How to scrub a turbo? Removing Coke from Heat Shield and Center Section
 

Heyo,

I just recently purchased an el-cheapo turbo kit from one of the fellow MT members and have been doing some work to get it up to snuff.
I decided to dissect the turbo and check for any issues.
I found a LOT of this:

https://www.miataturbo.net/attachmen...ine=1346735206
(Sorry for the focus on the motorcycle, you get the idea)

SO, I have a lot of "coke" buildup in/on/around the turbo, in the center section, on the turbine wheel, etc.
I tried dipping the heat shield in Chem-Dip as a cleaning test, but after 4 hours in the stuff, no luck.
My next step would be to borrow a buddies Soda Blaster and go to town on everything, but I would like to try something less abrasive. A brush and elbow grease works OK but wont get everything, and will do nothing for the inside of my center section.

Have any of you had good luck de-funkdifying your snurbos?

Thanks for the help!
-mike

It would be just like a member of this forum to deliver a turbocharger coated in cocaine. :party:

https://www.miataturbo.net/attachmen...ine=1346736723

Its EVERYWHERE!!!

Oven cleaner.

^^^That's a good idea and a good long soak in that stuff might go a long way.

I used a Dremel-like device with a bunch of small Scotchbrite pads for general cleanup, and tiny steel cutting burs to get in tight crevices. You can buy the pads mounted on mandrels already, and in different grades. If you use a bur you need to be exceptionally careful not to remove any metal from the wheel. I also found that I needed to clean out the groove where the snap ring style seal fit, as it was really gunked up too. I followed up each round of cleaning with some time in a hot ultrasonic bath, which helps soften what's on there as well. If you are not friends with a jeweler (who is likely to have an ultrasonic), you could probably find one who would be willing to help.

I tried soaking the heat shield in extra strength oven cleaner over night. No luck.

I am worried that there was enough exhaust backpressure in this guys system that he turned the carbon deposits into diamonds!

soak it in brake cleaner or seafoam.

I have tried SPRAYING brake cleaner several times, and I got very little or no progress.
I have NOT tried soaking in it, I will pick up some seafoam to try soaking the turbine wheel in it.

But I do have good news....

I have been experimenting with trying to de-carbonize(?) the heat shield. Scrubbing + Carb cleaner got some of the mild stuff off but left on lots of hard carbon chunks.

While trying to clean off the hard chunks I have tried:
Spraying Carb cleaner - No progress.
Spraying Brake cleaner - Nothing
Soaking in chem dip for 4 hours - Nothing
Soaking with High Strength oven cleaner over night - Nothing
Blasting with a sand blaster - EVERYTHING was off in 30 seconds! The heat shield looks perfect. :yippee:

My only worries now are cleaning off the turbine wheel, and inside the center section.
I don't want to mar any important surfaces inside the center section or on the turbine wheel, so I am hesitant to blast away.
Do you guys see any issues with sandblasting the turbine wheel and center section?

I will try soaking them in the Seafoam first.
Then I will then try the Scotchbrite dremel method.

I will let you know how it all goes!
Thanks for the help,
-Mike

P.S. I have wanted an ultrasonic cleaner for years. This may just be reason enough to justify one! :burncash:

I would not sandblast the wheel, as deformation of the blades may occur (depending on how high the pressure is), and you may also leave a textured surface that may affect airflow at some small level.

The Scotchbrite pads can theoretically remove metal, and alter the surface as well, but my guess was that it would be negligible if it did happen, and there would certainly not be any deformation of the wheel. AFAIK the turbo I rebuilt after cleaning with those methods is still OK.

Thanks Matthew,
What do you suggest for the inside of the center section? I don't think I can really get scotchbrite pads/etc in there.

Hmm, I didn't have to go that far. Is it the contact surfaces where the axle shaft spins, or the oil passages?

The oil passages inside. I will take photos when I disassemble it more.

That's probably going to be a bitch to clean out. If it's coked up so badly that the passages are restricted then some careful scraping/picking with dental tools might go a long way. Super coarse bottle brushes (if there is such a thing). If you have a built in restrictor in the chra then it'll be even harder to get in the feed side.

I'd try soda blasting. Its powerful enough to take off paint, surface corrosion, and varnish but not hurt glass, chrome, or bare good metal.

sorry, i meant brake fluid.

My buddy has a soda blaster. I have never used one before. I will check it out and see how aggressive it is.

DOT 5 or 5.1?

Its just baking soda and people make effective home made ones with some tube and tube fittings and just an air compressor blow nozzle so I'm going to bet its not all that harsh. They use it to strip the paint and most of the rust off cars now and they dont have to do any masking work, also seen it used to clean carbs so if it doesnt damage the brass in those things there's no way its going to do anything to a turbine wheel.

Hey guys,
Thanks for all the advise.

NONE of the chemical treatments worked for me, but:
The soda blaster was amazing!

It took all of the built up carbon off and did no noticable damage to anything.
Note: I didnt blast any of the internals or any journals or races.
On the turbine wheel I masked off the whole shaft with tape and the soda didn't do any damage to it.

If you have a turbine wheel or heat shield that are COVERED in carbon buildup, the soda blaster will take it all off for you, no problem! Don't waste your time/money with the chemicals.

-Mike