If there is even the slightest suspicion that a manifold has flashed, the processor should put a few pellets of a red resin or contrasting colorant into the melt stream (in the nozzle tip), then shoot the mold two to four times before it’s pulled to aid in locating the source of the leak.

While pulling a mold suspected of a manifold leak would seem like a waste of production time to many, the eight to 10 hours it might take to do this could save several days if you catch the manifold in the initial stages (less than one-third full) of total encapsulation.
But it takes an experienced processor to notice these signs and request that the mold be pulled for a manifold inspection based solely on suspicion. Many will just let it go until it becomes obvious that the toolroom has a problem. We will assume as much and elaborate on the above five steps.

On valve gate molds with valve stems accessible from the back of the clamp plate, it is possible to remove the valve stems cold with a small slap hammer, but this practice could cause the head of the stems to break off, so it is safer in most cases to warm up the nozzles and, if possible, the manifold to about 250 degrees to allow the pins to be removed with less impact.

As with all tooling, make sure the valve stems are numbered (use a carbide cutter in a hand-held grinder), a home location preferably somewhere on the head or stem, and place them in a wooden or plastic base drilled with an appropriate number of marked holes to keep them upright and separated.

Remove the backing plate (usually the “A” side clamp plate) to gain access to the backside of the manifold. Here you might see your first clue. Look for the path of the red resin. Manifold and nozzle seals that fail will allow the plastic to flow from that point outboard and follow the path of least resistance.

The plastic will flow through wire channels in a laminar method, just as it does through a runner, so the resin around the initial point of failure will be more burned (degraded). This means the freshest looking flow front is usually furthest away from the source of the leak, and has been cooking the shortest amount of time.

Notice the direction of the shot waves of resin that ripple away from the leak source paying particular attention to these flow fronts and the condition of the plastic. Is it burned (first place to leak) or fresh (last place to fill)?

Before attacking the plastic with a ham-mer and chisel, look hard at the source
of the leak (here is where the red resin really helps) and try to confirm by examining the seal point in this area looking for a resin film between the tooling that would indicate separation. If an area looks promising, remove the plastic and check things out before continuing on.

A faulty seal between a nozzle and the manifold is easier to detect since the plastic rod formed at the junction should be smooth with no plastic washer attached to it.
At this point you will either discover the source/root cause of the leak, or you will find nothing and proceed on with more melting/chipping/cleaning.

Make good use of the heat gun (a Master Appliance Heat Gun #HG-751-B works great) and your brass chisel. The heat gun will soften much of the plastic in the channels to a point that you can more easily remove it from around the wiring, while carefully working your way down the channels.

If nothing is found during initial plastic removal, then remove enough plastic to separate the manifold/nozzle/electric box assembly from manifold plate. This will allow the plate to be cleaned in the ultrasonic while the nozzles and manifold are being inspected and cleaned by hand. Crank up the ultrasonic temperature to 200 degrees and tilt the plate forward in the tank, so the resin/weepage will liquefy and run out of the counter bores and channels.

While the plates clean in the tank, you can now remove the nozzles from the manifold, carefully, one at a time looking for signs of seal separation and feeling/watching for loose bolts. If gate tip edges are critical, wrap the tips in masking tape to protect them from accidental dings

After all nozzles have been removed from the manifold, set them aside (still connected to the electrical box) and clean the manifold with a brass putty knife and ending with a fine/medium coarse Norton stone.