Cooling Question

[Hugh Mongus]

I checked my coolant a few days ago and it was a little low. My truck never overheats but I filled it up anyway. I started it and filled it up while it was running. Now I am having an issue with my gauge bouncing between its normal location and almost hot. If I stop and partially open the cap some air and coolant will come out and then I go on my way. The radiator cap is never hot, so I don't think its overheating.

My question is how to I get rid of the problem?

[RManson]

Your coolant level will go down over time regardless of whether your truck overheats or not. It's always a good idea to check it. I assume you're running some anti-freeze coolant and not just water.

The gauge could be bouncing as the thermostat opens and closes. When it closes, the temp in the engine climbs until it opens, then the cooler coolant from the radiator enters the engine, causing the fluctuation. It doesn't always happen with all gauges but I've had vehicles that do it.

If you don't have an overflow tank, you should think about installing one. Do a search and you'll get a whole bunch of ideas. This will help with maintain the coolant level as the system won't just burp out onto the ground.

I wouldn't be too concerned about the temp gauge so long as it reads accurately and your truck isn't overheating.

Hope this helps!

[FirstOwner69]

Coolant level without a recovery tank should be about 1-1/2" below the point where the cap seal sits to allow for expansion without overflowing. Original radiators, at least my original 4 row, are marked on the outside to show the fill level. However, that probably doesn't answer your concern.