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c-mac

2012 MP8 pressuring up cooling system

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I’ve got Mack chi 613 with an mp8 that’s blowing coolant out the overflow hose of the coolant tank mounted above the radiator. I’ve already pinched off the coolant lines to the compressor and it builds up to 15 psi in the tank. Is there anything other than a head or head gasket problem that will cause this?

Edited by c-mac

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Injector cup can cause the issue. If a worn tool is used to install the cup, then compression can come between the cup and head and cause is issue. But being a 2018 it’s unlikely 

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I edited my post. It’s a 12 model and I have an 08 with the same problem. I’m not sure if either has had the cups and injectors replaced. I work on a large fleet and they don’t keep good records..(oilfield). My self I write on the date and hours on the valve cover. I thought I had seen all the symptoms til now.

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Some coolant reservoirs have a burn hole in the pressure cap/overflow side that can cause coolant loss. Pushing coolant can also be caused from a bad air compressor head, leaking egr cooler, bad injector cup and cracked head. 

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The two most common as mentioned are the cups and egr cooler! Start at the cooler and work back remove the outlet of the egr hose lower front and check for dampness in the cooler! check the surge tank as mentioned however that should have showed up before  now!

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Ok I pulled the cooler because I seen what looks like tiny red droplets of coolant and the inside of the housing is damp and sooty. I’m not sure if what appears to be red droplets is coolant. What do y’all think? You may need to blow up the pic to see

7C06A244-3CF3-4649-86FB-679658B70E31.jpeg

Edited by c-mac

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Sorry bud you need a cooler! Keep this site on speed dial you will likely need encouragement as you go along!😡

Edited by fjh

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On ‎2‎/‎7‎/‎2019 at 11:03 AM, Mackpro said:

Injector cup can cause the issue. If a worn tool is used to install the cup, then compression can come between the cup and head and cause is issue. But being a 2018 it’s unlikely 

ok the cooler took care of the one I posed the pick of. The next one has a new cooler and compressor. I guess someone else has been

 

chasing this problem too. I checked the newish cooler, it was clean and dry. I clamped pinch off the coolant line to the compress and ran the engine at 1000rpm. The cooling system got up to 13psi. I left the system a little low of coolant so as not to blow it back out. I pulled the overflow hose up and stuck it down a bottle of water and light bubbles were present and the coolant tube from the back of the thermostat housing to the coolant tank was jumping. I cant thing of any other way of determining if it is cups or a head problem. This one is an 08 model built date is 11/07. Not sure if it has copper or stainless cups of if they have been changed

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Your only choice is to lift an injector to see what cups are in there in my opinion! Assuming it is cup issue

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There is a service bulletin on coolant push on early MP engines. It might take me a day to find it though 

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Quick question, on the expansion tank on top of your radiator. On the drivers side of it, is the pressure cap on it blue or black? The problems ones were blue, the updated ones are black. I got the service bulletin but I cant post it here due to size  but will PM you .

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On 2/15/2019 at 9:00 AM, Mackpro said:

Quick question, on the expansion tank on top of your radiator. On the drivers side of it, is the pressure cap on it blue or black? The problems ones were blue, the updated ones are black. I got the service bulletin but I cant post it here due to size  but will PM you .

It’s black and the tank is new

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On 2/14/2019 at 5:37 PM, fjh said:

Your only choice is to lift an injector to see what cups are in there in my opinion! Assuming it is cup issue

Gonna pull the injectors Monday. I guess if it has stainless, I’ll change just the cups. If there copper I’ll put in a six pack. The engine runs fine other than on cold start it has a little rough idle for about three seconds which my be a little coolant in the suspect cylinder 

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Pulled the injectors and the original copper cups. Didn't see anything out of the ordinary with the cups, all looked about the same. I'm going to go back with new injectors and cups. Hope this takes care of it, I dont want the boss to loose faith.

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