replace termostat NISSAN NAVARA Pickup (D21)

If you never did it before, just take your time. Thermostat's sitting under the alternator, so gotta drop the belts and pull the alternator first. After that, disconnect top hose, undo 3 bolts holding the housing, pull out old thermostat, clean surfaces, new gasket, put in new one the SAME way with the air bleed valve at top. All back together and fill/bleed coolant. Nothing crazy, done it twice in my driveway, about 2 hours both times.​​

Last time mine overheated, swapped the thermostat and flushed the coolant same day. If you can, snap a pic before pulling the old one to remember how it sits, don’t overtighten bolts or you crack the housing. Took me around 1.5 hrs, worst bit was lining up housing again without pinching the o-ring.​

Yeah mate, make sure new thermostat is for diesel DI specifically, some parts folk get it wrong. When putting it back, air valve spot MUST go facing up (helps with trapped air), and bleed the cooling system after or you’ll have overheating again. Can’t stress enough.​

Swapped mine recently. put some rags down under the housing, always lose a bit of coolant when pulling it. Used long extension for housing bolts, as one was a bit stubborn behind alternator bracket. Check hoses for cracks while you’re in there.​​

Did mine right before a road trip. O-ring was a pain, had to get another at the last minute ‘cause first one leaked. Always double check seal before buttoning everything up and running the engine. Ran fine after though.​

If the stat’s stuck, engine runs cold when moving or overheats stuck in traffic. For me, biggest hassle was bleeding air from the system after, just kept topping up radiator while squeezing hoses, took ages but was alright in the end.​

Ask a mate to help with alternator if you haven’t done that bit before, heavy and awkward first time. Watch out for coolant dripping everywhere when pulling the stat—kept some bottles handy to catch what spills out. Only use new coolant once you’re sure all is sealed.​​

Didn’t bother removing the whole alternator, just loosened it and pushed aside for some space. Not the cleanest approach but got the job done. Make sure you DON’T drop the bolts—absolute nightmare to fish out if they fall down the engine bay.​

Parts hunt was fun... local guy had genuine stat, got it same day. Reused old bolts, just cleaned them up. Make sure both surfaces are clean before fitting new gasket. After filling with coolant, ran engine with heater on to help get air out. Satisfying fix!​​

Agree with others on air bleeding, don’t rush it... Those engines hate trapped air. Had to do mine twice after first time overheated again—the bleed screw helps, but sometimes just squeezing hoses does the trick too.​​

take a photo of the original orientation, helps later on. I used aftermarket thermostat with no issues; just avoid cheapest options. Clean out housing if any gunk is left behind, and check for signs of head gasket issues when you’re in there (bubbles/oily residue in coolant).​