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jim phillips

presure in coolent tank

Question

I have 2016 Mack pinnacle cxu613 mp8 engine.I'm getting so much pressure in coolant tank its blowing out overflow hose.

been told by other owners its injector tube bypass. Been checking oil and no coolant getting in yet .I have 547000km on engine 

any feed back .truck still works well.

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Are you overfilling it? When the engine is cold, it gets filled to the cold line. It expands when it heats up, so if you put too much in when it's cold it'll push it out the over fill tube. 

Blown head gasket can put air into the water jacket and cause this too... Thought I'd start with the easy stuff though.

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not over filling. there is a great amount of pressure in coolant tank have to run with rad cap loose or it blows out coolant out overflow line.replaced overflow cap as well.

nothing in oil yet no coolant in air tanks as well.have talked with other drivers with same problem and there problem was injector cups also  said the coolant will turn a blue colour after a while.

I though head gasket as well trying to get a better idea what to plan for.  thanks for come back. the truck still works well.

also haven't seen coolant in fuel  

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Sometimes the head gasket blows across the fire ring straight to the water jacket, without crossing any oil galleries. On combustion, it'll force air through the head gasket to the water jacket, putting air (and pressure) into the coolant. I'd look into that sooner rather than later. If the head gasket gets bad enough, coolant will seep into that piston when it's shut off and you'll break your crankshaft trying to start it. Get someone to do a compression test to make sure your head gasket is still good...

Truck will work well until you're stuck on the road somewhere... 😓

 

Do you mean injector EUP or cup? Not sure what an injector cup is, not very familiar with the newer models.

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The most likely cause of a MP-8 pushing coolant is the EGR cooler or injector sleeves. The first step is to perform a combustion leak test on the surge tank, if the test fluid turns green combustion gas is present in the cooling system. Check the cooler first by removing the hose and elbow and looking for coolant or chunks of soot in the cooler outlet. If your cooler looks OK you should get the sleeves replaced. I have never seen a head gasket failure on these engines. If the test fluid stays blue check your air drier for coolant. 

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