exhaust leak gt-40 head

xrracer · 07-18-2007, 11:39 PM

I have an exhaust leak on a 95 Cobra.It leaks at the center of cyl head by the intake.small round hole on intake face of the head by the exhaust cross over port.what plugs this hole. i want to have something to fix it with before teardown.thanks for any info.

**cobrabitn** · 07-18-2007, 11:48 PM

I just got mine fixed about 3 weeks ago at VIR, I'll get measurements for you tonight as I found my spare bolt I kept from Scott. The length needs to be an inch or less and I'll measure the head of the bolt for you and let you know tomorrow.

**cobrabitn** · 07-19-2007, 10:34 PM

Here is what I have on the bolt for the back of the head.

13/16 is the size of the head of the bolt
9/16 is the diameter size of the bolt (I used a 9/16 inch wrench to measure over the bolt. )
13 is the thread count

xrracer · 07-20-2007, 01:34 PM

This is not the thermactor holes at the end of the head.It is the hole on the intake face of the cyl head.I will have to remove intake to get access.These are cast iron cyl heads.I can just barely see the hole beside the intake edge but exhaust is coming out.

**cobrabitn** · 07-20-2007, 10:04 PM

I have my 94 GT 40 heads in the garage in a box ( I replaced them with AFR 185's) and I'll go look at what you are talking about? You said they are on the front of the head??

xrracer · 07-23-2007, 11:25 AM

no on the intake face next to the exhast crossover port.these are cast iron heads.i think the cast iron heads are the only ones that have these round holes.

**cobrabitn** · 07-23-2007, 06:36 PM

Now it sounds like you are referring to the EGR port in the center of the head that the intake mates to?? If you are, that should be sealed with an intake gasket and should not leak. If it is leaking then you have to replace the gasket.

xrracer · 07-24-2007, 10:17 AM

no neither the intake nor gasket completely cover the hole it has to have some type of plig.i have the replacement gasket and it is straight across but the top of the hole is above the outside edge of the intake.

**cobrabitn** · 07-24-2007, 09:20 PM

Call me tomorrow night (Or tonight before 11:00 p.m. eastern time) or I can call you and I'll go out in the garage and find exactly what you are looking for. 803.371.0725 or e-mail me your number at mrmach@comporium.net and I'll call you tomorrow night.

blueblazes · 07-24-2007, 09:58 PM

take pictures this might help diagnose the problem

Larry95 · 07-25-2007, 07:55 AM

If you solve this off line, please be sure to post the final answer. This one has really got me wondering. Just a thought, but is there a possibility that the heads you have are made for the early SB 260 or 289 and don't fit the later intakes?

Philcsag1 · 07-15-2008, 11:20 AM

My Assumption

The cast Iron GT 40 heads were used on the 93 Cobra and 93 to 95 Lightning, in these applications the exhaust for the EGR came form the cross over in the cylinder head up thru the intake. These vehicles use an EGR spacer between intake and throttle body.

The 1994 and 1995 Mustang Cobras 5.0 and 5.8 R models ha the exhaust supplied to the EGR valve via the passenger side exhaust header thru a piece of tubing to the EGR valve.

I do not think ford changed the GT 40 head casting and the cross over passage still existed in the head

They probably placed a plug in that port in the head to prevent the exhaust from leaking and heating the intake manifold

And this is where your exhaust leak is coming from.

The only way I can see repairing this will require you to remove the upper and lower intake manifold

Phil

07-18-2007, 11:39 PM	#1
xrracer Registered User Join Date: Jul 2007 Posts: 4	exhaust leak gt-40 head I have an exhaust leak on a 95 Cobra.It leaks at the center of cyl head by the intake.small round hole on intake face of the head by the exhaust cross over port.what plugs this hole. i want to have something to fix it with before teardown.thanks for any info.

07-18-2007, 11:48 PM	#2
cobrabitn Dr Jekyll on the street, Mr Hyde on the track Join Date: Jun 2001 Location: Rock Hill SC Posts: 14,649	I just got mine fixed about 3 weeks ago at VIR, I'll get measurements for you tonight as I found my spare bolt I kept from Scott. The length needs to be an inch or less and I'll measure the head of the bolt for you and let you know tomorrow. __________________ Cobrabitn 2016 Ruby Red Metallic with Caribou accent F-350 Crew Cab Stump Puller! 6.7 Diesel Automatic with Chrome Package, Off Road Package, 3.55 Locking axles, and Ultimate Lariat Interior Trim Package! 2017 Shelby GT350 Coupe - track car! Mods: JLT True Cold Air oil catch can 2009 Vista Blue Shelby GT 500 Coupe - Garage Queen Tinted Windows JLT True Cold Air Kit Pro-Dyno Tune 526 rwhp - 511 rwtq 1994 Rio Red Indy Pace Car #22 "Runabout" Snake in the grill MGW shift knob 1996 SVT Cobra Wheels 1969 New Lime Mustang Mach 1 Sportsroof - Second owner - bone stock with shaker. One SVT Cobra, one Shelby GT500, one 69 mach 1, and a Shelby GT350 is better than nothing! Custom Data Plates for your Mustang or Ford! Buy "Cool Merchandise" at Data Plates Plus www.dataplatesplus.com See my MSR Video here!

07-19-2007, 10:34 PM	#3
cobrabitn Dr Jekyll on the street, Mr Hyde on the track Join Date: Jun 2001 Location: Rock Hill SC Posts: 14,649	Here is what I have on the bolt for the back of the head. 13/16 is the size of the head of the bolt 9/16 is the diameter size of the bolt (I used a 9/16 inch wrench to measure over the bolt. ) 13 is the thread count __________________ Cobrabitn 2016 Ruby Red Metallic with Caribou accent F-350 Crew Cab Stump Puller! 6.7 Diesel Automatic with Chrome Package, Off Road Package, 3.55 Locking axles, and Ultimate Lariat Interior Trim Package! 2017 Shelby GT350 Coupe - track car! Mods: JLT True Cold Air oil catch can 2009 Vista Blue Shelby GT 500 Coupe - Garage Queen Tinted Windows JLT True Cold Air Kit Pro-Dyno Tune 526 rwhp - 511 rwtq 1994 Rio Red Indy Pace Car #22 "Runabout" Snake in the grill MGW shift knob 1996 SVT Cobra Wheels 1969 New Lime Mustang Mach 1 Sportsroof - Second owner - bone stock with shaker. One SVT Cobra, one Shelby GT500, one 69 mach 1, and a Shelby GT350 is better than nothing! Custom Data Plates for your Mustang or Ford! Buy "Cool Merchandise" at Data Plates Plus www.dataplatesplus.com See my MSR Video here!

07-20-2007, 10:04 PM	#5
cobrabitn Dr Jekyll on the street, Mr Hyde on the track Join Date: Jun 2001 Location: Rock Hill SC Posts: 14,649	I have my 94 GT 40 heads in the garage in a box ( I replaced them with AFR 185's) and I'll go look at what you are talking about? You said they are on the front of the head?? __________________ Cobrabitn 2016 Ruby Red Metallic with Caribou accent F-350 Crew Cab Stump Puller! 6.7 Diesel Automatic with Chrome Package, Off Road Package, 3.55 Locking axles, and Ultimate Lariat Interior Trim Package! 2017 Shelby GT350 Coupe - track car! Mods: JLT True Cold Air oil catch can 2009 Vista Blue Shelby GT 500 Coupe - Garage Queen Tinted Windows JLT True Cold Air Kit Pro-Dyno Tune 526 rwhp - 511 rwtq 1994 Rio Red Indy Pace Car #22 "Runabout" Snake in the grill MGW shift knob 1996 SVT Cobra Wheels 1969 New Lime Mustang Mach 1 Sportsroof - Second owner - bone stock with shaker. One SVT Cobra, one Shelby GT500, one 69 mach 1, and a Shelby GT350 is better than nothing! Custom Data Plates for your Mustang or Ford! Buy "Cool Merchandise" at Data Plates Plus www.dataplatesplus.com See my MSR Video here!

07-23-2007, 06:36 PM	#7
cobrabitn Dr Jekyll on the street, Mr Hyde on the track Join Date: Jun 2001 Location: Rock Hill SC Posts: 14,649	Now it sounds like you are referring to the EGR port in the center of the head that the intake mates to?? If you are, that should be sealed with an intake gasket and should not leak. If it is leaking then you have to replace the gasket. __________________ Cobrabitn 2016 Ruby Red Metallic with Caribou accent F-350 Crew Cab Stump Puller! 6.7 Diesel Automatic with Chrome Package, Off Road Package, 3.55 Locking axles, and Ultimate Lariat Interior Trim Package! 2017 Shelby GT350 Coupe - track car! Mods: JLT True Cold Air oil catch can 2009 Vista Blue Shelby GT 500 Coupe - Garage Queen Tinted Windows JLT True Cold Air Kit Pro-Dyno Tune 526 rwhp - 511 rwtq 1994 Rio Red Indy Pace Car #22 "Runabout" Snake in the grill MGW shift knob 1996 SVT Cobra Wheels 1969 New Lime Mustang Mach 1 Sportsroof - Second owner - bone stock with shaker. One SVT Cobra, one Shelby GT500, one 69 mach 1, and a Shelby GT350 is better than nothing! Custom Data Plates for your Mustang or Ford! Buy "Cool Merchandise" at Data Plates Plus www.dataplatesplus.com See my MSR Video here!

07-20-2007, 01:34 PM	#4
xrracer Registered User Join Date: Jul 2007 Posts: 4	This is not the thermactor holes at the end of the head.It is the hole on the intake face of the cyl head.I will have to remove intake to get access.These are cast iron cyl heads.I can just barely see the hole beside the intake edge but exhaust is coming out.

07-23-2007, 11:25 AM	#6
xrracer Registered User Join Date: Jul 2007 Posts: 4	no on the intake face next to the exhast crossover port.these are cast iron heads.i think the cast iron heads are the only ones that have these round holes.

07-24-2007, 10:17 AM	#8
xrracer Registered User Join Date: Jul 2007 Posts: 4	no neither the intake nor gasket completely cover the hole it has to have some type of plig.i have the replacement gasket and it is straight across but the top of the hole is above the outside edge of the intake.

07-24-2007, 09:20 PM	#9
cobrabitn Dr Jekyll on the street, Mr Hyde on the track Join Date: Jun 2001 Location: Rock Hill SC Posts: 14,649	Call me tomorrow night (Or tonight before 11:00 p.m. eastern time) or I can call you and I'll go out in the garage and find exactly what you are looking for. 803.371.0725 or e-mail me your number at mrmach@comporium.net and I'll call you tomorrow night. __________________ Cobrabitn 2016 Ruby Red Metallic with Caribou accent F-350 Crew Cab Stump Puller! 6.7 Diesel Automatic with Chrome Package, Off Road Package, 3.55 Locking axles, and Ultimate Lariat Interior Trim Package! 2017 Shelby GT350 Coupe - track car! Mods: JLT True Cold Air oil catch can 2009 Vista Blue Shelby GT 500 Coupe - Garage Queen Tinted Windows JLT True Cold Air Kit Pro-Dyno Tune 526 rwhp - 511 rwtq 1994 Rio Red Indy Pace Car #22 "Runabout" Snake in the grill MGW shift knob 1996 SVT Cobra Wheels 1969 New Lime Mustang Mach 1 Sportsroof - Second owner - bone stock with shaker. One SVT Cobra, one Shelby GT500, one 69 mach 1, and a Shelby GT350 is better than nothing! Custom Data Plates for your Mustang or Ford! Buy "Cool Merchandise" at Data Plates Plus www.dataplatesplus.com See my MSR Video here!

07-24-2007, 09:58 PM	#10
blueblazes Registered User Join Date: Apr 2006 Location: Hickory, NC Posts: 275	take pictures this might help diagnose the problem

07-25-2007, 07:55 AM	#11
Larry95 SCMC Member Join Date: May 2006 Location: Richmond, TX Posts: 469	If you solve this off line, please be sure to post the final answer. This one has really got me wondering. Just a thought, but is there a possibility that the heads you have are made for the early SB 260 or 289 and don't fit the later intakes? __________________ Larry & Eloisa Ewers '95 Red Coupe #684/4005 (going back to stock) '95 White Coupe (track car)(378 rwhp, 394 rwtq) '03 Red Annv Convt #711/2003 (SOLD) '12 Boss 302 LS '13 King Ranch EcoBoost F-150 (Eloisa's ride) '13 King Ranch 6.7L F-250 (daily driver & tow vehicle)

07-15-2008, 11:20 AM	#12
Philcsag1 SCMC Member Join Date: Mar 2005 Location: New York City Posts: 116	My Assumption My Assumption The cast Iron GT 40 heads were used on the 93 Cobra and 93 to 95 Lightning, in these applications the exhaust for the EGR came form the cross over in the cylinder head up thru the intake. These vehicles use an EGR spacer between intake and throttle body. The 1994 and 1995 Mustang Cobras 5.0 and 5.8 R models ha the exhaust supplied to the EGR valve via the passenger side exhaust header thru a piece of tubing to the EGR valve. I do not think ford changed the GT 40 head casting and the cross over passage still existed in the head They probably placed a plug in that port in the head to prevent the exhaust from leaking and heating the intake manifold And this is where your exhaust leak is coming from. The only way I can see repairing this will require you to remove the upper and lower intake manifold Phil __________________ 1993 Cobra # 329, Cover Car Fox Body Recognition Guide 1994 Cobra Convertible # 73 sold 11-11-2011 1995 Cobra R #45 2012 Boss 302 LS #699 2017 GT 350 # H6024

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