Printable Version of Topic

Posted by: RestoReese May 10 2021, 02:05 AM

As title says, I have an exhaust leak because one of my stud holes in the case is stripped and will not hold. Tried loctite red, but didn't hold with tightening. Also, wasn't sure it would hold with the heat. Thought about JB weld but then reconsidered.

I know I can tap to a larger diameter but wondering if others have had a similar issue and what you would recommend. Any guidance would be helpful.

Case is for 1971 1.7L.

Posted by: aharder May 10 2021, 03:05 AM

I had th same issue years ago. Went to Belmetric and got a Step Stud tapped it out and installed the larger diameter in the case and it solved the problem. I ended up changing all of them out.

Posted by: Arno914 May 10 2021, 03:14 AM

I would fix it using a threaded insert like "Helicoil". You wouldn´t have to drill much larger. These things work really well, even adding additional strength because of the slightly larger thread diameter. No worries about heat affecting chemical repairs, too.

Posted by: RolinkHaus May 10 2021, 04:18 AM

Recently, I used a helicoil on the exhaust which only lasted a week, broke into pieces. Timeserts are much stronger.

Posted by: RolinkHaus May 10 2021, 04:23 AM

There might be helicoil out there that are strong, but everything I'm reading says otherwise.


Attached thumbnail(s)

Posted by: Mark Henry May 10 2021, 04:44 AM

Step stud or timesert only, and once fixed 18 lbs torque only.

If your exhaust is still leaking it's not the stud, the gasket is cocked, tube ears are bent, tubes ends are not square, etc.
Resist the temptation of over torquing the exhaust nut, it's a recipe for disaster.

Posted by: Shivers May 10 2021, 08:10 AM

The time-sert is a bit more work, and more expensive. You'll need to get the kit with proper installation tools. But, for me it was never an issue again.

Posted by: rjames May 10 2021, 09:37 AM

Another vote for time-sert. I've done it with the engine in the car. Just take your time, use lots of cutting fluid when drilling, and mark your bit so you don't drill in too far.

Posted by: pilothyer May 10 2021, 09:51 AM

10-4 on Time-Sert once and done.

Posted by: RestoReese May 10 2021, 12:48 PM

Sounds like Time Sert or the step stud is the way to go. I called Porsche and they sell the M9-M8 as a Genuine part for $5.10 each, so thinking I will tap out the M9 and try that first. Time Sert is nearly $90 for the kit, and after 22 months of cost overruns, will be going cheapest route I can

And prior to installation, I took a large file and filed the exhaust inserts to be level (saw this on a YouTube video when I first started this project), and have new gaskets that firmly in place prior to placing the exhaust in. I could see the area where the gases were leaking and it was exactly where the stud wasn't torqued tightly so hopefully new studs will do the trick. I never found torque setting for these studs so will use the 18ft/lbs to be sure I don't over tighten.

Thank you everyone for the quick responses and great advice. I am close to the finish line with my restoration (22 months in), and once complete will post the project on the board and thank all of the many people on the fine forum who have helped me along the way.

Posted by: aharder May 10 2021, 03:10 PM

Belmetric has a 10 x 8 for 3.99ea

Posted by: Mark Henry May 10 2021, 03:39 PM

No get the M9 x M8, the M10X8 would be the last ditch Hail Mary.

If you tap for M9 (or helicoil) a regular timesert will no longer work, you would have to now use a "Bigsert"...so a whole different timesert kit.

You only have so much meat to work with...so you can only go so far oversize.

Posted by: ChrisFoley May 11 2021, 05:42 AM

18 ft-lbs is ok for oem heat exchangers but too much for aftermarket exhaust systems imo.
When I use a torque wrench on exhaust nuts I use 14 ft-lbs.

Posted by: rjames May 11 2021, 09:56 AM

I now only tighten them to 15 ft-lbs after stripping an exhaust stud and installing a time-sert a while back. No exhaust leaks so far.