Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
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.
 

Welcome Guest ( Log In | Register )

2 Pages V  1 2 >  
Reply to this topicStart new topic
> Chasing Exhaust Leaks, This is maddening, so many issues.
ctc911ctc
post Apr 7 2020, 02:56 PM
Post #1


Senior Member
***

Group: Members
Posts: 885
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

Attached Image

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
Attached Image

Attached Image

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!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Rand
post Apr 7 2020, 03:14 PM
Post #2


Cross Member
*****

Group: Members
Posts: 7,409
Joined: 8-February 05
From: OR
Member No.: 3,573
Region Association: None



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)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
TonyA
post Apr 7 2020, 03:47 PM
Post #3


Nachmal
**

Group: Members
Posts: 455
Joined: 17-November 16
From: Hilltown PA
Member No.: 20,596
Region Association: North East States



I remember seeing a Youtube from a guy in Florida that filed down the HE tubes to square them up.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 7 2020, 03:48 PM
Post #4


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



Certainly, someone has come up with a sure-fire 100% good-guy guaranteed method for tightening and securing this assembly? Anyone? Anyone?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
BeatNavy
post Apr 7 2020, 04:11 PM
Post #5


Certified Professional Scapegoat
****

Group: Members
Posts: 2,921
Joined: 26-February 14
From: Easton, MD
Member No.: 17,042
Region Association: MidAtlantic Region



QUOTE(ctc911ctc @ Apr 7 2020, 05:48 PM) *

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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
IronHillRestorations
post Apr 7 2020, 04:42 PM
Post #6


I. I. R. C.
*****

Group: Members
Posts: 6,707
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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 7 2020, 05:29 PM
Post #7


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



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


QUOTE(TonyA @ Apr 7 2020, 03:47 PM) *

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

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 7 2020, 05:33 PM
Post #8


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



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!




\
QUOTE(BeatNavy @ Apr 7 2020, 04:11 PM) *

QUOTE(ctc911ctc @ Apr 7 2020, 05:48 PM) *

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.

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 7 2020, 05:36 PM
Post #9


Senior Member
***

Group: Members
Posts: 885
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


QUOTE(IronHillRestorations @ Apr 7 2020, 04:42 PM) *

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.

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 7 2020, 06:02 PM
Post #10


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



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?

Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Bleyseng
post Apr 7 2020, 06:30 PM
Post #11


Aircooled Baby!
**********

Group: Members
Posts: 13,034
Joined: 27-December 02
From: Seattle, Washington (for now)
Member No.: 24
Region Association: Pacific Northwest



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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
IronHillRestorations
post Apr 7 2020, 07:41 PM
Post #12


I. I. R. C.
*****

Group: Members
Posts: 6,707
Joined: 18-March 03
From: West TN
Member No.: 439
Region Association: None



QUOTE(ctc911ctc @ Apr 7 2020, 04:02 PM) *

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?

Attached Image


That's a negative, that will give you leaks for sure.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
r_towle
post Apr 7 2020, 07:50 PM
Post #13


Custom Member
***************

Group: Members
Posts: 24,501
Joined: 9-January 03
From: Taxachusetts
Member No.: 124
Region Association: North East States



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. (IMG:style_emoticons/default/smile.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
MartyYeoman
post Apr 7 2020, 08:35 PM
Post #14


Senior Member
***

Group: Members
Posts: 1,516
Joined: 19-June 03
From: San Ramon, CA
Member No.: 839
Region Association: Northern California



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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 8 2020, 10:21 AM
Post #15


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



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

Thank You!


QUOTE(MartyYeoman @ Apr 7 2020, 08:35 PM) *

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.

User is offlineProfile CardPM
Go to the top of the page
+Quote Post
IronHillRestorations
post Apr 8 2020, 10:40 AM
Post #16


I. I. R. C.
*****

Group: Members
Posts: 6,707
Joined: 18-March 03
From: West TN
Member No.: 439
Region Association: None



QUOTE(MartyYeoman @ Apr 7 2020, 06:35 PM) *

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.


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
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ctc911ctc
post Apr 8 2020, 07:30 PM
Post #17


Senior Member
***

Group: Members
Posts: 885
Joined: 9-June 18
From: boston
Member No.: 22,206
Region Association: North East States



*****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.

Attached Image

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

Attached Image

Starting it tomorrow, will advise.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
914_teener
post Apr 8 2020, 10:36 PM
Post #18


914 Guru
*****

Group: Members
Posts: 5,193
Joined: 31-August 08
From: So. Cal
Member No.: 9,489
Region Association: Southern California



QUOTE(IronHillRestorations @ Apr 7 2020, 06:41 PM) *

QUOTE(ctc911ctc @ Apr 7 2020, 04:02 PM) *

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?

Attached Image


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



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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
914_teener
post Apr 8 2020, 10:38 PM
Post #19


914 Guru
*****

Group: Members
Posts: 5,193
Joined: 31-August 08
From: So. Cal
Member No.: 9,489
Region Association: Southern California



QUOTE(BeatNavy @ Apr 7 2020, 03:11 PM) *

QUOTE(ctc911ctc @ Apr 7 2020, 05:48 PM) *

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.




No...no better ideas. How the heck are you Rob....waiting for this thong to blow over?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
porschetub
post Apr 8 2020, 10:45 PM
Post #20


Advanced Member
****

Group: Members
Posts: 4,695
Joined: 25-July 15
From: New Zealand
Member No.: 18,995
Region Association: None



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.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

2 Pages V  1 2 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



- Lo-Fi Version Time is now: 29th March 2024 - 03:26 AM