D12 Pressure in my expansion trank

I had that problem. I don’t know the details cause my mechanic fixed it. Believe It was a compressor leak. That’s why the pressure and bubbles. Have to get with my mechanic to get back to you

 

Relieve the pressure and make sure the reservoir is full. Put the cap back on and pump the brakes down. Then start the engine and rev it up about half throttle. When the air drier spits off, shut it off and see if the cooling system is pressurized (hoses are hard and you can't squeeze them). If so, then the air compressor head gasket is blown. See it all the time. When you rev it, the coolant level will drop. Also can't hurt to check the air tanks for coolant and see if any is coming out the air drier purge valve.

 

@Heavyd Good afternoon , got a truck over here inside a shop which is still a myth to me with its problem. Truck was over the road with a high pressure problem inside an expansion tank , it was so bad the pressure would push the coolant down under a coolant level sensor so the driver had to stop every 100-200 miles to pop the cap so the coolant would rise up , he finally made it to Chicago and yday i put it inside a shop and start working on it. First thing done was a combustion leak test and the thing passed without a problem. Put a tool inside expansion tank and let it run for good 10-15 minutes and it passed it. After that test done i figured out that there is only one thing left to do and that was the air compressor but i was wrong , thats why now im looking for help from you. My question is , since i changed air compressor , did the combustion leak test , EGR cooler and Egr valve are shut off and closed perfectly , my question is is there anything else that i could check out or do some other test before doing the cylinder head job , i got a Servicemaxx and DLB with me so any kind of test or a hint a trick of a trade is more than welcome. The truck is Internationl pro star with MF13 , on the idle it takes it 15-20 minutes with a PSI gauge on Expansion tank to hit a 20 PSI (Red Alert). Thanks in advance mr HeavyD

 

One of the good things about a Maxxforce is that the headgasket is a "dry" type. No coolant passes through the head gasket. So head gasket failure alone will not cause this. Now, coolant loss problems like you are describing, are over pressure situations or coolant getting "pushed" out. You are saying the coolant is getting down under the level sensor which I find slightly confusing. Are you seeing any coolant leak trails from it getting pushed out around the rad cap? If you see no leak trails, I would say the engine is "using" coolant or burning it. Since this engine has been deleted, you really can't tell what is happening with the egr cooler. Usually with cracked heads or liners, the oil will start to turn a milky colour as coolant is mixing with oil. It is possible that coolant is leaking from a crack near an exhaust runner and not mixing with oil, but in these cases, your combustion test should show positive. I really would not replace a head until that combustion test came back positive. Retest with new fresh test fluid.

 

@Heavyd Ok first things first. I was reading about that "Dry deck" Type of cylinder heads cause first when i saw it was on these type of engines and i also happen to have a Engine block on a ground cause i was doing some engine swap job and took cylinder head apart to see how it works so i know what you are talking about. Back on a subject the truck is not losing coolant (no visible leaks with a 20 psi pressure put inside a system) , mixing (no coolant inside of oil at all , the oil is clean and up to its own perfect level) , burning ( there is no a slight portion of white smoke coming out of the exhaust or visible coolant drops on exhaust manifold , turbo etc..) The level of coolant when the truck is off is on maximum level , i put on the Snap on Coolant PSI test tool i turn on the truck and watch the tool gauge and coolant level carefully , in 10-15 minutes of idling on 600 rpm the coolant is somehow dropping down in expansion tank and the pressure on the gauge goes up to 20 PSI i turn off the truck cause the coolant level dropped below coolant level sensor and cause of the PSI it has built and the moment i Depressurize the system coolant level goes back up to its previous level (max level as before i started the truck and do the test). Its really odd problem and im not giving up about that combustion leaks test cause if there was a slight leak of exhaust inside the cooling system it would turn green in a split second.

 

Wow, yeah, that is really weird. Unless the truck has some aftermarket or custom equipment on it, there is nothing else on the truck that would pressurize the cooling system like that. To rule out any air operated system, I would completely drain the air tanks and disconnect the compressor discharge at the air dryer and retest.

 

i have a 07 with a d12, this happened to me about 5 years ago.
everything tested ok. turned out to be injector cups

 

This is the part of my job that really sucks, having to guess. If only the combustion test turned colour like it should, the mystery would be easier to solve, LOL!

 

@Heavyd If it turned colored i could sleep last night lol. Already did that with air compressor discharge line and empty tanks and same thing. What i also did maybe it sounds funny to you but i was hopeless i disconnected HP turbo from intercooler and i also pinched coolant coming to HPCAC and same thing. the thing is after it builds up pressure inside a tank and pushes the coolant down below coolant level sensor with a truck off and PSI gauge still on , the pressure stays at 20 PSI but coolant starts to raise back to its normal level after 20-30 minutes and comes up to normal level with 20 PSI still inside the system.