1986 Volvo penta sea water impeller disintegration

[joleda]

What would cause my sea water pump impeller to disintegrate? Age or running dry? Engine overheated today because the pump wasn't working.Please help. Thanks.

 

[alldodge]

What would cause my sea water pump impeller to disintegrate? Age or running dry? Engine overheated today because the pump wasn't working.Please help. Thanks.

Age is the most common. While many have gotten 5 years out of an impeller, its usually best to replace every 2 years.

Next is the pump ingest some sand or the like, doesn't take long to wipe one out.

Running dry is the quickest way, it only takes 10 to 20 seconds to burn it enough to where it must be replaced

That is with the belt driven which one do you have?

 

[joleda]

Belt drive. It ran fine two weeks ago for 3 hours straight. But it has not been on the water in 3 years.

 

[alldodge]

Belt drive. It ran fine two weeks ago for 3 hours straight. But it has not been on the water in 3 years.

The impeller blades will create a set in them from not moving and will stay bent when they should flatten out as it rotates

 

[jerryjerry05]

Be very careful and remove the pump cover.
WD or PB blaster on the screws.
Let it set 24hr.
Remove the cover and the impeller and inspect the pump body and the cover.
Any grooves or cuts?
What shape is the impeller?

Any missing blades?
You need to find them if so.

 

[joleda]

No Title

 

[Bondo]

Ayuh,..... That one's alittle past over due,....

 

[Grub54891]

Holy snorkel's! Past due is correct, and look's to have been run dry.

 

[dypcdiver]

May I suggest you be a little more proactive with your maintenance schedule.

 

[joleda]

I am still trying to understand the sea cooling system and how it functions. I had a marine mechanic look at it before we went out this year and he said the pump was working fine. As a backyard mechanic, I understand closed cooling systems.
One person said that it only takes 20 seconds to cook the impeller. Okay. The sea water pump pulls the water from the lake and pushes it up to the engine. If the thermostat hasn't opened, does the water bypass the engine and discharge out the exhaust or does it just keep trying to push water to the engine. When we submerged the out drive in a barrel, it doesn't discharge water until the engine warms up to operating temperature.
When I replace the sea water impeller, the system will be dry. Should I manually fill the system with water to make sure the pump is not run dry? Please advise. Thanks.

 

[bruceb58]

When we submerged the out drive in a barrel,

Running the drive in a barrel is a very good way of wiping out your impeller. Don't do that anymore.

 

[alldodge]

Should be no need to prime but use a garden hose and muffs not a barrel

 

[joleda]

I can never get the muffs to work.
What seals might leak in the stern drive?

 

[Scott Danforth]

If you use a barrel, it has to be big enough to get the whole drive submerged ( as in float the whole boat). The water line needs to be about the same level as the pump to get it to self prime. Use the muffs (make sure they are muffs for a VP), and put a plug in the large drain port underneath. I use a cork.

You toasted the impeller by trying to run in a barrel. And yes, it only takes a few seconds to burn up the impeller.

 

[muc]

The thermostat is installed in the thermostat housing ---not against the intake manifold like a car--- this allows sea water to flow at all times, should be no difference between thermostat open or closed in the amount of water exiting the boat thru the exhaust.

The new impeller comes with a lubricant that allows the pump to prime itself. If you bought a cheap impeller kit that didn't come with lube --- use dish soap, never grease or oil.

 

[jerryjerry05]

Someone covered it: Scott I think. The muffs and a 1/2in hole on the bottom of the drive.
The hole's a drain and if it's not blocked the pump won't ever prime.
I use the tube or tip from a tube of silicone.
Then duct tape the muffs in place.
The drive needs to be clean and dry.

The closed system needs to be cleaned out now to get the pieces of impeller.
They can end up in the sea water strainer or heat exchanger.
Best bet is to take it apart and try to back flush.

 

[joleda]

Is the water only supposed to come out the two rubber tubes coming out of the side of the drive?

 

[joleda]

Any suggestions for getting the steering knuckle tube out?