Weil McLain 590-317-628 Gasket
The Weil McLain 590-317-628 Inspection Port Gasket seals the inspection port cover on the Weil-McLain GV gas boiler. The GV Series 3 and GV Series 4 parts lists both show it as an "Inspection Port Gasket," in the section assembly figures (Figs. 11/12) and again in the later assembly figures (Figs. 18/19), marked for all boilers on the list. It is a flat red rectangular gasket with two mounting holes, one at each end, shown in the photo against a ruler. It sits between the boiler and the 560-907-629 inspection port cover, which Weil-McLain lists for the same GV Series 3 and 4 boilers.
The inspection port is how a tech sees into the combustion side of the boiler, so it has to be gas-tight every time the cover goes back on. A gasket that is hardened, cracked or flattened by an earlier service lets flue gas escape into the room or lets room air in, and either one affects combustion and safety. A gasket also takes a compression set the first time the cover is tightened, and it rarely seals as well the second time, so it is a one-time-use item.
Always fit a new gasket when the cover has been removed. Clean the sealing surface, line up the two holes, set the cover and tighten evenly so the gasket seats without being crushed. Check the finished joint with a combustion analyzer for carbon monoxide after the boiler fires, and look for staining at the edges at the next service. If you are also opening the vent connection, replace the 590-317-629 starter tee gasket at the same time, since both are listed together on the parts lists. This gasket is not listed on the GV Series 1 and 2 parts list, so confirm your series before you order. A few minutes of work and one inexpensive gasket keep the inspection port from becoming a leak path.
Key Benefits
- Seals the Inspection Port: Keeps flue gas inside the boiler when the inspection port cover is installed.
- Listed for GV Series 3 and 4: Shown on the Weil-McLain GV Series 3 and GV Series 4 parts lists.
- Two-Hole Rectangular Shape: The flat two-hole gasket is shown against a ruler so you can compare it to your old one.
- Pairs With the Starter Tee Gasket: Order the 590-317-629 at the same time when the vent connection is also being opened.
Common Questions
- Which boilers list the 590-317-628? The Weil-McLain GV Series 3 and GV Series 4 parts lists.
- Can I reuse the old gasket? It is best not to. A used gasket has taken a compression set, so fit a new 590-317-628 whenever the inspection port cover has been removed.
- Does the cover come with it? No. The 560-907-629 is the cover and is a separate part. This is the gasket only.