engine and drivetrain Engine (Block) Coolant Drain Plug Location?

[Napes]

I found a drain cock that fit fine at Ace Hardware.  Only down-side was it cost $24.  This was on my wife's '76.  Next time I do my '75 (which is every 2-3 yrs.) I'll just live with the mess.  I'm able to catch most of the coolant in my large drain pan - a concrete mixing pan from Home Depot.  I use the smaller one (18" x 26" x 6" deep).

 

Bob Napier

[PaulTWinterton]

I did the deed.  I was expecting a very tight fit, but it cracked immediately with a socket on a breaker bar.  Yes, it gushed everywhere. Kiddie pool helped, but the stream was horizontal at first.   Mop up required.  I would have been smarter to gradually unscrew and let it drain slowly. Next time.

 

Good news is that (after 25 years) the discarded fluid was mostly clear with only a bit of rusty debris.  I'll look for a drain cock to replace plug.

 

Refilling with distilled water and 25% coolant.

 

Thanks for all the info.

[Kidasters]

 

 

Refilling with distilled water and 25% coolant.

 

Thanks for all the info.

 

careful.  I think BMW recommends more of a 50/50 mix from what I remember.

[Mike Self]

Bob, do you remember the thread on the drain cock that you found at Ace?  

 

And jimk...I think what I used was a brass, tapered (pipe) thread drain cock, or possibly a brass pipe thread adapter, and screwed the drain cock into the adapter.  Brass is much softer than the block's cast iron, and apparently the threads were close, so that the engagement was tight enough for it not to leak (I did this somewhere around 15-20 years ago).

 

Is the original bolt a 10 x 1.50 or 12 x 1.75?  Anyone know?

 

mike

[OriginalOwner]

I'm using distilled water + 10%-15% coolant, no problems.  Here on the flatlands of SoCal I don't need "freeze" protection so I use coolant only for it's rust inhibition, lubricity, etc properties.

 

Cheers,

 

Carl

Edited February 3, 2014 by OriginalOwner

[layers]

Bob, do you remember the thread on the drain cock that you found at Ace?  

 

And jimk...I think what I used was a brass, tapered (pipe) thread drain cock, or possibly a brass pipe thread adapter, and screwed the drain cock into the adapter.  Brass is much softer than the block's cast iron, and apparently the threads were close, so that the engagement was tight enough for it not to leak (I did this somewhere around 15-20 years ago).

 

Is the original bolt a 10 x 1.50 or 12 x 1.75?  Anyone know?

 

mike

Hi Mike--

 

The brass stop-cock is 3/8 pipe; it fits like BMW made it. See McMaster-Carr [http://www.mcmaster.com/#4921k34/=qiwvrg] where they charge over $7 now. Both times I made this conversion I bought 1/4 and 3/8, then took the 1/4 back.  Mike's idea to solder a 1/4" tube to the outlet, so you can attach a flexible hose when you drain, is great.  Even if it's a long reach to find the valve wings, with the tube you will not get a mess (unless the flexible tub does not fit the soldered tube).  This is one of those little great improvements.

 

Larry

[Napes]

Mike;  No I do not remember the thread size on the drain cock.  I took the block drain plug with me and we matched the threads, by using a loose nut.

 

Bob Napier

[PaulTWinterton]

Question: should there be a crush washer on the plug? Mine didn't have one, but before refitting I thought I'd ask for knowledge. I may still go the drain cock route if I can find one. We don't have ACE here, but we do have Home Depot and Home Hardware.

Larry, thanks for the link. Now I know what I'm looking for.

Original Owner, I'm following your experience from a previous thread but upping the coolant to 25% because I'm in a "frosty" climate. Rarely goes to sub-zero and the car lives indoors.

[jimk]

Yes on the seal ring (aka crush washer).  See roadhog's pic posted above on 1/31

[ndog]

mcmaster car sells that same drain cock(petcock) with a hose barb built in

[ndog]

 it wont work if you have this condition

it is also possible once you remove the plug no water will come out.  The rust and junk is just built up right behind the plug, with it out take a screw driver or punch and knock a hole through the crud and be prepared for the flood.

  Edited February 4, 2014 by ndog

[Napes]

Drain cock thread size:  no, Mike, I don't remember the thread size.  I took the old drain plug with me to Ace Hardware where the clerk found us a nut that went on easily and we then used it to find the correct drain cock.

 

Bob Napier

[winstontj]

I searched, hence bumping an old thread... Couple questions:

 

Is the block drain plug the lowest coolant drain point in the system? Including the heater box? (meaning will it drain all of the coolant)

 

How much coolant is in the system? I don't have a 5-gallon bucket but do have several 2-gallon buckets... 

 

Is there any better way to do a slow/controlled drain? Even with use of a siphon? Trying to avoid a mess. 

 

I have jackstands under the control arm bolts. Will they get in the way of a bucket?

 

Its been a while. Is this one of those jobs that are going to make a mess --where no amount of preparation will help so just suck it up and get it over with? 

 

Thanks!

[arminyack]

Bob, do you remember the thread on the drain cock that you found at Ace?  

 

And jimk...I think what I used was a brass, tapered (pipe) thread drain cock, or possibly a brass pipe thread adapter, and screwed the drain cock into the adapter.  Brass is much softer than the block's cast iron, and apparently the threads were close, so that the engagement was tight enough for it not to leak (I did this somewhere around 15-20 years ago).

 

Is the original bolt a 10 x 1.50 or 12 x 1.75?  Anyone know?

 

mike

 

M14 x 1.5

 

The draincock I bought wont fit, as it fouls on the emboss in the block next to it as i spin it in. @#^$%&^*(!!!

 

https://fumotodirect.com/shop/standard-non-nipple/f-106

[PaulTWinterton]

Is the block drain plug the lowest coolant drain point in the system? Including the heater box? (meaning will it drain all of the coolant)

 

Probably not.  Drain plug on the rad is likely lower.  Stopcock and plastic hose would probably do the trick.  I should do that too.  It's usually a wet job otherwise.  Any pan or in my case "baby bathtub" still gets water on the subframe and floor.

 

Not to say you shouldn't drain the block.  It's the only true "flush" method for the cooling system.   Another stopcock is possible on the block.

 

On a side note: I've gone back to 50/50 coolant mix.   I found that 25% coolant attributes to wear in the water pump.   It is most notable that if my car sits for awhile, the water pump will squeal on start up until warm.   With more coolant that doesn't happen.   Better lubrication I think.