# Coolant System Leak Detection in Upland > Can't find the coolant leak? Route 66 Auto Repair in Upland uses pressure, UV dye and hot inspection to pinpoint it, with photos before any repair quote. Source: https://route66autorepairshop.com/cooling-heating-ac-services/coolant-system-leak-detection Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** We find the leak with **pressure, UV dye** and a hot inspection. The goal is **one photo** that shows exactly where coolant is escaping. Some coolant leaks are obvious. Others only show up hot, drip on the exhaust and evaporate, or hide behind the engine. Route 66 Auto Repair in Upland uses pressure testing, UV dye and inspections at temperature to find the exact source. Leak detection is a diagnosis: you get a photo of the leak and a written repair estimate, and nothing is replaced until you approve it. ## When do you need coolant leak detection? - Coolant level drops but the driveway is dry - A leak only shows after freeway driving - Crust in several places so the source is unclear - A recent repair did not fix the loss - Sweet smell inside the cabin ## Which leak detection methods do we use? A cold pressure test finds most external leaks. UV dye added to the coolant glows under a light and reveals leaks that open only when hot or after a few drives. A hot inspection with a mirror and light catches leaks on the back of the engine. For internal leaks, a combustion gas test is added. We start with the method that fits your symptoms, and may ask you to drive a few days with dye in the system. The deeper test sequence is on [cooling system pressure test](https://route66autorepairshop.com/cooling-heating-ac-services/cooling-system-pressure-test). Once the source is known, [coolant leak repair](https://route66autorepairshop.com/cooling-heating-ac-services/coolant-leak-repair) covers the fix. ## Our leak detection process 1. **Clean the engine:** Old crust is cleaned off so new seepage stands out. 2. **Pressure and inspect:** The system is pressurized and every hose, gasket and seal is checked. 3. **Add dye if needed:** UV dye is added, the engine is run hot, and we look again with a UV light. 4. **Photo and estimate:** You get the leak photo and a written estimate with need-now and need-later lines. ## What's included in coolant leak detection - Engine bay cleanup at suspect areas - Cold pressure test - UV dye and UV light inspection when needed - Hot inspection with mirror and light - Cabin check for heater core leaks - Photo of the leak point and written estimate ## Is it a need-now or need-later repair? **Need now:** - Loss fast enough to lower the level between drives - Coolant inside the cabin or on the exhaust **Need later:** - Slow seep found and monitored with weekly level checks - Old crust with no active leak ## How pricing and timing work Leak detection is diagnostic time. The fee is stated at the counter before testing and applies to approved related repair. A dye test may need a second short visit after you drive a few days. If the car is losing coolant fast, it can come in as a tow-in, and an after-hours key drop is available. ## Aftercare While you wait for the repair, check the level cold before each drive and carry a jug of the correct coolant. Watch the gauge. If it climbs, pull over safely. The dye in the coolant is harmless and stays until the next coolant service. For a periodic look, see [radiator condition inspection](https://route66autorepairshop.com/diagnostics-and-inspections/radiator-condition-inspection). ## Frequently asked questions ### What is UV dye coolant testing? A small amount of dye is added to the coolant. Under a UV light, it glows at the leak point, even on a leak that only opens when hot. ### Why can't you find my leak on the first visit? Some leaks need heat and time to show. Driving a few days with dye usually reveals them. ### Will leak detection damage my engine? No. The tests use normal system pressure and dye made for cooling systems. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.