1978 55HP Water Pump / Impeller Flow

[hotsnarby]

Hi,

I am a little worried about my water pump etc on new purchase.

Please note that I have never had a boat nor worked on any outboard before.

I just purchased a cheap runabout with a 55HP Evinrude outboard - similar to the Johnson Seahorse I believe.

It runs great and initially (around a beach) there was a constant stream of water spurting from the [special name] hole out the back. Later that day in brackish water I noticed that the water stream had somewhat diminished to a random trickle.

I have dropped the lower unit and removed the water pump and impeller.

My problem is that I am not sure exactly what the problem is and / or what to replace here. The thing is that the impeller does not look offensive, though I have no reference point as this is the only impeller I have seen. There is some sand around that I guess has accelerated the wear. The local boat dealer said he would reuse the impeller and was surprised when I wanted all new seals. My experience with high-performance motorbikes has been to replace critical gaskets and seals.

So here are my specific questions:
- Should I be looking for somethings else - like temporary blockages rather than focusing on the impeller
- Where would the thermostat be if I had one
- What seals should I replace
- What are the critical seals - it just amazes me how minimalist the seals are, especially the single small o-ring at the top of the drive shaft
- Should there be a gasket or goo between the lower unit and the main outboard or is it ok for water to seep in as the critical areas area sealed
- Is the flimsy seal on what looks like an exhaust port effective or does this not really matter since water will get both sides of the seal anyway

If I am way off please let me know.

Thanks,

 

[durban]

Re: 1978 55HP Water Pump / Impeller Flow

IF you start from the bottom & work your way up , the first thing i heck for if seals & impeller are good ,like in your case .. then the next step is check the little breather hole in the top half of the pump cup , if its blocked , its the same as putting a bottle upside down into a bucket of water , the water will not go into the bottle k , but if u make a little hole in the top of the bottle { the base k , cause its upside down} THE WATER WILL COME INTO THE BOTTLE < the same thing applies to the water pump k > if the hole is blocked the water will not go in < < cheers

 

[hotsnarby]

Re: 1978 55HP Water Pump / Impeller Flow

Hey thanks mate. I will have a look when it is light. In the meantime I have worked out how to get to the thermostat - a real pain to get to IMHO - and it was all clogged up with crap. It would be nice it this was easier to get to and I could reverse fluch the sand from time to time. Anyway, I cleaned it off and it tested out ok on the boil i.e. it opened when it got hot and shut when I coolled it down. I know that is relatively inconsequential as I have ascertained by now that the **** hole sperts water regardless of what the thermostat is doing. It also seems to me that the tiny o-ring at the top of the drive shaft is only protecting agaist splash as that tube is not preasurised with leaking water from the pump.

 

[Haffiman]

Re: 1978 55HP Water Pump / Impeller Flow

If you do not know the age of the impeller, newer than 3 years, Change it!
Then hook a water hose to the water tube and slowly apply pressure. If too much pressure is needed before water starts trickling out (down inside the leg), you may be in for some more serious tear down. If sand only, you may be able to flush it out - if lucky!

 

[hotsnarby]

Re: 1978 55HP Water Pump / Impeller Flow

Just to close this off, I checked the hole and it was fine, I managed to dissasemble everything fine, found the thermostat etc. Replaced impeller, thermostat and every seal and or gasket I touched. Worked perfectly for three days and ran like a dream - including me single skiing behind it! ...till I stuffed the gearbox - see next thread.