changing coolant

rasbury

I have had my boat for about four years and have never changed the coolant. Most of it was lost in another incident some time back so it had a lot of fresh coolant. Being that the engine is sitting in my garage would seem like a good time to change it. I will do a little searching but I'm sure someone van give me the best way to do it and to fill it without over heating the motor ..350 mpi 2006 motor. I'm almost ready to put back in the boat..will bring the boat home to pull the out drive and hook the steering back up. Then, get scheduled with the marina!

randy56

Wait till it's back in the boat. IMO

212rowboat

Go to one of box parts stores like AutoZone, advanced auto, pep boys, oreileys, ect, and rent an airlift... Once you use one you'll never do it another way... There will be no air to burp... 

Drain, flush with water, fill.  You'll need a air compressor. The airlift sucks air out creating a vacuum, and then you throw a valve and fresh coolant is pulled in... It May take several cycles to fully charge coolant, but when its full there is zero air in system.. 

Another thing its good for is pressure testing coolant system.  Simply draw a vacuum, say to 10 inches of vacuum, and walk away.  Let it sit for however long, say an hour, and when you return to it there should still be 10 inches of vacuum on system... If there isn't, your system isnt sealed and an open system will overheat.  I think (iirc) one pound of pressure raises boiling point of water 3 degrees... So, has to be sealed.  The 13# cap allows a 39 degrees over 212degrees at seas level.  The problem with open system that isnt designed to be open is the coolant is pushed out and there will be no cooling at all.... The airlift will find if youre not sealed quicker and far easier, with a certainty, and is worth the trip to shop to rent... I like it so much I bought one. 

rasbury

well @212rowboat savvy advice I'm sure but I don't have a compressor. Not sure how I have gotten by all these years without one but I don't...so old fashion way for me. So, either in or out of the boat, what is the best way to drain it and tips on filling/burping the system to get the air out is what I will have to work with...

212rowboat

Rent a compressor or get a small one... You dont need much for this... Allowing gravity is functional, but isnt certain... The airlift is certain, and will save you from having to have a jug of coolant aboard topping off for first several weeks after exchanging coolant as air burps..... Its astounding how much air the engine will hold in nooks and crannies, and those areas cause two major problems- hot spots and cavitation.. The cavitation is real concern as the coolant expands and mixes with air, then slaps metal with tiny supersonic bubbles capable of breaking down metal just like sandblasting... The hot spots or softer metals are especially at risk.  

If it were me I'd find a compressor and an airlift and be certain its done right... 

rasbury

OK, so you got me thinking on that.....so how do I get the coolant out, is there a specific drain point? I would think if I'm going to make a mess, out of the boat is better than in the boat....

212rowboat

Getting out is just drain pull plug and gravity, but reason the flush is so important.... Fill with water drain again... Do it three times if not satisfied with second.  If changing type of coolant, then do it six times minimum.  

jhofmann

Up here in New England, I would worry about any leftover water freezing in the outdrive, but this is probably not an issue in Florida.

rasbury

So where is the drain plug?

212rowboat

Should be bottom of exhaust manifold, below a T fitting.. Make sure and take reservoir cap off to prevent locking some in there.  Should also be blue cap below pump, pull it too... Sometimes its a pecock valve... Sometimes there are two blue plugs on either side of block under cylinders 5 and 6.... If not blue plug its likely threaded plug with inset 3/8" key you use a ratchet and short extension to pull (sans socket on end).  

rasbury

20 4...tips on filling? What a mess this would make in the boat?

212rowboat

Not really that messy filling.. Can be very messy draining especially in bilge... Jist about better to let it spill and collect it at bilge drain and rinse it well... If you dont get air out your temperature will spike and drop, spike and drop, and you're taking a chance of it blowing through cap and spraying down entire engine bay, which is messy too... If air is extracted via airlift, none of this will happen.  You fill via vacuum until you have to draw another vacuum, and in end there is zero air only coolant and filled properly... No "topping off" every hour of the first ten or so hours of running, no spiking, no mess, and no cavitation.  And, you'll knkw of yoir system is sealed or leaking somewhere.  You can pull a vacuum the poit the hoses collapse... I usually draw to just the point they start to and stop... 

Liberty44140

Been thinking about doing this too, same engines and same year. How often is everyone draining and re filling coolant on a closed cooled engine? Every 5 yr, 10 yr? I’d doubt mine has ever been done. 

212rowboat

You can test it with a kit, fill tubes shake em and see what color they turn, or another where you ise immuno assay strips dipped in it and turn colors, closely akin to that pool test strips use.  Both available at parts store.  You can add nutrient pack to it accordingly and save the flush+fill... Or, just flush and fill and know you're good for five years or three hundred hours. 

Good coolant goes about its business one of two ways... It either puts a skin on parts that protects them, or it makes them super slick.  You can't mix these.  If you go from one to another you've got to flush thoroughly. Even better if you use restore and restore+ following directions to a T, but hard to do to marine engines. 

Liberty44140

Yea I’ve done the floating ball test from the auto store ($2) and all good. Will keep monitoring raz progress 

Glassguy54

That guy 212rowboat is one smart dude! A wealth of info.