Mercruiser 5.0 MPI thermastat location and removal of fuel cooler drain plug

b4tn

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The manual says to remove the six drain plugs for winterization. I have found all the plugs but the fuel cooler drain plug down near the oil pan on the port side is impossible to get to. I did drain a good amount of water from all the other plugs. Is that plug necessary to remove for winter draining? Also the manual says to fill the engine with antifreeze. I cant find the thermostat to pour in antifreeze. Is there another location on top the motor I can pour it in? Thanks... Painfully learning as I go.
 

Scott Danforth

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thermostat housing is in the same location on all V-motors. up on top of the intake manifold, in front of the motor, between the cylinders.

Hint - the thermostat housing has a bunch of hoses connected to it.

regarding the fuel cooler, yes, you need to drain it.

you are using the factory manual correct? and not a Haynes/Chilton/Seloc knee pad, correct?
 

alldodge

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The manual says to remove the six drain plugs for winterization. I have found all the plugs but the fuel cooler drain plug down near the oil pan on the port side is impossible to get to. I did drain a good amount of water from all the other plugs. Is that plug necessary to remove for winter draining?

Yes it needs to be drained, and stick a wire or long screw up inside the holes to make sure they are clear.

Also the manual says to fill the engine with antifreeze. I cant find the thermostat to pour in antifreeze. Is there another location on top the motor I can pour it in? Thanks... Painfully learning as I go.

Its on top the motor and has all the hoses going in and out of. You don't remove the thermostat, you remove a hose
 

b4tn

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Thanks, I will try and figure out a way to get to that drain plug, my hand does not fit in the space. I might see if I have some extra long needle nose plyers or something.

​I am using the factory manual. It says once the plugs are removed replace then and fill with antifreeze. I didn't think to just remove one of the large hoses. Does it matter which one?
 

alldodge

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Thanks, I will try and figure out a way to get to that drain plug, my hand does not fit in the space. I might see if I have some extra long needle nose plyers or something.

Follow the hose coming from the cooler and remove the hose clamp at the cooler, or remove it from the thermostat. If hose is removed from the thermostat lower the entire length of the hose down into the bilge so water can drain out of it. If you get it low enough then your doing the same thing as removing the plug
 

alldodge

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​I am using the factory manual. It says once the plugs are removed replace then and fill with antifreeze. I didn't think to just remove one of the large hoses. Does it matter which one?

Use the large circulating water pump hose (item 5) and fill from the top of the hose.
http://www.mercruiserparts.com/bam/s...31849/8093/210

You can also remove the hoses going to the manifolds and fill them

BTW you do have raw water cooling and not a heat exchanged (closed cooling)?
Serial numbers are best
 
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QBhoy

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You sure you have the right manual ? Most of not all Merc 5.0 mpi came with the single point drain system. Ok, some will have the system removed for safety, but the manual should not suggest that.
If it’s like my 5.0mpi and does have the single point drain (blue coloured handle down towards the right of thermostat looking aft) you need to open that, remove the only blue drain plug (normally) on the right of the thermostat to vent...and watch it drain out down below the belt and bottom front of engine.
Then I always take off the quick connect fittings around the single point drain network (on each side of the block and manifolds etc) just to make sure. The single poInt drain system has a habit of clogging up, especially if the engine is left without antifreeze in it over winters or the user has operated the boat on shallow sandy water.
I then remove the big hose on the left of the thermo stat and fill with antifreeze until it comes back out the thermostat housing hole it was attached to. Now you know the block is full.
Then I take off each hose attached to the manifolds and fill with anti freeze.
Finally I take off the thin inlet hose to the thermostat on right hand side (suction pipe from leg if Alpha) and pour antifreeze down that until it comes out the drive.

Good to go !
 
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