Engine Flush Valves

[swokrams]

Has anyone tried this?

-Steve

[HerbertFriedman]

flush valve

I installed a tee in the input hose to the water pump to flush out the salt water but not the setup you show. Could you explain what "man" and "BP" stand for and explain the diagram a little more?

[swokrams]

Herb,

Man and B.P. are markings on the thermostat cover. MAN = Manifold, B.P. = By Pass.

Under normal operation, the bottom valve is shut (top one open).

When flushing the engine, the top vavle is shut (bottom one open). This allows you to leave the thermostat in-place when power flushing, acid washing, etc. The thermostat is by-passed.

The housing is reversed to allow easier connections of hoses and valves.

Steve

[swokrams]

This new diagram may help. The red items are the only new additions to the regular set up of a late model engine. Water temperature sensors have been removed for simplicity.

If the valve is turned to take water from the temperature sensor port (a new route), then the thermostat exit is blocked and no water can flow through it. All water must go through the block and head and out the temperature sensor port.

Flush procedures usually call for the removal of the thermostat. This scheme would make thermostat removal unnecessary.

I welcome any and all criticism.

Steve

[Don Moyer]

Steve,

In this diagram it appears that you have the thermostat housing back in the normal configuration which it seems to me is a good thing, and the addition of the three-way valve is a nice convenience. You really have come up with a very convenient method for not only flushing, but pumping antifreeze through the engine during winterizing as well.

Congratulations!

Don

[HerbertFriedman]

engine flush valve

Great idea, especially the configuration pictured in your new diagram. I flush my (salt water cooled) A4 after each use but need to get the engine temperature up to where the thermostat opens to be sure fresh water floods the block, so this really helps. The hose from the thermostat to the manifold is short but I think sufficient to insert a three way valve. Question for you or the A4 maven, Don, exactly where is the temperature sensor port and what kind of fittings do I have to add to install the new hose?

[swokrams]

Don,
Thanks for the kudo's. Coming from you makes it especially nice.

Herb,
I haven't got a clue for the fitting sizes. In my first drawing I tired to fit in two T fittings for two temperature sensors - one for a gauge and one for an alarm. I just know it is tight.

Don,
Are you interested in putting together a kit for this?

Steve

[Don Moyer]

Mr. Friedman,

I'll bow to Steve on the issue of widgets since he's been there and done
that.

I would only add that if you end up rotating the thermostat housing, you
will have to make sure that the MAN side still connects to the manifold.
Notice that Steve connected the MAN outlet of the thermostat housing to the
manifold in his first diagram, even though the housing itself was rotated 180
degrees.

Don

[swokrams]

Actually I haven't done this yet. So far I am at the theoretical stage. When I was in school, the math textbooks would sometimes say, "The rest is left as an exercise for the student." Also know as, "The devil is in the details."

I don't know what size the fittings are. I am guessing that the thermostat housing is 3/8 inch, the temperature sensor port looks like 3/4 inch. Don't know what the exhaust manifold takes. Maybe Don can weigh in on these dimensions. Water hoses seem to be all 1/2 inch.

I am planning on using a cross (aka an "X") fitting off the temperature sensor port. This will provide one leg for the head, one leg for the hose, and two legs for temperature sensor devices (gauge and idiot alarm).

On the exhaust manifold, the elbow could turn forward. The 3-way valve could fit horizontally with an elbow pointing down on the outside to connect with the thermostat port down-leg of the cross fitting.

This might allow the thermostat to stay in its normal orientation by giving some room for the hose connection. I don't want to rotate the thermostat unless I have to.

Steve

[swokrams]

I know I must have too much time on my hands to keep thinking about this, but here is another idea.

Here is a fresh water cooling system with a twist. How about using an electric pump to circulate the engine coolant, and use the engine pump to feed the heat exchanger with sea water?

This has the convenience of mounting the elctric pump wherever would be good for access and maitenance. Plus, the heat exchanger pump (the one on the engine) runs with the RPM of the engine and keeps the proper flow of water to the exhaust.

Steve

[Don Moyer]

Steve,

This suggestion surfaces every 4 or 5 years and never quite makes it through
the R & D process. Downsides include reliance on electrical power and the
need for a control circuit to have the pump come on only when the engine is
running to avoid flooding back through the manifold. There is also the
issue of electric pumps having a constant flow rate instead of attenuating
as engine RPM reduces and increasing as RPM increases.

Don

[swokrams]

Hello Don,

I think you misunderstood. I planned to use the existing accessory drive engine pump to feed the heat exchanger and riser (according to engine rpm) and to use the electric pump to pump the anit-freeze coolant through the engine.

On the research side, I can't find an electric pump that will take the high temperature of engine coolant. Rats!

One could use the fresh water kit and connect the PTO pump to an electric motor instead of the engine. But this is a long way to go just to avoid the cramped space situation on my boat. This route would involve more than just mounting an integrated electric motor/pump with only four mounting screws to worry about.

Steve

[HerbertFriedman]

engine flush valves

I like the last iteration on the fittings and since I flush the engine every time I run the engine, I like the convenience and assurance that all my fresh water flush goes through the block. But is it difficult to remove the 3/4" temp sensor fitting. I have heard that these tend to break off and then you have a mess getting the threads out. Does PB blaster and tapping usually work here or am I facing a real hardship?

[swokrams]

Herbert, I hope you are wrong about this. I am planning to replace the manifold elbow as well. If there are problems with the temperature sensor port, what must the manifold port be like?

BTW, I am "assuming" that the temperature seonsor port is 3/4 inch but I don't know for sure. Also, I am "assuming" that the manifold coolant input port is 1/2 inch. The information I have is from drawings. I haven't actually looked at these yet in person. The thermostat and water pump connections are all 3/8 NPT to 1/2 inch hose barb fittings (I think).

Don, can you verify these port sizes for us? Thanks in advance.

Steve

[Jesse Delanoy]

It's just my opinion, but I think this issue is getting way more attention than it deserves.