[bimdaddy]

Originally Posted by Brisk

its really hard to hear the E pump on after shut down, i heard it once and i had my ear aganist the dashboard. lol

Your wife/gf was probably wondering what the heck you were doing. Kinda remind me of a commercial of a guy in his garage giving his RX8 a hug while the wife looks at him from the driveway

[A418t81]

Originally Posted by Brisk

dont really let my cool off ever.
these are ball bearing, twin scroll turbos that run synthetic oil in them. this alone goes along way in helping the turbos last longer

with water cooled turbos, the water actually goes around the bearing, cooling it so the oil does not cook inside. but this has marginal effect once the car is shut off. in the N54's case, this water cooling continues to flow and does not allow the oil to cook even when the engine is shut off.
bmw is not stupid guys.

Your whole post is simply wrong.

The turbos are not ball bearing, they are standard journal bearing. They are certainly not twin scroll either, standard turbine housing. Finally, water currents DO move through the turbo without the water pump thanks to convection and its effects are far from marginal.

[e46e92love]

Originally Posted by 5sokol335icoupe

i guess bmw's isnt good enough

You got it.

[e46e92love]

Originally Posted by A418t81

No need to idle and let your turbos cool unless you just got done beating on the car and came to an immediate stop. The turbos are water cooled which saves the oil in the bearings from coking.

Originally Posted by My1stbimmer

At times I could hear ther turbo's still spooling after I shut my car down.

My1st has finally made a great point. See A418 what you fail to factor into your line of thinking is that the turbos are spooling down with no oil pressure, and even mild boost can induce 100,000 rpms from our little guys. Spooling down with no oil pressure can lead to earlier turbo bearing fairlure. Remember, they only warranty our cars to 50K, so for me (I own mine) I am doing the little things to make sure they make it 100k and maybe further

[Cyruz]

the 335's turbos are not fully oil cooled. this was talked about alot about a year ago. it was a big concern for a lot people who left the S4 world to come over here. it was a big weak spot in the S4.

[A418t81]

Originally Posted by e46e92love

My1st has finally made a great point. See A418 what you fail to factor into your line of thinking is that the turbos are spooling down with no oil pressure, and even mild boost can induce 100,000 rpms from our little guys. Spooling down with no oil pressure can lead to earlier turbo bearing fairlure. Remember, they only warranty our cars to 50K, so for me (I own mine) I am doing the little things to make sure they make it 100k and maybe further

What you fail to factor in is that I have been playing with, and rebuilding turbos for years. I know more than you what kind of rpm the turbos turn and when they do it. I'm also here to tell you that unless you went full throttle and shut your car down, you AREN'T hearing your turbos "spooling down." The wastegating system on the N54 shunts ALL exhaust away from the turbine when the wastegate is open, which is all the time you don't have your foot decently into the gas. Even with this occuring there is still a bit of rpm in the turbo when you shut it down, but not nearly enough for you to hear anything. In a conventional turbo with a pressure actuated WG, it does not hurt the bearings with decreased oil pressure for the turbo decelerate to a stop once you shut down your engine (turbos spin at a fairly fast rate at idle as well, no amount of idling will slow them down any more.) ...And I own my car outright as well.

Cyruz, the S4 k03s are oil and water cooled exactly like the mitsus on the 335 are. The problem with the K03 was the amount of heat they and their support oiling and coolant lines were subjected to, as well as the insane shaft speeds needed for those absolutely tiny compressors to make any amount of appreciable boost.

[AWD Addict]

Originally Posted by Brisk

dont really let my cool off ever.
these are ball bearing, twin scroll turbos that run synthetic oil in them. this alone goes along way in helping the turbos last longer

with water cooled turbos, the water actually goes around the bearing, cooling it so the oil does not cook inside. but this has marginal effect once the car is shut off. in the N54's case, this water cooling continues to flow and does not allow the oil to cook even when the engine is shut off.
bmw is not stupid guys.

So much news in this thread!

We have TWIN SCROLL turbos?!?!

I thought these were sleeve bearings, no? I def don't think they're BB though.

[A418t81]

My post up towards the top of this page fixes his most egregious errors

[bimdaddy]

Thanks guys for all the infos provided. I've learned alot about turbos reading all these posts. Those two little guys sure work hard and never complains. All I know is it's a hell lot of fun stabbing that Go-pedal.

[arefog]

On page 57 of the owners manual under "Switching off the engine" there is no admonition about letting it idle before turning it off. I have owned older turbo cars where the manual specifically suggested a cool down period. Just a data point to add to the discussion.

Dick Fogg

[BoostedBMW]

Originally Posted by e46e92love

My mechanic suggested that every-time I stop that I leave it running for 15 secs or slightly longer to make sure oil is being forced through the turbos as they slowing stop turning. The turbine section can accelerate upwards of 200,000 rpms and when you turn your car off it the turbos are still rotating they are slowing down with no oil moving through them, and that can kill a turbo, especially the bearings.

I am also someone who lets the car idle for a minute before shutting the car off after driving the car hard since I want the oil circulating also. As far as the turbine spinning though, pretty much as long as the car is running, the turbine will be spinning. On my last car I had a top mount setup so the turbo was right in your face when you would pop the hood and after shutting the car down after idling you could hear the turbo spinning down for a good 8 seconds or so after shutting off the car. My last car was even smaller displacement with a decent sized turbo so this car should be no different with the two small snails (well, actually, it is a little different since the wastegate setup on this car is not like a typical turbo car where they are always shut until your desired boost is reached, but I wouldn't think that would change the fact that they are still spinning at idle). Basically, if the car is running, the turbines are spinning so no matter how long you let it idle for they will never come to a full stop.

[unagi1]

If you can't see them glowing, then it's ok to turn the car off.

Seriously, unless you are running high boost I wouldn't even worry about it.

[Wosby]

Originally Posted by 1clean335i

yea, i take it easy the last few miles and let it idle for about half a minute or so then i shut it off...

+1 I do the same thing.......

[bullmrkt]

Originally Posted by bimdaddy

After some aggressive runs, I usually take it easy the last 1-2 miles to give the oil time to cool off the turbos. I haven't had a turbo car since my 85 Isuzu Impulse Turbo 1st gen. Back then, shutting down immediately after a hard run can cause the oil to cook on you turbos = early turbo death. With today's advance tech, not sure if you still have to do that, but I always do.

I let mine jump in the pool for a quick dip. Theyre so cute spooling around in the water...sigh theyre growing up so fast!

[bimdaddy]

Ok so after a hard run yesterday on day two of SSTT, I did hear the epump buzzing after shutting down for like 15 sec now that I'm listening for it. That's good to know BMW is on top of things.

[DrTurbo-Ö]

Half a minute should be enough for reaching a well temp at the turbos.
BUT: More important is to slow down the throttle leg until reaching the correct oil temp after starting the cold engine. Thanks god we have the oil temp gauge...
M.

[5soko]

these turbos are not BB? somenone is in trouble!! time for a linky.

[unagi1]

Aren't these things TD-03s? Even if they were retrofitted with BB CHRAs there wouldn't be that big of a difference. Please let's not go into a BB vs. sleeve bearing tangent on baby turbos...

[A418t81]

Yes, TD03s. They are sleeve bearing, and as you stated, no reason for BB with such tiny turbos.

[BayerischeMW]

seeing as not only the turbos get hot, driving carefully 5-10 mins and idling a bit is a good idea. ever been on the track and stopped your car without a cooldown? blue, smoking brakes that won't brake

allowing the turbos to cool down is good thing.

[bimdaddy]

BB vs Sleeve? All I know those two suckers put a smile on my face everytime I plant the right foot. To me, taking it easy the last few minutes is like saying thanks for all the hard work, little guys