How to Troubleshoot an Isuzu NPR That is Overheatingby Alibaster Smith
Your Isuzu NPR uses cooling chambers in the engine to cool the engine and prevent its internal components from seizing. When the cooling system is not working properly, the engine may end up overheating. If your engine overheats significantly, it may suffer a catastrophic failure. To know whether or not your engine is overheating, and what might be causing it, you need to do some troubleshooting.
Start the engine on your NPR and wait for it to heat up. When the needle on the temperature gauge sits at or near the middle mark, your engine is sufficiently warm. If it rises above the center mark on the gauge, your engine is starting to overheat.
Check the exhaust. If there is steam coming out of the tailpipe, then your head gasket has failed, and this is likely causing your engine to overheat due to [engine coolant](https://itstillruns.com/what-is-engine-coolant-13579658.html) leaking into the combustion chambers instead of cooling the engine.
Open the hood and check the coolant reservoir tank. If the reservoir tank fluid level is at or below the lower mark on the reservoir tank, fill your reservoir tank with a mixture of 50/50 engine coolant and water.
- "1994 Chevrolet, GMC & Isuzu NPR, W4, 4000 Diesel Commercial Truck Forward Tiltmaster Service Manual;" Isuzu Motors Limited; 1994