Kroon Harness for 944 Turbo

[NCGermerican]

I remember eyeing up that insert on my manifold somewhat recently since it looked like some of the original sealant had fallen out. I convinced myself it was not an issue, but should take another look. What material do you think is best to make the repair: JB Weld?

JB weld would be the only thing I would trust to seal it up if I wasn’t going to remove the threaded insert. However if I’m able to remove and reinstall, any type of high temp thread sealant should also work.

[Tom]

I have an update and HOPEFULLY can get some closure on my issues.

1) I found an intake leak at the banjo bolt fitting. It looks like the threaded insert into the IM has come loose.
I was finally able to find this through a boost leak test and some soapy water. I don't think the smoke machine caused enough pressure.

2) I found (2) exhaust leaks while smoke testing the exhaust system through the primary o2 bung in the crossover pipe. The first is easy - it was at the junction flange that Lindsey Racing made. Easy enough to tighten down. The second was more.....disheartening. I was showing smoke at the crossover to turbo junction. I took everything apart AGAIN and tightened down all 4 bolts. Such a fun thing to do. I got them as tight as possible and STILL SMOKE! The problem - the weld must have cracked from the pipe to the flange. I saw a post on another forum that someone had the same issue. Since today is Memorial Day, there doesn't seem to be an exhaust shop open to have it welded up. Honestly, the factory welds inside the flange are pretty crappy. I'm surprised they didn't weld on the outside of the flange to the pipe, unless they were worried about a weld getting too close to the bolt holes, not allowing for a washer to sit flush against the flange?

Regardless, both of these could at least be contributing to my issues. Especially the exhaust leaks that could (in theory) be introducing oxygen prior to both o2 sensors, creating incorrect AFR readings on the o2 sensors.

The leak at the small banjo fitting could be affecting your fuel pressure too, since the fuel-pressure regulator uses vacuum from that port as its reference. At idle/vacuum, that could push the AFR richer, while the vacuum leak itself would push the AFR leaner — so anyone’s guess where it nets out. Even less predictable as you actually drive the car... Bottom line, that’s an especially bad place for a vacuum leak, so very good thing you found it!

As for the crossover, be careful with ordinary muffler shops. Very few are set up to weld the factory 951 exhaust pipes properly, since they are made from a close cousin to Inconel — a high-nickel “super alloy” that really wants TIG welding with the right filler material. I’d try to find someone who specifically understands that material, rather than just letting a general muffler shop burn it together. Did you get that from Lindsey? They should stand behind it, no?

[NCGermerican]

The leak at the small banjo fitting could be affecting your fuel pressure too, since the fuel-pressure regulator uses vacuum from that port as its reference. At idle/vacuum, that could push the AFR richer, while the vacuum leak itself would push the AFR leaner — so anyone’s guess where it nets out. Even less predictable as you actually drive the car... Bottom line, that’s an especially bad place for a vacuum leak, so very good thing you found it!

Definitely - and it didn't show it's ugly head until I put more pressure to the system than what the smoke test could generate. I tried to remove those inserts and it really requires some sort of special tool to get them out without destroying them. I have them tightened as much as I can and will use some J/B weld around any gaps. If that still doesn't do the trick....looks like I'll be on the hunt for another intake manifold.

As for the crossover, be careful with ordinary muffler shops. Very few are set up to weld the factory 951 exhaust pipes properly, since they are made from a close cousin to Inconel — a high-nickel “super alloy” that really wants TIG welding with the right filler material. I’d try to find someone who specifically understands that material, rather than just letting a general muffler shop burn it together.

I took it to one of the most well known, independent exhaust shops in the Raleigh area. Nothing against your typical MAACO or any other shop like that, but the place I use is trusted by all the car nuts around here. They put together all sorts of custom exhausts, including stainless, titanium, etc. I talked to them about how it's a steel flange and some special type of allow tube. Strange Porsche would use 2 different materials that probably don't play well together with welds to begin with. They TIG welded both the outside and inside of the flange as well as flattened out the flange with a belt sander. It wasn't super warped, but the belt sander did show it wasn't perfectly flat anymore. It all looks great but I'll smoke test the system again once it's back together.

Did you get that from Lindsey? They should stand behind it, no?

I had bought another crossover pipe from eBay and I sent it to Lindsey to have the modification done, so I doubt they would accept any responsibility for one of the factory welds to have failed. I still have my original crossover as a failsafe, but who knows if that one is leaking at the flange seams as well. I really don't want to go through all the work of bolting it up to find out it's also leaking.

[Mscromer]

I just had to remove mine to reseal them. To remove them get a long bolt that threads into the inserts. I believe it was 8x1.0. Along with a nut for the bolt and a washer and lock washer. Thread the nut all the way on the bolt then lock washer and then regular washer as to not mess up the flat sealing surface of the fitting. Then screw in the bolt until all the threads are engaged in the fitting. Hold the bolt and jamb the nut onto the intake fitting very tight. Then you should be able to use the bolt to unscrew the fitting.

[NCGermerican]

I just had to remove mine to reseal them. To remove them get a long bolt that threads into the inserts. I believe it was 8x1.0. Along with a nut for the bolt and a washer and lock washer. Thread the nut all the way on the bolt then lock washer and then regular washer as to not mess up the flat sealing surface of the fitting. Then screw in the bolt until all the threads are engaged in the fitting. Hold the bolt and jamb the nut onto the intake fitting very tight. Then you should be able to use the bolt to unscrew the fitting.

That's a great idea! I'm going to give this a shot. I hope ace hardware has some long M8 x 1.0 bolts and threads.

What did you use to seal it up when you reinstalled?

[Tom]

The leak at the small banjo fitting could be affecting your fuel pressure too, since the fuel-pressure regulator uses vacuum from that port as its reference. At idle/vacuum, that could push the AFR richer, while the vacuum leak itself would push the AFR leaner — so anyone’s guess where it nets out. Even less predictable as you actually drive the car... Bottom line, that’s an especially bad place for a vacuum leak, so very good thing you found it!

Definitely - and it didn't show it's ugly head until I put more pressure to the system than what the smoke test could generate. I tried to remove those inserts and it really requires some sort of special tool to get them out without destroying them. I have them tightened as much as I can and will use some J/B weld around any gaps. If that still doesn't do the trick....looks like I'll be on the hunt for another intake manifold.

As for the crossover, be careful with ordinary muffler shops. Very few are set up to weld the factory 951 exhaust pipes properly, since they are made from a close cousin to Inconel — a high-nickel “super alloy” that really wants TIG welding with the right filler material. I’d try to find someone who specifically understands that material, rather than just letting a general muffler shop burn it together.

I took it to one of the most well known, independent exhaust shops in the Raleigh area. Nothing against your typical MAACO or any other shop like that, but the place I use is trusted by all the car nuts around here. They put together all sorts of custom exhausts, including stainless, titanium, etc. I talked to them about how it's a steel flange and some special type of allow tube. Strange Porsche would use 2 different materials that probably don't play well together with welds to begin with. They TIG welded both the outside and inside of the flange as well as flattened out the flange with a belt sander. It wasn't super warped, but the belt sander did show it wasn't perfectly flat anymore. It all looks great but I'll smoke test the system again once it's back together.

Did you get that from Lindsey? They should stand behind it, no?

I had bought another crossover pipe from eBay and I sent it to Lindsey to have the modification done, so I doubt they would accept any responsibility for one of the factory welds to have failed. I still have my original crossover as a failsafe, but who knows if that one is leaking at the flange seams as well. I really don't want to go through all the work of bolting it up to find out it's also leaking.

Tell the exhaust shop they were welding Incoloy 800 (pipe) to a flange that is either mild steel (if magnet sticks hard) or ss304 otherwise. It's a cousin to inconel, so if they are set up for Inconel (filler 82) they should be able to get a lasting weld. If they treated it as stainless, which a lot of people mistakenly do, it is likely to crack. I'd call and ask. If they can't give you specifics on the process/filler (I.e., not, don't worry we know how to weld, etc.) I wouldn't trust it. Of course, I have trust issues with most shops.

[NCGermerican]

Tell the exhaust shop they were welding Incoloy 800 (pipe) to a flange that is either mild steel (if magnet sticks hard) or ss304 otherwise. It's a cousin to inconel, so if they are set up for Inconel (filler 82) they should be able to get a lasting weld. If they treated it as stainless, which a lot of people mistakenly do, it is likely to crack. I'd call and ask. If they can't give you specifics on the process/filler (I.e., not, don't worry we know how to weld, etc.) I wouldn't trust it. Of course, I have trust issues with most shops.

Well great. Now you have me scared.....

They broke out a huge magnet and it almost flew out of his hand onto the flange, so I'm thinking it's mild steel. It's already all welded up. They definitely weren't laying dimes, but it also only cost me their shop minimum ($75).

They also recommended using some copper high temp exhaust gasket RTV. They said in a perfect world the crushable donut gasket should be enough, but I'm not dealing with a perfect world.

IMG_8048.jpeg (161.09 KiB) Viewed 97 times

IMG_8049.jpeg (150.84 KiB) Viewed 97 times

[Mscromer]

I just had to remove mine to reseal them. To remove them get a long bolt that threads into the inserts. I believe it was 8x1.0. Along with a nut for the bolt and a washer and lock washer. Thread the nut all the way on the bolt then lock washer and then regular washer as to not mess up the flat sealing surface of the fitting. Then screw in the bolt until all the threads are engaged in the fitting. Hold the bolt and jamb the nut onto the intake fitting very tight. Then you should be able to use the bolt to unscrew the fitting.

That's a great idea! I'm going to give this a shot. I hope ace hardware has some long M8 x 1.0 bolts and threads.

What did you use to seal it up when you reinstalled?

I used Earl's Performance Instant Pipe Sealant or any type of high temp pipe sealant would work.

[Tom]

Tell the exhaust shop they were welding Incoloy 800 (pipe) to a flange that is either mild steel (if magnet sticks hard) or ss304 otherwise. It's a cousin to inconel, so if they are set up for Inconel (filler 82) they should be able to get a lasting weld. If they treated it as stainless, which a lot of people mistakenly do, it is likely to crack. I'd call and ask. If they can't give you specifics on the process/filler (I.e., not, don't worry we know how to weld, etc.) I wouldn't trust it. Of course, I have trust issues with most shops.

Well great. Now you have me scared.....

They broke out a huge magnet and it almost flew out of his hand onto the flange, so I'm thinking it's mild steel. It's already all welded up. They definitely weren't laying dimes, but it also only cost me their shop minimum ($75).

They also recommended using some copper high temp exhaust gasket RTV. They said in a perfect world the crushable donut gasket should be enough, but I'm not dealing with a perfect world.

IMG_8048.jpegIMG_8049.jpeg

It's my understanding, based on various people who have tested these parts and reported the results online, that the flanges can be either mild steel or stainless, while the pipe itself is Incoloy 800 (or an unbranded alloy of similar content). Sounds like your flanges are mild steel — mine are too.

Try putting a magnet on the pipe itself. Assuming the magnet does not stick to the pipe, it is likely Incoloy 800.

I don’t mean to scare you, just trying to save you some extra work down the road. From the photos, those don’t look like TIG welds to me. They look more like MIG or stick welds, which makes me wonder/doubt whether the correct filler and process were used.

I’d still call and ask exactly how they welded it and what filler rod/wire they used, but I wouldn’t be overly optimistic unless they can give a confident answer. On the other hand, it’s impossible to say from here how long they might last — a month, a year, a decade? It’s not the space shuttle, so you could always install it as-is and cross your fingers. I’d just go in knowing there’s a real risk they will crack.

[NCGermerican]

Tell the exhaust shop they were welding Incoloy 800 (pipe) to a flange that is either mild steel (if magnet sticks hard) or ss304 otherwise. It's a cousin to inconel, so if they are set up for Inconel (filler 82) they should be able to get a lasting weld. If they treated it as stainless, which a lot of people mistakenly do, it is likely to crack. I'd call and ask. If they can't give you specifics on the process/filler (I.e., not, don't worry we know how to weld, etc.) I wouldn't trust it. Of course, I have trust issues with most shops.

Well great. Now you have me scared.....

They broke out a huge magnet and it almost flew out of his hand onto the flange, so I'm thinking it's mild steel. It's already all welded up. They definitely weren't laying dimes, but it also only cost me their shop minimum ($75).

They also recommended using some copper high temp exhaust gasket RTV. They said in a perfect world the crushable donut gasket should be enough, but I'm not dealing with a perfect world.

IMG_8048.jpegIMG_8049.jpeg

It's my understanding, based on various people who have tested these parts and reported the results online, that the flanges can be either mild steel or stainless, while the pipe itself is Incoloy 800 (or an unbranded alloy of similar content). Sounds like your flanges are mild steel — mine are too.

Try putting a magnet on the pipe itself. Assuming the magnet does not stick to the pipe, it is likely Incoloy 800.

I don’t mean to scare you, just trying to save you some extra work down the road. From the photos, those don’t look like TIG welds to me. They look more like MIG or stick welds, which makes me wonder/doubt whether the correct filler and process were used.

I’d still call and ask exactly how they welded it and what filler rod/wire they used, but I wouldn’t be overly optimistic unless they can give a confident answer. On the other hand, it’s impossible to say from here how long they might last — a month, a year, a decade? It’s not the space shuttle, so you could always install it as-is and cross your fingers. I’d just go in knowing there’s a real risk they will crack.

Well, at this point there's probably no going back regardless. I guess it was a good idea for me to hang onto the original crossover pipe in case I need it. Note to my future self though - if I (or anyone else) is in the same situation in the future, probably better to look for a machine shop to see if they are more knowledgeable in welding those types of metals together.

At least that part is after the primary o2, so I'm thinking if it does crack in the future it will only mess with my WBo2 readings.