SimonSaucy
Active Member
- First Name
- simon
- Joined
- Apr 13, 2026
- Threads
- 6
- Messages
- 33
- Reaction score
- 20
- Location
- Uniter States Las Vegas
- Vehicle(s)
- 2021 ford ranger STX
- Occupation
- engineer
- Thread starter
- #1
For the last few months, I’ve been chasing a mystery coolant leak.
About a month or so ago I thought I found it in a quick connect fitting that had gone bad on the backside of the engine, feeding the transmission cooler lines.
Replaced that fitting and refilled up the coolant and didn’t really look at it.
Today, I’m driving home and have to pull over because the car thinks it’s overheating. Come to find out the coolant reservoir was pretty much empty.
Thus has started the search for where could the coolant leak possibly be. I had to fill up the reservoir with probably half a gallon. Luckily there’s still a good bit uv die in the system. I spent a little over an hour tonight looking in every nook and cranny for any leaks. But I can’t come up with that looks obvious. Or has any splatter marks like I saw last time.
The only two things I found were these T connectors in the driver’s wheel well that have to do with the transmission heater.. while they do glow slightly green. I’m not really convinced they’re actively leaking or leaking at all. I’d expect to see more residue and splatter around the area and I don’t. In addition, I tried cleaning off those fittings with brake cleaner. And the greenness did not change…. In addition this area could’ve been an area that the previous leak was leaking on.
I also started the truck up after it was cold and let it idle for a while until it was up to operating temperature. And then felt around all of these fittings and couldn’t find any wetness.
Looking for any recommendations on what I should do. I know there’s a few threads about possible EGR cooler issues. Honestly, that seems to be my best. Guess at this moment. Although I’m not having any codes of any sort.
No white smoke. No misfires. No obviously leaks.
Has anyone ever had a leaking radiator internally? It they didn’t show up on a black light or show any signs of leaking.?
About a month or so ago I thought I found it in a quick connect fitting that had gone bad on the backside of the engine, feeding the transmission cooler lines.
Replaced that fitting and refilled up the coolant and didn’t really look at it.
Today, I’m driving home and have to pull over because the car thinks it’s overheating. Come to find out the coolant reservoir was pretty much empty.
Thus has started the search for where could the coolant leak possibly be. I had to fill up the reservoir with probably half a gallon. Luckily there’s still a good bit uv die in the system. I spent a little over an hour tonight looking in every nook and cranny for any leaks. But I can’t come up with that looks obvious. Or has any splatter marks like I saw last time.
The only two things I found were these T connectors in the driver’s wheel well that have to do with the transmission heater.. while they do glow slightly green. I’m not really convinced they’re actively leaking or leaking at all. I’d expect to see more residue and splatter around the area and I don’t. In addition, I tried cleaning off those fittings with brake cleaner. And the greenness did not change…. In addition this area could’ve been an area that the previous leak was leaking on.
I also started the truck up after it was cold and let it idle for a while until it was up to operating temperature. And then felt around all of these fittings and couldn’t find any wetness.
Looking for any recommendations on what I should do. I know there’s a few threads about possible EGR cooler issues. Honestly, that seems to be my best. Guess at this moment. Although I’m not having any codes of any sort.
No white smoke. No misfires. No obviously leaks.
Has anyone ever had a leaking radiator internally? It they didn’t show up on a black light or show any signs of leaking.?
Sponsored
cold, the water will leak, if its a leak and you can track it down a lot easier. With the engine hot, parts expand sealing the small gaps that create leaks. 
