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.

www.AshevilleEngine.com   The worlds best, most cost effective Ford Powerstroke replacement engines.  We Keep You Strokin’

Asheville Engine, Inc.

18 Comments

  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.

  3. Bobby on April 22, 2020 at 9:00 pm

    What would cause diesel fuel to get into the engine oil and over fill the crankcase?

    • Asheville Engine, Inc. on April 24, 2020 at 2:34 pm

      Bobby, Fuel getting into the crankcase can happen for several reasons and the most common is different with different engines. If you have a 6.4, the most common reason is the DPF system but it can also happen because of a leaking connection in the fuel line inside the valve cover. In all engines, it can happen because of a faulty injector or leaking injector seals or an injector cup. No matter which engine it is, DO NOT run it until you find the problem and have it fixed or you can end up with a catastrophic engine failure.

  4. John on May 19, 2020 at 5:36 am

    Is it possible to have the head gaskets go bad again after replacing one head and gaskets with arp studs. I have fuel in my degas bottle again after spending $5500. Mechanic says turbo is bad needs two injectors.

    • Asheville Engine, Inc. on May 19, 2020 at 12:47 pm

      I’d find a different mechanic if he thinks fuel in the degas bottle comes from a bad turbo or injectors and if he replaced your head gaskets previously for fuel in the degas bottle, he’s a real moron who shouldn’t be working on trucks.
      You’ve got a head that is cracked in the injector bore right where it shows in the picture in this post. Find a shop who knows how to determine which head is cracked and replace it. Most shops don’t want to diagnose which one it is and always replace both heads when they get one that has fuel in the coolant, which costs their customer twice as much.

  5. Steven Warmouth on May 30, 2020 at 11:16 pm

    Have a 02 power stroke 7.3 have got fuel in my coolant has never been hot and I bought it brand new 400 000 miles on it this is the only problem I have had with it is it the injector cups

    • Asheville Engine, Inc. on June 1, 2020 at 11:58 am

      Steven, It’s impossible for anybody to pinpoint exactly what the problem is over the phone, on a computer or any other way than doing it in person. You should probably consult a competent repair shop to diagnose the problem. Once a diagnosis is made, a machine shop can pressure test and magnaflux the heads if they need to come off. If they check out, they can do the machining to give you a set of heads that will go another 400,000.

  6. Gus on July 17, 2020 at 12:00 am

    When i pressurize coolant system coolant comes out fuel line leading up to secondary fuel filter. Thoughts?

    • Asheville Engine, Inc. on July 17, 2020 at 12:54 pm
      • Marlene j on August 15, 2020 at 4:42 am

        Hello
        Our 2016 Range Rover has diesel fuel in the coolant .
        We had a cracked gasket and they replaced that and now the engine light keeps coming on to show overheating .
        They have flushed the coolant system out twice and test drive it and it still is over heating and they can smell the contaminant in the coolant .
        No codes will come up and they don’t know what to do . It is at the dealership and they say they have never seen this problem before .
        They tell me someone must of poured some diesel fluid in the coolant but from what I’m reading I see it can leak in on it’s own?
        They said they will flush it a third time and then want me to ok 4 hours of diagnostics to figure out what is wrong .

  7. John Wicke on August 7, 2020 at 12:22 pm

    When I pressurize the coolant system i get bubbles from the #4 injector cup. is this the cup or is it likely to have a cracked head. i have removed the cup and inspected with a bore scope dont see an obvious crack just a small amount of pitting on the head/cup seal surfaces. any ideas?

    • Asheville Engine, Inc. on August 7, 2020 at 2:45 pm

      If the coolant is bubbling out around the top of the cup, it could just be a bad seal. Injector cups are cheap, I’d glue another one in place and after it’s had time to cure, re-pressurize it and see if that takes care of your problem. If the head is cracked where we indicate in the picture in this post, you should be able to see it weeping out of the crack.

  8. Dylan on September 11, 2020 at 10:31 pm

    Thank you for being so diligent with responses to this post from more than 2 years ago, I’m very impressed and will be coming to ashevilleengine.com for information first from now on.

    That said, what complications arise from a bus being driven with this problem? I have an opportunity to purchase a bus that was retired with this issue, what is the ballpark price range for this repair, and what should I be aware of while inspecting it?

    • Asheville Engine, Inc. on September 14, 2020 at 3:19 pm

      Dylan, The complications from having diesel fuel getting into your coolant is that all of the plastic (degas bottle) and the rubber (hoses and seals) in the cooling system also need to be replaced when you replace the cylinder head because the diesel fuel deteriorates them. If you are doing the work yourself, all of the parts will cost $1600-$1800. If you are having a shop do it, that varies widely across the U.S. and from shop to shop. Make sure that you flush the cooling system and replace the oil cooler while you are doing it.

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