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Powerstroke problems – Diesel fuel in coolant bottle

If you have ever wondered how a cylinder head cracks to allow diesel fuel to get into the degas bottle in a 6.0 Powerstroke or VT365 International, here is a picture and description of where they crack.

Refer to picture:  In this cut away of the cylinder head, you can see a thin wall between the injector bore (where arrow is) and the coolant passage to the right of the wall.  Cracks are generally caused by over heating and because this area is thin, it is most susceptible to cracking.  The fuel pressure from the injector rail cast into the head (small hole to the left of the arrow) is far greater than the pressure in the cooling system.  When a crack occurs, diesel fuel easily passes into the coolant.

Here is a Tech Tip from Asheville Engine:  Many shops want to replace both cylinder heads but there is no need to fix something that isn’t broken.  You can pressurized each head individually by adapting an air fitting to the front of a cylinder head and putting shop air to it.  With a pressure gauge in the degas bottle, if that head is cracked, pressure will register.  It may take a couple hours for the pressure to show on the gauge if the crack is really small.  This is best done if the engine is at operating temp before you put air to the head.  If one head holds air, then go to the other head and do the same, it might save you a lot of work and money.   The worlds best, most cost effective Ford Powerstroke replacement engines.  We Keep You Strokin’

Asheville Engine, Inc.


  1. Don Reeder on October 31, 2018 at 2:15 am

    What would you think is wrong when oil in the exhaust pipe

    • pwsadmin on October 31, 2018 at 2:07 pm

      There are several things that could cause that. The first thing that you should do is check to see if your engine has excessive blow-by. The easiest way to check that is to pull the rubber oil fill cap off while the engine is running, turn it upside down and try to lay it back over the fill hole. If there is a lot of blow-by, you won’t be able to set it down, it will blow off. If that happens, it’s time for a new engine.
      If you can set it over the hole, it may vibrate off but the blow-by is not excessive. If the blow-by isn’t bad, I’d recommend taking it to a qualified repair shop to have the problem diagnosed.

  2. Justin Neff on December 6, 2019 at 9:50 am

    How hard is it to change the injector cups on an 07 6.0 and would it be expensive??

    • Asheville Engine, Inc. on December 6, 2019 at 3:32 pm

      Justin, it’s pretty easy to do and not all that expensive. It can be done in the truck without having to remove the heads but you’ll have to locate a shop that will do it because not all will.
      That being said, it’s pretty rare for injector cups to start leaking on a 6.0 so you may want to get an opinion from a reputable diesel shop as to whether it actually needs to be done.

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