What Goes Here?

[FL911SC]

Greetings all,
I am getting ready to start the overdue project of replacing my SC trombone type cooler with a Carrera type including a fan.
At the top of the oil cooler, on the opposite side where the oil lines are, there are two threaded holes (see picture). The larger one is for the thermostat switch, what is the smaller hole for?
While researching it looks like it is just a bolt, is so why is it there? When I look into the hole, it does look like a very small hole at the bottom, so do I need rubber washer are anything special to seal it up?

As always, thank you for all the help!!

Keith

[Joe Bob]

Thermostat?

[FL911SC]

Joe B, I think the other, larger, hole is for the thermostat. But I have been wrong before. :0)

[HarryD]

Not sure but it could be a vent hole. The PET catalogs do not show this hole.

[proporsche]

there goes nada look here...
Ivan

[Joe Bob]

I'm still going with a thermostat for the cooler fan. I'm old and it's been awhile......

[JRSIII]

The smaller, threaded hole that doesn't go through is for the ground lug, if you are using the single connector type thermostat switch. If you convert to the BMW two connector switch like many do to get the fan to come on at lower temp, it's not used.

[Joe Bob]

Contact BAT Inc. they will give you the schizzle....

[proporsche]

the thermo switch goes on left..
Ivan

[JRSIII]

Yes. Switch on left. Ground on right. At least for an 1988 factory setup.

[gomezoneill]

Possibly a drain?

[stevie 77 930]

Originally Posted by JRSIII

The smaller, threaded hole that doesn't go through is for the ground lug, if you are using the single connector type thermostat switch. If you convert to the BMW two connector switch like many do to get the fan to come on at lower temp, it's not used.

+1 this threaded hold is for a ground wire. In theory, the oil cooler is supported by the rubber bushings, there by lacking ground continuity. The larger hole on the left on the OP picture is for the thermostat.

[stevie 77 930]

[FL911SC]

Thank you to all, I always appreciate this forum. I was looking at more post and pictures over the weekend, (trying to make me feel better about installing this myself) and will have to agree with the ground-wire answer. There are some pics out there which show a brown wire there. As well, stevie 77 comment about the assembly being insolated by the rubber bushing makes since that the radiator would need to be grounded. Since I am planning to install a fan (FL heat and traffic is horrible) then I be sure to include a ground wire to the radiator.
Thank you again everyone!!!!