I got set up this weekend to change my antifreeze, jacked up the car, found the block drain plug, and gave up trying to get a wrench on it. I drained the radiator only and refilled.

What an insane location for a drain bolt. Any other way to change out coolant in the block, or what kind of wrench can be used to open this puppy?

I'm open for any reasonable advice.

C-n-L

 

I did. Though I didn't touch the block drain plug.
Drained & refilled with water, drained again, then filled up with Prestone 50/50 & a bottle of water wetter.

 

the plastic drain plug is located on the passenger side bottom of the rad... it is plastic... it should come off pretty easily.

take a 10MM socket and remove the 2 bolts to the thermostat housing on the drivers side..

put the housing back on with the thermostat pin at 10-12 position and fill the rad...

start the car and let the fan cycle 3 times... watch you temp gauge in the car... if it goes past 1/2 way you have some air in the system and have to wait for it to cool down before you open up the radiation cap.

 

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Is the block drain even accessible? Anyone able to access without removing a bunch of engine components?

 

I swapped out my coolant when I put in my Mugen stuff and SC. I got to the block drain plug from underneath. Attached a hose to the drain tube so it didn't dump on me. I think I just used a ratchet and a 6 point socket. It's been a while but I don't remember any complications.

 

Wow, didn't even have to remove exhaust or engine mount components?

 

Nope. Did it all with normal hand tools.

 

Please help explain - I could barely get my hand on it maneuvering around a lot of stuff. No way I could get a socket on it and turn the socket. With the tube on, did you use an open end wrench??

Maybe my hands are just really too big.

 

Is Prestone ok or is it safer to go with the honda stuff?

How much is that honda antifreeze anyways?

 

just get the honda one. I think they are less than 10 bucks. O and look up honda coolant, and many compare it with other coolants and rank the honda ones up top

 

Im assuming water wetter is safe too. Seems like everyone here uses it

 

My preference is Honda premixed antifreeze and Redline water wetter. If you don't use a premixed version of antifreeze, dilute with distilled water to avoid putting any minerals into they system.

 

Gmahn is right, that drain plug is a bitch to get to. Its like right next to the rear headers. I can barely stick my forearm through all the pipings to put my hand on it. You really have to wait till the engine cools down before you can fiddle with it.

Its a 17mm bolt threaded in middle with a drain thingie screwed into it. I'm guessing you only have to loosen the 17mm both a little and that would allow fluid to flow through the drain thingie. I think theres just enough space to get a wrench on it from the lower left to turn that bolt.

Allout what inner diameter was the tube that you attached? And can you verify what i wrote before about loosening the 17mm bolt and not the smaller one.

 

You loosen the inner bolt - not the whole drain assembly. It's been quite a while since I did this but I think it was 3/8 ID hose that I slipped over the tube. It doesn't need to be a tight fit since the purpose is more to direct the flow of fluid downward in a controlled manner.

 

So its the smaller bolt? Not the 17mm bolt? Well I was thinking of a tight fit, otherwise you would have to hold the tube in place while you try to unscrew the bolt. Which would be fairly hard considering the limited space.

 

Ok, it is the smaller bolt that you loosen instead of the larger 17mm bolt. The smaller one is a 12 mm. I actually didnt use a tube becuase i couldnt find it at the time. I just the it spill out, a bit messy but not too bad. It takes a fairly small tube to fit snugly on there. I'll say its either a 1/4inch or even 1/8th in. I have a 2003 CL-S with oil-jet kit. It might be different for others.

Overall, in hindsight, it might not be worth the extra trouble to get that fluid out of the engine block since its only about 1 quart that comes out of there. Like i said before, the drain plug is in a very tight spot and you have to get at it from the bottom of the car. If you have big forearms, forget about it. The majority of about 4 quarts came out of the radiator. The full coolant capacity excluding the reservoir is 5.1 quart. The reservoir is .8 quart.

I had put in a bottle of Prestone radiator cleaner a day before as well. So i had to get out all the fluids this time.

Anyways, 1 jug of Honda 50/50 Antifreeze, 1 bottle of water wetter and the rest tap water was used. I figured its ok since its summer. However only a few oz more of tap water were needed to fill the radiator to top. The rest went in the resevoir. Damn Honda, they make it like that so you have to buy 2 jugs of their Antifreeze. It was $12 per jug which isnt bad considering Prestone is around $7-$10. I think i saw it at Walmart for $6.88.

BTW Antifreeze smell pretty aweful. The temperature goes back to the normal spot. Is it suppose to be lower because of the water wetter or is that only with the therometer mod?

 

I know what you mean tried to get the engine drain plug off but after trying for 3 hours i gave up. Maybe i need a welding torch?
Found out they use locktight on the threads so who knew! Never has the plug been unbolted so after 7 years may as well leave it alone.

Seen someone has found a manual oil pump that sucks out all the engine oil out of the dipstick. Can this work for coolant or the pressure have to be higher then a hand pump can do?

 

One of the oldest trick in the book is to unplug the radiator hose leading to the radiator core, connect a larger hose to the existing hose so fluid doesn't splash all over your car, and let the engine warm up and the car will drain itself. Connect a water hose to the radiator core so you can flush out the engine.

Let the car run for 3-4 minutes until all the old stuff is gone.

The main thing is...WATCH the temp gauge so you don't burn up your engine.

 

This thread is kind of old but I figured I put in some photos just in case anyone is interested in loosening the drain bolt behind the engine block.

The space is very tight & I loosened the 8 nuts holding the strut bar in order to to get more room to reach in. Without loosening this bar, it is impossible to reach the drain bolt.


After loosening those nuts, I propped the bar with a block of wood. This allowed enough space to reach in but it was tight.



Use a 12mm socket wrench to loosen the drain bolt. Show on the picture is the approximate area where that bolt is sitting (see the red arrow). Do not use a 17mm socket as this will take out the whole drain body assembly. Also, remove the ignition coils to allow more space.



A closeup photo of the socket wrench extension.

 

What's wrong with getting at it from below, as described and pictured in the owner's manual p.224?

 

I remember chickening out of draining the block when changing the coolant a few years ago...seemed tough to get at.

 

I don't own a garage lift plus I wouldn't want to crawl underneath the car with jack stands supporting it.

 

I used to feel that way and still find it a little claustrophobic being under the car using jack stands. Much nicer working on it when it is on a hoist. When on jack stands I have trying to loosed seized up bolts.. got to love salt use on roads in winter.