Impeller repair

[Stevie.UK]

Hi all,

Took the the boat out for its first trip after winter and had a great day 8 hrs cruising and a nice lunch in a pub. (1992 2300 SCR)
Just as we were turning into our home mooring I noticed the temp gauge rising.
As we docked I checked the engine and it was hot to the touch and usually it's Luke warm.
I've arranged to get it out of the water next week on the slip to repair the water pump impeller and have sent for a repair kit and watched a few videos on you tube.
Firstly does anyone have any tips?
Secondly the kit doesn't seem to have a gasket for when you separate the lower leg with the pump in. Will I need one of these?
Also what gear oil should I use to refill the leg?

Thanks in advance

[mmwjr]

Title through me off as you are replacing the impeller not repairing it.

For lube use quicksilver high performance gear lube.

Not sure if you mean the gear lube gasket that seals the lower and upper lube passage, should be in the kit. Small round flat washer gasket.

Tips gear shift must be in forward to disassemble and assemble. The lower unit must be in forward when installing, applying slight pressure by turning the prop shaft just enough to ensure load is kept on the clutch to keep it in gear. Check that you can shift from forward to reverse with engine off before filling gear lube in case you need to separate the halfs to fix an improper install.

[Stevie.UK]

Hi Mike

I've sent for the quicksilver gear oil and squirty tube thing for filling the gearbox.
It's got all those seals in the kit but I was meaning for when you separate the lower unit from the top. Does this have a gasket?

[mmwjr]

Steve not sure what you are calling the lower unit.

There are mercruiser manuals under the Documents section of this site.

There is a gasket kit required for attaching the outdrive to the bell housing. You should not need this as you do not have to remove the entire drive.

There is a lube gasket that goes in the outer wall of the bottom half of the drive when mating it to the upper half, see manual. This gasket comes with the water pump kit.

[mmwjr]

Number 6 is the lube passage gasket I am talking about. Also do not forget to remove the trim zinc to access the rear bolt that screws in from below else you can crack the housing trying to separate it.

[Stevie.UK]

Thanks yet again wonder Mike.

I thought there might be a larger gasket that went around the edge of the lower unit but obviously not.

[Stevie.UK]

So I spent this afternoon replacing the impeller.
Got the bottom off the leg fine, got the old impeller out and it looked good as new but I changed it anyway and all the gaskets.
Re assembled everything
Because it's on the slip at our boat club they have a big barrel to put round the leg so I filled it way above the water intake.
Started her up great (using your routine Mike thanks again)
But after a few mins the temp started to rise Again and as the drum of water wasn't bubbling I assume it's not pumping water.
Sooooo what I'm thinking is there must be a blockage in a pipe or the engine itself?
Any thoughts? Or what to try next please I've only got the slip for the next 3 days so need it sorted ASAP.

[mmwjr]

Try removing the water hose coming from the transom assembly to the t-stat housing to see if water is coming out. This will isolate the issue and I can then provide direction from there.

[Stevie.UK]

Ok I'm pulling my hair out now and there's not much left.
I dropped the bottom on the leg again today and put a hose direct into the water I let tube inside the leg.
Water went in and round the engine and back out on either side of the transom.
So no blockages there.
I thought I might have put the impeller in the wrong way round so changed it and put it all back together but nope still not pumping?
I've only got the slip for 2 more days so it's getting urgent now.
Any ideas?

[mmwjr]

You may have a clogged inlet on the drive. Drop the lower unit again remove the water pump and try to pour water down the pumps intake passage to see if it comes out the drives intake holes on either side. There may be growth in there that needs to be cleaned out.

[mmwjr]

One other thing are you using the guide tube to ensure the upper coolant tube aligns with the water pump output?

[Stevie.UK]

Hi

Mike, yes I put the new seals in the guide tube and re fitted it.
When I took the boat out onto the slip there were a few fresh water mussels only small ones stuck to the out drive in the crevices.
After taking on the water input hose at the oil cooler and flushing it back towards the out drive I could see loads of little mussel shells inside the holes of the water intake. So I broke them all up with a tent peg (perfect size for poking in the holes) and flushed again and hey presto engine stayed cool.
Thanks for all your help

[mmwjr]

Originally Posted by Stevie.UK

Hi

Mike, yes I put the new seals in the guide tube and re fitted it.
When I took the boat out onto the slip there were a few fresh water mussels only small ones stuck to the out drive in the crevices.
After taking on the water input hose at the oil cooler and flushing it back towards the out drive I could see loads of little mussel shells inside the holes of the water intake. So I broke them all up with a tent peg (perfect size for poking in the holes) and flushed again and hey presto engine stayed cool.
Thanks for all your help

Glad you resolved the issue.