I agree. Thermostat difference is likely the cause. However....

Something that causes a change in resistance in that temp sensor
circuit, will affect needle read out. e.g. now clean or cleaner
connections to sensor or even sensor body to engine case. (ground
side)  But maybe my electrical logic is reversed here. The temp sensor
graph in Bentley will shed light on that.

From what little I know, if the cylinders were honed or are new and
honed, oil changes aside, seating the rings is one of the most
important factors during break in.

This image:

https://jrcengineering.com/wp-content/uploads/2016/03/184815_cylinder_break-in_diagram.jpg

from here: https://jrcengineering.com/technical-support/piston-ring-seating-problems/

helped me understand why one shouldn't "baby" the engine or idle it
too long during first few runs. That said, I see you're at the 2K mile
mark so I'd say that if you've done your first oil change(s), the
engine is "broken in".

Neil.

On 11/1/18, Dan N <dn92610@gmail.com> wrote:

> I have a rebuilt WBX 2.1 engine in my van and it's running with the temp.
> needle a fraction over the red LED light. With the old engine the needle
> stays under the red LED light, the difference is a bit more than the
> diameter of the red LED light.

>
> so I have these questions:
> - how many miles for a proper breaking in period on a WBX 2.1? 3K? 6K? 9K?.
> Mine has about 2K miles as it today.
> - is it correct to assume that every engine of the same model/size runs
> with different temp and there's no set value for reference?
> - will it runs cooler after the breaking in period?
>
> *note: the temp. sensor, thermostat are new. - I use 80° thermostat on the
> old engine and rebuilt engine has a 87° thermostat.*
>
> thanks
>
> dan
>

-- 
Neil n

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