Coolant leak, limp mode?

TEAMPICKETTS

MEMBER
2016 JEEP GRAND CHEROKEE
5.7L
V8
4WD
AUTOMATIC
145,000 MILES

My 18-year-old son has the vehicle listed above Overland. He came over today and as we backed out of the driveway, I noticed his RPMs were high and the vehicle was barely moving. I had him shut it off at which time I checked all the fluids and noticed the coolant overflow tank was good, but I couldn't see any fluid in the radiator.
We used my vehicle to run and get a gallon of coolant and the vehicle took the entire gallon.
After starting, we let it run and went around a few blocks.
During this soft drive, it was shifting very smoothly, kept going in limp mode and barely made it home.
After pulling in the driveway, I noticed it was spraying coolant all over the engine and out from underneath the front driver's side.
What could've caused this?

1 Reply

STEVE W.

MECHANIC
13,452 POSTS

From the description I would hunt down the leak and repair it. It could be a failed hose or radiator. Hard to say without seeing it. Then once the leak is repaired and the cooling system is filled, start it and see if it is okay. Running it low or out of coolant will overheat the engine and can put it into limp mode as it tries to protect itself. However, if it was run long enough it may have damaged the head gaskets or even a cylinder head or block.
I would probably fill it with coolant, then use a pressure tester (available as a loaner tool) to see if there are other problems before running it.

https://www.2carpros.com/articles/radiator-pressure-test