Cooling system blockage?

[monkeystealer]

1971 evinrude 50 (50173s).

Pulled the lower unit off to replace the impeller. While it was off, thought I should check that the cooling system is clear. (This motor hasn't run for 10 years according to the guy I got it from) I attached a hose to the water tube, but it seems like there's a blockage as the pressure just builds up until the hose pops off.
Is there any way to back flush this outboard? I suppose I could poke a hose into the themostat housing but do I need to pull the head off to get to it?
Btw, before anyone suggests binning the motor, I had it running the other day (only ran for a few seconds as I wasn't confident that the water pump would be working).

Thanks

 

[tashasdaddy]

Re: Cooling system blockage?

you probably have had critters living in the cooling system, they love it. take the pee tube off at the block, and clear it., try again. you only going to get the taletell pee until the thremostat opens. while off replace the impeller. it's hard and i will guarantee it will fail. here's 3 links for you. thermostat is #12 in diagram

http://i46.photobucket.com/albums/f119/tashasdaddy/7150hprude.jpg

excellant info

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1035575

http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=28;gtid=818798;gpid=818802

 

[monkeystealer]

Re: Cooling system blockage?

update:

It looks like the thermostat was the cause. Took the cover off, and the 'stat fell apart. Put the cover back on, and the water ran through fine.
While I was taking things apart, I thought it best to have a looky under the exhaust cover. Found a rubber grommet or part of a seal in there. I guess its from where the water tube connects to the powerhead ( theres a bit of a leak from that area). Probably wasn't helping the water flow either.
Now I've just got to replace that seal.

The fun just never ends...

 

[monkeystealer]

Re: Cooling system blockage?

Do I need to pull the powerhead off in order to replace the water tube seal or can I get to it through the leg?