Coolant Disappearing - No One Knows Why

HunterPach
Sat, 01 Aug 2020 16:10:45 +0000
Maintenance/Repairs

2013 F150 5.0 FX4 - 145,000 miles - over the past couple months I have noticed my engine running a little hot some times. What went from missing a little coolant and adding some every once in awhile has turned into every 10 days I have to add about a gallon to get it back to the correct level. A month or so ago I went ahead and replaced the water pump and thermostat along with the gaskets/seals/o-rings in most of the hose connections especially at the problematic T/Y connector. I have also gone through and replaced any fittings that seemed like they were failing.

I work in heavy Civil construction (roads and bridges) and I am always either hauling or towing along with driving a TON of miles. I am set up with my company’s vehicle maintenance program that is pretty good. Every 5000 I get the oil changed fluids replaced etc… The other day I had them run a pressure test and it held for 30 minutes at 16 psi which is what it is supposed to be. No external leaks were found after looking over it. I ran an engine block test with a kit I have and the blue fluid did change to a yellow/blue-yellow color indicating that there is some combustion gases getting into the system. But it wasn’t pure yellow - can something like a head gasket/cracked cylinder cause me to loose that much coolant without any trace? No leaks/pooling on the ground or in the engine compartment…

19 posts - 14 participants