[kcgman]

I'm a new BMW 335d owner. Bought the car two weeks ago and still going through the break in process (<3500 RPM and under 93 mph). Even at under 3500 rpm the car really seems to move. I'm looking forward to getting past the 1200 mile break in period. I have two questions about the turbos on the car.

1. When do the turbos kick in? I've put the car up to 3200 rpm (quite accidentally) while merging into highway traffic when two trucks had me in an awkward spot. The car accelerated VERY quickly at that point and probably engaged one of the turbos -- but in truth I don't know. Since then, I've been below 2500 rpm.

2. I've read that I shouldn't engage the turbos until the oil temperature in the car is warmed up. Unfortuantely, the 335d doesn't have an oil temperature gauge. I've heard different things about how long it takes to get the oil to its proper temperature. My question is, "What harm is done (if any) if the turbos are engaged when the oil temperature is cool?" I've been told by two different dealers two different things. The first said, "It's bad for the turbos." He wasn't specific, but it made me a bit paranoid. The other dealer said, "The turbos won't be very responsive when the oil is cool, but it doesn't do the turbos any harm. If that was an issue, the BMW engineers would have built in fail safe to prevent damage." That second answer seemed plausible to me, because it would seem pretty silly to remove the oil temp gauge if doing so put the turbos at risk. Anyway, I'd love to hear from someone who knows what the issue is/isn't.

Thanks in advance.

[Insider]

The turbos kick in as soon as you step on the gas to accelerate. There is no way not to keep the turbos from spooling when accelerating up to speed.

[kiwistu]

Hi

I have a 335d, turbos go the whole time, I would certainly follow the guidelines re run in, however don't get too paranoid.
My car definately warms up, but very quickly, I always use the heater as a guide if your getting hot air in the cabin - its warm, and then I give it a few more minutes, however the good news is with a 335d its so powerful you hardly need more than 3000 rpm...

Cheers
stu

[Xipher]

Originally Posted by kcgman

I'm a new BMW 335d owner. Bought the car two weeks ago and still going through the break in process (<3500 RPM and under 93 mph). Even at under 3500 rpm the car really seems to move. I'm looking forward to getting past the 1200 mile break in period. I have two questions about the turbos on the car.

1. When do the turbos kick in? I've put the car up to 3200 rpm (quite accidentally) while merging into highway traffic when two trucks had me in an awkward spot. The car accelerated VERY quickly at that point and probably engaged one of the turbos -- but in truth I don't know. Since then, I've been below 2500 rpm.

I believe with the sequential turbos, the smaller turbo is almost always going at the lower RPMs, then as you continue to speed up and get to the higher RPM's, that's when the second, larger turbo kicks in, giving you the quick acceleration you felt.

[Socom]

Originally Posted by Xipher

I believe with the sequential turbos, the smaller turbo is almost always going at the lower RPMs, then as you continue to speed up and get to the higher RPM's, that's when the second, larger turbo kicks in, giving you the quick acceleration you felt.

+1, BMW has been using this sequential setup in their diesels for a few years now.

[R1200RT]

Originally Posted by kiwistu

Hi

I have a 335d, turbos go the whole time, I would certainly follow the guidelines re run in, however don't get too paranoid.
My car definately warms up, but very quickly, I always use the heater as a guide if your getting hot air in the cabin - its warm, and then I give it a few more minutes, however the good news is with a 335d its so powerful you hardly need more than 3000 rpm...

Cheers
stu

I don't think the heater is a reliable source, since that uses the cooling fluent. IMO oil temp should be OK before you start to push.

It was explained to me that valves in the cooling system make sure there is a short circuit that heats up quickly and enables the interior to warm up soon after drive off. It than gradually lets in fluent of the bigger circuit until all of the fluent is at operating temp.

Considering that my dealer didn't bother to tell me to run it in and since there are no gauges for water and oil temp, it soes not seem terribly important to BMW. Probably because it is such a torquee engine and nobody has a need to high rev it under normal road circumstances. You can be very quick without high reving.

Bottom line: it's a theoretical issue.

[kcgman]

Thanks for the responses. My sense is that no one has heard of any issue with engaging the turbos prior to the oil getting to temp. To the extent that the turbos are engaged at any time the car accelerates, it would suggest that the turbos are fine when the oil is cool.

[Insider]

Originally Posted by kcgman

Thanks for the responses. My sense is that no one has heard of any issue with engaging the turbos prior to the oil getting to temp. To the extent that the turbos are engaged at any time the car accelerates, it would suggest that the turbos are fine when the oil is cool.

What they probably meant, as with the 335i, the car does not reach full boost when the oil is cold. Therefore, you won't be making full power on a cold engine.