Broken Thermostat Vent

[jbourne210]

Firstly, Merry Christmas and Happy Near Years to all!

So, it's finally gonna dip below freezing this weekend, so I decided to winterize the boat. I've never owned the boat during a winter, but had noticed that the little blue plug that you use to vent the thermostat house during a single point winterizing looked a bit dry and brittle, and the 'ears' had been broken off by someone else previously. Tried GENTLY to work the plug out, and yeah, it snapped off. Anyway, I tried working the plug out by every known means. Hot screw drivers, easy out, you name it. Decided to pull the housing along the way to gain better access, but to no avail. Most of the material is gone, but the threads are still gummed up with very hard, brittle blue stuff from the plug. I'm thinking I'll need to rethread the housing, and just put a metal plug in. Might as well change out the thermostat while I'm at it. Who knows how long it's been in there.

My other thought is to wait until the local dealership opens, grab a new plug, match the thread, and just clean it out the existing threads.

Of course, unless somebody has a better idea??? lol

Also, at this point, since the entire thermostat housing is off, can I just turn the blue knob on top, and ensure the fluid drains out of the bottom? My tiny brain tells me that should be sufficient, but this is my first go at winterizing a single point system.

Oh, and it's a 2007 4.3 mpi, with single point draining.

Thanks in advance y'all!

 

[Maclin]

As I understand this system, your engine is now in the same basic state as if the blue plug had been removed. When you open the large blue handle watch the bottom orange drain hose, make sure a LOT of water comes out. Should take almost a minute to complete, with solid water flow for the first 30 seconds or more.

The only way to be more sure than that is to remove all the single points "stuff" from the exhaust manifold and engine block drain plug holes, drain then replace with brass plugs for next time.

 

[jbourne210]

Roger that, thanks Maclin. That was my thinking as well.

I opened the valve, and everything drained as it should. I was actually surprised at how much water actually came out...

 

[achris]

As Maclin said, the better way (and the only way to guarantee) you get all the water out is to remove the hoses from the bottom of the manifolds and the engine block. You'll also need to poke those holes with a small screwdriver or a stiff length of wire to remove any crud that might be blocking them up. Also remove the water hose from the power steering cooler (at the back of the engine) and get all the water out of that, or you'll be putting a new oil cooler in come spring.

Also, that blue plug is not a vent. It's to 'plug' the hole left when that port of the housing is not used, like when the inlet water goes into the large circulation pump inlet hose, like when they use a 'single point block cracking system'... If you want to remove a plug to drain the thermostat housing, try the one on the very top.


The blue plug ('O' ring included) part number is 22-806608A02. The thread is 1/2" UNC (13tpi). And it was high strength Locitited in, which is why you couldn't get it out. You can't use any old plug either. It's not a tapered thread, so without the flange wouldn't seal. Need the Merc plug


Chris.........

 

[Fun Times]

Hey Chris, just to let you know jbourne210 is talking about item #13 in your diagram which goes to the port side of the T housing which is considered a vent to the cooling system for better draining. Item # 2 is the plug for T type fitting for certain models.

The threads for the blue plug are (.500-13) Royal Blue Plug Kit. 22-8M0119211