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07 6-6 sedan
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I will be changing the coolant on my 07 6-6 next week. Already have the 2 gallons of Type II Honda coolant ready to go.

I have searched the forum but was unable to find a clear picture of the coolant drain plug on the block. Will a 19mm box wrench do the job or is there not enough room? I have read that the bolt is on the block pretty tight.

Any thoughts/advice on what to expect would be appreciated.

Thanks! :thmsup:
 

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Make sure before you turn off the car the last time before you start this, you set your heater all the way to HOT so the valve to the heater core is open when you drain it, that will empty the whole system.
 

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There is a block drain on the back of the block, but I wasn't able to reach it. You have to use the block drain or remove the water pump to get all of the coolant out. Draining the radiator will only be a partial drain. If you remove the water pump (for the TB change @ 105k), make sure you put some cardboard down...it's messy.
 

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Draining the radiator will only be a partial drain.
True, but that "partial" drain equals 94% of the fluid. And the Honda procedure is to do it through the radiator. I know the OP asked for the block drain location and gwiffer correctly answered him, but....

Your oil change is technically a "partial" fluid exchange- I believe about 92%.

Your transmission fluid change (Automatic) is a 43%, 68% and a 82% exchange after 1,2, and 3 drain and fills, respectively.

The old stuff is not poison- just fluid that needs updating.

But yeah, if you are doing the timing belt (on a V6), do the water pump too and exchange 100% of the fluid!
 

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RIP my Acorn
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Going through the trouble of draining the block of coolant is absolutely not worth the extra drainage. If it was, Honda would recommend it. RickBlaine nailed it. 100% efficiency is not what is required by the car.

Do you take off the oil pan for an oil change?

P.S. I'm that guy that changes my oil with synthetic every 2500 miles, just to give you an idea of how seriously I take maintenance...
 

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BRWNFLSH now
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It may not be in the owner's manual, but it is in the service manual. The block drain is on the rear side of the engine, toward the passenger side. There is a nipple coming out from inside the nut, so you can fit a drain hose on it, then loosen the nut. A good bit of coolant will come out. A box-end wrench is the best way, because you need to have the hose attached to the nipple.
There is a procedure for doing the coolant change, which includes turning the heater up full hot (before draining), and starting the engine with the radiator cap on loosely (after filling), then running the engine until the fans come on at least twice. It's not as simple as drain and refill. Good luck
 
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Good advise from BLCKFLSH as usual. I would just like to add a few points.
I've drained my block a few times, but have never been able to get a wrench on the drain. The only thing I've been able to fit is a 12mm 3/8 drive deep socket and ratchet. I loosen the drain slightly to just hand-tight and attach a 1/4" ID hose. I then use the hose to loosen the drain. The 1/4" hose is a very tight fit, and I slit it slightly to get it to on.
Jack up the front end as high as you can, and remove the passenger side wheel.
It is worth doing this, at least on the V6, as I drain approx three quarts here after draining the rad.
 

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I leave engine block plugs alone. Screw one up and you're in a world of hurt. Not worth the small benefit. I'd rather drain twice.
 

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A good bit of coolant comes out of the block drain, and I didn't have any trouble with it leaking. It is tight though. You will use most of the 2 gallons if you drain the block, then have a little left over for adding later if need be. It's a real good idea to drain the block before taking the water pump off (if you're doing the timing belt), that way much less pours out when you remove the pump (less mess).
 

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Doing trumps "I've read".
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Drain Nipple

Reading all these posts, I can relate to all of them. I like my maintenance, I've referenced the Service Manual, but I have changed my ways slightly. The water jacket drain is a PITA to get to and yields about a quart of coolant. If you are even close to the regular service intervals, it's not necessary given the location and amount it yields. I did ask a Honda tech a long time ago and he told me that he/they did not drain it @ his shop. I drain the radiator every other year and what comes out looks as good as what goes in.
 

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A good bit of coolant comes out of the block drain, and I didn't have any trouble with it leaking. It is tight though. You will use most of the 2 gallons if you drain the block, then have a little left over for adding later if need be. It's a real good idea to drain the block before taking the water pump off (if you're doing the timing belt), that way much less pours out when you remove the pump (less mess).
BLCKFLSH is correct. The honda SERVICE manual not the OWNERS manual states to drain the rear of the block in addition to draining the radiator. And as BLCKFLSH stated, a good amount comes out from the rear block drain. It is in a very tight spot. I removed the front passenger side wheel for easier access. There is only about 2 inch swinging room for a combo wrench, but the drain bolt is only torqued to 7-8 ft-lbs so it wasn't too hard to loosen. You can loosen the nipple with a 12mm wrench. Just be patient getting your arm and wrench in the tight fitting spot so you don't damage anything. Also, attach a tight fitting rubber hose over the nipple to avoid making a mess. The drain bolt is supposed to be torqued to 7.2 ft-lbs according to honda service manual, but it was impossible for me to get a torque wrench in there. Just a quarter turn, if that, with the combo wrench, after finger tightening, did the job. Here's a picture of what the service manual states and a picture of it on my actual car. Just be patient and it's not difficult. This is only for 2003-2007 V6 accords. Do this at your own risk. Hope this helps.
 

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I'm with Rickblaine on this one. Draining the block is not really necessary. I'd rather drain and fill twice than touch that tight block plug. If your strip it or break something there, you're in for a world of hurt. Been there with an old car of mine so I learned my lesson well.

Edit; Just realized I repeated myself. Oh well.
 

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I'm with Rickblaine on this one. Draining the block is not really necessary. I'd rather drain and fill twice than touch that tight block plug. If your strip it or break something there, you're in for a world of hurt. Been there with an old car of mine so I learned my lesson well.
I also agree with Drew03Accord. I would rather just drain and fill twice from the radiator. Do this on seperate days so the coolant can mix well. That will be very close to a 100% change of coolant.:thmsup:
 

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I also agree with Drew03Accord. I would rather just drain and fill twice from the radiator. Do this on seperate days so the coolant can mix well. That will be very close to a 100% change of coolant.:thmsup:

And it's so much easier than.....

"It is in a very tight spot. I removed the front passenger side wheel for easier access. There is only about 2 inch swinging room for a combo wrench, but the drain bolt is only torqued to 7-8 ft-lbs so it wasn't too hard to loosen. You can loosen the nipple with a 12mm wrench. Just be patient getting your arm and wrench in the tight fitting spot so you don't damage anything. Also, attach a tight fitting rubber hose over the nipple to avoid making a mess. The drain bolt is supposed to be torqued to 7.2 ft-lbs according to honda service manual, but it was impossible for me to get a torque wrench in there. Just a quarter turn, if that, with the combo wrench, after finger tightening, did the job."
 

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I loosened the drain going in from the front of the car, and feet out by the bumper. No need to remove the wheel. I didn't feel like there was much chance of stripping anything, since the bolt doesn't even come all the way out. I saw that the service manual said to drain the block, so I did it. No big deal. If you don't want to do it, don't. I'm just giving the information.
 

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I'm going to do coolant replacement the service manual way sometime this week. While I'm at it, I'm going to repeat the P.S. fluid complete replacement the second and final time. Should be good for the next 2-3 years, assuming nothing breaks down during that period.

Thanks BLCKFLSH for telling us how you approached the block drain bolt without removing the wheel. I'll try this route.
 

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Bumping this thread to drop a warning: the brass block drain is super-mega tight. The spec on it is 7 ft-lbs or so (which is basically "snug") but to break it loose it had to have been >30 ft-lbs. Cracked loose -> hand got stabbed by a bracket. I highly recommend using a long ratchet from below rather than a wrench from the side as a safer way to put torque on it without risking injury.
 

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On the V6, block coolant drain = removing the water pump. The warning is to not crack that block drain open if you are in the snow belt, you risk breaking that screw.
 

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On the V6, block coolant drain = removing the water pump. The warning is to not crack that block drain open if you are in the snow belt, you risk breaking that screw.
I'm removing the waterpump anyways for the timing belt, but I figured to make less of a mess of having water gush out from the pump onto the subframe and splash everywhere. We'll see. I can hear there's still a little bit of fluid in the pump below the inlet and outlet ports.

Aiming for mild spill and less "major disaster" on the garage floor.
 
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