[jaredreed496]

An alternative or belt and suspenders method is to fill the engine with non-toxic antifreeze . This also helps minimize corrosion of the inside of the water jackets. We like to drain the engine regardless as this minimizes dilution of the antifreeze you are going to add and eliminates the need to have the engine running. Once the engine is drained and the plugs are replaced find the hose that comes from the sea water pump (or from the sterndrive if you have an Alpha). Disconnect the hose from the thermostat housing and connect a piece of hose (usually 1 ¼ inch id) to the thermostat housing. It should be long enough so you can put a funnel in the other end and be higher than the highest point on your engine. Slowly pour non-toxic antifreeze into the funnel until antifreeze starts coming out of the exhaust. This is going to take about 2 gallons, maybe more.

[pharaon]

Loosen or remove the plugs (depends on type of fitting). You need to check and make sure water actually comes out. It is common for the opening to be plugged with sand or corrosion. Remove the plug completely and use a short piece of wire to clear out if needed. If you are going to add antifreeze (see next paragraph) replace the plugs at this time. If not put them someplace safe and install in the spring. [links]

[qqi456]

There are a number of different ways to accomplish this. Some Mercruiser engines have an “Easy Drain” system. It is best if you consult your owner’s manual for instructions specific to your engine in this case.

[JustGamerS]

If you have conventional drain plugs the process is straight forward. There are plugs in the following locations –

[T_X]

PLEASE NOTE – this will do nothing for the oil, power steering cooler, etc – they must still be drained. As most impellers will swell from the antifreeze this will leave your impeller out of the circuit even though it should be changed in the spring. If you are not concerned about the impeller replace the drain plugs in your coolers. Put your funnel in the hose that you took off the T stat housing and slowly fill with antifreeze allowing trapped air to exit.

[distant]

[earllmoran344]

I went back out to the boat, got a light a really looked at the tubing etc for the water cooling. I found out the the intake water first goes into a tube that splits off into two other pipes leading to the what I think is the trasnission. It then goes out a third tube that leads to a water pump, which is brass and appears to be brabd new. From there, a hose goes to the top of the engine to a snall housing that has two hoses, that go to each side of the engine and connect to the front of the exhaust manifolds.
I think there is another hose coming off the pump that goes to, what looks like another pump that is on the front center of the block, which looks like a smaller version of the water pump on a regular car engine. I am not sure what this is or does? [links]

[Cyberdog]

Rare : Mercruiser-V8 Fresh-Water-Cooled, Fresh-Water-Through-Manifolds Water-Flow-Diagram :

[MYurong20]

Post by larglo » Tue Nov 09, 2010 1:00 pm [links]

[DALDEI]

Post by rossjo » Sat Nov 06, 2010 10:37 am

[nixoid]

rossjo, the web address did not work for me for the flow diagrams.
Jamie, do you know where I can get part numbers for the impeller, etc for the 318 engine. [links]

[oadriannadeleong]

This forum is for comments and the exchange of information relating to Trojan Boats and boating. Please do not post used parts or boats For Sale in this area. For general, non-boating topics please use our "General Discussions" section.

[jeriellsworth]

COLD MANIFOLD SYSTEM
Typical Cold Manifold Flow Diagram

[The Eternal Coin]

Warm versus cold marine exhaust manifolds refers to the temperature of the cooling water that is introduced into the exhaust manifolds on a marine cooling system. This specific system feature can apply to raw water (also known as open cooling) systems as well as Fresh Water (also known as closed cooling) systems. For the purpose of this article we will be primarily detailing the raw water cooling systems. To read more about 1/2 versus full closed cooling systems, select this link.

[hughbarnard]

In a cold manifold system the warm water that flows through the thermostat, as well as this excess bypass water are joined together in the thermostat before exiting and being introduced into the bottom of the exhaust manifold. The fact that your are mixing together a lesser amount of 160 degree F engine water (8 GPM) with 10+ GPM of cold lake water allows the aggregate coolant temperature in the manifold to fall below the 110 degree F threshold needed to prevent the accumulation of condensation in the exhaust system. Notice in the picture below that there are only (4) hose bibs as these systems are typically identified by this fact.

[cstacynicholsonj]

The standard raw water cooling system operates via a pressure balance. The easiest way to think about these systems is that you have a circuit of coolant being circulated through the engine via the engine circulating pump. There is also a supply pump that introduces cooling water into this circulation loop, depending on the position of the thermostat and amount of coolant being allowed to exit the system. For example the circulating pump on a standard small V8 GM based engine will flow approximately 50 gpm through the engine. The typical raw water supply pump inside the Alpha sterndrive is capable of flowing about 18 – 20 gpm depending on the gear ratio and restriction the system experiences. A standard 300 Hp small V8 engine dissipates approximately 300,000 Btu/Hr of heat into the coolant. To maintain a thermostat temperature of 160 degree F at wide open throttle this engine would need a pump to flow about 8 gallons per minute (GPM) of 70 degree F water into the system to maintain this engine temperature. Since the Alpha raw water pump can flow 18-20 GPM there is significant bypass (excess) water supplied, which therefore has to be dis-charged somewhere. here

[atonmack87]

In a warm manifold system the warm water coming out of the engine and through the thermostat is the only coolant that actually passes through the exhaust manifolds before passing through the manifold riser gasket joint and mixing with the cold bypass water that is being introduced into the riser. The fact that your mixing point for the coolant is above the manifolds allows the temperature to be maintained above 110 degrees F and therefore prevents the accumulation of condensation in the exhaust system. Notice in the picture below that there are (6) hose bibs as these systems are typically identified by this fact. NOTE: The thermostat cover is not shown but actually contains the additional (2) hose bibs.

[BlueAchenar]

[kaja]

I also noticed some antifreeze leaked onto the block in an area that has no hoses so I have no idea were that leak is coming from. here

[blurden]

Re: How many hours can a raw cooled engine block last - mercruiser 3.0 liter here

[AStephen2011]

I'm gonna guess that at about 800-900 hours (8-10 more years), I will want a new long block

[ronaldmaustin]

I also noticed some antifreeze leaked onto the block in an area that has no hoses so I have no idea were that leak is coming from.

[painge]

Ayuh. Welcome Aboard. Generally speakin', they last til the 1st winter it ain't drained.