Draining the Thermostat?

My bike 1993 R100GS

While going through the Moto-bins on-line catalogue I saw a tool used to drain the oil from the thermostat.

I went to my Owners Manual, Haynes Manual and Clymer Manual nothing is mentioned about this procedure.

I e-mailed Moto-bins to ask and they said the tool was needed.

Anybody else have an opinion, or instructions?

Snowbum writes that the GS doesn't have a thermostat but uses a sized hole to control the flow of oil.

http://bmwmotorcycletech.info/oilingsystem.htm

Thermostat

The tool in question is used on the bottom of the thermostat that is part of the oil cooler attached to the block at the oil filter. A GS doesn't have a thermostat.
But if you have an RT or RS, then you'll find a 6mm plug on the bottom. Inserting the tool will open the thermostat and allow the oil to drain out of the cooler that is mounted in front of the engine.

It's not really about draining.

Rather, forcing the thermostat open with this tool allows the oil cooler to refill after being drained. You don't want that to occur at 5K rpm.

The GS doesn't have a thermostat as noted, and oil flow through its cooler is constant and refill after an oil change is automatic. The GS frame is such that there isn't room for the thermostat BMW used on R100RS and R100RT, although I've seen one for GS from the aftermarket, perhaps Siebenrock.

On my R100RS, I always removed the lines from the thermostat before removing the thermostat from the engine block, so draining was pretty much a given. Still needed this tool to get the cooler refilled.

lkchris said:

It's not really about draining.

Rather, forcing the thermostat open with this tool allows the oil cooler to refill after being drained. You don't want that to occur at 5K rpm.

Click to expand...

This is what my local BMW expert mechanic told me too. He suggested installing the bolt and that I crank it over with the plugs shorted until oil pressure builds up. This fills the oil filter and the oil cooler. However, I rode bikes equipped with oil coolers for years before I learned this trick and never had any problems.

Wayne

thermostat bolt

The use of the bolt, as has been noted in this thread, is NOT for the GS models, which do not have a thermostat.
GS models use a sized hole in the cover. GS models need a cover over the cooler if weather is COLD.
BMW changed the size of the hole in the cover of the GS model, and has a bulletin out, long ago, on this.
all the info is in my website.

The special bolt, 10 mm hex, and threaded area 23 mm long (some faulty ones, longer, were made...DO NOT USE)...is used to refill the cooler.
You really do not need to use the bolt for ''draining''; nor refilling. That original advice was 'sort-of' superceded. DO it if you want to.
The cooler will be drained anyway when the thermostated or GS type plate is removed for an oil filter change. On the GS, it drains back some after resting a bit.
Since it is USUALLY OK to do a filter change every other oil change, using the bolt is really a personal choice on non-GS models. Using it will give less fresh oil contamination by old oil.

Photos and part number, blah blah, on the thermostat special screw are in the following article, but you will have to scan downwards
to item #23:
http://bmwmotorcycletech.info/tools.htm

There are FIVE articles on oil, lubrication, changing oil and filters, critical measurements.....and an additional oiling system sketch article, on my website.

Snowbum

toooldtocare said:

This is what my local BMW expert mechanic told me too. He suggested installing the bolt and that I crank it over with the plugs shorted until oil pressure builds up. This fills the oil filter and the oil cooler. However, I rode bikes equipped with oil coolers for years before I learned this trick and never had any problems.

Wayne

Click to expand...

Nothing wrong with the plugs shorted technique, but it's overkill. Any engine can start and run after an oil change without damage as long as kept at idle speed. It only takes maybe at the most 15 sec for the oil pressure light to extinguish--just like on your car, etc. Remember there are some cars with metal-jacket oil filters that are fitted upside down, so it definitely takes the motor running to fill that filter the first time.