Leaking exhaust at head..., multiple copper gaskets / more muscle on those exhaust nuts Options

[Jax914]

Okay,

I'm looking for some ideas....

I have a 1971 1.7 - stock heat exchangers, manta exhaust.

I've replaced the copper gaskets between the heat exchanger and the head, applied what I think is way too much torque to the exhaust nuts and can't get it to stop leaking. I removed the exchanger and made sure the top of the flange is level and smooth. When I start it up and crawl under, I can feel the leak.

My thoughts are to try running two gaskets?!?

Anyone else have similar problems?

TIA,

[Bartlett 914]

The ears on the HE pipes may be hitting the boss for the exhaust stud. I had a similar problem but in my case the copper gasket had fallen out of position when installing the HE's. I could tell because the copper gasket was deformed.

[rhodyguy]

if you went thru the torqueing sequence and ran them up fully as you put them on, you may have cocked the he's with a built in leak. did you lightly pass a big wide file over the tops of the pipes, one side, both pipes at one time? try just loosening all 4 nuts so the he is just free. press it up so you can feel full contact and no rocking of the he. with you free hand take the torque up in a few passes. just reefing down on the nuts trying to cure the leak could be disasterous. be careful.

[HAM Inc]

Because the studs are outside of the sealing flange the torque sequence is crtitcal too. If you tighten one stud more than its mate you will rock the he unevenly and that will keep it from drawing down flat against the copper.

The previous advise is all good and you should follow it and then when you reinstall the he take all of the slack out of the 4 nuts as you apply even pressure so the he is flat against the copper. This is a job where that third arm would be very handy!

[rhodyguy]

forgot to add, make SURE all the rings are out! when they get all blacked, it's any easy mistake. take a awl/ice pick and scratch a small line where the ring lives in the head. if you see shiney copper, get the ring out.

[KaptKaos]

I was installing mine this weekend. I just want to be clear on what I should see as well. When I looked into the exhaust ports, I see a small recessed area for the copper gasket. When I put the new one in there, it would fit into that recess. Is that what I should be seeing?

[DanT]

I was installing mine this weekend. I just want to be clear on what I should see as well. When I looked into the exhaust ports, I see a small recessed area for the copper gasket. When I put the new one in there, it would fit into that recess. Is that what I should be seeing?

yep (IMG:style_emoticons/default/smile.gif)

[rjames]

just reefing down on the nuts trying to cure the leak could be disasterous. be careful.

Mind Kevin on this one!!

[BMartin914]

Torque exhaust nuts to 18 ft/lbs. More and you risk running into KaptKaos' problems...stripped threads.

[KaptKaos]

Torque exhaust nuts to 18 ft/lbs. More and you risk running into KaptKaos' problems...stripped threads.

Hey Now! My exhausts are good. I broke the intake. Same diff I guess. (IMG:style_emoticons/default/blink.gif)

[davep]

Len did not mention it, but he has commented in the past that the seating surface for the copper rings can warp and will no longer seal. On one of my heads that he rebuilt there was a large hole that required welding. I do believe that all heads that he rebuilds have the seats remachined.

Never ever double up on the copper rings. Always leave the nuts loose until the entire exhaust system is installed. Once you have a loose fit on all the parts, only then you can start to torque up the various nuts.

[Cap'n Krusty]

Begin with the assumption that double gaskets NEVER work. Because they don't. File the pipes flat and parallel, something that may take an hour or more. Big file, both pipes at the same time, with the HE held flat on the bench. Slow and careful are the key words here. Make sure the gaskets are new, flat, and properly seated. tighten them evenly and in steps, and retighten once the engine is running. Get rid of that TON of muffler, and get something that puts less load on the system. Be sure the hanger is intact and properly secured at all 4 points. The Cap'n

[jk76.914]

If you haven't seen this already.... I tried it on mine, and it works. The copper rings are definitely softer, you can tell if you slightly bend them (warp them really) by hand....

http://www.ratwell.com/technical/Exhaust.html

[Jax914]

thanks everyone....hopefully I'll have some time tomorrow to crawl back under and see what I can do.

[jk76.914]

Be careful on the torque. I'd say 18 ft-lbs is on the high side. It's OK for M8 steel threads in the steel nut, but the other end is steel threads in aluminum, and any torque you apply to the nut pulls on the aluminum threads in the head with the same force. M8 x 1.25 in aluminum is only good for 14 ft-lbs. I think the late VW T2 spec is 14 ft-lbs. And it's low enough that you'd better use a torque wrench or you'll overshoot.

I printed this chart out and keep it in my tool box.....

http://dodgeram.org/tech/specs/bolts/M_bolts.html

Sorry if it's "Dodgeram". It's the clearest chart I've found.

If you go to an 9mm/8mm step stud, in clean and full aluminum threads, you're probably good for the full 18 ft-lbs.

Ever wonder why the 1.8L had 9/8 step studs? Or why they bothered with 8/7mm studs for the rocker pedestals? The larger aluminum threads can then match the strength of the steel on steel at the other end....

Just my engineering opinion. Your actual experience may differ.

[Chris Pincetich]

My system for almost all repairs is to tighten, drive around town a bit, then tighten again. I had a leak when I replaced my heat exchangers at first, then I slowly torqued more each day after several consecutive days of driving and it went away. The hot/cold/bumpy cycles allowed things to settle in.

Also, did you take 4 old copper gaskets OUT? You will definitely have a poor seal if you left one in there. They are REALLY hard to see up in the port, even with a decent flashlight. I had to make a special tool to get mine out. Good luck (IMG:style_emoticons/default/beerchug.gif)

[Jax914]

Haven't done anything yet....but to answer - yes, I've removed the old coppers. I'll be careful on the torque - one already needed a helicoil before I got to it. I appreciate the link to the ratwell site....I'll check the "flatness" and "level" of the manifolds when I remove it this time.

Troy