4.5 MPI Mercruiser Single Point Drain Leaking

[77vetter]

I just winterized my 2005 200 sport for the first time (just bought it this spring) I ran the boat till temp came up to 170 and then drained the system. I opened the valve and removed the vent plug from the thermostat and let it drain for 30 minutes. I then thought I would remove the blue plug from where the water was draining from the hose just in case there was any additional water there. I let it drip till it stoped and then put the both plugs in and tighted the drain valve.

Then i started it up and ran 5 gallons of anti-freeze throught it and shut it off. thats when i noticed a small drip from the bottom plug. Wasnt sure what to do so i tightened the main valve a little more with no luck. It was dripping about one drip every couple of seconds. So I thought maybe some plumbers tape would help so took the bottom plug back out and had my wife wrap some plumbers tape around the plug while i plugged the hole with my finger and then re-inserted the bottom plug. Still no luck, if I pull the red drainage hose forward it appears thats where the water is coming from as then it appears not to leak from the plug, but if I let the hose go back then it appears to leak from the plug so not sure where its really coming from but somewhere in the housing or the plug im guessing.

Can i tighten the main single point valve too much? I tried to be carefull not to tighten too much but couldnt get the dripping to stop. It wasnt leaking prior opening the system and adding the anti-freeze i am certain of that.

Not sure what to do to stop the dripping, I am assuming it wont be an issue over the winter if the anti-freeze leaks out but will for sure need to address before spring but would like to get it fixed this fall if possible. Any ideas what is going on?

TIA

 

[Lazy Daze]

Is the o-ring still on the blue plug? It's also possible the housing is cracked.

FYI, running the engine up to temp then letting it sit for 30 minutes defeats the purpose. Either way, without removing the t-stat you can still have some trapped water in the upper part of the engine. Plus, the small hoses that drain the block/manifolds sometimes get clogged and don't allow all the water to drain.

If you want to be 100% sure there's no trapped water, drain it fully by also removing the small hoses from the block and manifold and poking the holes to make sure all water comes out. It's not all that hard to do and you have pretty good access in your boat. Then, backfill the system through the hoses on the t-stat housing.

 

[Espos4]

That water distribution housing tends to crack on the bottom along the threads of the drain plug.