TheSamba.com :: View topic - Any way to seal exhaust with manifold bolt missing?

Tue Aug 20, 2013 7:07 am

Hello!

So I bought this '91 weekender and one of the stainless exhaust manifold bolts is broken off in the head. Previous to my ownership, it was drilled on and now it is a lost cause short of pulling the head and getting it drilled at a shop. After reading the wealth of info here about pulling heads, the cracking between valves etc. and the fact this engine has 250k on it, I would rather do a quick fix and save $ for a new (rebuilt) engine than remove the head.

What is the best way to get a good seal without replacing the bolt?

I have a bunch of new gaskets - can I stuff a bunch of "the right stuff" between the gasket and the head/pipe? JB weld?

Any temporary trick fix tips would be appreciated!

Tue Aug 20, 2013 7:29 am

It is unlikely you will get it to seal permanently without two attachments per flange. Short of that, instead of a gasket, use ultra high temp silicone, the copper stuff to seal the flange to the head. We use this on racing headers successfully, but have the proper fasteners.

I can't see the damage, but someone with real "skills" should be able to fix the head without removing it, but the exhaust would need to come down. Not sure why someone would use stainless bolts in aluminum to begin with. Anyhow, welcome to the Samba. Doing things on the cheap usually end up costing more in the long run.

Tue Aug 20, 2013 7:40 am

I've fixed several like this in the past using a plasma cutter. I take the exhaust off and cut off and remaining portion of the bolt that is sticking out. I put a nice new tip on the plasma cutter and blast the bolt right in the center carefully. Most of the time it melts out about 80% of the bolt just leaving the threads. The remaining part is red hot so usually it turns right out just by putting a screwdriver or such in the hole and backing it out. Sometimes you will have to helicoil the hole or install a stepped stud. Anyone with a little experience using a plasma cutter should be able to get it out for you.

Stainless steel bolts are fine for exposed areas like the poptop hardware but a poor choice for the engine compartment. They are brittle and the threads get damaged easily.

Tue Aug 20, 2013 8:27 am

The problem is that the bolt is broken off about a 1/2" inside the head...Don't know for sure that it is stainless, but it is shiny, so just assumed that it was.

If I have to replace the head, can I just do one side and leave the other side as is? I am going to assume that it is not worth taking the old head out, getting it drilled and then re-installing with new gaskets, etc - or is it?

Tue Aug 20, 2013 8:39 am

You should not have to remove or replace the head. We are not there, so perhaps a picture would help. I have drilled out many broken bolts and studs on the vehicle. I even have a 90 degree drill. I like the idea of using a plama cutter, but that could get exciting. Syncrozilla has given you some options for repairing the hole once you get the old one out if the threads are damaged beyond use. A helicoil, a timesert and step stud are all good options to pulling the head and replacing it.

If you have small pencil magnet, see if it sticks to the broken stud, if so, it is mild steel and can be drilled with conventional high speed steel drill bits.

Tue Aug 20, 2013 8:41 am

There is no reason to replace a head for one snapped off bolt.

A right angle drill and brand new excellent quality drill bits will put a center punched hole right into the bolt.

You can use EZ outs or left handed extractors for the hole once made large enough.

When in doubt, have a professional do this job.
The best $100 bucks you will have spent in a long time.

Yes, drill it off center or too deep and you will need a new head.

Tue Aug 20, 2013 8:41 am

The real take-away..
Quote: Doing things on the cheap usually end up costing more in the long run.

Tue Aug 20, 2013 8:42 am

HeliCoils are OK, Timeserts are far superior IMHO.

Tue Aug 20, 2013 8:47 am

FYI on stainless....ARP make beautiful stainless steel studs with washers and flange caps for the Porsche.
They work wonderfully on the waterboxer.
I use stainless steel specific Loctite to set the studs and have had no issues with them here in New England.

Tue Aug 20, 2013 10:39 am

Syncrozilla wrote: I've fixed several like this in the past using a plasma cutter. I take the exhaust off and cut off and remaining portion of the bolt that is sticking out. I put a nice new tip on the plasma cutter and blast the bolt right in the center carefully. Most of the time it melts out about 80% of the bolt just leaving the threads. The remaining part is red hot so usually it turns right out just by putting a screwdriver or such in the hole and backing it out. Sometimes you will have to helicoil the hole or install a stepped stud. Anyone with a little experience using a plasma cutter should be able to get it out for you

This is cool ! I've never heard of using a plasma cutter for this job. I have lots of experience drilling and migging nuts to studs for removal. I've got a high success rate with my methods. Maybe I need a new toy for the shop ?

Tue Aug 20, 2013 10:46 am

Rallyedude wrote: Syncrozilla wrote: I've fixed several like this in the past using a plasma cutter. I take the exhaust off and cut off and remaining portion of the bolt that is sticking out. I put a nice new tip on the plasma cutter and blast the bolt right in the center carefully. Most of the time it melts out about 80% of the bolt just leaving the threads. The remaining part is red hot so usually it turns right out just by putting a screwdriver or such in the hole and backing it out. Sometimes you will have to helicoil the hole or install a stepped stud. Anyone with a little experience using a plasma cutter should be able to get it out for you

This is cool ! I've never heard of using a plasma cutter for this job. I have lots of experience drilling and migging nuts to studs for removal. I've got a high success rate with my methods. Maybe I need a new toy for the shop ?

I'm also quite intrigued with this plasma method...as I now have this new tool in my shop

Tue Aug 20, 2013 10:48 am

I too have a plasma cutter, but have never tried that.
Interesting idea for sure.

Tue Aug 20, 2013 12:04 pm

Try it out sometime. I used this method for the first time on a car that a someone else had already tried unsuccessfully to drill out the broken bolt and had drilled a hole terribly off center and it was a real mess. I use my plasma cutter a lot for artistic projects so I'll pretty comfortable with it. It's a great metal sculpting tool. Like a drill if you make a mistake you can easily cause more harm than good. When I'm burning out a broken stud I always use a new tip as that will ensure your hole is straight (well as straight as you are holding the gun anyway) and not too large.

Tue Aug 20, 2013 1:56 pm

If the stud is 1/2" in the head, you don't have a plasma cutter, and you're trying to do things on the cheap then maybe (patiently) over-drilling the hole and going with a larger bolt or insert might be worth a try?

If there's a 1/2" of hole then (over-)drilling straight shouldn't be too bad. Since you are already running without a bolt you probably won't make things worse and if you truly have 1/2" depth already then you might not need a lot more to get enough purchase to prevent a leak.

I've also had friends swear by left-handed drill bits, though I've never used one. If you go with an extractor, make sure you buy the best. I'd bet I've broken as many as I've used successfully and they always break right at the bolt surface leaving no chance of removing them and no shot of re-drilling the center of the stud.

If you do get an extractor in there (and you don't want to put heat on the head) I've had amazing success with a product called CRC Freeze-Off.

Tue Aug 20, 2013 1:58 pm

This is the best tool I've found to help with drilling.....

Quikcenter.com

http://m.youtube.com/?reload=7&rdm=uby9j5z1#/w...bDF9P1uDyk

Wed Aug 21, 2013 9:03 pm

OK - so I fixed it! Here is what I did:

1) bought carbide Dremel Bit (tear drop shaped) at local hardware store ($13)

2) With the Dremel, drilled a center hole/dimple deeper than the two off-center holes that were already there (see previous posts).

3) With a 1/8th inch extra hard bit, drilled a pilot hole pretty deep - discovered that it was not a stainless bolt as it was actually pretty soft once I got a good grip on it.

4) Used a screw extractor to....make the hole bigger? The extractor would not bite well enough, it just felt like it was stripping

5) Moved up to the next size extractor - which then made the hole bigger still.

6) Repeated step 5 until the hole in the bolt was getting really large, almost to the block.

7) Used the Dremel tool to grind out the bolt and make the hole cylindrical, not cone shaped like the screw extractor.

8) Drilled the messy hole with a 17/64th bit

9) Re-tapped that hole for the original bolt size

10) Re-installed the exhaust - I cranked on it just like you would normally and it felt solid

It seems like the bolt had fused with the head - there was no discerning where the bolt ended and the head began, so I figure it is strong enough to hold. If not, then I can drill with the 21/64th bit and tap for a helicoil.

Hope this helps someone that finds themselves in the same place.

Wed Aug 21, 2013 9:32 pm

Nice, I love a good resolution to a vexing problem. Pat yourself on the back and then enjoy whatever reward you turn to for a job well done.