The Dorman intake manifold simply adds a pin behind the check valve to prevent it from disappearing. However, this doesn't prevent it from cracking, getting gummed up, clogged with deposits, or leaking. Furthermore, you can't even see the valve from the top of the PCV port because it's recessed further back than on the OEM manifold, so you can't even test it to tell if it's working correctly. I've actually had people install my kit and when they punched out the old valve and shook it out of the manifold, they found it had already cracked, so take what you will from that.
The PCV fix kits have been successful. I've been shipping those out now for 4 years. The V1 kit remains solid and comically over-built, but the most expensive. The V2 used to use the brake booster tee fitting, but I went away from that as it had a potential maintenance requirement to clean the fitting (and the manifold nipple it's connected to) periodically to ensure that no deposits get built up inside. To that point, I've had people check theirs at 25k, 45k, 65k, 80k, and 110k miles (different people) and the fitting was clear, but still something I didn't want people to have to do. Also, there are more potential leak points with that T fitting. The V2.1 change uses a Y splice on the evap purge valve line, the same way the V3 kit does. This also helped me reduce my inventory overhead. It's getting cramped in here with how much inventory I have to carry to meet demand.
I have a V2 to V2.1 conversion kit available for anyone that wants to switch off of the brake booster tee. The V1 and V2.1 kits also have the pipe upgrade add-on for $22, which replaces the crack-prone corrugated PCV pipe/hose. The V1/V2.1 brass check valves have been lasting about 80k-120k miles before they need to be cleaned, after which they can be placed back into service. I've only ever had to replace ONE for a customer, which was operated in extreme conditions in Israel.
The V3 kit was updated to V3.1 with a new custom made T fitting that I designed and had a mold made for. This is also sized better on the 5/16" side than the old T fitting, all resulting in the kit requiring 4 fewer parts than the V3 kit. The main advantage to the V3.1 kit is that it can be installed from the top of the intake manifold without removing it, which saves a great deal of time. I've had a few people report issues getting the clip in place, but I'd say based on how much feedback I get on that and how many I ship, 95-98% of people have no issue with it. The kit, by design, also replaces the crack-prone PCV pipe, so it's the best value kit, being two fixes in one. The drawback to the V3.1 kit is that the check valve isn't as nice, and depending on your driving conditions, may need to be replaced every 10,000-30,000 miles. I'm currently working with my supplier to improve the quality of that valve with a higher grade Viton so it would last longer. Fortunately, the valves are very cheap;
I have them on the site for $9.00 a pair shipped (or less, in a 3-pack or 4-pack) so you can swap them out periodically like you used to with older cars.
The stock valve WILL fail, it's just a matter of when. At least on the V3 kit, you can swap out a new valve for a few bucks and be on your way.
All of these kits are half the cost of a new manifold, so you really can't beat the value.
