How many drain plugs are on a 4.3 liter inboard motor?

Question

How many drain plugs are there and where are they located on a 4.3 liter inboard outboard motor with a mercruiser stern drive. I believe the motor is a GM. What is the best way to put the RV antifreeze back into the engine block. If done with muffs and running the motor, does this wet the impeller enough to not damage it from running dry. How much antifreeze should fit in the motor?

Answer 1

If this engine draws water from the Lake it probably doesn't have a heat exchanger. I have one and always put antifreeze in the block after taking the plugs out. Mine actually has 4 drain valves on the engine and 2 on the exhaust manifolds. I make sure I have anti freeze in the block, manifolds and out drive. We had one we drained and it froze and cracked the block. That is expensive. If you live in the south you might get away with it but i wouldn't take a chance.

Answer 2

you have 5 plugs all of them are blue and they are located 1 in the very front and two on either side near the middle of the engine.  the ones on the side will probably be hard to spot the first time but after that it is just a matter of remembering where they are.

If you leave the plugs out there is no need for antifreeze but you still want to stabilize your fuel system properly. And fog the cylinders properly.

And make sure you trim your out drive all the way down to the ground to keep moisture from collecting there.

lastly remember to unhook all your batteries even the battery for the trolling motor if you have a fish and ski

Answer 3

5.0 and 5.7L blocks take almost 4 gallons of coolant. Your owners manual should have one. You should really invest in a mercruiser sterndrive manual, it tells you all of the specs for the engine: spark plugs, spark plug gap specs, engine coolant, oil capacity, compression ratios, horsepower, lower unit fill capacity, and much more, AND they tell you where the drain plugs are.

On mine, and probably yours too, there are two main petcock valves, one on each side of the block. They directly in the center of the block, but on each side. On mine, you have to reach down underneath the exhaust manifold, and you will see a small petcock valve. You also have drain plugs under the exhaust risers, but I don't drain those since I run coolant throught the system. But, you definitely want to drain water out of the block before you flush with antifreeze.

Answer 4

Do you have a "Fresh water system" or "Raw water"

A fresh water system has anti-freeze in the block with a heat exchanger that has the sea water pumped thought it to cool the engine water.  That system is enclosed and has a radiator looking cap on top of it and is filled like a car.

If you have a raw water pump, the water that cools the engine is pumped up from the sea (or lake) and goes though the engine directly, there is no anti-freeze in the system.

To put anti-freeze in the system for a fresh water cooled engine, you need to put the "Muffs" on the outdrive with water going to it before starting the engine.  

Fill the heat exchanger with the proper anti-freeze mix as stated on the jug. When it is full, start the engine and keep filling the heat exhanger until it is full, the normal engine water pump will fill the engine block as it runs.  The water coming in from the "Muffs" will fill the sea water side and keep the impeller wet so it won't burn up.

If you are winterizing either system, just add anti-freeze in though the "Muff's", with an supply of RV anti-freeze so you won't get in trouble spilling it on the ground.  Run it though the engine until the "Red" RV anti-freeze comes out the exhaust.  Do the same for both types of cooling systems and you will be set for the winter.

Answer 5

most have a bolt (1/2 inch head on the left side of the block between freeze plug 2 and 3. that was old school ones.. The motor will fit 1.6 gallons of af. pure AF fill in the block will protect it thru the winter.