Coolant Change - 06' Merc 350 MAG MPI Horizon

Liberty44140

I doubt that my coolant has ever been changed. No issues but I would think that by now I need to change my coolant. They are horizons so I have heat exchangers and coolant running through the block, not water. How do I change the coolant? Is this something that I can do over the winter? Simple as drain and re fill? Thanks! 

Liberty44140

So from what I can tell there are a couple of plugs on the block to pull to drain coolant and then I just re fill and make sure to top off after the first couple of runs. Sound right? Anyone know where the drain plugs are? I am going to buy an antifreeze tester for a few bucks before I do this to make sure my coolant actually needs replaced. 

randy56

Not having one, you would think it has the same blue drain plugs for winterizing? see your manual. 

FDNY49

Check out YOU TUBE they may have a video

Liberty44140

I ended up buying an $0.88 coolant tester from Walmart. Tested the heat exchangers in both engines and 4 to 5 balls floated meaning my coolant is fine so not going to change this year. Really surprised that there is no info here on anyone doing a coolant change, must not need to be done very often as I had thought. 

reneechris14

Come on @Liberty44140 I was following this to learn something more then go to Wal-Mart and spend $.88. Lol . All the cars I ever done I just pull the lower hose from the water pump and splash all comes out.

Liberty44140

Ha, sorry to disappoint Renee when I talk to my mechanic this fall about doing my gimbal bearings this winter ill still ask him how to change the coolant, he respects that I diy and pay him for big stuff and has no problem giving me 10 min of coaching. Stay tuned....

RWBLACK6

Liberty; Just saw your post today . Changed both my 6.2 horizons ,2004 , last year. Just removed 1 short bolt plug located on starboard side ,low middle of engine block. very easy to remove plug. use socket ratchet. removed bilge drain plug and drain into a big pail. Then I Removed thermostat housing and filled from there. replaced thermostats while at it. I do remember Alswag stating a few years back that coolant  life is based on heat cycles and that you may go many years before having to change.  Note : I did not test mine ,so it may have still been good. 

Dream_Inn

I always thought I was a good day when the boat floats, but hey, if it's balls, well that's ok too.

Spyderweb

FWIW, I have the same engine in my 2007 Bayliner 285.  Manual says change antifreeze every 5 years.  1st time I had it changed, mechanic had a hard time and had to "make" some kind of tool to complete the job.  Don't know if that was a function of how Bayliner positions the engine in the boat, or the nature of that engine.

Paul

Liberty44140

Good stuff. If I end up doing this or gather more info on it I'll comment back.