mazdaspeed7

Got any pointers? Im definately mechanically inclined, do my own porting and rebuilding, and everything else on the car, and I trust my abilities. I just want to hear if anyone has special tricks, tips, etc. And do the rebuild kits come with instructions, or is there a write-up on how to properly disassemble the turbo? Im pretty sure I know what to do, I just want to be 100% sure.

Flyrx7

iTrader: (1)

First of all, index all of the housings with alignment marks (punch tool), so you know how it all goes back together. Same goes for the turbine shaft and compressor wheels (little scribe marks). Add alignment markings and numbers for each.
If possible, line up a bead blaster, it'll help clean up the turbines and housings, if not, well, brass brushes and elbow grease are what you need. You can even use carb dip for the shaft and wheels.
Abother tip is to get or make a giant c-clip tool. The compressor housing C-clips are MONSTERS, and need a monster tool to get em' off. I ended up making mine by welding small pieces of music wire to a set of channel locks, worked awesome, actually.
Other than that, it's pretty straight forward, as long as all of your parts are decent, but I wouldn't hold your breathe (I'm somewhat of a pessimist I guess, having been there, done that)
Good luck.

Frank

mazdaspeed7

Thanks. My bead blaster definately gets lots of use...

Anyone else?

pp13bnos

iTrader: (1)

You stepping into the 3rd gen world? Welcome aboard. CJ

mazdaspeed7

Well, kinda. My 90 TII is getting a REW. I didnt plan on the conversion, I was just going to restore the car, but I was given a running REW long block. I believe the front turbo had some oil blow-by, but other than that, the turbos are in great shape. No shaft play, etc. I just want to rebuild them to be sure. And Im looking into upgraded compressor wheels too...

Kahren

iTrader: (13)

how much do the bearings and the wheels cost?

Brentis

ok - I've seen it mentioned many times.. what the hell is a bead blaster?? Sandblaster? thanks.

Kahren

iTrader: (13)

its a device that uses a little nossle, say inside of a box inside which u put the parts u want to get cleaned or blasted and u operate it with gloves. the device either uses sand or little beeds

spooledUP7

People tend to panic when they see oil coming out of the compressors. This is pretty normal as long as they don't lose a quart of oil every 100 miles through it.
If you are going to rebuild them, take a long hard look at putting in new cartridges, or else don't bother separating the compressor housing from the cartridge. I would separate the turbine housing so that you can check for any major cracks, or scaling. Also, if you are going non-sequential, you can port out the wastegate while you are there. If you go that rout then you should also grind out the precontrol wall and grind the second exhaust path into a more streamlined shape. Cracked manifolds are perfect candidates for non-sequential setups.

mazdaspeed7

Spooledup7, thanks for the reply. The turbos will be non-sequential, an dthe wastegates are getting ported within a few days. I already have the turbine and compressor housings off both turbos, and the cardridge disassembled on the turbo that I believe was leaking oil. I prefer to replace the seals anyways, and Im considering upgrading the turbos too.

And a bead blaster is the same thing as a sand blaster, but it used glass beads instead of sand, which are considerably finer. And its all in a nice cabinet...

BTW, I dont think either of these turbos *really* need a rebuild, but I would rather do it now, than later down the road.

cournal

make sure you check the manifold very carefully useing a flash lite. there WILL be many cracks inside. this is where a lot of boost is lost. i don't know if rebuilt turbo units come with new manifolds. they most likely don't and are not perfect either.

Flyrx7

iTrader: (1)

Correct, all rebuilds are using suspect, used housings. If you can find a used housing out there worthy of using in a rebuild, my hats off to you. The only way to get good housings is to buy an entirely new turbo from the dealership, as you can't buy just the housings. Mazda pretty much fucked up with these turbos by not offering replacement parts on an individual basis. So as a result, people hack on these and go non-sequential, or go single turbo. Every one of those cars' resale value goes down as a result. MAzda would have sold more of these cars I'm sure if the turbos system was a little more user friendly, or at least serviceable.

Frank

Flyrx7

iTrader: (1)

And I believe it's nearly impossible to weld the housings too, as there just isn't enough nickel content in the metal. If anyone has had there housings welded, with good, long term results, please post your findings here.

Frank

cournal

you are correct als. every one i take off has boost loosing cracks. when i did my motor i put new from mazda turbo assembly. what a difference.

cournal

you are correct. every one i have removed has boost loosing cracks. when i replaced my motor i put new mazda turbo assembly on also, what a difference.

FD4S

Hey you guys, the real problem I've seen with the stock turbos is the manifold. It seems that a mojority of these turbos have cracked manifolds due to the heat cycling of the sequential system. IMHO, I would go with Flyrx7 and have a GOOD look at the manifold and if it seems OK, then the chances are that the turbos themselves are in even better shape.

spooledUP7

(old thread)
If or when I rebuild my motor, and if or when I replace my turbos with new ones, I will be sure to ceramic coat the internals, and wrap the turbos with insulator tape.
Cast iron can withstand the test of time if it cools at a slow pace (hence the need for turbo timers). The only problem with turbo timers is that they cannot gradually decrease the exhaust temps far enough to cusion the cool down rate between on to suddenly off.
Insulator tape should slow the cool down process to a less crack prone rate as well as hold back underhood temps.

duboisr

Garfinkle has had two sets welded and milled . One set has 20,000 miles with no return cracks the other set came from BNR with many cracks , and he had them welded before putting them in the car. The parts to be welded need to be v-groved and preheated before welding . Then the gasket surfaces need to be milled back smooth .

Flyrx7

iTrader: (1)

Any idea who welded them? How big were the cracks you're talking about?
When I talked to Turbo City and Turbonetics the said that unless the cracks are 8mm or less (IIRC) that it could be done, but most turbos I"ve seen have been cracked much further than that.
Also, where were the cracks you're talking about, at the flange, wastegate, turbine housing, pre-spool bridge? It seems the most severe cracking occurs in the turbine housing and wastgate area, both very difficult areas to weld (if that were even possible).

Frank