[StiffUpperLens]

Hi all, can anyone tell me what normal coolant and oil temps are for the 330d?

I've been sus about mine running too low for a while.... in cold weather, I am seeing mid 70's (c) on the hwy... low 80's in traffic and 90 when I'm booting it.

I'm also seeing similar temps for oil only a couple of degrees higher for each of the above.

Coming from petrol land, I would have thought coolant should hover around 90 and oil 100 but maybe the diesels are different?

A new thermostat is on order as it's an easy fix to swap it out, but maybe someone here can shed a bit of light on this?

[StiffUpperLens]

A polite and cheerful bump..

[POBEP]

Coolant temp ~ 89C, thermostat is 88C

The coolant temp will rise above 90C during DPF regen, uphill driving, towing.
(my 335d never goes above 95C, X5d record is 104C uphill with loaded trailer)

It may also drop below 88C during no-load/downhill driving.
(my 335d never goes below 84C, X5d record is 80C after 15min downhill in the winter)

Oil temperature maybe be different from coolant and usually slightly higher.

Your 70C at highway speed is classic sign of failed thermostat.

Change it ASAP as it has costly downstream impact on glow plugs, DPF regen, etc
Unlike petrol, BMW diesel is by far less tolerant to coolant temp.

[StiffUpperLens]

Originally Posted by POBEP

Coolant temp ~ 89C, thermostat is 88C

The coolant temp will rise above 90C during DPF regen, uphill driving, towing.
(my 335d never goes above 95C, X5d record is 104C uphill with loaded trailer)

It may also drop below 88C during no-load/downhill driving.
(my 335d never goes below 84C, X5d record is 80C after 15min downhill in the winter)

Oil temperature maybe be different from coolant and usually slightly higher.

Your 70C at highway speed is classic sign of failed thermostat.

Change it ASAP as it has costly downstream impact on glow plugs, DPF regen, etc
Unlike petrol, BMW diesel is by far less tolerant to coolant temp.

POBEP, you are a gentleman. Thank you, stat has been ordered.