Chasing Exhaust Leaks, This is maddening, so many issues. |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Chasing Exhaust Leaks, This is maddening, so many issues. |
ctc911ctc |
Apr 7 2020, 02:56 PM
Post
#1
|
Senior Member Group: Members Posts: 892 Joined: 9-June 18 From: boston Member No.: 22,206 Region Association: North East States |
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 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 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! |
IronHillRestorations |
Apr 7 2020, 04:42 PM
Post
#2
|
I. I. R. C. Group: Members Posts: 6,717 Joined: 18-March 03 From: West TN Member No.: 439 Region Association: None |
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. |
ctc911ctc |
Apr 7 2020, 05:36 PM
Post
#3
|
Senior Member Group: Members Posts: 892 Joined: 9-June 18 From: boston Member No.: 22,206 Region Association: North East States |
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 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. |
Lo-Fi Version | Time is now: 14th May 2024 - 09:02 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |