# Radiator Overflow Hose Repair in Upland > Reservoir not filling or coolant spitting on the ground after shutoff? Route 66 Auto Repair in Upland repairs cracked or loose radiator overflow hoses. Source: https://route66autorepairshop.com/cooling-heating-ac-services/radiator-overflow-hose-repair 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:** A cracked **overflow hose** lets coolant escape after every drive. We replace it and confirm coolant **flows back** into the radiator as it cools. The overflow hose is the thin tube that runs from the radiator neck to the coolant reservoir. Coolant moves out through it as the engine heats up and is drawn back as it cools. When it cracks, kinks or slips off, you lose coolant a little at a time. Route 66 Auto Repair in Upland replaces the hose, checks the cap and reservoir it connects to, and confirms coolant moves both ways. ## What are the signs of a bad overflow hose? - Small puddle near the reservoir after parking - Reservoir level that never changes between hot and cold - Radiator low while the reservoir is full - Hose that is brittle, split at the end or off its nipple - Coolant spray on the inside of the hood ## Why does coolant need to flow both ways? As coolant warms, it expands and pushes past the cap into the reservoir. When the engine cools, a small vacuum pulls coolant back. If the overflow hose has a crack above the coolant line, the radiator pulls in air instead. Over a few weeks the radiator runs low even though the reservoir looks fine, and that trapped air can cause hot spots. This is why we check the cap's return valve at the same time. A hose that is fine plus a cap that will not let coolant return gives the same symptom, and that case is covered on [coolant system pressure valve repair](https://route66autorepairshop.com/cooling-heating-ac-services/coolant-system-pressure-valve-repair). ## Our overflow hose repair process 1. **Inspect the path:** We follow the hose from the radiator neck to the reservoir, looking for cracks, kinks and loose ends. 2. **Test the cap:** The cap's pressure and return valves are checked, since they work with this hose. 3. **Replace the hose:** New hose of the correct size is routed away from the fan and hot parts and clipped in place. 4. **Confirm return flow:** After a heat cycle, we check that coolant moved to the reservoir and was drawn back as it cooled. ## What's included in overflow hose repair - Overflow hose and nipple inspection - Radiator cap pressure and return valve test - Replacement hose with correct routing and clips - Reservoir inspection for cracks - Coolant level correction and heat cycle check ## Can an overflow hose repair wait? **Need now:** - Hose disconnected or split through - Radiator low and temperature rising - Coolant spraying under the hood **Need later:** - A hose that has hardened but still seals - A slightly loose clip with no coolant loss ## How pricing and timing work The hose itself is low cost and usually quick to reach. If the reservoir nipple is broken, a [coolant reservoir replacement](https://route66autorepairshop.com/cooling-heating-ac-services/coolant-reservoir-replacement) may be needed, and that shows as its own line. Your written estimate lists each item before we begin. Most overflow hose repairs are done while you wait when the board allows. ## After the repair Look at the reservoir cold and again after a drive for a few days. The level should rise when hot and fall back when cold. That movement is the sign the system is breathing correctly. If it stays still, call [(909) 608-7699](tel:+19096087699). ## Frequently asked questions ### Can I use any clear tube for the overflow hose? It needs to handle hot coolant without softening or collapsing. We use hose rated for coolant temperatures and the right inside size for the nipple. ### Why is my reservoir full but the radiator low? Coolant is not being drawn back. A cracked overflow hose or a cap with a stuck return valve is the usual cause. ### Does every car have an overflow hose? No. Cars with a pressurized reservoir have a different layout with a vent line. We work with whatever your vehicle uses. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.