20G assembly
Starting with a good DSM 19C
Add: a rebuild kit
a new 20G compressor wheel
a new take off 5H turbine shaft
The new compressor housing has a 3" inlet flange
Disassemble: This turbo has unknown miles on it. It was purchased used then we used it on two different Conquests before it ended up here. The turbine shaft does have a tiny chip off the end of one fin so this shaft won't be reused here. Since the cartridge was already enlarged for the exducer of the 19C compressor wheel it was an easy decision to swap to a 20G wheel -they have the same diameter exducer.
The new 20G wheel and the new take off 5H turbine shaft.
Clean the empty cartridge, inspect for cracks, use a Dremel tool to smooth the surfaces you can. After it is clean, rinse it again by spraying with some brake/carb cleaner. Wipe dry all cracks and grooves. If any old oil or rust is still present re-clean the cartridge.
Looking at the back of the cartridge you can see the surface that the rear oil seal seats to. Just below (inside) where the seal rests you see a thin groove -make sure this is cleaned out you may have to use a razor blade or similar tool to scrape the coked oil from. The surface for the seal must be clean, smooth, free of rust cuts or scrapes. The oil seal is less than 1/8" wide and it has to press into its final resting position so the path must be clean.
Below is the turbine shaft. The oil seal (ring) fits into a groove on the shaft and that is all that keeps the turbo from leaking out oil into the exhaust stream and causing a turbo to turn your car a smoke machine. This seal has nothing to do with "shaft play".
The two bearings are pressurized with oil. The oil goes all around the bearing inside and out to keep the turbine shaft to floating in oil. No oil = dead turbo and it takes just seconds to do that.
If your turbo has allot of "shaft play" that is up/down then these bearings are worn but it will likely also be the center of the thrust plate. Front/back "shaft play" is the thrust plate. The thrust plate is soft material, the bearings are a little harder. These are serviceable parts to save the turbine shaft from damage but nothing will save a turbo if it has no oil pressure.
You can see the flow of oil (this is kerosene) enters from the oil feed on top and goes to both front and rear bearings but the most oil goes to the thrust plate. Thrust plate has several moving surfaces and the front oil seal to lubricate. At full boost a turbine shaft can spin in excess of 150,000 rpms. Can you now see how a turbo gets oil and why it needs it?
Below, the front bearing goes in the center. You can see the oil supply hole/groove
This is the same as above only shown further back, there is the large cavity where the oil collects and where it drains from.
This is the oil feed in the top. The large hole going outward (towards the top) is the thrust bearing/front seal oil passage and the lower smaller hole is for the front bearing.
This hole is the oil passage for the rear bearing which passes some of that spent oil on to the rear oil seal. Most of the oil from the two bearings goes towards the center of the shaft and drains out.
This is the rebuild kit. It contains all the moving internal parts you need. The only parts you will reuse if you use this kit are the cartridge, the turbine shaft and the compressor wheel. All the other parts go in the trash can. Some kits do not contain all the parts so look closely at what you are buying. This kit has the curved back plate to use the new style compressor wheel.
Have clean oil to dip all the pieces in. Put the oil seal on the turbine shaft. Insert the rear bearing into the cartridge. (it doesn't matter which way it goes in it is the same either way)
The cover for the back of the cartridge should lay flush with the top of the cartridge.
Carefully insert the shaft through the bearing stopping just before the oil seal has contact with the cartridge. The oil seal now has to compress and seat into the cartridge. If you cleaned the cart. well and you have oil on the seal it should go in easily. The back of the cartridge where the seal slides in is tapered to make to allow this to be easy. If you have difficulty you can press in on the sides of the seal with two long thin screw drivers but you shouldn't have to do that. Hold the shaft from now on until all the front pieces are in or it will come out and repeated moving in/out of that rear oil seal is not a good idea.
Slide the front bearing over the shaft. Did you remember to dip this in oil first? You can see the holes all around the bearing, this is how the oil gets to the center to lubricate the shaft. Its these few tiny holes on the front and rear bearings that allow this turbo to function. These are floating bearings -not to be confused with "ball bearings".
Push the bearing back into its resting place. There are small snap rings to keep each bearing from falling into the center. You can usually reuse these unless you started with a junk dead oil starved turbo cause they are a real pain if you don't have long needle snap ring pliers.
This piece seals to the rear face of the thrust plate. If you have allot of front/back shaft play, this is the piece that ate the center out of the thrust plate and it will allow allot of oil to pass through to the front towards the oil seal.
This is the thrust plate, notice the small hole and the bullet shaped detent. The detent is to disperse the oil over the back and the small hole is to keep the plate from rotating.
The plate will only go in one way. The small hole you can see goes over a roll pin. Notches in the thrust plate at the center are on both sides.
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Next push the o-ring into the groove.
Pay attention here, don't get ahead of yourself or you'll have to pull the oil seal off.
DO NOT AT THIS TIME DO THIS
You don't put the oil seal on yet, this part has to go through another part first. See below this picture.
This part goes in like this before you put on the oil seal.
If you had put the oil seal on first you won't get the seal to pass through this plate.
Now you can put the oil seal on, just hold in the middle and push the two sides outward and onto the part. Don't flex the seal and put on side in then the other. Twisting isn't good, just like you shouldn't twist piston rings but that is another section.
This is the front oil seal now pushed into the backing plate. You can see this is a backing plate for a curved back compressor wheel. This front oil seal won't pass into the center of the plate like the rear oil seal did. Using something thin like two tiny screwdrivers, push the ends of the oil seal into the groove. With a little finger pressure, mash the pieces together. Of the whole turbo rebuild this is the hardest part. The crucial part is making sure the cartridge is clean before you start -just remember to dip each piece in oil.
From the back, this is what you should see. The backing plate has a groove around the outer edge for the tin shield to pay in.
You're almost finished. The o-ring makes pushing this last piece into place harder, just keep it flat and the turned down portion on the shield goes void where the oil collects to drain. You may have to use something to push this down into the cartridge it fits really tight with the new parts.
Install the snap ring, tap gently with something to make sure the snap ring goes in all around not just the two ends.
Put the large o-ring on that seals the cartridge with the compressor housing and push on the new compressor wheel.
Use some type of locktite on this nut and torque it down. This shaft/nut are left hand threads.
Locktite bonds in the absence of air. It will harden up after you put the nut on.
Here's the new cartridge.
Next fit the cartridge to your turbine housing and mark where you want the compressor housing to be indexed. Pull the cartridge back off then put the large snap ring into the compressor housing.
This next step is very important and I'm sure more than one turbo was ruined from not priming it before starting the engine. You can do it "by the book" if you have nothing to do for 3 hours except watch oil slowly drip into that tiny feed hole but if you want a quick and more effective way try this: Using an old oil feed line, cut it off and connect a short piece of vacuum hose to it.
Go to a pharmacy, like CVS and they will give you a small syringe for free. Suck up some oil and then inject it into the cartridge while you spin the blade with your fingers. Do this 5 or 6 times- or more if you like. The oil goes in easily and this just takes a couple minutes then attach your oil feed line. Roll the engine over long enough to allow the oil feed line to fill with oil BEFORE you let the engine start.
If you are not sure the oil feed line has filled with oil, remove the oil drain hose and place that in a bottle. Roll the engine over long enough to see the oil flowing from the drain hose BEFORE you let that engine start!!
There it is. Ready for the water lines.
