|
|
|
|
| Author |
|
|
Registered User
Join Date: Dec 2010
Posts: 30
|
Exhaust nut torque
I have just refitted headers and muffler to my early mag case engine and torqued everything to spec, but the exhaust is leaking quite badly.
Should I go higher than the recommended 25NM or should I use some sort of exhaust paste ? |
||
04-15-2013, 04:35 AM
|
|
|
Schleprock
Join Date: Sep 2000
Location: Frankfort IL USA
Posts: 16,639
|
Don't use paste. That stuff turns rock hard and is a real bear to clean up.
Try loosening and re-tightening the offending parts. On headers I like to start with the middle pipe first, tightening from the center outward.
__________________
Kevin L '86 Carrera "Larry" |
||
|
04-15-2013, 08:29 AM
|
|
|
Member 911 Anonymous
|
Are you certain your torque wrench is calibrated properly? You did crisscross pattern to evenly mount the component?
+1 no paste.
__________________
'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
||
|
04-15-2013, 08:32 AM
|
|
|
Registered
Join Date: Jul 2002
Location: Atlanta
Posts: 7,125
|
I am assuming you checked the surfaces carefully. How about gaskets? I think the double metal sided gaskets that our host sells are the trick, not sure if they fit the earlier cases?
Also, confirm its leaking at the head to exh header seal. Can you show us a pic of how you have have it bolted up to the head (installed header pic - up close to one of the cylinder head/header interfaces)?
__________________
erik.lombard@gmail.com 1994 Lotus Esprit S4 - interesting! 84 lime green back date (LWB 911R) SOLD  RSR look hot rod, based on 75' SOLD 73 911t 3.0SC Hot rod Gulf Blue - Sold. |
||
|
04-15-2013, 08:39 AM
|
|
|
Capitalist and Patriot
Join Date: Sep 2006
Location: Freedomville
Posts: 1,923
|
I just did a full R&R of engine trans exhaust etc... When I started car had massive exhaust leak somewhere... I let the engine warm up anyway and most of sound went away. That told me I needed to remove HE and file the flange faces flat. When I got the HE off I could see where the hot gases blew by the gaskets.
I used flat files on all flanges on each HE to head surface as well as cross over pipe. That did the trick. Evidently these surfaces erode over time and need to be trued up! All good now. 18ftlb torque on HE flange to heads. Check yours out. Just a suggestion. I don't think over torqueing will fix your problem. |
||
|
04-15-2013, 08:44 AM
|
|
|
Senior Advisor
|
what brand headers, some off brands might never seal
__________________
08 Cayenne Turbo |
||
|
04-15-2013, 08:44 AM
|
|
|
|
Registered
Join Date: Feb 2008
Posts: 353
|
excellent info...just fired up my 3.0 and have similar exhaust issues...will pull the hxchgers and dothe same...
|
||
|
04-15-2013, 10:02 AM
|
|
|
Registered User
Join Date: Dec 2010
Posts: 30
|
The worst leaks are at the heads and the headers are actually factory HEs with the outer tin cut away.
I've already filed the surfaces flat and I fitted everything loose to start with and tightened up gradually. The gaskets are from our host, would it help to use two gaskets sandwiched together ? |
||
|
04-15-2013, 01:57 PM
|
|
|
Capitalist and Patriot
Join Date: Sep 2006
Location: Freedomville
Posts: 1,923
|
You have leaks at the heads after filing the HE flanges flat? Flat across mounting holes? If so there shouldn't be any leaks from that area. Wouldn't hurt to use two of the metal mid year gaskets but I don't know how this would help if already flat from flange mounting hole to flange mounting hole. Did you use a metal straight edge to check/verify they are perfectly flat?
|
||
|
04-15-2013, 04:05 PM
|
|
Marble Grey
