Garrett VNT-15 Turbocharger


A few years ago, I was merging onto interstate 74 and revved up my TDI to 4500 RPM. Suddenly, this thing took off like a bullet. I took my foot off the accelerator and discovered that  it really didn’t matter one bit. To keep the RPM down so the thing didn’t blow up, I started riding the brake. The smoke this thing was giving off had people behind me pulling off the road. It was just plain awesome until it made a great bucking and started missing. I limped home. After I shut it off, it would restart but only after you cranked it while it hit on one cylinder. After a compression check it was evident that I had slugged it with a bunch of oil from the inter cooler. Three rods bent. Unbelievable. What was more unbelievable was the $400.00 dealer price of a new set. These are just production con rods and not some high power racing stuff. No one had any used rods. Rebuilt? Nope. By the way, I have one good rod if you need it. What caused it? Turbo bearings worn out. I need to replace the turbo. Ooooooooooo only $800.00 bucks, The cheapest I could find at the time. GPOP turbo shop time. For less than a century note, you can be the proud owner of a rebuild kit. They are on EBAY now for $59.00. So while I have the intake and exhaust manifolds off, it is time to stop the oil migration from the engine to the inter cooler. Before I started on the intake, I gave the bolts on the turbo a good shot of rusty buster. Then while I had the intake off, for they are prone to coke up real bad, I thought to clean it out. I took the sucker outside along with my propane torch and started to heat it up. There was so much smoke that the neighbor came over because he thought the garage was on fire. By the way, you really don’t have to heat it up enough to melt the aluminum. Once it quit smoking, we were done heating. I let it cool off and then used duck tape to close off the ports and the handful of small nuts that I counted before I dumped them in. Closed off the other end and shook the crap out of it. The nuts knocked loose all the carbon inside.  Remove the tape, dump out the carbon and nuts, count the nuts so you don’t leave any in there, blow it out with air, inspect and repeat if necessary. It really works.

Wiggle and rotate the turbine. If this is locked up or there is a great deal of movement, you are probably wasting your time. This unit has some play but nothing excessive. (The turbines do not hit the scroll housing.)  Pass or fail dimensions require a dial indicator.

Remove all the bolts from both housings. Use care that you do not twist off the bolts in the cast iron or aluminum housings.  If you don’t know how much pressure you can safely apply, perhaps you have went too far already.  Stop, buy a rebuilt unit, bolt it in place.  Really though, if you managed to get the manifold off in the first place, your very good so no fear.  I had to grind and bend a Harbor Freight open end wrench to keep the turbo return oil tube from turning the boss in the block.
I scribed marks on the housings to index the rotation of the outlet and inlet.
The scroll housing shows that the turbine has moved around enough to rub shinny spots.

Remove the C clip that holds the servo arm to the lever. Yes, the bolts are still in there. My picture sequence is off a bit.

A little heat goes a long long way towards getting this thing apart. Don’t get carried away. 500 degrees is plenty to expand things.

I used a pair of large Channel Lock pliers. DO NOT TWIST. Use a ball peen to tap on the pliers to break the spool loose. DO NOT TWIST.

There is a tab on the spool that fits into this notch.   It will tolerate a little twist but not much. Usually this ring is locked up with carbon.
Remove the three pins and rollers. Set these pins and rollers aside and keep them seperate because there are three more rollers of a different thickness coming up
Remove three screws.
These are the vanes that control the angle the exhaust hits the turbine. At lower RPM the vanes are nearly closed giving a quicker response with a greater boost. As the RPM picks up and the ECM reads the boost, the vanes are adjusted to maintain this set boost number.
The advantage is a smaller turbo which gives quicker response without deadly overspeed.
Note: these are locked by carbon build up due to the E75 control being full of rust??????  It took a new E75 and a new servo to correct.
I am told that these can be freed up on the car with oven cleaner. I haven’t tried that yet but it is logical.
I set up the indicator just to see how bad the bearings are.
Again; this is a left hand thread.
Note the jaws on the vise. The vise now holds the exhaust side turbine by the flats on the center.

It is a LEFT HAND thread so be careful.
Four torq screws to remove.
Be very careful with the parts of this turbo. If you drop the turbines, you now are the owner of junk. Well, you can buy the parts for it but your cheap overhaul just went up in smoke.
The awl points to an o ring in the groove. Use a hook to remove .
Please notice the groove worn in the brass plate. That is the reason for the leak and the compressor vanes hitting the scroll housing.  
Four screws to remove.
Remove the “C” clip.
This little bugger keeps the bearing from turning in the housing. Remove with needle nose pliers. You will reuse
Bearing slips easily off the shaft.
Note this arrangement. The heat shield location and which direction  it’s cupped.
Seal rings keep the exhaust out of the bearing. They will be replaced along with the bearing and thrust plate.
No damage to the drive side. Small damage to the compressor side wher it was getting into the case. The oil and carbon were wore off. Check the shaft for any sign of wear. If the shaft is damaged at all, replace it. All these parts are available On the  Internet. The new Beast.
Congratulations!!!!! You have made a pile of parts.
The turbo number on the compressor housing. I cross checked to make sure I have the right kit. The kit fits several models and years. You have to pick the right parts. This is not hard except one bearing flange is larger in diameter for longer life.  

The one you took out.
The new one.