Are these flanges in need of resurfacing?
 

Hey guys, I'm about ready to throw my FM turbo kit on within the next couple of weeks, but I just took another look at all my flanges and am wondering if they're in need of resurfacing. After cleaning them a bit, the original machining marks are all clearly visible, but the surfaces do have some slight corrosion / pitting in certain areas. It's also somewhat difficult to get the downpipe elbow on and off of the turbo (takes 30-60 seconds of pulling and wiggling to get it off the studs), but I'm not sure if that's common for that part or if it means it has warped slightly. Let me know what you guys think.

https://lh3.googleusercontent.com/OY...0=w508-h677-no

https://lh3.googleusercontent.com/Tb...c=w508-h677-no

https://lh3.googleusercontent.com/GQ...E=w508-h677-no

https://lh3.googleusercontent.com/hb...U=w508-h677-no

https://lh3.googleusercontent.com/z1...s=w903-h677-no

https://lh3.googleusercontent.com/_w...A=w508-h677-no

Speaking of that downpipe bend... I also noticed a couple things I'm not sure if I should be concerned about there. On the flange to the turbo there is a small hole. Not sure how that happened, but it seems like there's a good amount of wall thickness all around it. Also, looking on the inside of the pipe, there's some strange orange/amber colored... stuff... that almost looks crystallized. I'm not sure if anyone's seen something like this before or what it might mean. I don't think its affecting the structural integrity of the downpipe, but it intrigued me when I saw it.

https://lh3.googleusercontent.com/a0...o=w508-h677-no

https://lh3.googleusercontent.com/xh...c=w508-h677-no

https://lh3.googleusercontent.com/49...A=w508-h677-no

https://lh3.googleusercontent.com/WG...4=w508-h677-no

Thanks for your input guys, I'm a bit new to turbo stuff so I appreciate the help.

I would just resurface them. It would probably cost a lot more to install them and then realize it is a problem. Cost even more, if the car is already at the track and you realize the trackday has ended because of something you were wondering if you should have fixed in the first place.

Boost leaks just plain suck, if you are ok with spending a bit to get them machined flat, really machined, not belt sanded, you'll appreciate it rather than going through the hassle of tracking down your leak.

Hit it with a wire wheel to remove all the rust, and use a new gasket on the manifold to head surface. That will be fine for that surface.

For the manifold to turbo surface, do the same, no gasket, see how it looks after cleaning it. Flat is what matters, but so does smoothness. I surfaced my turbo flanges with sandpaper and a flat block to get them flat but also, smooth. Then apply a tiny amount of grease and bolt together. Flat and smooth won't leak, grease burns up to carbon to help seal it further. Carbon won't burn out like a gasket will.

That is so genius I hate you.

The grease trick is pretty genius, something like that would never have occurred to me. I'll probably try that out on the manifold->turbo and turbo->downpipe surfaces.

Anyway, I had tried contacting a couple local machine shops with no luck, but I just remembered today that I have a friend who works in a shop that builds a lot of machinery. He said I can drop it off Thursday and he'll get it done for me next week for the price of some beer, so that's looking like a no-brainer now.

That said, I didn't ask what kind of equipment he was planning on using. I'm assuming they're going to be able to actually machine it based on the work they do, but if he does end up using a belt sander, what about it would cause that not to seal well? Is it the lack of control over how much material is taken off? Not doubting you, just curious.

Belt sanders aren't flat, generally. I'd bet given the right sander I could get flanges pretty damn flat though, it would just take a really obscure and large belt sander.

Your friend is a saint if he's gonna grab and mill all that crap for the price of beer. That gas separation tab is going to make machining the downpipe a fun one for sure, belt sander or not.

Personally, I'd get a stone and block that rust and small stuff down myself. Find a real straight edge and make sure nothing is really out of whack, there's no need to make unnecessary work for anyone.

Go get you this big brick, use the soft side. Use grease like Pat said, I did the same and it works fantastic.

Sharpening Stone - Combination Sharpening Stone

The weird orange deposits look like what you get from using certain octane boosters in gasoline. I stopped using off the shelf octane boosters (switched to race gas) after I noticed orange crystalline buildup on my spark plugs back in the late 90's in my Mitsubishi Galant VR-4.

Keith

I use gaskets and copper gasket spray on pretty much all my metal gaskets. Even my v-bands have gaskets. #NoLeaks.

Surfaces have to be flat and smooth. Belt sand will for sure make them smooth, but not necessarily flat unless it's a big ass belt sander that IS flat, AND they guy using it knows what he's doing.

Milling it will make it flat. If they keep the feed rate very low, it will also be smooth which is good, but a lot of shops go fast and leave obvious cutting-marks on the surface (not smooth).

Thanks for the knowledge bombs everyone :)

I was thinking the same about the separator on the downpipe, so like you guys are saying I'll probably try and smooth this stuff out myself first and see my friend can just check for straightness at his shop. Home depot has a similar sharpening stone, so I'm gonna head out there in a minute and grab one.

Plus make sure you specify no belt sanding and don't pay for the work until you inspect the piece.

My shop supposedly machined my flanged on my old manifold and upon inspection after a shit load of boost/exhaust leaks was obviously belt sanded.

Yes. Best is to talk to your machinist. I always ask how they are going to machine it, what machine, what surface finish and feed rates. These are good questions so you know what to expect.

So I tried my hand at blocking them all myself last night with a sharpening stone from home depot. I used the fine grit side, and all surfaces seem smooth now. The pitting is still slightly visible as tiny dark spots on the surface, but I think its just discoloration as I can't feel anything. The stone even squeaks a bit as it slides across the surfaces now, and the original machining marks have been mostly worn away, so I think I have the smooth part of the equation down.

As far as flat, I'm not so sure. An unavoidable part of the blocking process was the fact that as I ran the stone across the surface, it would very slightly tilt as it came to the edge, so there's maybe between 2-5 mm or so on the outer edge of every surface that got worn down more than the rest. I'm not sure if that's going to be a problem, but the rest of the mating surface looks flat and I can't see any gaps on the edge when the surfaces are placed together. There are also some small areas that don't look like I've even touched them even after spending 20 minutes on that surface (especially on the downpipe inlet, that separator is really a bitch to work around), leading me to believe I'm either not wearing it down evenly or it wasn't flat to start with. I'm trying to do broad sweeps across the entire surface in order to keep things flat. I'll spend some more time on it later today and we'll see how it turns out.

Go pick up a machinist flat edge and some feeler gauges. You'll know if you did it right after that. You really don't want to find out after you bolt it all back together again only to rip it apart.

Well I told my friend I tried smoothing it out myself and he told me I was wasting my time lol. He even said the separator on the downpipe should be no problem for them and that his coworkers were looking forward to helping with it (they're all huge car guys) so I guess I'll just let him take it from here. They're going to machine everything, no belt sander, so I think I'll be in good hands.