All,

'74 914, 2L, original engine - about 20K miles

I started a new thread because the ones I could find did not address this issue. Perhaps it is me????

Last month I purchased new gaskets (thanks Mark @914R) and annealed them as per instructions. Used super glue to stick them in place. Mounted the heat exchanger/manifold and locked them in with around 20lbs of torque. Copper goo on the nuts, etc.

When I started the car it was the sound of my youth - smooth, strong,,,,,,ahh

After a few days the sound changed, using a rubber tube held to my ear I found exhaust leaks in the junction to the muffler (used new gaskets, alum sandwiched ones).

Here are the leaks

Copper Gasket Leaks

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Seems as if the nuts were not tight enough. I made certain that the edge of the pipes were square and both on the same plane.

Questions as to the copper gaskets:

1. Seems that one was not seated concentrically with the pipe, that exhaust was leaking from day one - is there a method to square this or center it?

2. the other gasket it seems did not get seated at all, so it seems as if it was concentric just not tight enough?????

Now the aluminum Gaskets
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I really tightened the bolts, I have ordered new gaskets and am brushing smooth the flanges which were both kind of cruddy, any advice as to installing these?


THANK YOU TEENERS!

Exhaust leaks are a plague. Of course you have filed the mating surfaces? Annealing is a subject of debate on the copper rings. (They
do that themselves)

I remember seeing a Youtube from a guy in Florida that filed down the HE tubes to square them up.

Certainly, someone has come up with a sure-fire 100% good-guy guaranteed method for tightening and securing this assembly? Anyone? Anyone?

No, but there are some things that help.

Filing the HE's so they are the same height can help. IMO, most important to seal at the head, then get the muffler to tight to the HE's. Torque the HE's slowly to exhaust studs and leave the muffler somewhat loose at first. Try to verify that you can see gasket on each side of the HE as you tighten to head. Once you think you have it, lightly torque the muffler to the HE. Then check the seal by using a shop vac set to blow, instead of suck, and put it on the exhaust outlet. Feel around the bottom of the head to see which, if any, of the mating surfaces may not be seated, and adjust everything as needed.

Remember not to overtighten! Drive around a couple of times, then check the torque on everything again.

Others will have other, probably better, ideas.

What do the sealing surfaces look like on the heat exchangers and muffler?The gaskets show where it's leaking, but maybe not why. Pics of the sealing surfaces might be helpful.

In the first pic shows that the exhaust flange wasn't centered on the copper gasket. You should see copper around each exhaust flange before you tighten to spec.

Checking the sealing surfaces with a file can reveal discrepancies that can cause a leak.

Are these stock heat exchangers or SSI's? Factory heat exchangers have a much better sealing surface than SSI's, which are only thin tubing. It's also common for the flanges on SSI's to not be level with each other, put a good straight edge across the surfaces to check them.

I bolt it all together finger tight before tightening to spec which is much less than you think, 11 ft lb IIRC

I think it does help to anneal the copper gaskets. I had trouble with a leak on one car and it helped. Just get them hot enough and quenching isn't really required, except to put them in faster.

Yes, there is a very good engine build video where this is done - mine are square and the two are on the same plane.

Great advice, I will try this tomorrow

The exchangers are SSI, and I would think a larger mating surface would help, that the pipe edges are the mating service seems a bit weird.

THANK YOU B-Navy!




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Wow, as to the surfaces at the muffler, wavey-gravy! Will have to think about how to seal that interface, the SSI steel seems a bit soft......hhhhmmmm,

The tube surfaces are very straight and even. The two surfaces are even straight in relation to each other.

Will follow this great advice tomorrow along with B-Navy and the vacuum idea!

THANK YOU IHR

Prior to blowing me out of the water, might a layer of this on both the copper ring AND the pipe interface assist with the bonding at the interface?

Click to view attachment

No, file the HE's flat with a big flat file. I put them in without the muffler and wiggle them in or tap with a plastic BFH . Once they are truely seated then I tighten the nuts slowly wiggling the HE's as I tighten. Before torquing I then put the muffler (Bursch or Triad exhaust) and tighten those to the HE's. Then I tighten the HE nuts down, of course I have put a dap of anti seize on the studs.
I haven't had any leaks on the 914 or the Westy this way.

That's a negative, that will give you leaks for sure.

Hang the HE on the muffler hanger, tighten HE, wiggle and tighten again.
I have used double gaskets between the HE and the muffler before.

You might want to check that the bolt mounting loops aren't bottoming out before the mounting faces (pipe end and copper gasket) seat properly. I had to file mine to create some necessary clearance. Just say'n.

Had not considered this - I will look for this while installing

Thank You!

This jogged my memory of another car I had in with non OE exhaust studs that were a bit too long to torque the exhaust nuts on two cylinders. It had some washers stacked to compensate. It was a low budget situation, and I wasn't going to pull the exhaust studs and open a can of worms

*****UPDATE******

It dawned on me that the reason you file the HE pipes that interface to the copper gaskets is NOT to level them as much as to square the pipe to the face of the gaskets.........so German.

Soo, I put a good face on the pipe and used these nuts from BelMetric. They went on super smooth and when I cranked they were very smooth no squeaks, etc.

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As you can see this is what they look like installed and I was able to examine and see copper on all sides of the pipe PRIOR to synching them

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Starting it tomorrow, will advise.

Yes...it will.....I.ve used it several times.Did a whole long thread on it and have had two glasses of wine so....search my name and look dor it.

No...no better ideas. How the heck are you Rob....waiting for this thong to blow over?

Last build I had leaks,filed the flats of the flanges and they were really off,refitted that side with 10ft/lbs and leaks gone,other side was fine.
I never overtighten the nuts for the reason that this can pull out the studs from the heads,strip or snap them off.
I have never annealed the copper sealing rings ,in this case there is poor alignment of the pipes into the heads and overtightening has caused the sealing rings to deform.
The other issue is damage to the machined face of the exhaust port,I have seen some pretty rough ones,very hard to fix.

Torque is 14lbs. "About 20"? Did you use a torque wrench? Never saw a setting that said about. Overtightening will cause the ears to bend and possibly crack, and can strip the threads in the head. Torque to 10, then 12, then 14. Torque slowly, and "feel" for anything that doesn't seem right. Install muffler, but just snug before torqueing he's. I had a Bursch muffler that just would not seal. The flanges were thin, and warped. Had my welder make new flanges from ¼" steel. 4 years and no leaks yet. Won't buy another Bursch! The last one l bought still had wet paint out of the box, and you could see where they beat a cavity in it to accommodate the misplaced pipes. It cracked at that point.

Excellent Guidance!


I used a 1/4 inch drive. I hand tightened them to a good strong but not teeth-gnashing torque. New lovely copper nuts, synch, tighten, tighten, round and round while watching the copper gaskets making certain they were proud on all sides of the pipe.

Putting the final touches on today - will post results.

CTC911CTC

there could be a host of problems that I can explain to you but do not have the time to type them all in. Please call me and we can go over it

Com'n George! Don't be so lazy. Post what you know here, like the rest of us. I'm not too old (71) to learn something.

imho a torque wrench is a must for this job as it's way too easy to over tighten them.

*******CONCLUSION*********

Some of you have been following my "long on knowledge, short on experience" exploits with this new to me '74 2.0 barn find.

Getting it started then running right, then tuned properly then tuned again, then again and now exhaust leaks.

1. I remounted the SSI HE (shat does ssi stand for, are they still in business?) using methods described by George and others (THANK YOU TEENERS) and am able to see shiny copper on all sides of the pipes at the heads now.

2. Used new copper BelMtetric nuts, synched all around until firm

Started the car today, pure 1974 music. Just the muffler sound and the crazy clockworks or that 4 cylinder German masterpiece. Ahhhhhhhhh.......

Long road, on to the next challenge!

Nothing like resolving a problem, good work!

Take care removing the exhaust nuts in the future, as the nuts you got are "prevailing torque" lock nuts which can cause exhaust studs to back out.

Well done

thanx so much for the pictures.. i need to check mine 914 luva

This is how I did it a few years ago. For the rear aluminium gaskets I use the exhaust goo that goes solid once warmed up.

http://matsgarage.com/?p=1124