Radiator plugged/leaking?

I discovered the other day that I have a radiator leak on the drivers side of the radiator. (Seems to be near the top) It doesn’t appear to be coming from the coils. But I noticed today, after driving about 20 miles, that the radiator cap was still cool to the touch. I was able to remove the cap without ANY issues. And the temp gauge is running just a bit behind the halfway mark. I have plenty of heat. The truck runs fine. And the water pump is new. (Within the last year) I’m not sure what I have going on besides the obvious leak. Any ideas? Please and thank you.

You mentioned cooling leak first. Was the radiator full or low? How cold is the outside temps where you are? Coolant in the radiator will be cooler that coolant in the block.

If the radiator has a leak, this doesn’t allow the cooling system to build any pressure. That’s why you were able to remove the radiator cap without a problem.

If the temp gauge is running a little lower than normal the problem might be with the thermostat being stuck partially open. You can get 140 degree heat from the ventilation system. And that feels pretty good. But unlees the coolant temperature reaches 150 degrees or above the computer does’t go into the closed loop mode. And the engine uses more fuel.


“radiator leak on the drivers side of the radiator”

That means the radiator tank is leaking . . . in other words, the radiator needs to be replaced

“temp gauge is running just a bit behind the halfway mark”"

The thermostat is stuck open

Here’s what you replace:

Radiator cap

Carefully inspect the hoses. If any are questionable, replace them

The radiator on my Corolla spring a leak at where the top plastic tank meets the metal part of the radiator. It was caused by the radiator coolant fan not coming on when it should have. Plus the radiator was 17 years old contributed I imagine. Anyway, I fixed the fan problem and replaced the radiator, no problem since. While at it, good idea as mentioned above to replace the coolant, the cap, and the thermostat, those wear out and/or gunk up over time.

The temp gauge runs two lines short of the center line. I’m not sure how “low” that is. But I have LOTS of heat even when we have temps of -25f outside. I picked up a used radiator today from a pull it yourself yard. (Money is tight) It looks fairly new/clean. And the engine compartment was clean. So I’m planning to rinse it out and install it.

IF I have to change the thermostat. How difficult is this on my truck? It seems as though you have to tear half the engine compartment apart for most things under the hood on these trucks.

Some temperature gauges tend to run low. The gauge in my B250 van usually hovers around 1/4 or 1/3. So unless your gauge is running lower than “normal,” I wouldn’t assume the T-stat is stuck. Plus the fact that you’re getting lots of heat at -25F…sounds to me like the T-stat is fine.

Assuming you have an S10 blazer with the 4.3 V6, changing the thermostat is not difficult

Shouldn’t take you more than an hour or two

You could try replacing the radiator cap first, in case that’s the source of the problem, along with your “new” radiator.

If you have plenty of heat it is unlikely you have a significant thermostat problem. Your dash gauge or sender unit may be slightly off is all, or it is just designed to show that level on the gauge when working properly. I wouldn’t focus on that, at least not in the middle of the winter, when working on cooling system problems isn’t much fun. The radiator is the first priority. Come summer, considering replacing the thermostat. Thermostats are indeed wearing items, do corrode with various deposits and rust and can start to stick slightly open, or not open fully, given enough time. How long they last before replacement is needed depends in part of how frequently the coolant is changed out. Keeping the same coolant for years on end is tough on all the components in the cooling system, especially the water pump and thermostat.