Ford Truck Enthusiasts Forums - FIXED Ford 4.9 300 cid Exhaust Manifold Leak at Head FIXED Econoline Bronco REMFLEX GASKET

So there are a number of threads on this problem and lots of attempted repairs. Finally, after living with this noisy exhaust leak, where the exhaust manifold mates to the head, somewhere between the #3 and #4 exhaust, bad noisy leak for years and years.

I bought this van in 1999 and the exhaust leaked when I purchased it. I spoke to a Ford mechanic and he told me that it was probably a broken ferrule or a broken pipe on the air injection system. And yes, he was right, one of the pipes had cracked and was making quite a lot of noise.

I removed the intake and gained access to the rail on the top of the head and got all the ferrules out except for the one on #1. It cracked and split and broke off. Even with four days of PB Blaster treatment. Maybe if it had been heated with a torch, it would have come out. All i had was propane and I knew that wasnt hot enough. After reading post after post. I decided to plug the holes with screw in metal plugs and fill the broken ferrule with JB weld. As at this time, I wasnt ready to remove the head and didnt want to.
So I finally go the engine back together and started it up. And the loud noise was still there, So it wasnt just the air rail.

I took the top end of the engine apart again and found that there was a where the exhaust manifold meets the head between #3 and #4 cylinder. So I proceeded to remove the intake and then the exhaust manifolds. All went well until I tried to remove the double stud bolt on the very front of the motor that holds the alternator bracket and the exhaust manifold. It broke, flush on the side of the head. I tried to do an extraction and the sxtractor broke off also. Not much I can do after that, Hardened Steel,so I removed the head and took it to the machine shop. Probably a good thing that I did, this engine has 234k on it and it appears that it was about to develop a water leak where the head gasket looked to about to fail.. So, maybe this was a good thing. I took the head to a machine shop and after a week, they had the broken stud out and the threads looking like new. I went to the junk yard to get a new double ended bolt and had the valves done and the head surfaced along with the exhaust manifolds.

Finally it was time to put it all back together. All New Fel Pro Gaskets! The combo Intake/Exhaust gasket set was a one piece metal and paper gasket overlay. The exhaust manifolds didnt want to fit properly. This particular year, 1994, used 2 exhaust manifolds, one in front and one in back. When I tried to reassemble them, starting from the middle and working out, the last two holes were not centered. It appeared that the manifolds had shrunk some. I expanded the outside holes, as other here have had this same problem, using a dremel tool and a carbide bit. It didnt take much, but after this modification, the heads fit perfectly. Torqued manifolds to factory spec, 12lbs. AND--STILL LEAKING BETWEEN #3 and #4. It seems that the head was really pitted where the original exhaust leak was, probably from deposits of moisture that were left on the head after running the vehicle. It probably just pitted it out over time since the leak was never fixed early in the life of the engine.

I took the intake and exhaust off the vehicle again and I did note the pitting on the head, this must be the real problem, it was too deep for resurfacing to fix. So I began to research this leaking problem again and didnt find any good answers. It appears that this engine was assembled from the factory without a intake/exhaust gasket. Any reassembly after use, people were using a combination exhaust and intake gasket. The flanges of the exhaust manifold and the intake manifold are different thicknesses and when reassemble is done, there is an added gasket on top of the exhaust gasket, just for the intake gasket, to facilitate this difference.

I finally came across a posting for a Remflex Gasket. It was very different from all the other gaskets, these gaskets are solid Graphite, and thick. Check them out at Remflex.Com. This particular gasket was about $50.00. Thats a lot more than any other gasket but I was ready to try anything now. There was only one other posting about this Remflex gasket and it had a pretty positive review.

I called Remflex and spoke to them and they were very nice and knowledgeable. I ordered the gasket and it arrived quickly. It is significantly different than any other gasket I have used. The instructions stated to torque the gasket to 20 - 25lbs. I started to reassemble the manifolds and ended up cracking the rear flange on the intake after trying to torque to the specified measurements. I got to 18 and then tried to get to 22 and it cracked. This flange is noted to be a problem with most of these intakes, there are lots of them cracking. I called Remflex and spoke to Allen and he sent me a new gasket, priority mail. I found a new intake for a great price and began to reinstall the assembly. THIS TIME I WAS ONLY TORQUING TO 15 LBS.. DO NOT TORQUE HIGHER. BE sure that the threads on the manifold bolts and the threads in the head are clean and clear. I used a tap and die to clean it all up and it made a difference..

So I finally got the engine back together and started it up and I have never heard it run so quietly. This gasket solved the problem, NO QUESTION.

THIS REMFLEX GASKET SOLVED THE PROBLEM FOR ME AND IT WILL FOR YOU!

I Know its a bit expensive but this gasket is the best option. Call them.

I hope this write up will help someone with their issue. THis is a 1994 Ford E150 Van with a 4.9 300 cid straight 6

During the process of all this, I also

Cleaned the fuel injectors and gave them new o rings and filters,, each fuel injector has an internal filter.
New Oil Pan Gasket
New Knock Sensor
Cleaned Wiper contacts
Cleaned AC Control contacts
New EGR Valve and Pipe
New Cat and Downpipe
New Valve Cover Gasket
Replaced Distributor Ignition Pickup
Replaced Spark Plugs
New Serp Belt