Project Title: Root Cause Diagnostics: Eliminating Intermittent Overheating Failures
Client Sector: Telecommunications Infrastructure
Equipment: 300kW Onan Diesel Generator (Model 300DDA)
Service Category: Advanced Diagnostics & Emergency Repair
1. The Challenge
A critical telecommunications site in Florida was plagued by a baffling and dangerous issue with its 300kW Onan backup generator. The unit would start and run normally during brief tests, but would unexpectedly trip and shut down on an “Overheating” alarm once it reached operating temperature.
This “ghost” failure mode is the worst-case scenario for a telecom provider: the generator appears healthy during quick checks, but is guaranteed to fail during a sustained power outage, potentially taking the site offline.
2. The Generator Source Solution
Instead of simply resetting the alarm or topping off fluids—a common “band-aid” fix that leads to repeat failures—Generator Source deployed a lead diagnostic technician to perform a root-cause analysis.
Phase 1: Deep Diagnostics
The technician (Chuck) recreated the failure conditions, monitoring the engine’s thermal rise in real-time.
- Observation: Coolant levels were sufficient, and the radiator appeared clear, ruling out the most obvious causes.
- The Discovery: By inspecting the mechanical drive system under load, the technician identified that the fan belt was loose. It maintained enough tension to spin the fan at idle, but as the engine heated up and load increased, the belt would slip, causing a rapid spike in temperature that triggered the safety shutdown.
Phase 2: Corrective Action & Service
Once the root cause was isolated, the team executed a comprehensive repair and service protocol to “reset” the unit’s reliability:
- Drive System Repair: Removed the worn belt and installed a new, properly tensioned V-Belt to ensure consistent airflow at all RPMs.
- Thermal System Reset: Drained the overheated coolant and refilled the system with a fresh, manufacturer-specified antifreeze mixture to restore heat transfer efficiency.
- Preventative Maintenance: Performed a full oil and filter change (using Napagold fuel/oil filters and 15W40 oil) to remove any oil that may have degraded during the high-temperature events.
3. The Results
- Reliability Restored: The unit passed a verified run-up test, holding steady operating temperature without slipping or overheating.
- Asset Protection: By catching the slipping belt early, the repair prevented catastrophic overheating that could have warped the cylinder heads or seized the engine.
- Site Security: The telecom provider regained confidence that their backup power would last for the duration of an outage, not just the first 15 minutes.
“Intermittent failures are the most dangerous kind. Our technicians are trained to look past the error code and find the physical cause, ensuring that when we leave, the problem is truly gone.”