Mechanics: Coolant Leak Only During AC Operation

*::: taking notes ::::
A friend of mine with considerably more mechanical expertise than I have is going to stop by in the near future and we’ll look the truck over together. If it’s something the two of us can fix we’ll do that. If it needs more than what can be done in the parking lot of my current apartment building I’ll enlist one of the local mechanics.

Since I have another working vehicle this is not an urgent matter and it may take a few days to take care of it all. I’ll be sure to check back in with you all and let you know what’s going on. Meanwhile, suggestions and guesses still welcome.

Well, went out to examine the truck this evening. The hoses look good/intact, no leaks or fluids detectable by eyeball or hand/paper towel. At least some of the hoses are newer than the main body of the truck, having been replaced as needed. Radiator is full. No oil in the radiator or the fluid reservoir. No radiator fluid in the oil. No leaks under the truck from where it has been for 36 hours. Cooling fan is operational. The radiator cap is original to the truck. Inspection showed that it looked, well, old for lack of a better term and not in good shape. We opted to get a replacement. If I’m lucky that’s a fix, if not, it probably needed replacing anyway and I’ll look into the matter further. Can’t replace the cap with the new one until everything cools down and we were losing light by then so I’ll swap the caps tomorrow afternoon when I get home from work.

The radiator system did get a flush a few years back, and was tested for leaks then. Back then everything was fine but of course the truck has a few more years and few more miles on it since then. My friend said that if I still had trouble after putting on a new radiator cap to have the system looked at including the thermostat.

I think all Rangers had engine-driven fans. that’s why I mentioned the fan clutch.

it may be spinning while the engine is running, but if the clutch is never engaging then it may not pull enough air through the condenser and radiator.

Keep in mind that if it was hot out and the AC was pushing too much heat into the radiator, the coolant may have just expanded a bit further than normal. That’s supposed to happen, in which case a new radiator cap won’t change anything. The few drops you were seeing on the ground may have just been some residual liquid that was left in the overflow hose when you parked.

Now, if you want to try your hand and finding the leak, rent the cooling system pressure tester while you’re picking up the new cap. It’s not that difficult to use and it’ll make the finding the leak, in most cases, just take a few minutes. When you take the radiator cap off, you can connect a small hand pump to it, put a few pounds of pressure on the system and look/listen for liquid spraying out.

While it wasn’t gushing it was more than “a few drops”. But only when using the AC. And like I said, I’ve been driving this truck for 20 years (in May it will be 21) and have long been accustomed to doing walk-arounds, looking under it, and so forth. I’ve driven it on days in the high 90’s without anything other than water dripping off it. This is a new development.

Already bought the cap.

Not interested in renting machinery, because if I did and I did find a leak it would still have to be fixed and I don’t have the skills, the tools or a place to work (my current landlord doesn’t mind me checking fluids or topping them off, but would definitely frown on DIY truck repairs on the parking lot). So I might as well go to a mechanic shop. All the ones I currently know/use have no problem with me watching the work and/or showing me what’s wrong/what’s needed.

Not everyone is interested in doing this sort of repair work, you know - I have changed my own oil, but these days I happily pay someone else to do that because I really do not like lying under machinery, dirt, grease, bugs crawling on me… I dislike it enough to pay someone else to do it and these days I make sufficient income to have that “luxury”. I like to know what’s going on with my machine, but I don’t really want to be a mechanic, it has no appeal for me.