Cat C15 constantly putting coolant in Oil

Water pump or cavitation has gotten to the liners.

Drop the pan and pressure test overnight.

Dry cardboard under it and trace the drip.

Oil cooler also possible.

 

I would agree.

Leave the coolant full and just put a pressure tester on the surge tank. Hand pump or air pressure up to 15-16 lbs.

Usually only one will be leaking but they are all are pretty bad at that point.

 

Man, what a nightmare. I hate it for ya.

Which serial # are the engines? First 3.

The 3406E and C15 around 99-2000 as far as I'm aware had problems with heads cracking. The 1LW serial # series had crankshaft breakage too, slightly bent cranks vibrating at about 72-75 mph on mine. But that's another issue.
The heads were not remanufactured on Cat reman engines; they put on new heads, because the head casting has a known metallurgical weakness at the bridge between the intake valves.

What starts the undoing is usually overheating. Low coolant, a restricted or plugged radiator, a stuck thermostat, or a failing water pump create hot spots that push the head past its design limits.

Maybe your engines were rebuilt and the liner protrusion was set wrong or improperly seated liners.
Low pressure in the cooling system from a bad radiator cap lower boiling point and inadequate SCAs in old coolant cause cavitation to occur sooner.

I guess overall it looks like improper engine building or improper maintenance.

 

Just wondering if the liners are pitted, what kind of coolant or additive was used to/or not to prevent it if applicable.

 

I had a BXS some years ago. Put an oil cooler on it because it was mixing both ways and flushed it real good. Came back a couple months still mixing. All liners were pitted bad. 2 leaking thru. Odometer showed 700k- ECM had 28k hours

Ultimately cavitation occurs from neglected permanent antifreeze(green). Course adding well water when mixing Proly doesn’t help. I think a lot of folks change out the crappy coolant and jut put in ELC but a lot of times the damage can already be done.

 

Permanent green antifreeze is fine, but more work to maintain. Always use premix or mix with distilled water. Monitor green with 3-way strips to keep in balance. Add conditioners accordingly. Every PM. And yes I mean every PM.

Really hard to beat the ELC technology. Dump it and go. Just monitor freeze protection and make sure it doesn’t get diluted.