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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: wrchunter on August 29, 2016, 11:27:31 PM

Title: Coolant drain plug blocked by engine
Post by: wrchunter on August 29, 2016, 11:27:31 PM

My very first run in with a miss-designed BMW motorcycle part...had them for decades...airheads, K bikes, oil heads...and I went to drain the coolant from my newly acquired 1993 K75 S and found I could not completely unscrew the drain plug because of interference with the engine.  No problem...just pop off the coolant hose...but it is disappointing.  Just wanted to rant! Or did I do something wrong????http://www.motobrick.com/Smileys/MB_Smiley/falldown.gif

Title: Re: Coolant drain plug blocked by engine
Post by: Laitch on August 29, 2016, 11:53:36 PM

Welcome, wrchunter!

How about posting a photo of this low point in your life so we can all live this drama along with you?

Title: Re: Coolant drain plug blocked by engine
Post by: Motorhobo on August 30, 2016, 01:26:57 PM

I've found that some screws can only be removed with the OEM allen key -- not enough clearance to get any kind of socket or extension in there. Did you try it with the allen wrench?

Title: Re: Coolant drain plug blocked by engine
Post by: The Mighty Gryphon on August 30, 2016, 01:49:56 PM

+1 on the photo.  I have three K bikes and have never had a problem removing a drain plug on any of them, even using my Harbor Freight Allen wrenches.  Even after replacing the plug with a sender for the temperature gauge I've not had any trouble.

In two+ years of hanging around these forums for the k bike I've not heard of anyone else having your problem, either.

Title: Re: Coolant drain plug blocked by engine
Post by: Chaos on August 30, 2016, 04:35:27 PM

It has a drain plug?  I just pull the hose off the bottom.

Title: Re: Coolant drain plug blocked by engine
Post by: F14CRAZY on August 30, 2016, 04:57:31 PM

Either just pull off the bottom hose or be cool and have a temperature sensor instead of a drain plug

Title: Re: Coolant drain plug blocked by engine
Post by: wrchunter on August 30, 2016, 05:25:48 PM

See attached photo. The rust colored drain plug, when unscrewed with a allen wrench, and then after removing the wrench, trying to unscrew the plug entirely...it butts up against the rectangular portion of the engine.

Title: Re: Coolant drain plug blocked by engine
Post by: Martin on August 30, 2016, 05:30:39 PM

Weird I have a 92 K75S and never had a problem screwing mine out. :dunno

Title: Re: Coolant drain plug blocked by engine
Post by: The Mighty Gryphon on August 30, 2016, 06:32:22 PM

That's not the drain plug.  The coolant drain plug is on the cylinder head side of the water pump.  If you have a temperature gauge it will be the sending unit for the gauge.

I am pretty sure that what you are trying to remove is the plug over the oil pressure relief valve.

Title: Re: Coolant drain plug blocked by engine
Post by: The Mighty Gryphon on August 30, 2016, 06:38:50 PM

If you have two sending units on the cylinder head side of the pump assembly, the water pump unit will be the lower one.  The other is for the oil pressure idiot light.

A word of caution, if you do have a sending unit for a temperature gauge, be careful not to put too much torque on it.  The walls are thin, and it isn't hard to twist the head off the sender resulting in a costly replacement.  Tighten it just about a quarter turn beyond finger tight.

Title: Re: Coolant drain plug blocked by engine
Post by: The Mighty Gryphon on August 30, 2016, 06:45:49 PM

As far as removing the plug in the photo, it is easy when the pump has been removed from the engine.  Since the pressure relief valve controls the oil pressure in the engine, I wouldn't doubt that the BMW engineers in their Teutonic wisdom opted to make it difficult to tamper with.

Title: Re: Coolant drain plug blocked by engine
Post by: Laitch on August 30, 2016, 06:55:06 PM

Take a look, wrchunter. Conveniently located for gravity operation.

Title: Re: Coolant drain plug blocked by engine
Post by: wrchunter on August 30, 2016, 10:10:13 PM

Duh!  Thanks for the info.  My faith in the BMW engineers is restored and my fearlessness in the garage will have to be tempered!

Title: Re: Coolant drain plug blocked by engine
Post by: The Mighty Gryphon on August 31, 2016, 08:37:51 AM

We were all newbies at one time.