4.3 MPI Drain Question

[SteveRay]

Getting a newer boat with a 4.3MPI Merc and it looks like it has the single point drain system.....how do I verify that I have it and also is that all I need to do to ensure that the block won't crack?
I have winterized my previous boats removed the drive, changed gear lube, etc....Just worried about the block on this newer set-up

 

[Don S]

Re: 4.3 MPI Drain Question

Even if you actually do have the single point drain system, the real problem with the system is that you CAN NOT verify that everything is drained.
Those systems, IMO, are dangerous. And WILL cost someone an engine as the system gets older.

 

[SteveRay]

Re: 4.3 MPI Drain Question

Don,
Would you recommend draining and then filling with the non toxic antifreeze then?
I effectively winterized my '92 3.0L previously but this is a different block and seems a little more indepth.......even though the goal is the same.

How is everyone else doing it?

 

[dvan1901]

Re: 4.3 MPI Drain Question

SteveRay; I have the 5.0 MPI that has a the 3 point drain, but the manual (have you read it?) has all drain systems in it. In the manual it recommends that you drain it and then "for further protection" it recommends that you pour antifreeze through the thermostat housing. Also, if you look at the cooling system diagram you will see that the manifolds and everything drain back into that single point system.

 

[Don S]

Re: 4.3 MPI Drain Question

If the water doesn't drain out properly, you can put all the antifreeze in there you want, but where the water is, it will freeze and break. You MUST drain the block, manifolds, coolers, hoses etc. so they are empty. At that point nothing will freeze and break. If you want to add AF for corrosion protection fine, but you have to get the water out first.
If I was to purchase a boat with a single or multi point drain system on a raw water cooled engine, the first thing I would do is remove those systems and put plugs in each place. Then you can remove the plugs and use a wire to probe the block and manifold to make sure there isn't any dirt plugging the holes........ Which happens to be a very common problem on raw water cooled boats.

 

[SteveRay]

Re: 4.3 MPI Drain Question

So is there a sure fire way to check if all the water is out?

How many plugs would there be to drain, not including hoses, if the "single point" system wasn't there?

Would it be a safe assumption to follow all the drains back to the engine?

 

[Bt Doctur]

Re: 4.3 MPI Drain Question

2 block drains, one on each side
manifolds/risers one in the manifolds on the very bottom ot just pull the hose to drain
riser one , unless they drain back thru the manifolds
power steering cooler ,if equipped
raw water side of heat exchanger, if equipped

 

[SteveRay]

Re: 4.3 MPI Drain Question

Does anyone have the link to the Mercruiser Manual?

It's an '05 4.3MPI - Alpha

Thanks guys

 

[dvan1901]

Re: 4.3 MPI Drain Question

Does anyone have the link to the Mercruiser Manual?

It's an '05 4.3MPI - Alpha

Thanks guys

http://www-alt.mercurymarine.com/mnetdata/sisdata/srvcovr.pdf

 

[SteveRay]

Re: 4.3 MPI Drain Question

Nice!