Hi guys. Like the title says, I was porting the wastegate on my ebay T3 turbo, and being my first time, I made the rookie mistake of porting toward the top of where the flapper seats juuust a smidge too much. The flapper occasionally catches on the edge. Would it be possible to take it to a shop and have them weld in a 1 or 2mm bead, then smooth it down, or am I just out of luck at this point? It is just maybe less than a millimeter of material missing that is causing this. I also found a couple threads on this, and it seems some used a C-clip on the rear of the flapper to get rid of some of the play the flapper has:
https://www.miataturbo.net/diy-turbo...ng-open-66148/
https://www.miataturbo.net/diy-turbo...-inside-33373/

My tuning appointment is May 12th, and I’m stressing out now about getting this fixed. Any help is really appreciated! I’ll upload a video below of what is going on:

 

The material is weld-able, but the access may be quite difficult. Take it to a shop and see if it will cost you more than the turbine housing.

Maybe they won't laugh at you?

 

What he said ^
Thats a really tight spot but jamming a mig gun in there might be possible. I could see a couple trigger taps and grinding to solve it

 

Thanks guys, I actually can remove the flapper door portion, as its held on by 5 bolts so then the turbine housing will be on its own and the hole is easily accessible. Not sure if that made sense, but I can take a pic if needed. Do you think any welding/auto shop may be able to? I also have no idea where to buy only a turbine for one of these turbos, usually its just the whole turbo that Im seeing.

 

Doesn’t that turbo cost like $5 shipped? Just buy another one lol

 

Probably, it came with my MKTurbo kit so whatever Lars uses is what I have, lol. I was able to solve it though I think; I made a little bevel around where it was hitting, and it now seems to glide right over the edge and seal down as expected. Hopefully that solved it, I tried getting it to hang for 5-10 minutes straight, and it seems good to go.

 

ahhh, that’s good news that you got it from him. He seems to have found the “best” of the “Chinese” turbos. Two words that don’t typically belong together when it comes to quality control.

 

Yep that is what I've heard! This issue was my own rookie mistake; its my first turbo car ever, and my first time ever porting a wastegate, so live and learn. At least now I know for the future. I noticed where I beveled there is a slightly less than 1mm gap there where light is able to pass through, but hopefully it won't cause too many issues with holding boost. The more I know for future builds the better. At least it closes now without hanging up.

 

If you weld it then it may be difficult to then get a machine flat seat for the wastegate penny due to the access - could even make sealing worse across the whole panny area. I'd possibly try it as it is unless a replacement is v cheap - I'd then just jump straight to replacement.

You might find you get poor boost response and there is a risk of overspinning the turbo to reach your boost targets if you are accidentally wastegating. Will it actually be an issue - no empirical answer but it can't be performing 100%.

 

Have you asked Lars if he can get you a replacement housing? He may also know of customers that have upgraded and would have used turbo to sell. I would def contact him.

 

Thanks guys, I actually did contact him and he gave me a link to a replacement turbo, they aren’t terribly expensive so I went ahead and ordered one. Going to use the housing off of it, and then I’ll have the rest of the turbo as a spare. Going to be more conservative and careful this time around. Any tips to make it go smoother this time? I’m going to avoid the top portions of the wastegate and just cut where I have plenty of metal to work with.

 

I have used a die grinder with a rounded carbide bit for porting. The rounded bit means you are less likely to take a chunk by accident.

I marked around my closed wastegate penny with sharpie while it was closed then openned it and marked within the penny seating area by another amount - say 3mm and marked that so that I had a no go zone that would leave at lease 3mm of seating area. Work slowly, light pressures - a good bit will do all the work and eats cast steel like butter.

 

Great, thank you for the tips! I ordered some carbide bits off of Amazon, and will need to go pick up a die grinder from harbor freight. I originally used a Dremel, and it was a bit of a nightmare, so hopefully the die grinder will make it easier and smoother. Going to definitely work much slower this time around.

 

I welded a thick washer in my turbine housing to shrink the passage. It was a little tricky to get the area flat enough to seal but it wasn't so bad.

You guys do realize that the flapper assembly is removable, OP said it already.

 

If the wastegate flap is removeable and you have a clear vertical shot at the wastegate port then I would simply drill it with a pillar drill and suitable sized drill bit - easy and accurate. I know people that have successfully done this and you get a perfect round hole.

I never had this option so used a die grinder with a good carbide bit - it was little fuss to be honest.

The problem is then feeding your grinding addiction - have to be careful what you have in sight in the garage as you're going to have to feed that hunger going forward.

 

I put paint on the flapper and closed it tight. Shows exactly where the edge is. I left a millimeter or two away from the edge. Mine wasn't centered on the hole, so when I started grinding, the hole became more an oval than a circle. I didn't take any material from inside the housing. I'm only running 11 lbs. of boost but no creep.

 

I’m going to need to use paint or grease on the flapper face this time, thank you! I figure it should be an oval since it seems there is a lot more material towards the bottom the first time around.