Mercruiser Winterizing issue

[bigdogg1]

Looking for your thoughts or suggestions on this issue - I have a small block mercruiser that has developed a very slow leak at the bottom engine drain plug - one of the little blue ones. The boat is a 2-3 months fresh water only lake boat and the drip is so slow (1 drop per 10 seconds) that it doesn't impact the cooling while operating whatsover.

I have replaced the plug, wrapped tape around the plug and even tried Marine-Tex by coating the inner threads and screwing the plug in and out to see if the threads could improved. Haven't tried White Stuff yet - maight be the next step.

My question is around winterizing. I go all in by warming the engine, running antifreeze through ,etc. The engine block is then set up with a Pali Engine compartment heater.

This past Spring, when I cracked the plug to drain the AF, it was completely dry - nothing came out.

So, what are your thoughts:

1. Do I continue to pump AF in and know it will eventually leak out over the winter?

2. Do I open all plugs and hoses, blow out with a compressor and leave it open for the winter (rust issue in the block is my concern here)?

3. Is there another way to repair the threads that I am missing?

Thanks

 

[ship happens]

I'm pretty sure those little blue plugs seal with an oring. Just replace the plug or the oring. Avoid putting anything on the internal threads. Could put something on the oring to make it happy, like grease or possibly pipe sealant. Something that will not harden completely. Those little plugs fail all the time.

 

[bigdogg1]

Is there room chase the threads with the same size tap and if that doesn't work tap a bigger size?

Thought about tapping but worried I would open up Pandora's Box. Feels like that would be the same as changing a vanity and doing a whole bathroom renovation somehow!

 

[bigdogg1]

I'm pretty sure those little blue plugs seal with an oring. Just replace the plug or the oring. Avoid putting anything on the internal threads. Could put something on the oring to make it happy, like grease or possibly pipe sealant. Something that will not harden completely. Those little plugs fail all the time.

This will go on this weekend. Will post update

White Stuff

Part No. Size Case Weight 400-001 2 oz. tube 72 11 400-002 4 oz. can 24 13 400-003 8 oz. can 24 20 400-004 16 oz. can 12 22 4000-005 32 oz. can 12 39 NSF Certified NSF 14 (PW, DWV, SW) NSF 61 (C.HOT 180°F) NSF 372

www.jomarvalve.com

 

[ab1752]

Dont torque it down right away let the junk set up a bit first for say 20 mins then snug it up.

 

[noluck]

if it does not have closed cooling, then pull all the blur plugs, then i use a short piece of coat hanger and push into the holes to make sure they are not plugged and drain properly, as ship said there should be a o-ring on the plug

 

[Sir Reel]

You can buy new plugs on Amazon and yes they do have an O ring.
I'd start with a new plug and O-ring

 

[Max123]

Curious - I've always just fully drained my fresh water cooling system (5.7 Indmar V8). Easy, just disconnect all the coolant hoses, and then there are two drain plugs at the bottom of the block (one of the plugs is a knock sensor). What's the advantage of the RV Antifreeze? Are some blocks designed in such a way that they don't fully drain?

 

[Sir Reel]

You can just run RV antifreeze through and not remove any plugs. However I actually do both just to make sure no pure water is present in the cooling system.
I believe the RV anti freeze has some anti corrosion properties too

 

[Coyote Spooner]

Is the blue plug on this housing? If so they’re known to crack and leak.

 

[bigdogg1]

Timely response by CS. After removing and draining that housing, I cleaned the dickens out of it in and out. It still leaked. I took an inspection mirror to the underside and sure enough, there is a small hairline crack along the underside. Slathered JB Weld, let it set and seems to have worked!

 

[bigdogg1]

BTW, the reason to drain then refill with AF is for rust/corrosion protection - advised by many smarter than me that take these things apart to do this.

 

[Coyote Spooner]

These housing are know for this and they’re expensive. I’m a member of this FB group. Lots of good info and help on there. I haven’t done this work around myself, but looks like it would work. You’d just loose that drain point. Depending on your cooling system and how you winterize, it may not matter?

 

[bigdogg1]

hmmm - that looks really interesting! Motor is drained and lines are blown so should be good until I return from NZ. Thanks for this

 

[Squire]

Timely response by CS. After removing and draining that housing, I cleaned the dickens out of it in and out. It still leaked. I took an inspection mirror to the underside and sure enough, there is a small hairline crack along the underside. Slathered JB Weld, let it set and seems to have worked!

I had to buy two new water distribution housings for a 350 MAG MPI at over $300 a pop when I had my lake boat. Just replacing the plug finger tight cracked the housing along the seam on the bottom which runs right through the drain plug opening. Around that time I discovered that new blue plugs could come with different sized o-rings. Because the plugs had tapered threads, the thinner o-rings wouldn’t start to seal until after the threads had expanded and cracked the housing. After the second cracked housing I just made sure I changed out the o-ring if it came with the thinner one.
Because of the poor design with the seam I looked in to it a bit and discovered the housing is “vibration welded” which obviously doesn’t take much force to separate. I would have done a similar work around to that posted above if it had happened to me again.