The exhaust manifolds of my 390 FE keeps leaking.... I took them off last time and sanded them level (so I think). They where quiet for aprox. 150 miles and then they started to leak again... Would copper gaskets cure this problem? I also heard that FE exhaust manifolds keep leak-free with out gaskets?? Many thanks, Ramon
Well I'll tell ya, I had to put one of mine up in a mill and fly cut the surface to get it perfectly flat and smooth. FE exhaust manifolds are notorious for leaking.
When I worked in the gas station this was always a problem with the trucks too (wreckers). My old boss used to put some wheel bearing grease on each side of the gasket. When it got hot the grease would cook and make some nice carbon and seal it up. Almost never had a come back with this method over the years but don't go too crazy with the grease, just a nice coating on each side. Cliff Ramsdell
What gaskets have you been using? I started with the cheap-ass paper ones on my last FE and the leaks would always come back (even after surfacing the manifolds). I switched to the gaskets that are two layers of aluminum with a material between them. They sealed up much better! Copper gaskets might work, too. Malcolm
My buddy had the same problem, he had them surface milled and installed copper gaskets, no problems in 3 years. Syl
After assuring both surfaces are completely flat (milled). Make sure the bolts are in excelent shape (not streching or rusty). Apply a coat of neversieze to each port and all bolts. You do not need much but enough to let it slide around with heat cycles. Then assemble with the correct recomended pattern and tourque specification. I have done this with 2 FE's one with the factory manifolds and one with Headman elite headers. I had excelent results in both cases. Manifolds should not use gaskets if they are in good shape along with the head surface....
...OR, coat the surface of the manifold with that muffler seal paste, then bolt them down. I did this on 2 sets of leaking headers, and it did the trick...
Use quality exhaust manifold gaskets. Lay a thin bead of hi temp silicone (we used to use the ultra copper stuff) around both sides of the ports. Let set up for 20-30 minutes & assemble. Keep an eye on the bolts, check & retighten every day for the first week or so. Never had a problem after that.
I replaced my exhaust manifold gaskets on my 352 three times, and had the surface "decked". Continued to blow-out. Someone suggested doubling the gaskets. I did. It's been good for six or seven years so far. Purchase the best quality gaskets you can afford.
On my 390 in my thunderbird I do not have any gaskets. I had both surfaces milled and I put a light coat of hi-temp permatex on it and bolted them up. No leaks anymore and been running this way for a few years now.
They came from the factory with no gaskets, and as long as both surfaces are straight, it will work. You could also put some RTV to seal it up.
I won't use anything but Remflex. Leaks are now a thing of the past. http://catalog.remflex.com/category_s/97.htm Stan
Run a 300 HP 390 in my car hauler, Ebay for copper gaskets and make sure you hammer them flat [ they are designed for headers ] and belt sander for the manifolds to make them flat, use a 1" hole saw and make flat washers out of 1/4 steel then drill center to 3/8, running 4 years now still no leaks, some times the heads get damaged from the leaks so make sure they are flat also.
Use the gaskets listed above or the embossed copper ones from Summit if you have regular "FE" log type manifolds. If you have the factory type cast iron headers, especially the tong tube ones, then you need to consider having the manifold surface machined flat. The use of gaskets on these will very likely cause them to crack if the surface can not move as designed. Scott...
Thanx for the input guys! I think I go with the Remflex gaskets. I only need to sort out what the shipping/handling to Amsterdam, the Netherlands is...Any alliance member who sell Remflex?
I have done a few FEs and had good success with good quality gaskets and Hi-Temp sealer,but you must put a straight edge on the head surface.If left to long with a leaking manifold the head will get burnt away requiring removal and surfacing.
I had to surface the exhaust side of the head and the manifold (long tube factory iron headers) to stop the "bleeding". 5 years on 427, 64, XL and no issues at all.
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