Hi! I have a 2003 Honda Accord, 4 cyl 2.4 liter engine with manual xmission. It is time replace my coolant first time after 10 years. The official Honda shop manual says it is enough to drain the coolant via the radiator drain on the bottom as well as empty the overflow reservoir (yes there are details like setting the heater to max heat, let the engine cool etc), and refilling with new coolant. On the other hand, the Haynes manual has some added steps, like also draining from the engine block drain bolt and flushing the system, not mentioned in the Honda shop manual.

It seems to me that in order to do a complete job, I should also drain the coolant from the engine block and flush the system. Normally the Haynes manual has good pics of part locations with an arrow pointing to the part. However, in this case, the manual doesn't tell me where the engine drain bolt is located. Can someone point me to the location?

Anup

 

It is on the rear side of the block.

 

Redbull, thanks for the reference to the diagram. It was very helpful. I was able to locate the plug with a mirror and a flashlight. It looks like I will have to jack up the car in order to get anywhere near it and will have to use an allen wrench. Do you know what size of wrench it will take? My other concern is the allen wrenches do not provide a great deal of torque and the plug may be difficult to budge.

Anup

 

I have never removed it. IIRC, it is a 10mm hex. You'll need a 10mm hex bit socket and ratchet. Be warned, supposedly it has red loctite on the threads.

You might want to see this link regarding red loctite, can be difficult to remove.

How to Remove Red Threadlocker

 

Redbull, thanks for the info. I do have a torch to soften red loctite but given the already hard to reach location and other parts in the vicinity that might not withstand the heat, I'm giving up the idea of removing this plug. Do you still recommend flushing the radiator with plain water before refilling with antifreeze?

Anup

 

A little bit of a risk of trying to remove the engine block plug.

For myself, I don't flush with water. I would just do a drain and fill with Honda Type 2 long life coolant.

 

Additionally, if you wish to drain more of the coolant from the system be sure to have the heat turned to the ON position before draining as this opens up the heater core to draining as well. Also, if you really feel you want to drain the majority of the block it would probably be easier to remove the serpentine belt and remove the h2o pump. If the car has over 120k on it you might want to replace the h2o pump anyway as part of general maintenance. Since you have a timing chain most people don't think about changing the pump where as people with t-belts usually have them changed every 100k during belt service.

 

Just do a drain and fill, with no flushing IMO. If you flush with water, the water that remains in the system after flushing will dilute the 50/50 mix of type 2 Honda coolant (you would have to flush with type 2 coolant, to get the correct mix). Definitely no need to remove the water pump or change it. The water pump on the 4 cylinder can easily be changed at any time (so you change it only if it goes bad), while the V6 water pump is a long process involving timing parts removal, so people change it when the do the timing belt.

 

Changing the water pump every 100-120K is good preventative maintenance. For the 4 cylinder, dealer and most shops will still charge about 2-3 hours labor, as the power steering pump is moved or removed, drive belt tensioner removed, and then water pump removed.

I had my water pump go out at 125k, luckily, it wasn't at too an inopportune time.

 

Thanks for all your replies. I'll keep it simple and will just drain and fill, paying attention to the remarks concerning the heater.

Anup