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Ask Master Tech Merlin Your Own Question
Master Tech Merlin
Master Tech Merlin, Technician
Category: Heavy Equipment
Satisfied Customers: 120
Experience:  15+ years experience that includes hydraulic systems and hydrostatic drives
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My ISX still losing the antifreeze, even the whole EGR cooler

Customer Question

why is my ISX still losing the antifreeze, even the whole EGR cooler was relapsed in a summer of 2008 and the valve earlier in spring
Submitted: 8 years ago.
Category: Heavy Equipment
Expert:  Master Tech Merlin replied 8 years ago.

In the past, I have found that in applications with an excess of 500k miles, that the deck seals (between the head and the water manifold) have worn or possibly been pushed out by compression and subsequently cause a leak that is not detectable on the outside of the block.

Now just for the sake of argument, I will also say that I have seen leaks from the radiator cap that are nothing more than a mist and have left no positive identification as well.

It is possible for a cap to leak as much as a gallon per week without showing any external signs. I would start with the cap, believe it or not, and proceed after that. If you have access to or know someone who has a cooling system pressure tester, you can pressurize the system to above pressure capacity (15 to 18psi) and that will allow a more thorough visual inspection. If you pressurize the system, leave it for about 30 minutes and still see nothing, watch the stacks when you start it up again and if it is leaking into the exhaust, you will see a mist out the stacks.

Hope this helps... Good luck

If you need anything else, please feel free to ask...

Customer: replied 8 years ago.
Thanks for quick reply I herd before about the radiator cap, actually My Kenworth have only expansion tank cap but I gonna start with that, if it works reword is yours, my truck is 4 years old but it has only 255kMi on the clock,but anyway about that water manifold is that near water pump housing iam not sure where is that? Any help is appreciated, Sergey.
Customer: replied 8 years ago.
Hy Merlin, i remember you, and took on your advise about expansion tank cap - replaced with new one. But it was a block heater seal that showed up a leak than, but the real problem was a little nut (with cooper wires "mesh" as sound dead ending) on the fan clutch valve, that get rusty (plugged up). The valve would not let the air out quick enough, where cosing the fan to engage late (about 45sec.) and getting the whole cooling and AC systems overheat and leak... a LITTLE, but costing me much money and worries. I hope this info will add some experience in your expertise.
Thanks , Serg.