from these ports as well as exhaust gases. If there is water where is it likely coming from, In the exhaust plate or from the powerhead.
thanks for any help
jumbo3905

 

[roscoe]

The cooling water goes through the powerhead, and then is dumped into the exhaust. So yes, there should be water there, and some of it will splatter out the exhaust relief ports.

 

[Jumbo3905]

Does the cooling water exit through the inside of the exhaust tube with the exhaust gas or does it run on the outside of the exhaust tube to also cool it. I ask as I have exhaust and water leaking from my lower power head to mid section gasket and I am wondering where it is coming from

 

[Chris1956]

Not sure your question has much to do with your leaking powerhead-to-midsection problem.

You should clean the mating surfaces and replace the powerhead base gasket, to stop the leak.

Normally the exhaust gas and some water are routed into the exhaust tube, down to the prop exhaust ports. Only Water exits the gratings above the antiventilation plate.

At idle, water and exhaust will exit the idle relief ports at the base of the powerhead, but on the midsection. Obviously there is a small passage from the exhaust tube to the idle relief ports.

 

[Jumbo3905]

Not sure your question has much to do with your leaking powerhead-to-midsection problem.

You should clean the mating surfaces and replace the powerhead base gasket, to stop the leak.

Normally the exhaust gas and some water are routed into the exhaust tube, down to the prop exhaust ports. Only Water exits the gratings above the antiventilation plate.

At idle, water and exhaust will exit the idle relief ports at the base of the powerhead, but on the midsection. Obviously there is a small passage from the exhaust tube to the idle relief ports.

thanks Chris, appreciate the response. So the water that exits the grates above the antiventilation ports, does this water run external to the exhaust tube and down the cavity of the mid section to the grates and out. If yes then this water could be what I am seeing leaking from the lower powerhead to mid section gasket, does that make sense. I also understand the exhaust port seal to the exhaust tube (upper) is not a tight seal so can some exhaust gases escape into the mid section.

 

[Jumbo3905]

thanks Chris, appreciate the response. So the water that exits the grates above the antiventilation ports, does this water run external to the exhaust tube and down the cavity of the mid section to the grates and out. If yes then this water could be what I am seeing leaking from the lower powerhead to mid section gasket, does that make sense. I also understand the exhaust port seal to the exhaust tube (upper) is not a tight seal so can some exhaust gases escape into the mid section.

I do have a new lower powerhead gasket and will be replacing it. Just trying to understand where that water and exhaust is coming from.

 

[Chris1956]

The powerhead bolts to the exhaust extension. They have passages for cooling water into the powerhead, exhaust out and cooling water out of the powerhead. You might identify these passages when the powerhead is off.

I think your assumption is correct that cooling water flows over the exhaust tube and out the gratings. My guess is that exhaust gas and outside water back up into the exhaust tube and spill out the exhaust relief ports, when motor is idling.

 

[Jumbo3905]

The powerhead bolts to the exhaust extension. They have passages for cooling water into the powerhead, exhaust out and cooling water out of the powerhead. You might identify these passages when the powerhead is off.

I think your assumption is correct that cooling water flows over the exhaust tube and out the gratings. My guess is that exhaust gas and outside water back up into the exhaust tube and spill out the exhaust relief ports, when motor is idling.

thanks Chris . I'll have a go at the powerhead gasket this weekend and see what I find.

 

[Jumbo3905]

thanks Chris . I'll have a go at the powerhead gasket this weekend and see what I find.

I replaced the powerhead to midsection gasket, there was traces of the old gasket left behind( my bad) , and once re-assembled and started up I had no leaks from the powerhead to midsection. This also eliminated the exhaust gases leaking out which were causing the motor to choke itself when the cover was installed. Rebuild is running strong so far, appreciate the help from this forum.