Jgillespie218

I promised myself I was gonna come back here to make a final post after the issue had been fixed. But I'd like to start by saying I found this thread because the original post said something about overheating and low coolant levels and some kind of foamy liquid in the overflow resevoir.

With that being said I have a 2018 F150 w/ 3.5 Ecoboost and my original issue was the coolant fans running obnoxiously loud. This truck has NEVER overheated and NEVER thrown a code. I checked the coolant level (it was low) so I topped it off. The fans settled down a bit but started back up a couple weeks later. I checked the coolant again and it was low. Again. So I of course topped it off, but noticed some foamy brown liquid in the resevoir.

I took it to the dealership and they said the foamy brown stuff was tranny fluid. So, I was getting transmission fluid in my coolant. The dealership confirmed I had gotten a TINY bit of coolant in my tranny but they were not worried about it. Turns out my tranny cooler had failed. The tranny cooler and radiator are integral to one another.

The fix was to replace the tranny cooler/radiator, perform a coolant flush and a tranny flush. Everything is fixed now except...my fans still are kinda annoying. Not near as loud as before but if I'm on cruise control at 60 mph I can hear a distinct "whine" of the fans. When I come to a stop the fans will settle down and eventually turn off. Is this crap normal???

mass-hole

A 2018 3.5 has a standalone trans cooler under the truck. The coolant gets pumped back and then passes through the cooler. It is not part of the radiator like the older trucks were.

Can you monitor the engine coolant temps? The fans should not be kicking on until the coolant is like 215 I believe, but it can also be driven off of the A/C and the Transmission temperature.

ssingh6213

hi did you find out what was wrong. I have a 2015 F150 and I have oil in my coolant resivor but no coolant in oil. Truck doesn’t over heat no loss in power just make a ticking sound. Any help would be appreciated

dsg2003mach1

since this keeps getting brought back up - the F150 3.5 has an external, not internal water pump, it doesnt tend to leak behind the cover and destroy a motor like the one in the Explorers

BareBonesXL

I saw a video by a guy who has a channel, I Do Cars, where he tears engines down to resell the parts. He pointed out in one of them that some internal water pumps actually have a channel in the block/timing cover that exits on the side of the engine, for leakage from the weep hole of the pump. So there is a sign of impending doom, if a person checks that area. It was not obvious. I'll post the video if I can find it.

I found this one on a quick search and he says that the 3.5 EcoBoost has the internal pump and no weep hole. He seems to know his stuff. 10:38.

BareBonesXL

But, apparently, he was wrong and got corrected. There is a weep hole. Here's a later video on a Taurus 3.5, the one I was thinking of. Later in the video he shows the channel and the exit point.

Brad54

Figured I'd chime in here since I went through this last year on my '16 3.5l Ecoboost. It ended up being the oil cooler, right where you mount your filter too. There was a slight crack and the high pressure from the oil made it's way into the coolant. Ended up finding a cooler on eBay for around $80.

davidnesbett

thank you for your input. I have not removed mine yet, but I am pretty sure that is the problem, so thank you for the lead.

BuiltFT

Plz need help