How to DIY change engine coolant?

[shawndoggy]

So my engine is closed cooled ("fresh water cooled").  The PCM manual recommends changing the coolant every two years.  I just finished my fourth season on the original coolant and I'm thinking that I sure better take care of this during my prep in the spring.  PCM says if I use DEXCOOL (orange) coolant that the change interval is five years instead of two, so that's definitely what I'm going to replace with.

My dumb question... how do I change the coolant?  I mean I see that the manual tells me what to drain, but how do I not make a mess with antifreeze everywhere?  Is there a way to capture the antifreeze, oh and p.s. assuming I can get this stuff reasonably well captured, where do I dispose of it?  Also the manual doesn't mention the heater circuit, but presumably I'm going to need to blow that out too?

 

I notice the raptor motors also have a two year coolant change interval, so I'm assuming some of you have done this already?

[Nick in the TC]

I have a ‘96 prostar with closed cooling and let it dump into the bilge and put a bucket under the boat in the driveway.  You should be able to take it to a county recycling center. The cleanest way to do it might be with a shop vac.  Pull engine plugs and suck the anti freeze as it’s coming out of the block. Then you will have to suck out all hoses hooked to the heat exchanger. Filling it up is more of a PITA because it is hard to bleed the system. I pour coolant right into the block thru the thermostat opening and fill the reservoir and all hoses to heater and heat exchanger. You will still have lots of air in the system so run it up to temp and it will take everything from the reservoir and you will have to refill it again. May have to do top it off 3-4 times until completely full

[Nitrousbird]

I just get the nose high and left it dump out the rear drain plug.  I do the lazy man coolant change by simply draining the heat exchanger and replacing the coolant with fresh stuff.  Sure, I'm mixing old with new but whatever.  Do it regularly enough and it will stay fresh-ish.

No corrosion visible in my filler neck and my refractometer reads good.

[shawndoggy]

1 minute ago, Nitrousbird said:

I just get the nose high and left it dump out the rear drain plug.  I do the lazy man coolant change by simply draining the heat exchanger and replacing the coolant with fresh stuff.  Sure, I'm mixing old with new but whatever.  Do it regularly enough and it will stay fresh-ish.

No corrosion visible in my filler neck and my refractometer reads good.

Im totally down with lazy man. But I think I would like to run the orange for the five year change interval, which means at least once I need to do a full purge. 

[Nitrousbird]

4 minutes ago, shawndoggy said:

Im totally down with lazy man. But I think I would like to run the orange for the five year change interval, which means at least once I need to do a full purge. 

If doing the full purge, perhaps consider the stuff the Germans use.  Supposed to be "lifetime."  Of course, German cars are always leaking something so it never gets the chance to live a full life!

[justgary]

I recently flushed mine.  Not much choice but to let it drain into the bilge and then catch it in a bucket. 

I back flushed with the garden hose, flushed the heater separately, blew the heater out (with lung pressure), then flushed the block with a gallon of distilled water.  Then I closed everything up, added half the book volume of straight antifreeze, then added distilled water until the system was full.  Then I warmed the engine and topped off with distilled water. 

The idea is that with half the book volume of antifreeze, I don't have to worry if a gallon of water was still there after the flush.  I get at least 50/50 that way. 

[Sparky450]

What about flushing with water a few time  to clean all the old stuff out. Then blow out and fill with the new. Can a little water hurt the antifeeze?  If so fill and flush with antifreeze. Cost a little more but might be worth it. And I would probably jack up the front and run it out the back drain plug, then rinse a few times. You could easily put a bucket under the drain plug.

[Eagleboy99]

2 hours ago, Sparky450 said:

Can a little water hurt the antifeeze?

No - in fact, pure antifreeze freezes at a higher temp than water-diluted.

[justgary]

7 hours ago, Sparky450 said:

What about flushing with water a few time  to clean all the old stuff out. Then blow out and fill with the new. Can a little water hurt the antifeeze?  If so fill and flush with antifreeze. Cost a little more but might be worth it. And I would probably jack up the front and run it out the back drain plug, then rinse a few times. You could easily put a bucket under the drain plug.

Yes on the flush and blow out, but you never really know how much water you might have left in the block.  If it all drained perfectly, nobody would worry about their winterization after draining. 

Anyway, my point is that if you are trying to hit a 50/50 target of antifreeze/water, adding diluted mix may not get you there.  I don't mind being just a little over 50% antifreeze since I'm mostly looking for corrosion protection, so I use full strength antifreeze and put half the engine's volume in and then top off with distilled water.  I do that for my truck and tractor as well.

It just seems a little better than leaving a gallon here or there, adding 50% mix, and thinking I have a 50% mix in the end.

[Woodski]

Not questioning the manual as that is the go to reference on service, I am a bit surprised at the coolant change frequency suggested.  Coolant change in automotive applications are at a longer frequency and given the low hour averages of a boat compared to a car the coolant barely gets 'used' between flushes.  I would certainly check it at a higher frequency than suggested, a leak may not go detected depending on user bilge inspections.

[justgary]

I agree.  I just changed my boat, tractor, and truck coolant at around six years on each.  Didn't mean to go that long.  I don't have a refractometer that goes high enough for coolant, so I can't test it (well, I could dilute it to 25% and test it on my 0-10 Brix refractometer).

Around here, coolant is for rust protection primarily. 

P.S.  If you are looking for help spending money, Shars has refractometers for about $70.  www.shars.com.

[Nitrousbird]

10 hours ago, justgary said:

I agree.  I just changed my boat, tractor, and truck coolant at around six years on each.  Didn't mean to go that long.  I don't have a refractometer that goes high enough for coolant, so I can't test it (well, I could dilute it to 25% and test it on my 0-10 Brix refractometer).

Around here, coolant is for rust protection primarily. 

P.S.  If you are looking for help spending money, Shars has refractometers for about $70.  www.shars.com.

You need to shop better.  You can get refractometers on Amazon for $20.  I have one for coolant and a different one for testing alcohol content on the beer I brew.

[justgary]

3 hours ago, Nitrousbird said:

You need to shop better.  You can get refractometers on Amazon for $20.  I have one for coolant and a different one for testing alcohol content on the beer I brew.

Perhaps, but I was offering to help you spend money, not save it!

[Nitrousbird]

11 hours ago, justgary said:

Perhaps, but I was offering to help you spend money, not save it!

To help @shawndoggy spend money, he needs to buy this:

https://www.amazon.com/gp/product/B01BW39HJS/ref=ask_ql_qh_dp_hza

I was forced to get it when I did the water pump and thermostat on the wife's S4 this summer, as it is the only way to get the air out of the system on those motors (awful job on those cars too - supercharger has to come off and that's the easy part).  Amazing tool and I will never fill coolant again without it.  Only easier way to bleed coolant than this is on my BMW, as you just activate a bleeding mode with the electric water pump and walk away for 10 minutes, done.

[shawndoggy]

sweet jeebus I'm starting to regret having asked this question!

[Nitrousbird]

27 minutes ago, shawndoggy said:

sweet jeebus I'm starting to regret having asked this question!

I promise it is a tool you will use for years to come.  I wish I had bought this long ago.  It gets the air right out and sucks the coolant in very quickly.  It also pressure tests your system - was a big deal when doing the wife's S4, as I was only going to do the thermostat but this tool let me diagnose that the water pump was (just barely starting) to leak.  I mean, so little the coolant level had not really changed but I would have been screwed in a couple months had I not known.  It's only $80.

[justgary]

And it makes a great Borg costume kit for Halloween! 

[CarveItUp228]

Personally, I don't like the idea of using something in my engine cooling system that is made for potable water systems. If you can drink it, it is most likely missing many of the corrosion-inhibiting compounds that keep your internal parts in good shape. But I get the point of not using ethylene glycol in a marine environment. So what is the right one to use? Well, there is the Indmar stuff which is $50 per gallon. For my system, that would mean $100 plus 2G of distilled water. But I did find something a little cheaper that fits the bill: https://www.westmarine.com/buy/west-marine--engine-antifreeze-coolant-gallon--337447?recordNum=1

$35/G concentrate (so mix 50/50 with distilled water).

I am going to swap out the coolant here at the end of year two. But I don't think I am going to change it every two years. Maybe 3 for the next time.

 

Cheers

 

 

[formulaben]

14 hours ago, CarveItUp228 said:

Personally, I don't like the idea of using something in my engine cooling system that is made for potable water systems. If you can drink it, it is most likely missing many of the corrosion-inhibiting compounds that keep your internal parts in good shape. But I get the point of not using ethylene glycol in a marine environment. So what is the right one to use? Well, there is the Indmar stuff which is $50 per gallon. For my system, that would mean $100 plus 2G of distilled water. But I did find something a little cheaper that fits the bill: https://www.westmarine.com/buy/west-marine--engine-antifreeze-coolant-gallon--337447?recordNum=1

$35/G concentrate (so mix 50/50 with distilled water).

I am going to swap out the coolant here at the end of year two. But I don't think I am going to change it every two years. Maybe 3 for the next time.

I think you're confusing closed and open cooling.  Folks like me who have open cooling use propylene glycol based antifreeze to winterize the engine (non-ethylene only, and as you say normally used in RV potable water systems.) 

This thread and the conversation above is about closed cooling, in which the engine cooling system retains the antifreeze and circulates it, just like an automobile, but uses the lake water and a heat exchanger to cool it instead of a radiator and air.

[CarveItUp228]

On 11/4/2019 at 2:37 AM, formulaben said:

I think you're confusing closed and open cooling.  Folks like me who have open cooling use propylene glycol based antifreeze to winterize the engine (non-ethylene only, and as you say normally used in RV potable water systems.) 

This thread and the conversation above is about closed cooling, in which the engine cooling system retains the antifreeze and circulates it, just like an automobile, but uses the lake water and a heat exchanger to cool it instead of a radiator and air.

The threads have intermingled, I think. But I was responding to the folks who were talking about changing their coolant, so I assume this was a closed-cooling discussion as far as that goes. My closed cooling also uses propylene glycol (as spec'd in the manual). I am just choosing to use something a little more robust than "the pink stuff" for that and thought I would share a good source for what I found. My system also uses raw water in certain parts (like exhaust manifolds) but I just drain those for the winter without adding anything else.

Cheers

 

[Hentz]

Does anyone have a video or pictures of the coolant drain locations. Dumb question, but are you just filling through the reservoir tank then?

[justgary]

8 hours ago, Hentz said:

Does anyone have a video or pictures of the coolant drain locations. Dumb question, but are you just filling through the reservoir tank then?

No photos, but the drains are the same as if you didn't have coolant and wanted to winterize.

I flush the engine and exchanger with water, then flush with about a gallon of distilled water, put the plugs in, fill through the heat exchanger with the book amount of 100% coolant, fill with water (usually distilled water), crank the engine, run it until it warms, and top off with water as I rev the engine a bit.  Then I put the pressure cap on and fill the reservoir to the "cold" line with 50/50 mix.

[jmbeiner]

Sorry, guys, but to ask this question again: can anyone tell me where the block drains are on the M5? Or the lowest point to drain the coolant?  I have a 2019 and would like to drain, flush, and replace the coolant (closed loop, not raw water).  I can find the petcocks to drain the raw water system, but find no drains on the block to drain the coolant in the closed loop system.  Please be specific or send pic--going crazy w this. Thank you !! [email protected]

[justgary]

55 minutes ago, jmbeiner said:

Sorry, guys, but to ask this question again: can anyone tell me where the block drains are on the M5? Or the lowest point to drain the coolant?  I have a 2019 and would like to drain, flush, and replace the coolant (closed loop, not raw water).  I can find the petcocks to drain the raw water system, but find no drains on the block to drain the coolant in the closed loop system.  Please be specific or send pic--going crazy w this. Thank you !! [email protected]

I am not terribly familiar the the M5, but most likely the lowest block drains will be the knock sensors on either side of the block just above the oil pan.  I would also check for a plug low on the heat exchanger or return pipe to dump the coolant from there as well.  It may be that the entire end cap of the exchanger comes off.  They seem to have done a good job of reducing the number of hoses and getting all of the cooling in one place.