Hello, I'm looking for some insite and hopefully someone has experienced this issue before. The issue is with a Cat C11 engine in a 966H loader(A6D000408) when the ambient temp is -15 c or colder the engine will start great, but only run for 5 min then die. When you crack the fuel bleed off valve on the secondary filter it pushes a bunch of pressurized and airrated fuel out with some force. Re prime the system and it will fire back up. -There is no loss in supply pressure when the -engine dies. (Test done with manual guage) -All fuel lines replaced. - Injectors replaced. -Transfer pump replaced. - Both filter bases replaced. - New fuel pressure check valve in secondary filter base. In warmer weather it runs great as it should. Thanks in advance
What if anything have you done with the fuel tank and filler cap.?
You would think that it has to be something freezing. I assume they are using #1 diesel or similar.? You really need some input from one of the members more local to you. I don’t work in cold climates. Calling @Mobiltech and @Simon C …..
It could be freezing and still have fuel pressure depending on where the fuel pressure gauge is installed. Cold air passing over fuel that is only partially rated for winter can cause fuel to freeze, more so if the fan is running too strong. Have you replaced the fuel filters recently, a fellow mechanic just told me a Wheel Loader they had died and so they changed the filter. Then it died a minute after, couple days of screwing around later they found out the new filter had gotten hit with a cup of water again and was plugged. Not saying that is your problem, but another filter will cost less than someone to look at it. Could be some ice in the tank melting off and plugging the filter. Put air to the tank and remove the fuel line after the last filter and fuel should just pour out , not just one gulp coming out. Simon C
What caught my attention in the original post was the term ‘airrated fuel’ (aerated?). Is there air getting in fuel lines when cold or maybe only affects it when cold?
Might be a good idea to put some air pressure, about 2PSI to the tank with key switch on and with a rag ball over the opening while putting air to the tank. Takes 2 people to do, and don't put too much air or you will have a fuel bath. Is there any leaks visible, fix them and test again. Could be sucking air somewhere. Need to start somewhere. Simon C
And firing the Parts Cannon big-style first up wasn't it............
Just re-read the first post and saw that machine runs good in warm weather. In warm weather all ice would melt and tend to block a filter. Did you drain the filter into a glass jar to check for quantity of water? Does that thing have any codes active . Reason is that ice in the bottom of a tank is not a big deal until it starts to melt. Is the machine parked in hot or cold.? This seems to point to it not being a fuel issue as the colder it is the water will be ice. All water in the bottom of the tank would be hard on a cold morning. It could not go up to the filter, but it could block off the fuel pickup when frozen and nothing going up to filter. Where is it parked. Simon C
Where is the machine spending the night. Simon C
Some great insite guys thank you, this unit has been in multiple shops for this reason and been a problem for a few years.(hence the parts cannon between all the shops) -To answer your question Simon, the machine stays outside most of its life. -Definitely running quality diesel, or the best we can get. Multiple other units on the same site run the same fuel with no problems. -I'm not finding any ice in the filters at all. -It is leak free, very clean.
Does that thing have a fuel warmer maybe that is not working properly. The fact that when it dies the fuel filter is full of air leads me to believe something is blocking the fuel inlet in the tank. Have you blown back into the tank from the filter feed line with air. Know of a machine at a now closed mine that had a clear like sandwich bag floating in tank that would kill it, but your's only dies in the cold. That almost rules out junk in the tank blocking off the outlet. Does that unit have a fuel pump that runs off the engine gear train like some I have seen. It could be sucking air in if it had one, and would be more prone to do it in the cold. How many hours on this engine? Simon C
I’ve seen where the pickup tube inside the tank near the top crack from vibration. Or maybe the viscosity of the fuel being thicker when cold the pump can suck air but not show a leak.
Thought about your problem and how about putting 2PSI to the fuel inlet with a rag ball over the opening on a cold morning. Maybe something is leaking under pressure, but only in cold. You will have to push quite hard on the rag ball and will feel the tension coming back at whoever is on the variable flow blow gun. It takes 2 people obviously and it is hard enough to hold after 2 minutes but could produce a leak in an o-ring or hose. Best to do with tank more full as it takes less air in and when you stop the blowing there will be less of a gush of air coming out of the rag as you let it off. Be extra cautious or someone will have a bath. No money involved and unless you have already done out in the cold, it may reveal something. When you posted new transfer pump are talking electric as I seem to recall they have one and maybe have a Gear type one also. Can't remember. Only other thing I can think of is what Highwayghost said about a crack in the pickup tube. Simon C
It has an electric priming pump as part of the primary fuel filter/water separator assembly then a mechanically-driven fuel transfer pump to supply the fuel rail in the head. As I understand it the function of the electric pump is simply to prime the system after filter changes, not to act as a transfer pump.
Does this machine have a diesel burning coolant heater on it like an espar heater? If so where is it drawing it's fuel from. ALso has anyone checked the fuel cap vent when it's cold to see if there's a vacuum on the tank?
Mobiletech I was thinking the same thing and wondered how the machine would run with the fuel filler cap loosened off and rags wrapped around the neck held by electrical tape to hold any leakage. Test should be done when cold but can't imagine how cold would affect the cap, Simon C
Could that gear driven mechanical pump suck air only when very cold through the shaft like a hydraulic pump can. Fuel is lighter than oil, but air is lighter than fuel. You would think there would be fuel leaking into the engine if it was leaking air inwards. I have seen coolant lines that were new and on clean steel that leaked every night at Minus 40, but would leak nothing when hot. Cold and seals and rubber change some at the temperatures he posted. Minus 15C or more. Your thoughts! Simon C
Sorry I dunno. I have zero experience of working in ambient temperatures like that.
I don’t know this engine, but would it be possible to rig fuel supply from say a 5 gallon fuel bucket and pickup pump, maybe with a three way valve with the fuel tank included on the other leg to substitute a fuel supply? Eliminate everything up to the injector pump for testing? Pumpguy might know if internal injection pump air leaks are possible here, and how temperature might factor in. Did we find out how many hours on it and what hours it started? Interesting… Thermal dynamics? Changes in metal or sealing properties that are temperature related? I’m curious, never ran across this before. Sorry that I have more questions than answers!
I thought if the breather was frozen as the fuel in the tank cooled from being hot while running it would create a vacuum in the tank. I have seen some espar heaters plumbed wrong that would draw the fuel out of the primary filter leaving it full of air. The engine will run until it empties the secondary filter .
Two winters ago we touched -40c here; noticed a small but steady coolant leak from the lower radiator hose on our C12 (truck sits in our yard all winter) Has never leaked a drop since…(or before).
Exact same experience is what I have seen in the cold. I thought about what Mobiletech said about the breather being the problem. It could be, and is easy to check as well. Cold can do things. Simon C