second time its done this- car is fine driving to work but come time to leave , the bolts at the head have come loose. i DID crawl under and from what i saw the idiot who rebuilt the motor stripped about half the bolts out so are only half of them still there. i tightened em up- whats left - and it was ok , but it just did it again and im wondering if anyone else has come across this problem.

i am likely going to be ripping out the exhaust and re-tapping all the bolts up a size or so , which means also re-drilling the pipes for the new sizes . hopefully that fixes the problem.

thanks in advance ,
Lincoln

Are you using the correct locking nuts?

yea i believe so, also am using locktite red and locking washers , and that usually will stop things from shaking loose , but not this time i guess heh

First of all it's not bolts, it's studs washers and nuts. If he is tightening them as bolts I bet the threads in the head are galled. Most likely he will need to redrill and tap or helicoil or insert. Bitch in the car but, I've done a couple. I also ruined 1 head.

Requires one very strong anal sphincter or a trip to good machinist.

Dave

Check the studs. I had the same problem and after messing with the bolts I tried tightening and putting some locktite on the studs no more exhaust leaky. Remove the studs completely with a double nut then locktite and replace them the same way easy cheasy. Should solve your problem.

At what temp does red locktite burn up? I know here at work we use blue and sometimes to get things apart after we heat with a torch. Maybe the red is getting too hot on the exhaust and becoming non-sticky (Not working any more)?

not sure actually of temp for red locktite, but i have come up with the only truly positive solution.

problem is this- half the studs are missing , and by the looks of it the holes where they belong are completely stripped out , so tapping for slightly oversize is what i believe should be done- that or the HARD way ; ie being to pull the heads, weld up the stud holes and then drill and tap them correct sized

redrill and retap for correct grade studs like its sposed to have for starters. i also notice that there is no exhaust hangers at all on the 914 exhaust so ill be adressing that area as well, with the stress of the whole shebang hanging on only the studs its gotta be stressing them a bit so ill be adding some sort of support to hang the pipes from , which should alleviate the stressed areas , combined with new re-tapped studs this should solve this problem as well as future problems with this exhaust. of course the hanger supports will probly not work when i finally get around to getting a better muffler than this cheapo GT set up

Red locktite breaks down with a LITTLE heat. Forget it on the exhaust.

Mark

all told this fix done correctly and i wont need it , have all the weekend to get it done . again, thanks all for the help. might even remove the rear shift rod and straighten it out so i can shift into 4th right while im under er heh

Half the studs missing == bad news.
Wrong hardware == bad news.
No muffler hanger == bad news.

In each of the above cases, "bad news" means "extra stress on the existing exhaust studs". Which can easily lead to pulled studs or other problems.

Sounds like you know what you have to do: Drill and tap for "step-down studs", or for inserts of some kind (e.g., TimeSerts). I would strongly suggest using the correct (yes, kinda expensive!) copper-coated locking nuts with the built-in washers instead of whatever it is you've been using. Nyloc nuts don't seem to like heat that much, so using the factory-type "slit-sided" nuts or the aftermarket-type "squashed" nuts will better keep them from loosening. Pelican sells OEM and aftermarket (from an Audi application, perhaps?) nuts, as do other sources.

--DD

Make sure you have studs and not bolts. Bolts instead of studs is not good, and runs the risk of stripping out the tapped hole in the head.

I use a BMW or Mercedes copper coated prevailing torque nuts with a flange, that I get from GPR. They have a 12mm hex head. I think these are the same thing Dave is talking about. Never had any problem, I don't re-use them though.

"Locking washers"? NEVER USE ANY KIND OF LOCKING WASHERS ON AN EXHAUST SYSTEM. Period. Ever. They get hot, relax, and there goes the fastening. The Cap'n

We'll see. I wanted to try locking washers, because otherwise the self-locking nuts lock to the studs themselves. I wanted to lock them to the heat exchanger, so when the time came to remove them there would be less (still not zero) chance of breaking or pulling the stud out.

So, I took my flanged copper locking nuts, chased the threads to make them un-locking, and installed them with a flat washer followed by a split lock, followed by the non-locking nuts. For the reason you describe, I'm trying titanium flat and split locks. I'll let you know how it works out. I'll be checking the torque at the end of the season.

Split locks are the WORST. The Cap'n

You're going to have a lot of dis-similar metal in there expanding and contracting at different rates. As I understand it the stock copper plated flanged nuts are all that is needed. I have had no loosening problems since I took off the washers and non-flanged, non-locking nuts and put on the OEM nuts.

Also, I was able to fix stripped head threads by using studs that are oversized on one side and standard thread on the other. I got lucky and was able to drill out the stripped threads in the head and tap oversized threads with the engine in the car. You can't be in a rush or have been drinking too much coffee. With a fresh drill bit it can be easy to go too deep into the soft head material.

I believe that key to keeping the seal leak free is to make sure that the header flanges and ends are square and lined up with the studs and mating surface on the head, and to use clean, smooth, copper rings (where required). Each nut should be tightend gradually so the end of the pipe mates square to the copper ring and surface on the head.

-Jeff

Lincoln,

I understand your frustration.

And yeah you have to put in stepped studs, or heli coils and stock studs.

Thats for sure.

And I suggest you listen to these guys when they are telling you to NOT USE all the whacko harware to hold this together.

Stock fastening scenario works great for many engines that have gone over a hundred thousand miles.

No washers. Just the stock nuts from pelican or the Audi style nuts rock.

As DD pointed out. they have washers built into them.

If you want to use an anti-sieze that works forever and won't allow the nuts to come loose...

Use Milk of magnesia as the anti sieze. Thats a standard anti-sieze compound used in USAF jet exhaust housing fasteners. Works especially well if used on dissimilar metals. And our Heads, Studs, Exhaust Flanges and nuts are not EXACTLY the same steel and aluminum (heads) alloys.

I use it on all my exhaust nuts and header bolts. Works bitchin....
And 1 bottle will last ya a life time. Just shake and brush on.. SIMPLE.

Crusty and Scruz914 were also dead on accurate. I couldn't agree more..!!

Regards,

Twystd1

Better fix it right.

Learned a long time ago on Type1 aircooled engines that exhaust leaks near the head are bad. What happens is as the hot ball of exhaust gas comes shooting out of the head and shooting down the exhaust, it creates a vacuum which can suck in air. If there is a leak at the head exhaust gasket area, there is a chance the sucked in air can burn a little unburned exhaust gas near that exposed part of the valve shaft sticking out of the valve guide. The extra heat is what causes the valve to stretch and break and can cause valve seats to come unpressed.

Ya, I know the motors aren't exactly the same, but they are the same basic design, share some of the same basic problems, and were done by the same factory engineers.

I bet a lot of people can't tell the difference between T1 and T4 shortblocks unless you point out the differences.

Yep, the sound of a newly seperated valve head rattling around inside an engine when you are doing 75 can be unpleasant.

Ken

The factory nuts are expensive but the best! The copper ones are ok if you shot peen them to keep them from moving.

I wasn't trying to mislead anyone, just inputting my opinion.

Forgetting the "whacko" hardware, I still think the problem that needs to be solved is that we shouldn't be locking the nut to the stud. When it comes time to remove it, between corrosion on the stud, and thermal fatigue on the stud and the aluminum threads in the head, the locking just exacerbates the problem of broken studs and pulled threads. So maybe titanium lockwashers aren't the answer, but that's the problem as I see it.

Other air cooled cars I'm familiar with used a sheet metal locking washer with two tabs for the exhaust studs. After you torqued the copper nut, you bent one tab against a flat of the nut and another one against the side of the exhaust tube for locking. To disassemble, you bent the tabs back and unscrewed the non-self-locking nut. I'm not advocating that either, but it's a data point.

I also think that there are better materials for the stud itself, but that's a controversy for another day.

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