89 Alpha 1 5.7L cooling question

[dubs283]

Thank you, I’m not questioning just trying to learn, what is the importance of the impeller on the drive if it doesn't provide cooling to the engine? I will order and change the seawater pump and housing, then I will know the date it was changed.

through transom water passage hose from the drive cut on the outside and the through transom barb removed and capped off, this is so the pump in the drive still provides cooling for the drive

the reason for my long post is so you, and others can be provided with a thorough explaination, this will help all who have read and will read this thread. it was said earlier that your setup was a "bad idea". mercruiser designed this cooling system this way because it is the only way for it to properly work. they tested and concluded two pumps were necessary, bad idea or not it's what works hence why there are not very many setups like yours out there, it's convoluted

you might say, "gee dubs283 kinda seems redundant to have a seawater pump in the drive" the upper gearset requires more cooling than just the gear oil can provide when the drive is under heavy load, i.e. boat on plane and the driveshaft housing is not submerged in the water. the sea water pump in the drive provides the extra cooling necessary for the upper gearset and driveshaft housing then just dumps the water back into the lake due the water passage hose being cut off before passing through the transom assy

 

[Rick Stephens]

the reason for my long post is so you, and others can be provided with a thorough explaination, this will help all who have read and will read this thread. it was said earlier that your setup was a "bad idea". mercruiser designed this cooling system this way because it is the only way for it to properly work. they tested and concluded two pumps were necessary, bad idea or not it's what works hence why there are not very many setups like yours out there, it's convoluted

you might say, "gee dubs283 kinda seems redundant to have a seawater pump in the drive" the upper gearset requires more cooling than just the gear oil can provide when the drive is under heavy load, i.e. boat on plane and the driveshaft housing is not submerged in the water. the sea water pump in the drive provides the extra cooling necessary for the upper gearset and driveshaft housing then just dumps the water back into the lake due the water passage hose being cut off before passing through the transom assy

Very well stated.

 

[mattfluck]

the reason for my long post is so you, and others can be provided with a thorough explaination, this will help all who have read and will read this thread. it was said earlier that your setup was a "bad idea". mercruiser designed this cooling system this way because it is the only way for it to properly work. they tested and concluded two pumps were necessary, bad idea or not it's what works hence why there are not very many setups like yours out there, it's convoluted

you might say, "gee dubs283 kinda seems redundant to have a seawater pump in the drive" the upper gearset requires more cooling than just the gear oil can provide when the drive is under heavy load, i.e. boat on plane and the driveshaft housing is not submerged in the water. the sea water pump in the drive provides the extra cooling necessary for the upper gearset and driveshaft housing then just dumps the water back into the lake due the water passage hose being cut off before passing through the transom assy

That was what I was thinking about providing extra cooling for the gear oil. I appreciate the in depth response, I’m here to learn and understand how the system functions as a whole. Ill keep everyone updated on this project.

 

[mattfluck]

This is what the risers looked like when i pulled them

 

[mattfluck]

Cleaned up, would you suggest having them sandblasted?

 

[mattfluck]

Lastly, what gasket do I use? Im thinking the stainless blank off plate, but imagine I would need a paper gasket on each side?

 

[achris]

Whatever you use, make it genuine Merc. The aftermarket gaskets are known to leak.

Chris.......

 

[mattfluck]

So an update, had risers sandblasted came out great. Took it out last weekend, still running warm. Figured since I had already checked the raw water pump next stop would be the heat exchanger. After seeing inside that was definitely the problem.

 

[tpenfield]

Barnacle buster may be something to try to clean out the HE.