Inline 6 exhaust leaks - The 1947 - Present Chevrolet & GMC Truck Message Board Network

El Nido Kid · 11-03-2006, 03:04 PM

Can anybody help me find a source for a better quality exhaust gasket? I had the manifold surfaced but the head has some minor pitting an the stock (metal on both sides gasket) just isn't making it.

Ram-Man · 11-03-2006, 03:09 PM

I think you need 2 gaskets one for each side of the 4 cylinders. So pull the motor and slap in a small block. No just kidding, you should be able to get Fel Pro in a synthetic gasket and not all metal one.

**Palf70Step** · 11-03-2006, 04:36 PM

I used some Permatex High-Temp Ultra Copper RTV Silicone Gasket Maker on my 250 with NAPA gaskets and never had a leak or an issue.

Brad · 11-03-2006, 08:52 PM

When you machined the manifold did you have them both bolted up together? Or did you only do the exhaust?

El Nido Kid · 11-03-2006, 09:05 PM

They were bolted together with a new gasket that didn't leak.

Brad · 11-04-2006, 02:37 AM

Take a look at my post (3rd one down) here:http://67-72chevytrucks.com/vboard/s...d.php?t=209362
This is a good way to make sure everything seals well. If you still have an exhaust leak, could it be coming from the area where the donut is? That's been a problem for me when I had stock exhaust. Make sure the tail pipe is squared up to the outlet port when you're bolting it all together and always use a brand new exhaust donut. Let us know...

**'68OrangeSunshine** · 11-04-2006, 07:59 AM

I've had to replace some of the OEM bolt fasteners with studs. Especially on the ends [#1 + #8], where the stock set up uses non-threaded guide pins.
Of course I'm running an Offy intake and Clifford headers on a 292 L6, but studs [3/8-16 UNC_3/8-20 fine thread] would give you much better holding even with a stock manifold.
For the gasket, the FelPro metal one [with Permatex Copper-Spray-A-Gasket] ought to work. The NAPA one is the same thing.

El Nido Kid · 11-07-2006, 12:35 AM

Just curious --- are the fixed studs at the ends threaded into the head or do you have to drill and tap? The latter would not be an inframe chore as I see it.

**'68OrangeSunshine** · 11-07-2006, 08:00 AM

Quote:

Originally Posted by El Nido Kid

Just curious --- are the fixed studs at the ends threaded into the head or do you have to drill and tap? The latter would not be an inframe chore as I see it.

They come out CCW with some WD40, big vice grips and a small ball pien. The holes are already tapped 3/8-16 UNC. The studs are about 3" long and the first inch is threaded 3/8-16 then about 1/2 inch of non-thread and ending with about 3/4 of a finer thread 3/8-20 -or -24 [whichever]. Common at fastener suppliers. A flat washer, a lock washer and the nut complete the set up.

Brad · 11-07-2006, 01:07 AM

They are screwed in. Just get a Vice-Grip plier and unscrew.

11-03-2006, 03:09 PM	#2
Ram-Man Senior Member Join Date: Aug 2006 Location: Minnesota Posts: 943	Re: Inline 6 exhaust leaks I think you need 2 gaskets one for each side of the 4 cylinders. So pull the motor and slap in a small block. No just kidding, you should be able to get Fel Pro in a synthetic gasket and not all metal one. Last edited by Ram-Man; 11-03-2006 at 03:10 PM.

11-03-2006, 04:36 PM	#3
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,251	Re: Inline 6 exhaust leaks I used some Permatex High-Temp Ultra Copper RTV Silicone Gasket Maker on my 250 with NAPA gaskets and never had a leak or an issue. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

11-03-2006, 08:52 PM	#4
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,672	Re: Inline 6 exhaust leaks When you machined the manifold did you have them both bolted up together? Or did you only do the exhaust? __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...

11-03-2006, 09:05 PM	#5
El Nido Kid Registered User Join Date: Nov 2006 Location: San Jose,Ca. Posts: 4	Re: Inline 6 exhaust leaks They were bolted together with a new gasket that didn't leak.

11-04-2006, 02:37 AM	#6
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,672	Re: Inline 6 exhaust leaks Take a look at my post (3rd one down) here:http://67-72chevytrucks.com/vboard/s...d.php?t=209362 This is a good way to make sure everything seals well. If you still have an exhaust leak, could it be coming from the area where the donut is? That's been a problem for me when I had stock exhaust. Make sure the tail pipe is squared up to the outlet port when you're bolting it all together and always use a brand new exhaust donut. Let us know... __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...

11-03-2006, 03:04 PM	#1
El Nido Kid Registered User Join Date: Nov 2006 Location: San Jose,Ca. Posts: 4	Inline 6 exhaust leaks Can anybody help me find a source for a better quality exhaust gasket? I had the manifold surfaced but the head has some minor pitting an the stock (metal on both sides gasket) just isn't making it.

11-04-2006, 07:59 AM	#7
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,517	Re: Inline 6 exhaust leaks I've had to replace some of the OEM bolt fasteners with studs. Especially on the ends [#1 + #8], where the stock set up uses non-threaded guide pins. Of course I'm running an Offy intake and Clifford headers on a 292 L6, but studs [3/8-16 UNC_3/8-20 fine thread] would give you much better holding even with a stock manifold. For the gasket, the FelPro metal one [with Permatex Copper-Spray-A-Gasket] ought to work. The NAPA one is the same thing. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 11-04-2006 at 08:07 AM. Reason: more stuff

11-07-2006, 12:35 AM	#8
El Nido Kid Registered User Join Date: Nov 2006 Location: San Jose,Ca. Posts: 4	Re: Inline 6 exhaust leaks Just curious --- are the fixed studs at the ends threaded into the head or do you have to drill and tap? The latter would not be an inframe chore as I see it.

11-07-2006, 01:07 AM	#10
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,672	Re: Inline 6 exhaust leaks They are screwed in. Just get a Vice-Grip plier and unscrew. __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...



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