plugged 2QM20 manifold jacket

[Bob Clark]

Hi gang. I tried to drain the water from my 2QM20 yesterday. I live in Maine, and winter is coming! When I opened the drain plug on the exhaust manifold, no water came out. I removed the hose and poked up into the brass fitting, but no luck. I tried to unscrew the brass fitting from the bottom of the manifold, but couldn't. It hit the housing below the manifold before it unscrewed completely. Should I remove the manifold to clean it??? Do exhaust manifolds ever need replacing?Thanks!Bob Clark

 

[Bob England]

Pressure with caution

I changed my antifreeze yesterday on a 2GM20F with no problem. But I did find a lot of scum/sediment in the system. It required two flushes with fresh water to get it clean. If that is your problem, a little sediment may be blocking the valve. An idea you could try with caution -- and I take no responsibility for the consequences -- is to warm up the engine a bit, not to full operating temperature, and open the drain valve while the engine is warm and before you remove the pressure cap. A little pressure in the system might clear the blockage. I actually did this by accident, and I found that the fluid came out with a good gush!Good luck and don't get burned.Bob England

 

[Bob Clark]

tried it...

Bob, I tried your idea, using the garden hose to provide water to the water pump via the Vetus water strainer (a nice piece of equipment). Unfortunately it didn't flush out the crud from the exhaust manifold water jacket. However I have a raw water cooled engine, so probably the pressure doesn't get that high. I am beginning to think I will need to take the manifold off to clean it. Darn!

 

[Gordon Torresen]

Manifold drain

Exhaust manifolds somtimes need replacing, especially with sea water cooling. As to the drain on the manifold, these are usually the straight through, 1/4 turn petcock type. You should be able to open the valve and poke through to clear the blockage. As I recall, the arm being in line with the tube doesn't always mean it is open. You might try it at 90 degrees. It cold be that you could ream it out with a small, pliers rotated drill bit.  If the blockage remains, it may pay to remove the manifold to clean it.