Honda 16620-Z8D-305 Thermo Wax Assembly

Fits perfectly

If you have a Honda engine (in this case, a 4-5 year old mower with Honda engine model GCV160) and are stumped trying to figure out how your once reliable, 1 pull to start up engine now requires many more, hot or cold, or won’t keep running once started (to include rough running / surging) this part is commonly the culprit. This part has everything to do with the “auto-choke” design of the engine, but can affect running performance, too. They wear out/ fail pretty frequently.Before you take apart your carb or replace spark plugs, etc. , remove your air filter element and check to see if the carb air intake valve is fully closed (as it should be with engine cold as shown in my pic), or if it is stuck partially open.Inside this part is a wax compound that expands/contracts with engine heat, and controls a small pin-like rod in its center. The pin contacts part of the carb intake air valve control arm.Engine cold = pin retracted and permits air intake valve to fully close (aka full choke).Engine hot = pin extended and prevents choke from being on, which isn’t generally needed to restart a warm engine.These pins usually fail to retract and just plain get stuck in one position, creating havoc for all things choke, idle, and running related. In my pics, you can clearly see how the pin of the old one is just stuck extended out a bit. This mower made its way into my shop because it suddenly required 7-10 pulls to start and surged once running, when a few weeks earlier all was fine with it.Shop manual references using a thermal paste on the body of the new part when installing. I never have and never had issues. Pics I included should help those unfamiliar with the parts location on engine. Getting the old one out frequently requires use of a needle nose vise grip pliers and a fair amount of wiggling. The aforementioned mower also surged badly until fully warmed up, and occasionally thereafter. Upon replacement of this part, engine is back to 1 pull to start and no surging issues.

Products worked as described. Shipping was quick and timely.

Just installed Thermo Wax Assembly and below components on a Honda Motor GCV160 with auto choke on a Troy Bilt mover and below recommended choke control, choke actuator (Thermo Wax Assembly) like many others here.Of course note gaskets placement and orientation as may block some ports otherwise. Worked perfectly and stopped surging. All these parts are inexpensive so happy there. I'd bought same carb just 2 yrs prios and stopped surging but it returned ! So this time replaced all 3 interrelated components.Honda 16600-Z8B-900 Lawn Mower Choke Control Genuine Original Equipment Manufacturer (OEM) PartHonda 16620-Z8D-305 Thermo Wax AssemblyHonda 16100-Z8B-901 Carburetor (BB76A A)

If your mower will start first pull then idle crazy, and or die and will not start. First clean the carb and if that doesn’t fix it, then it’s likely this quick choke feature that’s prone to failing on these mowers. Use some needle nose to pull out the old one.

About 3 years after buying my Honda Mower, the mower would not restart after it warmed up. I returned it to the dealer in the fall (Smith Farm and Garden) under warranty and a couple of weeks and $35 or $40 later I was told they "cleaned" the choke mechanism which wasn't covered under my 5 year warranty. The next spring I still had issues with this choke mechanism and with much frustration after finally getting it started and warmed up, I jammed a stick in the choke actuator to allow restarting when emptying the bag. Finally after months of frustration, I bought another mower (not Honda). Still having a need for this little 20" mower, I ordered this thermo wax piece, the choke mechanism it controls, and a new recoil starter and now I have a "new" mower. It now starts on the first pull cold or hot. It took about 15 minutes to change the parts and ~$35 in parts to fix months of frustration. If you have problems starting your Honda, but it runs fine when started, order this and the mechanism that "gets dirty" and save yourself the frustration of dealing with a finicky mower and a repair shop/weeks of delay/$$$.

This...this right here can solve a lot of problems. Before you hump your mower down to the local NASA Small Engine Facility where the highly trained (read as moderately sober) "technician" will tell you how fixing a mower is essentially brain surgery, spend the 10 bucks and 10 minutes to replace this part. Honda should send a handful of these with every engine that makes use of this Rube Goldbergian abomination or better yet just PUT A FREAKIN' MANUAL CHOKE on the engines like they did for years. When this part fails, the default condition of the choke becomes "on". While your cold mower may start and run you can pull til your arms look like Popeye's and you can't start a hot engine with the choke fully engaged. And for what it's worth these things can fail IN USE without prior warning, so you can start your mower just fine, mow a little and then go to restart it and NOTHING DOING. If you own a Honda powered mower keep a few of these on hand or better yet find an old piece of equipment with the same engine and a manual choke and swap the parts. Someone should kick Honda in their collective hineys for this.

Last year, my Honda mower wouldn't start after it had been running and the engine was warm. It would sputter at a very low idle for a few seconds, then die. If I would let it cool for an hour or more, it would start just fine. I bought this wax plug assembly, replaced the one in my mower with it, and it performed just perfectly.......until today, about a year later, now it is doing the exact same thing again. I would expect better from Honda. Not sure if I should buy the Honda part or gamble on a cheaper knockoff version.