You shut the boom off at the end of the pass and three or four tips keep dribbling for half a minute. That is not a console problem and it is rarely a valve problem. On a Quick TeeJet body the thing that stops the drip is a small diaphragm check valve under the end cap, held shut by a spring. When the diaphragm is cut or swollen, the cap is loose, or the body is cracked, the check leaks. Sometimes the whole boom drips because pressure is bleeding off slowly rather than snapping to zero. The parts are cheap; the trick is figuring out which bodies and which part.
1. Find where the drip comes from
- One or two bodies drip, the rest stop clean — diaphragm in that body. Cut, swollen, or a bit of grit holding it off its seat. Pull the end cap, rinse the seat, fit a new diaphragm.
- Drips from under the end cap, not the tip — end cap cross-threaded or loose, or the diaphragm is folded under the cap edge. Reseat it.
- Drips from the tip cap, tip seated — cap gasket or seat washer missing, or the cap is cracked at the wings. Replace the washer and cap.
- Every body on one section drips for a long time after shutoff — that section's boom valve is not closing fully, or the line is holding pressure above the 10 psi check setting. Check the valve, then check for a plugged boom end cap on a recirculating boom.
- Drips for a few seconds then stops, on all bodies — normal pressure bleed-down in a long boom section. A ChemSaver check needs 10 psi to open, so the drip ends once the line drops below it. If it takes a long time, the section valve is slow, the boom is oversized for the pump, or there is air in the lines.
- Body wets up on the outside, or drips from the clamp — cracked body or split eyelet, or a lost seal under the eyelet. Replace the body.
- Drip only on hot afternoons — air in the boom expanding. Bleed the boom ends after filling and after changing products.
2. Why it fails
TeeJet's standard ChemSaver diaphragm check valve opens at 10 psi at the nozzle and the body is rated to 300 psi. The diaphragm is EPDM as standard, with FKM (Viton) on request. EPDM handles most water-based crop protection products, but oil-based carriers, some adjuvants and solvent-type formulations swell it until it no longer seats. Dry products leave grit on the seat. Winter is harder on diaphragms than spraying is: a body left with liquid in it freezes the diaphragm against the seat, and a boom stored with product in it dries a crust on the seat. End caps come in different spring pressures (2, 5, 10, 15 and 20 psi) and the wrong one gives you either a drip or a tip that never opens on the outside of the boom.
3. The part for your body
| Problem | Part |
|---|---|
| Diaphragm cut or swollen (Quick TeeJet diaphragm check valve bodies) | TeeJet CP21953-EPR EPDM diaphragm |
| End cap stripped, lost or wrong spring | TeeJet 21950-10-NYB end cap, 10 psi (standard), 21950-2-NYB end cap, 2 psi (low-pressure) |
| Need shutoff at one nozzle (turf, estate) | TeeJet 58140-NYB manual ChemSaver (fits any Quick TeeJet body with a diaphragm check valve) |
| Tip cap cracked or leaking at the wings | TeeJet CP18032A-NYB winged nylon cap, CP8027-NYB cap |
| Seat washer or cap seal | CP19438-EPR seat washer, CP18999-EPR EPDM seal, CP18999-VI Viton seat gasket, disc-core tips |
| Single body, wet boom, check valve, 1" pipe | TeeJet QJ17560A-1-NYB |
| Single body, 3/4" pipe | QJ17560A-3/4-NYB |
| Single body, 1/2" pipe | QJ17560A-1/2-NYB |
| Turret body, 3 outlet, check valve, 1" pipe | TeeJet QJ363C-1-NYB |
| Turret body, 3 outlet, 3/4" pipe | QJ363C-3/4-NYB |
| Turret body, 3 outlet, 3/4" hose | QJ363C-750-1-NYB, QJ363C-750-2-NYB |
| Turret body, 5 outlet, 1" pipe | TeeJet QJ365C-1-NYB |
| Dry boom, check valve, 3/4" hose | TeeJet 19349-211-785-NYB QJ211 single, 19350-212-406-NYB QJ212 double |
| Add a check valve to a 1/4" NPT body | TeeJet QJ8360-NYB diaphragm check valve body |
| Split eyelet body with no check valve (replace if dripping, add 8360 or swap to 17560A) | QJ7421-1-NYB, QJ7421-3/4-NYB, QJ7421-1/2-NYB |
| Clamp screw for QJ360C / QJ17560 | TeeJet CP48255-1-1/4-302SS |
| Push-to-connect caps for tubing | QJ98588-1/4 PTC cap, QJ98586-3/8, QJ98598-90-1/4 90° |
If you are swapping a body, the QJ17560A series is the current single body with the diaphragm check valve: it mounts on a 3/8" hole in the pipe and takes a Quick TeeJet cap. The QJ363C and QJ365C turrets use the same ChemSaver check and give you positive shutoff between positions. The older QJ7421 split-eyelet body has no check valve and will drip by design.
4. Fixing it
- Depressurize the boom and open the end caps before you pull a diaphragm. Gloves and eye protection.
- Unscrew the end cap, lift the diaphragm, and look at the seat with a flashlight. Rinse the grit out, do not scrape the seat.
- Fit the diaphragm flat with the raised side toward the spring, and run the end cap down by hand until it stops. Over-tightening distorts the diaphragm and makes a new drip.
- Replace diaphragms as a set on a section, not one at a time. If one is swollen from the product, the rest are a week behind it.
- Check the check: with the boom on at working pressure the tip should start cleanly; with the boom off it should stop within a few seconds. A tip that starts late or sprays weak on the end of the boom has a stuck or over-sprung check.
- Air in the lines: fill, run the boom at low pressure with the end caps cracked until liquid runs solid, then close them. Trapped air keeps pushing product through the checks after shutoff.
- Pressure bleed: if every body drips for a long time, time how long the gauge takes to fall after the section closes. A slow fall is a section valve, not the bodies.
- Winterize with the diaphragms in and RV antifreeze through the boom, or pull the end caps and let the bodies drain.
Not sure which body, cap or diaphragm you need? Send a photo of the body with the cap off to sales@spraycenter.com or call (509) 838-2209.
Spray Center Electronics stocks TeeJet Quick TeeJet nozzle bodies, turret bodies, caps, diaphragms, end caps and seals in Spokane, WA. Part numbers here come from the manufacturers' parts sheets; if your meter, boom or fittings have been changed over the years, send a photo of the tag or the part and we'll match it before you order.