Isx15 popping radiator caps

[tree98]

Im not sure exactly what your doing but what im talking about is putting a hose on the pressure relief cap i circled here and put the other end in the cup of water. Is that what you did ?? Also the cooling system must be up to temp and all the caps on so the system is sealed.

   

If your sucking the water out of the cup you did something wrong.

[FnG92]

I re read what you posted after I replied. I realized I'm an idiot I will do the test. I don't think it's a liner now that I've watched some videos and saw how much pressure. It has had pressure but not what I saw online. Hopeful that if it's not a cap defect that it's only a compressor.

[FnG92]

No pressure on the return line. I must have over tightened the cap again. No discoloration in resivior or in engine oil. If anything changes I'll update this. As of right now I think I'm just freaking out. I'm sorry to waste your time guys

[RollinCoal]

What I have found with liner problems is usally you can pressure test them and they will hold,
Leave the tester on there with 0 pressure and crank it, if pressure build kinda fast then you have a delaminated headgasket and will need to pull the head and set the liners

[Rawze]

If the EGR cooler is starting to go bad then it can pressurize the coolant system too. Might want to ensure the EGR cooler is not leaking while your at it.

Seen more than a few people come over here and swear they had a bad head gasket, only to find out their EGR cooler was the culprit.

ref:

[Scooby d]

I was getting a tiny bit of pressure in my cooling system just once in a while. Fought it for months with just an occasional hose leak or cap gasket leak. Did several tests and couldn't pin down a problem. It turned out to be #6 liner had sunken and all other 5 were just to low. 380k miles on a 2012 cm2250 . If its your liners search around on here for correct liner heights. Cummins original specs were a bit low.