Raw Water Pump/ Overheating

[Rick Russell]

Volvo Penta 5.7 Gi-E Engine has been overheating at higher speeds. I did the clear hose test and thought that I had something going on in the outdrive. I replaced the entire cooling system outside of the transom, but decided to isolate the raw water pump and put it under 10 inhg of vacuum before I put the boat in the water. The pump would not hold the vacuum and I could hear air being sucked into the raw water pump through the weep holes.

Do you guys think this could be enough of a leak that it would cause the air entrainment in the system that would lead to overheating?

The raw water pump was replaced 2 years ago, so it would seem odd that it is bad already. I'm going to change out the sealing ring for $15. Thought that would be a good first step before dumping $400 + on a new pump.

 

[Scott Danforth]

check the hose that connects the drive to the transom shield. specifically the fitting that tends to corrode and break off.

 

[Rick Russell]

Thanks Scott. Although, I actually completely isolated the raw water pump from the entire system and put it under a vacuum. You can actually hear the leak coming from the weep holes in the pump. I'll try and post a video..

 

[Scott Danforth]

you are missing the fact that as the boat is moving forward, water is pushed into the raw water pump. however if you have the very very common raw water inlet casting broke off due to corrosion, wont matter. check the casting and hose, common issue going all the way back to the AQ series of drives

 

[Rick Russell]

OK,

Here's the link to the video. What you are seeing is my raw water pump with the hoses taken off to the engine. I placed a plug on the discharge end of the pump and a hose on the inlet end that leads to a vacuum pump on the other end of the hose. I pulled 10 inhg of vacuum and heard this through the weep hole of the raw water pump. Seems to me that if the pump were sealed properly, that I shouldn't hear any air leaking into it.

I ordered the shaft seal and will install it and then I'll run the vacuum test again and let you know what I find out.

 

[dypcdiver]

If you have a leak at the seal, then may I suggest you replace the bearing at the same time, they are not expensive.
Part number SKF 6006-2RS1 and the seal can be replaced with a better one, double lipped Viton 16x28x7_ TB_ VI
Your choice.

 

[kenny nunez]

If this problem persists after repairing the pump, the “O”ring that seals the lower gear housing to the suspension fork has been known to leak air when the boat is on plane. Add some clear hose on the suction side of the pump to check for air bubbles.

 

[Rick Russell]

Thanks Kenny! I'll change the O ring on the lower gear housing as well!

I'll let you know how it goes when I do the sea trial!! should be a couple of weeks from now. Thought that I'd paint the outdrive while I have it on the stand.

 

[Rick Russell]

Changed the shaft seal and got rid of the audible leak! Here's the video. Going to check to see if the oil HX is clogged to have allowed the vacuum to get too high to compromise the seal next.

 

[dannyual767]

Volvo Penta 5.7 Gi-E Engine has been overheating at higher speeds. I did the clear hose test and thought that I had something going on in the outdrive. I replaced the entire cooling system outside of the transom, but decided to isolate the raw water pump and put it under 10 inhg of vacuum before I put the boat in the water. The pump would not hold the vacuum and I could hear air being sucked into the raw water pump through the weep holes.

Do you guys think this could be enough of a leak that it would cause the air entrainment in the system that would lead to overheating?

The raw water pump was replaced 2 years ago, so it would seem odd that it is bad already. I'm going to change out the sealing ring for $15. Thought that would be a good first step before dumping $400 + on a new pump.

Absolutely! This is exactly what mine did before I rebuilt it with a new bearing and seal last spring (2017.) It's crazy how much these "non-rebuildable" raw water pumps cost brand new and you only got two years out of it!

 

[Rick Russell]

Great to know that someone else had the same experience and the fix worked!

i checked the oil Hx and it was clear!

engine compartment is now buttoned up. Just need to finish painting rhe outdrive and slap it back on the boat and run a sea trial. Probably during the Presidents’ Day week.

 

[Rick Russell]

OK! Painted the outdrive and put it back in the water tonight. Ran WOT without overheating! It turns out that changing the seal at the raw water pump did the trick!

Thanks everyone for all your help! It made the process a whole lot easier. This is an awesome forum!!!

 

[dannyual767]

Rick, I'm glad to hear the good news.