# Diesel Engine Overhaul in Upland > Diesel engine overhaul planning in Upland for blow-by, low compression and coolant in the oil. Test results, honest options and a written estimate first. Source: https://route66autorepairshop.com/diesel-engine-services/diesel-engine-overhaul 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 confirm internal damage with **compression, leak-down and oil tests**, then compare **overhaul, replacement engine and smaller repairs** with you. A diesel engine overhaul at Route 66 Auto Repair in Upland starts with proof that the engine truly needs one. Heavy blow-by, low compression, coolant in the oil or a spun bearing can all lead here, but so can problems that cost far less. Our ASE-certified technicians test first, then walk you through overhaul, replacement engine and repair options, and your written estimate shows every step. ## When does a diesel really need an overhaul? - Low compression on several cylinders that a gasket or valve job will not fix - Heavy blow-by that pushes oil out of the crankcase vent - Coolant and oil mixing through a failed internal component - A knock from the bottom end with metal in the oil - High oil use that continues after turbo and vent problems are ruled out ## What are your options besides an overhaul? An overhaul replaces wear parts such as rings, bearings, gaskets and seals, and inspects the major components for reuse. A replacement engine, new or remanufactured, swaps the whole assembly. A targeted repair, such as a head gasket or oil cooler, may be enough when the damage is limited. The right answer depends on the test results, the truck's condition, how long you plan to keep it and what it is worth. We tell you plainly when we think the numbers do not work. Sometimes the honest advice is to sell the truck, and we would rather say that than sell you a repair you will regret. ## Our overhaul planning process 1. **Prove the damage:** Compression, cylinder leak-down, cooling system pressure and oil condition tests show what is wrong inside. 2. **Lay out options:** We compare overhaul, replacement engine and targeted repair in writing. 3. **Teardown checkpoint:** If you approve an overhaul, we call you after teardown with measurements and any change to scope. 4. **Assemble to spec:** Parts are installed to the maker's torque and clearance specs, with fresh fluids and filters. 5. **Break-in and road test:** We run and road test the engine and give you break-in instructions in writing. ## What's included in a diesel overhaul estimate - Compression and leak-down test results - Cooling system pressure test - Oil condition findings with photos - Side-by-side options with reasons - Written estimate showing every step - Teardown call before any scope change ## Is engine work need-now or need-later? **Need now:** - A bottom-end knock or metal in the oil - Coolant in the oil or oil in the coolant **Need later:** - Rising oil use with steady compression - Mild blow-by on a truck you plan to replace soon ## How pricing and timing work Overhauls are among the largest jobs we quote. The total depends on the engine, what the teardown reveals, which parts can be reused and whether parts need inspection or reconditioning. Your written estimate shows every step, and we stop and ask before any change. Expect the truck to be with us for a longer stretch; we give you a realistic window and text you if it slips. AAA members save 10% on parts and labor, up to $75. ## Aftercare Follow the written break-in steps, avoid heavy towing until we say so, and come back for the first oil change early so we can check for debris. Before committing, many owners start with a [diesel engine compression test](https://route66autorepairshop.com/diesel-engine-services/diesel-engine-compression-test). If the damage is limited, [diesel engine gasket replacement](https://route66autorepairshop.com/diesel-engine-services/diesel-engine-gasket-replacement) may be enough. For gas engines, see [engine rebuilding](https://route66autorepairshop.com/engine-services/engine-rebuilding). ## Frequently asked questions ### Is it worth overhauling an old diesel truck? It can be, when the body, frame and transmission are solid and you plan to keep it. It often is not when several other major systems are also worn. We give you the test results and our honest view so you can decide. ### Where is the engine work done? Your written estimate shows every step of the job and every part, so you know exactly what you are paying for before we start. ### Will you call me if the teardown finds more damage? Yes. We stop after teardown, share measurements and photos, and update the written estimate before any additional work. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.