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The Maintenance Minder is showing A15 on our daughter's 2010 Pilot. The "5" signifies coolant change. I've done coolant changes on various Hondas in past, and the drill was always:

1. Drain radiator.
2. Drain block.
3. Add new coolant (diluted 50/50) at radiator, with bleed bolt open, till coolant comes out.
4. Close bleed bolt and continue filling, up to radiator neck.
5. Leave radiator cap off, start engine and idle, till fan comes on twice. Having a helper slightly elevate the idle speed helps speed the process, and you want to stand at the front, monitor the radiator neck, with a baster and cup at the ready. The coolant will tend to rise and drop as the air pockets work themselves out.

Now on the 2010 Pilot, the Shop Manual makes no mention of a bleed bolt, so guess there isn't one? The drill for adding coolant is this:

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Then the next page, things get "interesting". Step 13 seems fairly conventional, but then there's a near endless series of running the engine at raised idle, alternating between "max cool" and "max heat"

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Has anyone gone through a coolant change, and how difficult was it? Is a lot of this last page overkill? Or?
 

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Discussion Starter #2
Pretty quiet here? A further question:

There's no mention of a air vent bolt at the top of the coolant circuit, to help evacuate air during refill. There isn't one? Would it be worthwhile to temporarily disconnect a small diameter hose at the high point (assuming one is accessible), to help getting air out?
 

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I’ve never done it myself but I thought all you had to do was drain it from the radiator and then refill it. There may be some YouTube videos about it.
 

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Discussion Starter #4 (Edited)
Thanks for responding!

Yeah Youtube videos are pretty spotty. Nobody makes mention of the protracted fast idle at max cool, then max heat, back and forth. The best of the bunch suggests to do an intermediate water flush, which seems like bad news: pretty much impossible to get back to to 50/50 mix after that, especially with the Honda coolant being premixed. He also uses a non-Honda coolant (but compatible?). Anyway, he at least shows the radiator and engine block drain locations pretty good.


And from an environmental standpoint, that water "rinse cycle" is a lot of extra fluid with a fair percent of ethylene glycol, which I suspect he just pours down the drain. :(

Seems like a general automotive trend, to delete the coolant bleed bolt. The last time I was doing a coolant change, on an 06 Civic Hybrid, my son was pouring the fluid so I had my hands free: you could feel the air rushing out of the bleed bolt as the coolant went in. I can't see how deleting that item can be good. And yeah maybe temporary disconnection of a small diameter top hose could serve the same purpose. I'll see what I can find, might be over Xmas holidays.

If and when I get to it, I'll for sure post a follow up, how it went, tips, problems, and whatever.
 

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I filled mine after doing the water pump and it was uneventful. Just poured the 50/50 into the radiator, ran the heater and revved the engine a little (like 2000 rpms briefly). Capped it, got it hot, made sure I had heat. Added coolant to reservoir. Checked it next day when cool and it needed a little more. Same as it was 50 years ago.
 

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I can honestly say that I read all of that and think what a waste of time... It's winter so the heater will be in use, hence the core will circulate plenty of fluid. Otherwise I fill it up, let it warm up (maybe raise the front end if I'm not already on ramps), refill after a couple burps then drive the vehicle and check the level when cold each night. I usually find the first couple burps as the thermostat opens are the major ones, after that I rarely add much coolant.

Done this in every vehicle I've owned with no issues. My biggest issue is the newer vehicles that are deleting the draincocks, then I'm stuck pull off the bottom hose and getting messy.
 

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I'm not familiar with draining the block, but I do know that just draining the radiator will only get about half the coolant out of the system. I recently removed my radiator to replace my front engine mount and drained the coolant, refilling with new coolant which took about a gallon. Then two weeks later I replaced my timing belt and water pump, draining the radiator again. I got all the coolant out of the radiator, then when I removed the water pump nearly another gallon of coolant drained from the block/head. After that job, it took two gallons of coolant to refill the system.

I filled mine after doing the water pump and it was uneventful. Just poured the 50/50 into the radiator, ran the heater and revved the engine a little (like 2000 rpms briefly). Capped it, got it hot, made sure I had heat. Added coolant to reservoir. Checked it next day when cool and it needed a little more. Same as it was 50 years ago.
For someone who knows how to check coolant, this is perfectly fine (and exactly what I did).

Those overly complicated procedures in the service manual are for the Honda mechanics who need to ensure the system is properly filled so their customers don't have to return or check the coolant themselves in the days that follow.
 

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Been working on my honda's for 20 years, usually I park it on a slight incline, with the front elevated. Drain and refill. Also fill the resevoir to level. Start the car with the radiator cap off. Once the thermostat opens, (you'll see the water rushing inside the radiator), top it off and put on the cap. Drive it around for a day and check the level again once cool and top off as necessary.
 

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The coolant change is generally every 6 years or 100,000 miles. Make SURE you use Honda blue coolant and not some generic coolant. I used Zerex brand for Honda's (blue), Walmart carries it now.

The engine RPM thing is simply to try and increase flow and burp the system of any trapped air. Driving it should do the same, but it is good to do this while filling because you can top up for any air that gets displaced.

When I did mine timing belt/water pump recently, I drained the radiator, and sucked as much coolant as I could out of the engine water pump area with a shop vac. Filled normally, and I recommend using a filler/funnel that attaches to the radiator. I have this one and it is awesome: https://www.amazon.com/gp/product/B01I40ZQWE

I just turn the heater on to full blast, idle the engine to full operating temp, and have someone rev it to 3000 RPM for 20 seconds or so, then idle for 20, and repeat that 3-4 times. With the fill funnel attached, it makes it a dream to get completely full and get all the air out, with no spills or mess.
 

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Discussion Starter #10
Thanks for all the responses. I didn't get back for a few days, was starting to give up.

Yeah I was kind of thinking the Repair Manual instruction was overkill. Puzzling too: did Honda just cheap out, deleting the bleed valve??

I'll read through them all. I've yet to do the coolant change, biggest problem likely to be getting uninterrupted possession of the car for a half-day or so, lol.
 

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Since the OP mentioned the maintenance minder system showed that coolant was due, I thought I would ask this follow up question rather than start a new thread. Does anyone know the logic of the maintenance minder system for coolant flush intervals?

The first time '5' popped up on MM for our 2010 was right around the 7 year/115k mile mark but we already had it done before that during the 105k mile service so it was reset. But just this week it popped up again 2.5 years later at 165k miles. It has only been 60k miles since service was done and 50k miles since the last '5' for coolant reminder was reset. Is it supposed to be changed more frequently after the first interval for higher mileage cars?
 
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