4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

alandchris

Petty Officer 2nd Class
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Dec 25, 2007
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I probably should wait til I get home to read my manual before posting these questions.... but....

1) On the left side of my engine i have a flush connection, I remember the sales person telling me you connect a normal garden water hose to it and run the engine for a few minutes to clean out the salt water. Another guy at this boat place says he thinks you don't run the engine while flushing it. This is with the boat out of the water. What's the right answer ?

2) On the bottom of my fuel pump, there is a small diameter hose that goes up to the thermostat housing. Or at least I think it's the thermostat housing. Is that supposed to be for the fuel pump cooler ?

3) PS. I read all the posts of how not to use the 'muffs' with antifreeze etc, how the t-stat won't open anyway etc.... But after questioning my service department about something else, we got into a discussion on how his place puts the outdrive into a large container holding antifreeze and runs the boat (probably after draining out the water first) - and I said the manual states to just open up the blue plastic drains on the block and manifolds, the raw water and circulatin pumps and also the hose on the fuel pump. His argument is that's not enough because tiny amounts of water would still be left in the motor (where?) and draining just wasn't enough.

Your thoughts on the above 3 q's ?
 
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CaptainKickback

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Re: 4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

For question 1: i had twin merc 5.0s and bought a flush kit for each. It had one hose for connecting the garden hose. This went to a brass block that had 4 outputs (there were 4 places to connect to on the block, manifolds, etc).

Anyway, instructions said flush with engines OFF. If you ran the engines, the pumps in the drives would just keep bringing in raw water. BTW, this setup worked great.
 

Don S

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Re: 4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

1. On your Volvo (NOT Mercruiser) you have to run the engine, the flush hose attaches before the engine mounted raw water pump. Without the engine running, the water from your hose would not force past the raw water pump impeller, just run out the drive.

2. Yes, it's for the fuel cooler and needs to be drained.

3. "His argument is that's not enough because tiny amounts of water would still be left in the motor (where?) and draining just wasn't enough."


The guy you was talking to doesn't understand how ice breaks things. There has to be enough water in the system that it has no place to expand to break anything. If the block had a 1/4" of water laying in it, it would expand up and not break anything.
If you have the engine level (within reason) and you remove the plugs, and the drain hole is not plugged, there is no way in the world there could be enough water in it to break anything.
 

alandchris

Petty Officer 2nd Class
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Dec 25, 2007
Messages
106
Re: 4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

1. On your Volvo (NOT Mercruiser) you have to run the engine, the flush hose attaches before the engine mounted raw water pump. Without the engine running, the water from your hose would not force past the raw water pump impeller, just run out the drive.

OK, So the answer is RUN the engine with the hose attached. Thats what I thought...
Now, going back to the sticky regarding using muffs etc and the fact that the t-stat wouldn't open up anyway argument.... - is it also true that the t-stat would not open up with the hose attachement either while running - and if so - really my question is - how effective is flushing the motor anyway - or does the t-stat open just enough to get clean water into it....
 

bruceb58

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Mar 5, 2006
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30,591
Re: 4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

If you run your motor on muffs after you run in salt water, the thermostat definitely opens up to allow the water to circulate in the block. You just have to make sure you run it long enough so that it gets up to temperature.

If your question is regarding using the muffs to suck up antifreeze, all bets are off so just drain your block.
 

Don S

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Re: 4.3 VP GXi-J - engine flush and fuel pump hose question and antifreeze

If you boat in salt, brackish, or really muddy/dirty water, flushing is a good thing. But you also have to let it run for 10 minutes or usually more for the simple fact that even if the thermostat opens, only a small amount of water is going to be exchanged at idle because the incoming water is cold and tends to keep the stat closed until the water in the engine is hot.
If you boat in normal lake water, flushing doesn't do much. What would you be flushing out??????
 
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