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E99 turbo. How do I orient the compressor backplate?

2K views 14 replies 4 participants last post by  JimTJr 
#1 ·
First, why they didnt key these things is beyond me.

I may have reassembled my turbo wrong so I have it on my desk and want to tackle it today. I need to know how to orient the compressor backplate to the turbo base. its 4 bolts for the base to backplate, and 4 bolts for the housing to backplate. Of course it has rotational symmetry so i only have a 25% chance of getting it right.

When assembling the first time i had an 'oh crap' moment because I didnt think to take pictures of it. I looked online for pictures and tried to piece it together according to the pictures.

There are a few items I can orient this by. the weird looking bearing oiling assembly (probably most important part), the arrow behind the compressor wheel on the backplate, or the flat spot where it looks like a sticker goes on the backplate.

Ive also noticed the 1999.5 and later pictures are different, like its a 5 bolt housing. Ill post some pics as soon as i download them off my camera.
 
#2 ·
Ok I figured out that the oiler / bearing / whatever it is that goes into the back side of the compressor you can only put this in 1 way. Its keyed, I tried to get it to go another way and so far have not been successful. Am I right that it will only go 1 way?

Now for the actual backplate itself. Logic tells me that the smaller feed line is supposed to go to the machined valley area of the oiler around the bearing. (forgive me for wrong names) The largest port would be the return would go in the open area.

So am I right? Please see picture. The red lines are where everything will go when everything is put together, somebody please correct me if I am wrong, I dont want to be pulling this turbo out again. (although the first pull was 1 hr, the 2nd was 30 minutes. both on a hot engine.)

 
#3 ·
anybody?
 
#4 ·
I thought you would have figured it out by now. I see you have started another thread about this so I'll give you some info.

It is keyed, sort of. You have to look at the whole assembly. The compressor cover also only fits one way. So if you are going to connect the CAC tube to the compressor outlet, it should be obvious how everything fits together.
 
#5 · (Edited)
Nope. it doesnt fit only 1 way. mine is a 4 bolt not a 5 bolt. therefore I can rotate mount the compressor backplate in 4 different positions and the tubes still line up fine.

Look at the picture, i know you cant see the top bolt, but the whole thing has 90* rotational symmetry.
 
#7 · (Edited)
Nope. it doesnt fit only 1 way. mine is a 4 bolt not a 5 bolt. therefore I can rotate mount the compressor backplate in 4 different positions and the tubes still line up fine.

Look at the picture, i know you cant see the top bolt, but the whole thing has 90* rotational symmetry.
Instead of me looking at the pictures, why don't you look at the parts? Wouldn't that better solve your issue? The picture doesn't show the correct side of the backing plate to show what I'm talking about anyway.
 
#6 ·
Are you sure??

On my E'99 I realized that bolt holes would only line up a certain way - I would triple check that.

Either that, or the top can only go onto the backing plate one way and the whole assembly can only go one-way do to the outlet.
 
#10 ·
Either that, or the top can only go onto the backing plate one way and the whole assembly can only go one-way do to the outlet.
Nope, ive been able to put the backing plate + housing together each of the 4 ways and get the bolts started. I looked on the net for a picture of the non-symmetrical backing plate you guys are probably thinking of and havent found it. Ive found it before so I VAGUELY remember seeing it, but cant find a link.
 
#11 ·
Thanks, ive actually read through that a few times before doing the rebuild and just tried to find any documentation in those captions on how to orient the oiler with the pedestal with no luck.

What a simple question which can cause a simple mistake which could destroy a turbo due to lack of oil if the wrong choice was made. Like in my OP I think these things should have been keyed.
 
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