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Tornado Grenade - Troubleshooting Guide

A LOT of grenades are in use now and we've helped quite a few users through some technical difficulties with our product. We realize that our product is one that requires more maintenance than most airsoft products and it's operation has a few funny quirks that are new to most airsofters. This article is a compendium of our experience with trouble shooting that can be done with tools that most players have access to. Please be sure to read our "How it Works" article because it'll help you better understand this article.

Parts Glossary

Please familiarize yourself with this annotated section photograph. All of the parts in the Tornado will be referred to by the names indicated here.

Zones of the Tornado Grenade:

  • Delay chamber
  • Reservoir
  • Manifold
  • BB spirals

Parts of the Tornado Grenade

Bumper: Rubber bumper with integral plug and plug lanyard
Top Cap: Machined aluminum cap which provides timing delay functions
Delay Restrictor: Partially blocked opening in the TC which acts as a timebase for the grenade delay
Shuttle: Grenade SuperPart! The most complicated part which participates in timing, gas storage, gas filling, and firing processes
Fill Valve: Brass valve screwed into the core of the shuttle
Upper Delay Seal: Rubber seal sealing between the reservoir and the delay chamber
Lower Fire Seal: Rubber seal sealing between the reservoir and the manifold
Stem Orings: Orings on the stem of the shuttle
Body Tube: Machined aluminum tube which holds all the pneumatics together

Maintenance Videos:

Refer to these videos for instructions on disassembling and cleaning your grenade. They will be referred to in the following trouble shooting guide. 

Disassembly Video
Cleaning Video
Reassembly Video
Delay Flushing Video 

Grenade Malfunctions:

Long Delay or Seized Delay

1. Grenade is cold from filling. Please allow 5 minutes immediately after filling before testing your grenade. Grenades should be at room temperature (~20C) for best effect.

2. Grenade requires lubricant. Grenades must be lubricated with two drops of Tornado Grenade oil (not GunGas GBB oil) once every two deployments. GunGas GBB oil has a very low viscosity and does not provide sufficient lubrication for Tornado Grenades. Do NOT use Tornado Grenade oil as a GBB maintenance oil as it will coat the barrel with a heavy goo which will affect your GBBs performance until you clean it out. Tornado and GunGas oils are not interchangeable.

Be sure to get the lubricant deep inside the grenade past the exposed piston edge.

It is important to let the oil drip past the upper fire seal so the oil gets right inside the reservoir chamber of the grenade. When you fill your grenade with propane, the liquid charge will dissolve the oil and carry it to the upper delay seal. Oil which does not get into the reservoir will only lubricate the lower fire seal.

If your shuttle does not move smoothly, try this lubrication scheme:

  • Drip 4x drops of Tornado oil in one spot at the edge of the piston under the valve cover
  • Hold grenade upside down for 2 minutes to allow oil to flow into reservoir chamber (you can put your grenade upside down in a coffee mug as a holder)
  • Reset shuttle valve and set grenade for 3s delay
  • Fill grenade with propane and shake it for 10s to circulate liquid propane and lubricant

3. Incorrect Propellant or Insufficient Propellant

Most Tornado Grenades are tuned for propellant that exerts 120psi. In most cases, propane is the correct propellant at most playing temperatures. Most propellants packaged as "Green Gas" are primarily propane and are suitable, but some brands contain a significant amount of butane which can reduce fill pressure. Since most players are unable to make direct pressure measurements on their propellants, we suggest this general rule of thumb: use propellants that can propel a 0.2g pellet to 300+ fps out of a stock GBB. We are working on a list of propellants indicating fill pressures of popular airsoft propellants to help our grenade users pick appropriate propellants.

Grenades meant for distribution to Japan are tuned to work with gas exerting 75psi at 20C (HFC134a). These grenades are marked "LP" on the topcap to indicate that they are tuned for a low pressure propellant. LP grenades do not work properly with propane at room temperature as their delay will be very short.

It is important that you fill your grenades upside down with your fill bottle pointing downwards. There should be a charge of liquid in the fill bottle. You should be able to detect an amount of liquid swishing around your bottle if you shake it gently.

4. Leaking delay seal

If the upper delay seal is damaged, compressed gas from the reservoir can leak past the delay seal into the delay chamber. Gas leaking into the delay chamber can increase the pressure in the delay chamber and reduce the net force acting on the shuttle.

Testing for this condition is fairly easy with the following procedure:

  • Set delay for 3s and fill reservoir with gas
  • Remove delay plug
  • Replace delay plug
  • Wait 5min
  • Remove delay plug and listen for an escape of gas out of the delay plug opening

A leaking delay seal can be diagnosed if there is an audible whoosh of gas from the delay plug port when you remove the delay plug. If this condition is present, disassemble your grenade and clean the upper delay seal before reassembling it.

Disassembly Video
Cleaning Video
Reassembly Video

Be sure to use the seal shrouds when reassembling your grenade as jamming a shuttle past the sharp topcap threads in the valve body tube is the most likely cause of damage to a shuttle seal. Carefully clean the interior of your valve body tube before threading in the topcap to remove metal burrs or debris which may prevent the upper delay seal from sealing to the inside of the body tube. Do not scratch the inside of the body tube with sharp tools as scratches to the sealing surfaces of the body tube can cause leakage at the upper delay seal.

 If cleaning the body tube and upper delay seal does not fix a leaking delay seal and there are no scratches to the body tube, the shuttle assembly must be replaced. Unfortunately the upper delay seal cannot be replaced as is an integral part of the shuttle.

5. Fouled delay restrictor

The delay restrictor is the time base which determines how long your Tornado grenade "ticks" before it blows up. It is a controlled air restriction which gradually leaks air while the shuttle slowly moves. Flushing of the restrictor is required if it gets fouled with silicone oil (say you accidentally put oil in the delay chamber). The delay restrictor can be flushed with a mild solution of water soluble detergent followed by a water rinse.

View this video: Delay Flushing Video

Short or No Delay (Grenade blows up too soon):

1. Rubber delay plug is not pushed down or is popping out:

The rubber delay plug closes a large diameter hole in the topcap. If this plug does close this opening, air from the delay chamber is given an easy escape which prevents the delay feature from working properly. Check your grenades operation carefully to determine if the plug is not being replaced due to user error or if the plug is blowing out spontaneously. The delay plug should be retained by a shoulder feature in the topcap hole that it sits in. When pulling the plug out you should feel some resistance before it pops free. If this feature is missing from your topcap and you can confirm that the delay plug blows out, replacement of the topcap is necessary.

2. Damaged shuttle stem orings

Damage to the orings on the shuttle stems may allow air from the delay chamber to leak out when the pin is pulled. Leaking shuttle stem seals provide an alternate path for air to escape through which may significantly reduce the time delay on your grenade. Inspect your stem orings for damage or dirt contamination by disassembling and cleaning your grenade:

Disassembly Video
Cleaning Video
Reassembly Video

The most likely cause of a leaking stem oring is dirt contamination of one or both orings, but it is possible to damage an oring with a partial pin pull. In some infrequent cases, it is possible to accidentally partially pull a pin such that it sticks in the topcap such that the end scratches across the shuttle stem and the orings. Look for damage to the shuttle stem (a deep scratch) and orings.

3. Dirty topcap oring or body tube seating

Contamination or damage to the top of the body tube can prevent an airtight seal to the body tube. Air leakage past the topcap oring provides a secondary escape of air from the delay chamber which can reduce grenade delay. Disassemble and clean topcap threads, threads on the body tube, and the oring seating area before reassembling to fix this issue. Be careful not to scratch or damage the oring seating area with sharp tools.