2016 cuminns isx15 over pressure in overflow

[Rawze]

(03-25-2022 )702autotech Wrote:  wouldn't both of them cause bubbles thru the reservoir bottle witch I have none even at 1400rpms.

looking for bubbles in the coolant tank is mostly pointless. Dropped liner and head gasket issues usually almost always only show up when under an engine load unless they are really severe. Your description in your first post points towards maybe a dropped liner on that engine .. or maybe just a bad or improperly clamped hose after replacing the tank?.

The relief cap in the overflow tank will relieve any pressure greater than 15 psi.. and if it is a new one, you say you replaced the tank, they usually come with a new relief cap, then it should be doing its job to prevent more than 15-psi in the system.


As tree98 said ... and given the engine age, its likely time to drop the oil pan and pressurize the coolant system to 20 psi over night and look for seepage into one of the cylinders the next day.
ref: http://rawze.com/forums/showthread.php?t...6#pid25356

A dropped liner (which is always the cause of a head gasket failure) is a likely scenario if it is not simply a rotten/old hose or that "someone did not install a hose correctly" after replacing the tank.

If you end up dropping the oil pan to check it out ... even if you find out that this is not your problem .. then it would be a good opportunity to also replace the rod/main bearings.. as they are due by the 800k mileage mark any ways.

Just my thoughts on it.

Also, is this truck also de-mandated? (deleted)? .. if so then the delete program in it has a more than 90+% chance that can contributed heavily towards a dropped liner (head gasket) scenario.