exhaust gasket blows out

[Dennis/CT]

I have a rebuilt motor with less than 500 miles and the exhaust gasket let go around 350 miles and now again around 500 miles. The exhaust manifold ( heater type ) was machined. I used the copper type gaskets the second time and it still blew out. Engine runs fine with no problems. Is there a fix to this that will last a lifetime ?

Thanks to all that reply

 

[Bob C]

Was the intake manifold bolted to the exhaust manifold when
it was machined? I have a 2N Ford tractor that the block is eroded
by the number one exhaust port and blows the gasket out, the block
needs to be machined flat to fix it.

Bob

 

[Mitch//pa]

where is it blowing out? same area both times?
the rear or #4 port droops over time
are you using gland rings?
did you install new hardware studs, nuts and conical manifold washers.
are the washers installed in the right direction
are the tabs on the mainfold where the washers contact in good shape and not rusted away?

 

[Brentwood Bob]

Are you snugging the nuts after each run like you should be doing with the head ? Bob

 

[P.S.]

Is your muffler plugged or exhaust otherwise obstructed?

 

[Dennis/CT]

Bob C the block and head were machined but I don't know if together.

Mitch, the first time was #1 port this time, I haven't check it yet.
all hardware was new and I quess were installed the correct way by the
rebuilder.

Brentwood Bob, yes I snugged them after running the car for a while.

P.S. new muffler.

 

[Tudortomnz]

If you are using the copper edged gaskets, no need to try & get gland rings in. Ford abandoned them when they changed the gasket design early on in production.
Check that the cup washers on the studs are correctly installed ; they should be peaked outwards to the nuts, not cupped inwards. you need to get full pressure on them to hold the manifold to the gasket.
I also use a good manifold cement all over the gasket ; it seals any tiny leaks when you first start her up to temperature.
Leaks at no.1&no.4 exhaust port are common ; make sure the gasket is seating correctly before firmly tightening it all up.
Good luck

 

[Y-Blockhead]

Have you tried the copper sandwiched gaskets with the glands built in? They seemed to work for me (so far). I've had to re-torque the nuts a few times and found them loose after it cooled down.

I also had a leak at the manifold/head pipe connection. Might check that junction also.

 

[Brentwood Bob]

Are you trying to install the gland rings? or going commando? the gland rings need to be narrow enough to allow the manifolds to tighten securely. Also, the 2 bolts holding the to manifolds together I tighten before final tightening of the manifold to engine stud bolts. I check the mating surfaces with a straight edge and have used a file to fit. The manifolds should only be removed, and installed cold. Bob

 

[Purdy Swoft]

Over tightening the manifolds will warp and cause the outer ends where there is no stud and nut to kick outward and leak . I use to torque the manifolds and warped a few before I finally learned better . I now just use a deep socket and 3/8s ratchet. After it warms and cools I snug them up again. after repeating this process a few times they will usually settle in and hold enough tightness . When you remove the manifolds to replace the gaskets, hold a metal straight edge from end to end over the ports and check the outer ends of the ports .