Exhaust stud repair., WTF???????? Options

[BiG bOgGs]

This weekend I am doing a replacement of the push rod tube seals, my first valve adjustment, a repair of the pulled exhaust stud on the driver side, and a permanent plugging of the air injection holes with a couple bolts and a little JB weld.

This morning I put the teener up on some ramps and crawled under her to remove the exhaust from the heads so that I could re-tap the one loose stud and replace the gaskets with a set I got from the good Dr. in Atlanta. When I got under there, I saw two allen bolts in place of the nuts and studs I was expecting. And when I unscrewed them from the head I pulled out the timecerts that they were inserted with. plus, there was no copper gasket. Here is what I have now.





I will now have to cut the bolts in order to get them off of the exhaust, and as you can see in the one pic, they had to split the sides of the exhaust just to fit the bigger bolts. I was able to tap the head with a M12X1.5 tap, so I believe I will be able to put some threaded inserts in there along with some new studs, and the one stud I was doing this whole procedure for in the first place looks like it will be able to be re-tapped for the 8/9 studs I have on hand, but I might have to go to a 8/10.

At least it is a beautiful sunny day here in SW FL.

Any suggestions as to things I might consider as I get ready to put this bit of Porsche happiness back together?

Jim

[KaptKaos]

I'd consider a step down stud. A VW shop should have them as this is a common problem. A stud that is 10mm on one side and 8mm on the other. Tap the case for the 10mm and thread it in. No inserts needed. If that doesn't work, you're looking at the machine shop to fix them.

Don't forget new exhaust gaskets. The copper ones. I annealed mine prior to install. YMMV. I also used the correct copper nuts as well.

Good luck and don't get stuck in a gumption trap. (IMG:style_emoticons/default/biggrin.gif)

[BiG bOgGs]

I'd consider a step down stud. A VW shop should have them as this is a common problem. A stud that is 10mm on one side and 8mm on the other. Tap the case for the 10mm and thread it in. No inserts needed. If that doesn't work, you're looking at the machine shop to fix them.

Don't forget new exhaust gaskets. The copper ones. I annealed mine prior to install. YMMV. I also used the correct copper nuts as well.

Good luck and don't get stuck in a gumption trap. (IMG:style_emoticons/default/biggrin.gif)

I have an 8/9 step down stud right now, and if that doesn't work I will definitely hunt down an 8/10. The two holes for the bolts I pulled are already too large for the step down studs, unless anyone knows of a supplier for 8/12 step down.

[Bruce Hinds]

Very Very Important!!! is to not only use the copper gaskets, but the copper Nuts too. the problem with steel nuts or bolts is that they will expand too much and pull right out of the head like the allens you're taking out.

So regardless of what studs you use, make sure you can get the copper nuts....

B

[BiG bOgGs]

Very Very Important!!! is to not only use the copper gaskets, but the copper Nuts too. the problem with steel nuts or bolts is that they will expand too much and pull right out of the head like the allens you're taking out.

So regardless of what studs you use, make sure you can get the copper nuts....

B

Thanks for the info on why we should be using the copper. I have the copper gaskets and the nuts. I just wish this whole process wasn't driving me NUTS!

[BiG bOgGs]

8/9 studs are too small. Time to let my fingers do the walking for the 8/10 studs. (IMG:style_emoticons/default/headbang.gif)

[904svo]

Try george at AA, they have some of the repair studs in stock.

[Cap'n Krusty]

Very Very Important!!! is to not only use the copper gaskets, but the copper Nuts too. the problem with steel nuts or bolts is that they will expand too much and pull right out of the head like the allens you're taking out.

So regardless of what studs you use, make sure you can get the copper nuts....

B

This has become tiresome. How many times do we need to go through this? There ARE NO "copper" exhaust nuts. They're copper plated steel, and they cause problems of their own because they "lock". The factories (both VW and Porsche) used standard non-locking exhaust nuts, albeit with a Helicoil in the nut. No locking component whatsoever. Furthermore, to put it bluntly, your expansion theory is unsupportable hogwash.

In this particular case, the REAL way to fix the problem is gonna be to remove the head(s), repair the bosses by welding (as well as the almost certain cracks in the exhaust ports), and redrill the holes. BTDT, more times than I care to remember. 12mm is far too large for the amount of supporting material in the boss.

The Cap'n

[HAM Inc]

The Cap'n is right, unfortunately about the m12's. Once you tap that boss for a m12 there just isn't much meat left. That said, if you have been living right, you might just get lucky!
Welding new ex bosses in is not a big deal. However, pulling the heads is! And of course if the stud bosses to be welded are the ones closest to the ex valve seats (with the heads on the engine it would be the rows that are closest to the crank) those seats will have to come out and new ones installed.

As you can see the can of worms is big and wiggly! Be very careful down there!

[BiG bOgGs]

The PO had some 12M timeserts (outside diameter) in there and they unscrewed from the head when I removed the bolts that you see in the pictures. The POs fix worked, not pretty, but it worked. It was the other half of the head that had the pulled stud. I just cleaned up the threads with a tap and went looking for options on how to reinstall the exhaust. I was hoping to find a part number for the timsert kit I would need, or some other imaginative solution to the problem. Right now I am not interested in taking the time or money to get the heads welded and re-tapped. I am trying to save up for a full rebuild at which time the heads will either be totally rebuilt or replaced. So, the less money I have to spend now to keep her on the road is the route I am looking into. I know it is not optimal, but I don't have the funds to be optimal at this time.

[Cap'n Krusty]

Look carefully. There's more than a good chance they unscrewed (and took some aluminum with them) because the bosses are cracked. I realize you want to save money, and that's understandable, but you're ignoring reality and the advice of people who KNOW, not some blowhards who parrot what they've read in some "enthusiast" magazine or on the web. I've given you the bad news, and I'm done here. The Cap'n

[BiG bOgGs]

Look carefully. There's more than a good chance they unscrewed (and took some aluminum with them) because the bosses are cracked. I realize you want to save money, and that's understandable, but you're ignoring reality and the advice of people who KNOW, not some blowhards who parrot what they've read in some "enthusiast" magazine or on the web. I've given you the bad news, and I'm done here. The Cap'n

Not ignoring your advice, just telling you the reality of my situation. NO, and I mean NO, aluminum on the threads of the timeserts that came out. And while there may be a good chance they are cracked, I see no evidence of any cracking. The exhaust leak I was experiencing was not from this side of my head, it is just that this side had been messed with before. I am not ignoring reality. I may not have your years of experience, but I am also not a total effing fool either! Get off your high horse. I am not ignoring advice I am looking for it so that I can apply what I receive to the situation I have in my driveway and I don't need you to tell me the reality of what you have not seen. In past discussions on this board I have often given more weight to your posts because of the number of other knowledgeable people on here who also value your opinions. You have given me what you believe to be the worst of what my situation might be and I am watching out for that, but right now your post just mostly chaps my ass!

[sbonthemesa]

Find the exhaust leak, bolt everything up, take it for a ride, get it hot and then let it idle. Dip your hand in water and wave it over the suspect leak and feel for the pulse.

Then take it apart and take the Krusty one's advice.

BTW, I would also consider looking at the flanges to see if they are flat ad true, also look up in there to see if there isn't an extra gasket or something up there or anything else that the previous owner did that was fucking stupid.

I find that the PO is the only one is stupider that the current owner. By a slim margin. Tuff luv.

Enjoy your holiday.

[Rand]

Just another note about "copper locknuts" after seeing this topic a ton of times over the past few years...

What you get from your local VW shop might look like copper, they might try to sell you "lock nuts" which come in various styles including the "pinched" (slightly ovaled) ones... All of these are pretty likely to lock to your studs tight enough that you better be damn careful taking them off or you'll break a stud.

I've also noted that whenever Jake chimes in on this topic, he'll tell you he avoids copper-anything nuts in favor of double-nutting.