View Full Version : exhaust leak gt-40 head

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.

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. :thumbsup:

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

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.

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?? :scratch:

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.

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.

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.

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.

07-24-2007, 09:58 PM
take pictures this might help diagnose the problem

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?

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