Intake manifold leak

Well I don't know how well caskets seal, but I imagine in that application you might want a gasket?!  :-)  You could buy another set, and double everyting up, but that's about all I know to do, short of machining them flat.

What's it cost to machine a manifold these days? I'm spoilt cause an old mechanic near me did it for $5 last time I had one done. He's been ill lately so I'm not sure how long he can keep working. The sure fix is to machine the manifold if it has enough life in it yet.

Plane the manifold flat.  I'll add to Charlie's comment by saying 'belt sander', or even an abrasive flapper-wheel on the angle-grinder... but the last one I did, I just clamped it in a Bridgeport mill and mowed it down with a four-tooth end-mill... I took my time getting it setup right, and experimenting with cutters and speeds, but second time around was easy-fixin'.

If you carry it in to a local machine shop, I'd bet you'd be able to get it professionally enflattinized for under $50... just remember to tell them that it doesn't matter if the mounting face is paralell to anything... just flat.

Leaking exhaust WILL erode the cylinder head mounting face... I had one that was burned away at the #1 port something fierce, so I superflattenized the cylinder head, too... I was suprised at how much 'meat' was in the war-zone... when done, I'd cut out almost 1/4" off the front end of the head, 'till I finally got a good, flat manifold fitment... and darnit if that engine doesn't purr nicely now.

Put it in a vise with ports facing up, put a straightedge on it, mark the high spots by scratching 'em with a sharp point, then sand off the marks.  Wear old clothes and a dust-mask, use about 200-grit belts.

KGood wrote: I use a 24" table disc sander. I'am lucky we have one were I work. FYI My uncle bought a new intake manifold for his 185 and it was about an 1/8" warped out of the box I was able to get it flat. It was tricky because it was a little longer than the disc.

I had that problem on a Ford v-8 truck that I didn't want to take apart to mill the head. I tried some high temperature silicone with a thick gasket and it held until I opened the throttle on a hill and the muffler back pressure blew gasket and silicone out of the gap where it wasn't supported. (390, 4 barrel, in a 1 ton dually with a 5.375 rear axle). I considered but never made it to use a very soft (thoroughly annealed) copper gasket with some ridges smashed to take up the big gap. The plan was to cut a gasket wider than needed and squeeze it between plates with wires soldered on to make the gasket corrugated with the ridges perpendicular to the leak flow. It would probably have taken at least one annealing during the corrugation operation and maybe one with the manifold halfway in place squeezing the corrugations to fit the eroded manifold and head. Copper is annealed by heating it glowing read and cooling it. The cooling rate isn't critical, fast or slow copper gets soft. I don't have that truck anymore so the leak doesn't bother me anymore.

In the old days we might have rolled up some asbestos sheet to fill the gaps or made the corrugated gasket from pure asbestos sheet. Its entire possible that waterglass still might work to seal such a gap without the complexity of milling (but milling IS the right way to do the job, whether disk sander, special surface grinder, end mill, horizontal mill, or mill file. Many machine shops should be able to fix any gaps quickly if they have the parts loose and the studs out. Studs tend to interfere with machining flat.

Gerald J.