Got an s5 Turbo, had to remove the turbo to get a new exhaust inlet gasket and also had to replace the coolant gasket that went in between the turbo coolant line and the housing. Ever since I put it back on it has been leaking no matter what I do! I got the gasket from Atkins rotary and it wont seal, as soon as I fill up the car with coolant it starts leaking 1 drop every second or so, tried gasket maker and had even worse results, even tried creating my own gasket out of a 4 barrel carb gasket and it worked better than the other ones but it still leaked on the turbo! Extremely frustrated and not sure what else to do, I've removed the studs because I broke one trying to stop the leak, re-tapped the holes and found bolts to work for them, and I also cleaned the surfaces multiple times. Not sure what else to do so I'm Asking for assistance.

 

Those mating surfaces on both sides look like they are kind of rough - lots of pitting going on there that will make it harder to seal properly, whether you use a dry gasket, RTV sealer or a combo of the dry gasket and something like a Hylomar gasket dressing for the mating surfaces. That last option is what I'd use with those parts, as it will have the best odds of getting a decent seal with minor pitting like that.

Another thing to check is the length of those bolts you're using to replace the studs - if they are a hair too long, they may bottom out before getting that flange down tight. Whatever you do, make sure the mating surfaces are thoroughly cleaned (brake cleaner works great) and dry before applying any kind of sealer to them.

The last thought is a bit of an unlikely long shot, but it's possible that the leak is coming from the joint where the pipe is brazed onto the flange itself - I've seen some of those get pinhole leaks before from corrosion breaking down the brazed joint. If that's the case, you'll need to get a replacement new/used part, or get a welder to fix what you have.

 

This probably explains why the Carb gasket worked better then the other alternatives because it molded with the imperfections unlike the dry gasket. How would I go about making the surfaces smoother so it seals better or do I just have to work with what I have?

 

If you want better mating surfaces, get a flat surface, such as a planed piece of wood, flat plywood (what I usually use), or whatever you find that's flat. Get some headliner adhesive and some fine wetsanding paper. Glue the sandpaper to the flat surface. Wet with WD40, water, or whatever you want and lap both surfaces. After a few passes, you will notice any high spots are now shiny. Go until the whole surface is uniform. After sanding, check that your surfaces are still flat using a straight edge. Clean both surfaces, apply gasket, and sealant if desired.

 

I wouldn't bother trying to lap those surfaces to get them flatter - the pitting isn't that bad, and it may cause more problems if the result isn't quite flat. Instead I would get the surfaces super clean & dry, then use the Hylomar to put a thin coating on each metal mating surface, and use the OEM gasket, torque to spec & done. Link to Hylomar at Mazdatrix so you'll know what to look for -- but if you have a good NAPA auto parts store or an industrial supplier like Grainger nearby, you may be able to get it locally and/or cheaper.

https://www.mazdatrix.com/product/hylomar-tube-1-5-oz/

 

This Hylomar, Ive never used it. Is it like a gasket maker or do you apply this to the gasket? also where would I find torque specs for that in either the FSM or on the forums. I know there is a post that listed a bunch of torque specs but I couldn't find it on there. (if you don't know them)

EDIT: I retract my statement! Found it. 17-26 ft lbs. does that sound about right?

 

Hylomar is not really a gasket maker like RTV is; it's more of a gasket dressing. It never hardens, remains permanently tacky and is resistant to most lubes, coolants & automotive chemicals. It's typically used to keep O-rings from popping out of their grooves during assembly of parts, and get you a better seal on gaskets for flanged surfaces like your coolant pipe. Another side benefit of using the stuff on both sides of a gasket is you can usually reuse the gasket after disassembly - I use the stuff on the UIM to LIM gasket, and I'll get at least 3~4 R&R's jobs out of that gasket before it needs to be replaced.

Those torque figures sound about right for an M8 sized bolt, but if it's an M6 (which I think those are, IIRC), those are normally torqued to about 85~100 inch-lbs

 

85-100 inch pounds? so like 7-10 ft lbs? ok that's a little bit reassuring cuz if it only needs to be tightened that much then this should work as long as whatever I put on adapts to the rough surface to stop leaks. Ill go ahead and get some hylomar, i found some on ebay for 8 bucks with free shipping, should I use the seal I got from Atkins or should I make another gasket out of carb gasket since that seemed to be more effective?

 

I'd just reuse the Atkins gasket if it's still in good shape. To convert in-lbs to ft-lbs, just divide by 12 (12in = 1ft), so yeah, 100 in-lbs = 8.3 ft-lbs

 

Reviving an old post!
The hylomar didnt work! I still have a leak, what else can I try?
Edit: talked to my teacher about this, said I could try JB weld to fill in the pitting and scratching before sealing it back up with the gasket., wanted to run that by you guys, let me know what you think.

 

Skip the jb weld and sand both the pipe and the intake surface flat. Use a sanding block that's bigger than the surface in order to help keep it flat. Sand it until the surface has almost to no piting. Use a gasket with a little high temp silicone. If it doesn't seal after that then you've got something bent.

 

ok, ill try that, and let you know if it works or not. how hard do I need to sand it down, though? I remember hitting it with a wire wheel and one of those industrial sander wheels before and it didn't make a difference

 

That's surprising.... Did you check to make sure the bolts aren't a hair too long like I mentioned before?

Then there's this last possibility. Best way to test for this is with a coolant system pressure test kit - free rental at Advance Auto & other auto parts shops...

 

Checked both, the bolts, if anything, might be slightly shorter than the depth of the hole. And I checked for any leaks on the pipe itself, nothing. So what do you think I should do, my teacher looked at it and said to try filling the spots with jb weld and sanding it smooth again then putting the pieces again with the gasket and hylomar or RTV

 

Had the same problem before. Don’t use Hylomar, use rtv and let it cure for a day before refilling the coolant. Haven’t had a problem after that.

 

Like the other guy said let the rtv sit for a full 24 hours. Also a wire wheel is going to unevenly remove metal. The sanding block is to help flatten the surface. It'll take awhile and you might have to change grits.

 

what grit, or grit's, should I use? 150, 200? Ive also tried the grey RTV a while back and it started leaking the second I put coolant in it after letting it set. However today im going to try the black rtv which is thicker than the grey stuff and see if that works better (after waiting 24 hours that is).

 

i would put silicon on both sides of the gasket, put it together and let it set for 24 hours if you can, and see how it is.

 

ok, so quick update. I sanded down the pitting as much as I could on both ends. it turns out one side of the pipe is actually bent inward and that is almost exactly where the leak is coming from.
I went ahead and put black RTV sandwiching the original gasket. Its been an hour so im going to tighten it to spec and then pressure test it same time tomorrow, ill let you know what happens

 

Problem solved! sanding down both surfaces and then using Black RTV with the gasket sealed it right up. tested it with a pressure tester too just to be sure.

 

excellent!