Does 318 engine have coolant drain plug?

[GPappas]

I will soon be replacing/flushing the coolant in my Bimmer.

I have read the DIY writeups for coolant change at http://www.bimmerzone.com/coolant.htm and http://www.logun.org/radflush.htm. Both of these writeups mention two drain plugs: One on the bottom of the radiator and another coolant drain plug (and crush washer) on the engine.

Since both writeups are specific to the 6-cylinder engine, I am not sure if the 4-cylinder is similar.

Does the 318 series (4-cylinder, 1.8 liter engine) also have a coolant drain plug on the engine? If so, where is it?

[foRRREVerz]

Yeupp... there should be two coolant drain plugs...

One on the radiator itself, and the other on the engine block. The bolt is tucked behind the header, therefore the bolt is on the exhaust side of the block.

Be sure to use a hose/funnel up against the radiator drain... kinda pointless... considering once you let loose the engine block drain, coolant just gushes everywhere.

Feel free to PM me with any questions...

Also, a couple of the tensioners are setup differently as well, if you happen to be replacing the h2o pump.

[GPappas]

I finally got a chance to get under the car and try to find the coolant drain plug on the engine block.

I searched and searched but I'm not sure where it is. I found two drain plugs on the oil pan. The one on the bottom of the oil pan is the oil drain plug. The other one was about a foot higher (also on the oil pan), but I'm not sure what it is. I measured it at 19mm. Could this be it?

I looked on the exhaust side of the engine as you suggested. I saw four exhaust pipes coming out of the engine, but no drain plugs near them.

Would someone please give more of a description of exactly where the coolant drain plug is located.

[foRRREVerz]

: hmmm... perhaps the M42 and the M44 have them located in different spots. But I would highly doubt that.

The bolt should be just about 3 inches down from where the headers start. The bolt really isn't that visible, and you will definitely need to feel for it and get a good light positioned in order to see it.

I'll see if I can find a picture of it in the bentley and post it on here for you.

[bimmer95]

Originally posted by GPappas
The other one was about a foot higher (also on the oil pan), but I'm not sure what it is. I measured it at 19mm.

Seeing as the oil pan isn't 12" tall, that's probably the right bolt, the size is right. Double check where the oil pan bolts to the block, if the bolt is above the oil pan then it's the right one.

[GPappas]

I would like to make sure that the bolt that I take off the engine block (to flush the coolant) is the coolant drain plug.

I finally got another chance to get under the car and take another look.

I took a few photos of the bolt/plug in question...

The first photo is of the right-side (when viewed from inside the car) of the oil pan and engine block. It contains both the oil pan drain plug and the bolt/plug in question: Photo #1

The second photo is a close-up shot of the bolt/plug in question: Photo #2. Notice that the bolt/plug is on the right-rear of the engine block, next to the transmission (the silver/gray part just to the left of the bolt/plug).

As mentioned in a previous post, I measured this bolt at 19mm.

Is this the coolant drain plug on the engine block?

[bimmer95]

That's the one.