Small coolant leak….

[st381183]

Hi all,

I’ve attached a pic of a small coolant leak discovered using UV dye on my 2018 Expy. It’s been pretty intermittent with an about a 1/3 cup found under the truck one day a couple of weeks ago and then nothing since. My OCD so t let it go‍.

I had a tranny overheat issue in April 2023 which has been repaired, long story. Does this appear to be coming from the thermostat housing or the water pump? I’m going to take it in to the dealership next week but want to know what to expect. Thanks for looking.

 

[JasonH]

Hard to tell with the colors, but it appears to be the water pump seal letting coolant out. How many miles? If you're over 100K, may as well do both. It's not much more additional labor to replace the enter water pump once you've accessed the thermostat. The water pump on my Gen 1 Ecoboost failed around 140,000 miles, but it was likely going out well before that. Make sure to stay on top of the coolant levels.

 

[st381183]

Sorry, I should have added mileage, 50500 miles

 

[BMW2FORD]

It’s hard to tell for me as well. 2x points - the thermostat seal is really good in these trucks and I’ve never heard of one leaking and would lean more to the water pump BUT there is a new very improved T stat available from the dealer with a plastic seal ring that slides better so I’d say to replace both.

 

[Left Coast Geek]

I read the new thermostat fixes a sticking closed problem the old one had, nothing to do with leaks.

 

[beefsolar]

I had a small coolant leak around 50k It was hard to find at first but noticed one of the waterpump bolts had a bit of corrosion develop on the head. Was still under warranty so dealership replaced the unit.

 

[3rd Expyowner123]

My 2018 water pump was replaced, it was a difficult, slow leak to detect. Also needed to replace thermostat as engine was getting hotter than usual. As recommended by other members, replace both water pump and thermostat eat the same time.
I doubt the thermostat housing would be leaking.