Question about turbo?

[Sil80sushi]

im mostly having the white smoke thing but i dont think its my headgasket. Anyways how does the oil go through a turbo, does it go down the shaft of it? and if there is leak in the shaft can oil get into the turbo it self? also can someone tell me more about shaft play and what to look for if a turbo is blown?

[Hijacker]

Oil does indeed go around the shaft. There are two seals on the turbo that keep oil from getting into the housings. One is the thrust washer retainer. On a stock T25, it's held in place with a snap ringI labelled it compressor seal in this pic

The other side is what I had always called the dogdish. It's pretty much held tightly by the exhaust turbine.

Oil coking up the bearings, the shaft, or the backside of the dogdish (as you can see in the last pic) will cause failure. With excess coking of the dogdish, it can lead to oil leakage. Also, since it's held in place from tension of the exhaust turbine, shaft play can help lead to leakage as well.

when you're looking for shaft play, you're checking to see if the shaft moves up/down left/right. You can always expect a minor amount of play. It's the nature of things. If there was absolutely no play at all, the bearings and shaft would be locked up. But you want to look for excessive play. It's hard for me explain because I always go by feel, but the best I can describe it is that you need to see if it could contribute to wobbliness under high loads.

[Sil80sushi]

wow this is awsome info!! thank you very much Tenkawa_Akito i think ill be looking more into my turbo. is the turbo fairly simple to take apart and put together? alsowhen a turbo is blown is it because the oil is seizing the turbo or is it from shaft play?

[Hijacker]

Turbos blow for various reasons. It depends on the abuse the turbo has been under. Most bad turbos are just old turbos that are being asked to perform too much. So the subsequent problem is that the shaft gets some play in it as the old journal bearings start to get play in them.

Poor maintenance will lead to an oil problem causing your failure. Changing your oil regularly is the key to a healthy happy turbo. Since oil is used to lubricate, and help shed heat from the turbine shaft, the oil will begin its heat induced breakdown process earlier than NA motors. That's why we use synthetic oils. Synthetics resist thermal breakdown a bit better than traditional dino oils. As the oil breaks down, it leaves deposits behind, which results in coking. Like what was left on the back of the exhaust side dogdish. The dish was coked so badly, I couldn't get rid of all of the charred oil. I got rid of enough though.

I do have one correction to my original post. The dogdish isn't held in place by the exhaust wheel. It's held in place by the exhuast housing. The wheel just completes the seal in the center. Bad bearings will allow oil to seep in around that center seal.

Taking apart a turbo is not an easy task. Breaking it down to the CHRA and compressor/exhaust housings is easy. Just make sure you mark the orientation of both of the housings so you know how to line them back up. I made the mistake of cold carb dipping all of my parts with only using paint to mark my orientation. I'm glad I had taken pictures to get me back into the ballpark for alignment.

Pulling the center shaft out and replacing bearings is not a fun task, nor is it something I would recommend for those that are not good at mechanics. The c clips are a royal pain to get in and out without long, thin c clip pliers. we had to use makeshift pliers made of two long picks. And that made for some painful installation. What had caused premature failure on my turbo was that one of the c clips had either disintegrated or was rattled out of place. Either or, one of my bearings was free to move about, and cause some shaft play. Thankfully not anything catastrophic.

[Sil80sushi]

thank you very much again Tenkawa_akito i think my turbo is just old then i remember when the motor was out there was oil in the turbine area so turbo rebuild kit searching time

[doridori23]

Just a quick question. If your blowing white smoke what makes you feel it is the turbo at fault?

If your 100% sure it is not water vapor (from a head gasket or cracked head, or warped head all due to overheating or errors in torque pattern/values) then it is probably from running lean. If your running lean that means you dont have enough fuel for the amount of air in the cylinder and none of those problems go back to the turbo.

Some oil is to be expected in the intake after turbo. Even if your catch-can never over flows there will always be a small amount of oil vapor that will make its way through the intake and into the turbo/intercooler piping.

[Sil80sushi]

well im not 100% sure, well let me just tell you on what happens maybe that will help a little more?when i start the car no smoke, when i start driving though that is when smoke happens, when im cruzing in lower RPM's it happens but when i build boost its clear till i let off the gas after i do that its pooooooffffffff smoke. From what i have read people will bad Hg or Warped head they smoke constantly even when stopped and in all RPM ranges.............. also when i was looking at the turbo before the motor went in there was oil actuly in the turbine of the turbo.