My 2017 F150 3.5L ego boost has an oil substance in the coolant bottle. Runs fine, not overheating. Only thing I notice is the fan kicks up from time to time. Temp gauge is to the left of center. No water in oil. Some history on the truck, I bought it with 128,000 miles on it. It now has 135,000 on it. About a year ago it was overheating and when I checked it it had some weird substance in the coolant bottle and even in the hoses it looked like a silicone coating in it. I changed all hoses, thermostat & housing, water pump, radiator& coolant bottle. Not sure if the substance was some type of head gasket repair. Ran fine after that, didn’t overheat anymore. Just noticed the oily substance in bottle when checking the coolant the other day. Another question is doesn’t coolant go through the turbos? Is that ruining them? Thanks in advance for your help.

 

Is it possible that the oil cooler is bad?

 

the turbos are water cooled

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Trans temp on right, center right fuel gauge, left center engine coolant, left oil. These are not tru guages, but idiot lights with needle displays. You can get actual number readout in engineering mode as shown and 8 inch dash display can show numbers above the idiot guage with other options for some option packages. Shown is a base XL dash. KM

 

Well I replaced the oil cooler and flushed out all coolant lines, radiator and steering cooler. When flushing through the engine there was pretty much just coolant, no oil coming out. Didn’t know how to flush turbos. Ran the motor and so far so good. I know I will have to drive it a lot more to really tell. Just put water in for now.

 

Not sure what you flushed but there is no steering cooler. Your truck uses electric power steering. It is an electric motor on the rack itself. There is no fluid involved other than minimal lubricating oil for the rack itself.

 

Well maybe that goes to the turbos. Facing the firewall it is on the left side about 6” from the center of the frame, mounted on the frame. Has two water hoses on it, like 5/8” heater hoses.

 

When my truck wouldn’t move I discovered I was 2 quarts low on fluid. So it looks like it is ATF that is mixing with the coolant not motor oil. What I thought was a steering cooler is actually a heat exchanger for the transmission. I am waiting on the part to come in and hoping that is my problem. I sure am glad that I waited and didn’t pull my heads off or swapped motors because I would have still had the problem. Hard to believe no one has ever had this problem. Will update later.