[r3za]

I recently got my E90 335i - Right now it has ~ 200 miles total on it..

It takes the temperature gauge (below the RPM) so long to heat up to operating temperature, which I believe is 3 marks past the 210. Is this the case for everyone? Is my 335 running too hot?

I normally dont start to drive it hard until it gets to the 210 mark at least.

[BMW335TT]

thats the oil temp level.. not the temp of car

[rjm]

The Oil Temp will take quite some time to heat up. It is NOT a water temp gauge. Go ahead and drive it immediately according to the Operator's Manual.

[TahoeOG]

mine's been up their before 2 lines above 210. But you should turn on your car and go, no need to warm up. Drive at moderate speed -100mph and no higher than 3500rpm.... In other words drive it calmly untill it get's around the 210 marc... then your all good.

[akwhite330i]

Originally Posted by billmister

mine's been up their before 2 lines above 210. But you should turn on your car and go, no need to warm up. Drive at moderate speed -100mph and no higher than 3500rpm.... In other words drive it calmly untill it get's around the 210 marc... then your all good.

I find it hard to keep it low (under 3500 rpm? I thought 4500 is acceptable).... esp in these winters, it takes a good while before the car gets to 2 lines above 210. Oh well, I guess patience is a virtue...

[r3za]

okay so my understanding is that the oil temp is not the water temp and therefore does not actually correlate with how hard you can drive the car.

Is there no water temp gauge?

[Shawn_speed]

Originally Posted by r3za

okay so my understanding is that the oil temp is not the water temp and therefore does not actually correlate with how hard you can drive the car.

Is there no water temp gauge?

R3Za:

Congratulations on the awesome new ride, have a blast and avoid getting air borne at all costs.

Although the gage is for oil and not water, if you know how the engine management deals with engine heat, you will be able to use it properly.

The car has an electric ½ HP coolant pump. Unlike a mechanical coolant pump that circulates water as soon as the engine is turned on and shuts off when the engine is turned off, and its efficiency is RPM dependent, the electric pump does not start when the car is cold; consequently this engine warms up faster. You may notice you get heat inside the car pretty quickly.

By same token, once the car is shut off, the coolant pump may continue to run to deal with heat soak. This is why unlike older turbos; you don’t need to idle before turning engine off after hard driving. The oil won’t coke inside the turbos.

There is a paddle activated, mechanical oil pump inside the crank case. When the engine is turned on, the pump pressurizes and sends oil to the oil filter. The oil filter assembly has a by pass gate that is thermostat activated. It by passes the oil cooler and re-circulates the oil inside the engine for quite a while before allowing the oil to be routed to the cooler. I suspect the sensor for our oil temp. Gage is downstream of the oil cooler. Since the cooler is inactive for quite some time, it confuses the drivers because the oil temp gage doesn’t move for quite sometime after a cold start although there is clearly heat inside the car. Once the gage starts to move, it moves quite rapidly towards “normal”. As a general rule, I don’t push my car until the temp gage has started to move.

Now “normal” has different meaning in the case of this car and has caused a lot of consternation. We are used to temp gages that get to a point and just sit there. If they move up when it is hot outside or we push the car, we get nervous and assume the cooling system can’t handle the load.

This temperature movement between 210 and 240 in the 335i and some tweaking from Audi forum members has freaked out many 335 owners.

The real answer may be this car is like a big brother and “looks” and determines how you are driving. It uses four different maps based on your driving; 226.4 f economy, 219.2 f normal, 203 f high and 194 F high +map-thermostat (otherwise known as haul ass mode) for optimum cylinder head temperature. I suspect it also changes the allowable oil temp. coming out of the oil cooler in reverse proportion to the above cylinder head temperatures. Hence the rise in oil temps. witnessed during aggressive driving on the oil gage and all the rumors about heat transfer problems for this engine.

Shawn
Phoenix

[r3za]

Hi Shawn,

Thanks for taking the time to write that up. It was useful to me and I'm sure it will be to other members as well.

[Deveray]

+1 The most informative note I've read on this subject, thanks Shawn

[SpiralOut]

Excellent info Shawn. Thanks!

[poiney]

Thx for detailed write up.

So why do folks attribute that the engine temp of interest is correlated to water temp? Is this because water temp is supposed to measure the temp of water adjacent to cylinder walls and oil that fills the gaps, that is most critical to avoid damaging engine?

If my statement is correct, how do I estimate this temperature on BMW, since I also find that the temperature gauge is painfully slow to reaching steady state.

[Corey]

Water temperature is the temperature of interest because its job is to cool the engine and as such its temperature will give you a good idea of how well its doing. The primary job of your oil is to lubricate the engine however many cars are fitted with an oil cooler to aid in cooling the engine.

Generally it's not good idea to push the car too hard before the oil has warmed up because oil's viscosity (thickness, or resistance to flow) is greater at low temperates. If you start your car up and rev right up to 7,000 rpm the thick, cold oil may not flow well enough to keep up. This is why it's important to let the oil heat up before you push it too hard. On the other hand, if the oil becomes too hot it will not be viscous enough to provide proper lubrication so the oil cooler can be important for this reason also. Ideally the oil's temperature will allow a happy compromise of lubrication and flow.