It’s time again for the biennial coolant flush and change, and although I’ve been a fairly active reader and contributor to this forum for several years now I am uncertain about whether or not to change the thermostat this year.

I last changed the thermostat 33,000 miles and four years ago next weekend when I changed the head gaskets. It’s the stock LR thermostat, bought from P.T. Schram. According to the UltraGauge the truck runs consistently in the mid-190s, so I don’t see an immediate need to switch to the now-popular 180° stat. I know it can’t hurt to change it, but is it needed?

In other words, is there an expected lifespan for a Discovery thermostat?

On the other hand, with 143,000 miles on the truck I’m considering proactively changing the water pump. Unlike the thermostat the water pump is the original, and is likely nearing the end of its useful life. With the truck being relatively problem free the past three years I’m interested in staying ahead of the game and replacing things that can leave me or my son stranded. On the other hand there’s no discernable play in the pump shaft so instead I might just leave it alone for now and regularly test it.

What do you guys think?

 

either way. I like the "if it ain't broke" idea.
I keep parts,like these, as on hand spares. I'd rather have it, when I need it, instead of need and not have. I figure the weep hole warning system and looking for wobble and a good temp gauge, are good enough checks, for me. though it's not a 100 % reliable warning system, what really is?
your call on the stat.If it's not getting "hot". whatever works for you. but a lower temp puts you further away from the danger zone.

 

I'd change the stat to the 180.

The pump is a coin toss. I like the idea of preventative maintenance on these trucks, but it's true that it should start weeping and give you plenty of warning before it fails.

That said, if you haven't replaced the timing cover gasket, it might be worth doing it and the water pump to prevent either from being an issue in the future. You could do the oil pump at the same time, which is quite possibly cracked.

 

on these trucks I think I would change the stat after that long.

 

Thanks to all who replied. I decided to not change the water pump because the weep hole was dry and there was no unusual noise, etc. But before making the final decision I removed the shroud, fan and belt and tried to wiggle the pulley. There was just a little free play. I expect there would be none with a new pump but I still don't think this is enough of an indicator to warrant replacement now. I'll just keep an eye on it regularly, like so many other things on Redrover. After all i am not driving cross-country anytime soon nor is this an aircraft.

Any dissenters? If so, why? Is only a small amount of free play an indicator of "imminent" failure? I can afford a new pump, but as the son of parents who got married during the Depression I hate throwing away things that are functioning as designed.

 

I'm a fan of preventative maintenance, but unless you are road-tripping a lot, I'd likely leave it in there.

 

"i" would stock up on a wp,t-stat,clutch fan when on sale and have them in the wings waiting, you do after all have 140k on that pump.