Losing coolant

Looking for your thoughts and advice on this one.

I have a 2010, extended cab long bed V6 with about 217,000 miles on it. Just near the end of a 6 hour drive the other day, it overheated and blew off a bunch of coolant. No smoke, no knocks, but quite concerning. Replaced the thermostat, re-filled the coolant and cycled several times to get out all air. Managed to limp it home, but had to stop twice on the drive to let it cool, refill the radiator and cycle. The last stretch at the end of the day was a full tank of gas run at 70mph and the temperature gauge stayed pinned right at 50% until I got off the highway. Within about mile, it spiked up to the red just as I pulled into my driveway.

My next step today I think is to get a radiator flush and a new cap. But also wondering whether I should get a compression test done at a local shop, or whether maybe it's time to move on to a new truck. I'm single, it's my only vehicle, not exactly a wrencher and I like to get out into nature quite often, so dependability is kinda important.

 

Welcome to TW...So your losing coolant but no external leaks?

 

Running fine on the highway and the overheating near home seems, to me, to indicate a possible fan clutch failure. At least that’s where I’d start.

 

217000 miles, when was the water pump last replaced? Had a similar problem and a small leak around my water pump. Took some doing to spot the leak.

 

It's original.

 

The coolant loss could be at the reservoir due to overheating. As Vasman suggests, I too suspect the fan clutch. Google ‘how to test for a bad fan clutch’. A small leak at the water pump will not cause the overheating you are describing unless you are not topping off the reservoir.

 

217000 miles, when was the water pump last replaced?

What ever else the problem might be I’d replace the water pump.

 

Agree with the above.

However, if you have to go further and find a coolant leak, I highly recommend a MityVac style tester that allows you to pressurize your coolant system while it's cold.

$65 Mityvac MV4560 Radiator/Cooling System Pressure Test Kit for Asian, European, US Cars and Light Duty Trucks, Includes Hand Pressure Pump, 4 Cooling System and 2 Dual-Function Cap Test Adapters

https://www.amazon.com/dp/B003V9L05G

This makes coolant leaks so much easier to find because you can feel for leaks with your finger (without risking a burn) AND leaks won't evaporate off of a cold engine like they will a hot one. Best of all, it's like $65.

I've found leaks with this that I couldn't find without it.

 

I'm in the fan clutch camp based on those symptoms. Make sure there's no mud packed into your radiator as well.

Probably time to consider a new water pump, but doubtful that is the issue.

 

I will add to replace all the coolant components as preventive maintenenace. At 200K, if I plan on keeping vehicles to 300k+, I replace the radiator, fan clutch (if so equipped), thermostat, water pump, and all bypass hoses I can reach. And since access to the tensioner and idler pulleys will never be easier, I’d consider replacing those as well. At the very least test each one for play and smooth rotation. I did all this two years ago. I also replaced the plastic fan as those can harden and break off unexpectantly. Stick with Aisin for the water pump and fan clutch. I went with CST aftermarket for the radiator. If I recall, this all cost me a bit over $300. Most parts I got on rockauto, some from Amazon. I didn't replace pulleys nor the radiator hoses as those were replaced, as preventive maintenance, by 150K.