Collapsed cooling hose

[Jercoupe]

My friend has a problem on a penta 150 d3 on a 2012 25 tug. As you can see the sea water hose that goes to the transmission cooler seems to collapse at about 1300 rpm and the engine will overheat. The hose that exits that cooler is very rigid but this one is very soft. That seems odd that a intake hose would be soft. Has anyone else had this problem? I cant seem to find the part number for this hose if it needs to be changed out ?. Any help there? thanks in advance. Jack

 

[SKing]

I don't have experience on your particular issue but if a hose is collapsing the first thing I would check is for a restriction before the hose. If none then maybe the hose is to soft.

 

[Red Raven]

I have this engine and I agree with SKing. There is likely a restriction before that hose. The hose in the photo runs from the transmission oil cooler (foreground left in photo) to the raw water pump. Prior to this hose there are three most likely locations for a restriction. In order of flow, first would be the raw water pickup under the boat, second would be the sea strainer, and third would be the input to the transmission oil cooler. Assuming the sea strainer is clean I would first check the input to the transmission oil cooler. Remove the hose at the input to the cooler (port side, left of the photo) and check for an obstruction (likely eel grass or similar) at the input to the cooler. If not there, it is possible the pickup under the boat is fouled but that seems less likely given which hose is collapsed. Cleaning that would require a diver to clean or pulling the boat out of the water.

 

[Jercoupe]

I have this engine and I agree with SKing. There is likely a restriction before that hose. The hose in the photo runs from the transmission oil cooler (foreground left in photo) to the raw water pump. Prior to this hose there are three most likely locations for a restriction. In order of flow, first would be the raw water pickup under the boat, second would be the sea strainer, and third would be the input to the transmission oil cooler. Assuming the sea strainer is clean I would first check the input to the transmission oil cooler. Remove the hose at the input to the cooler (port side, left of the photo) and check for an obstruction (likely eel grass or similar) at the input to the cooler. If not there, it is possible the pickup under the boat is fouled but that seems less likely given which hose is collapsed. Cleaning that would require a diver to clean or pulling the boat out of the water.

Yes, I think now it is eel grass in the pickup. I wish they would have put the pickup where it could be reached from the dock. I was thinking a tee with a standpipe instead of a elbow at the scupper pickup would be better. At least you could undo the cap and run a dowel or something to clean out the grass!

 

[Jercoupe]

I guess another question for you with the same engine is does your hose feel soft enough to collapse? It seems this should be a hard hose on the intake side of the impeller.

 

[Red Raven]

I guess another question for you with the same engine is does your hose feel soft enough to collapse? It seems this should be a hard hose on the intake side of the impeller.

The hose is probably fine for now. They are fairly stiff but the raw water pump is fairly powerful and surely can still collapse even a new hose if there is significant restriction. I’d worry more about whether the impeller was damaged but if it was shut/slowed down when the overheat alarm went off if should be OK. I would definitely change the impeller on the next annual service. Changing out that hose at the same time wouldn’t be difficult and wouldn’t be a bad idea since it was stressed.

BTW, the hose collapsed is at the output of the oil cooler not the input. The transmission cooler on this boat is first in line from the seawater strainer and then runs to the raw water pump. It is confusing because the input hose to the transmission cooler runs from the seawater strainer (starboard side) all the way around the front of the engine before reaching the cooler (port side). The hidden other end of the collapsed hose is connected to the raw water pump input. That is why there is so much negative pressure collapsing the hose.

I have had this exact restriction situation occur at the raw water pickup from eel grass. I was able to dive under the boat with snorkel gear to clear it. It took a couple of attempts to clear it. It helped that it was a warm day I the summer!

 

[Jercoupe]

The hose is probably fine for now. They are fairly stiff but the raw water pump is fairly powerful and surely can still collapse even a new hose if there is significant restriction. I’d worry more about whether the impeller was damaged but if it was shut/slowed down when the overheat alarm went off if should be OK. I would definitely change the impeller on the next annual service. Changing out that hose at the same time wouldn’t be difficult and wouldn’t be a bad idea since it was stressed.

BTW, the hose collapsed is at the output of the oil cooler not the input. The transmission cooler on this boat is first in line from the seawater strainer and then runs to the raw water pump. It is confusing because the input hose to the transmission cooler runs from the seawater strainer (starboard side) all the way around the front of the engine before reaching the cooler (port side). The hidden other end of the collapsed hose is connected to the raw water pump input. That is why there is so much negative pressure collapsing the hose.

I have had this exact restriction situation occur at the raw water pickup from eel grass. I was able to dive under the boat with snorkel gear to clear it. It took a couple of attempts to clear it. It helped that it was a warm day I the summer!

Thanks Red . This is a wealth of information I needed!