presure test 15 min no leaks still down gallon antfreeze new 3.7 engine installed 18 months ago ???
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Loosening antifreeze had engine pressure tested for 15 minutes no leaks anywhere but down almost a gallon of antifreeze engine is a 3.7 liter 6 v engine is new had it installed 18 months ago only has 12000 miles so I am very puzzled thank for any help in advance Tim
A pressure test should also include the cap. You may have a bad cap and loose coolant during operation. Head gaskets can be decietful as well. Check compression and also see if cooling system pressure increases with engine running.
At the time you installed the replacement engine . . . did you bleed all the air from the coolant system?
Please don’t take this the wrong way . . .
How did you go about determining “no leaks anywhere” . . . ?
Have you 100% ruled out the heater core and radiator?
Is the truck on jackstands?
Did you roll under there, on a creeper?
Did you use an extremely bright flashlight . . . such as an led stinger, for example . . . and telescoping handheld mirrors, so that you could look in every nook and cranny?
Sometimes you won’t see dripping coolant, but you’ll see dried residue, which is a big clue
Some components only leak cold, whereas others leak when hot and warmed up
Another thing to consider . . . coolant getting into the crankcase
Have you performed a block test?
In other words, have you used one of these?