Plot just thickened on this "horror" story. It's been about six weeks since I put this beast back together and everyday after I drive it I will pop the hood to make sure everything is good. Well, it's back. Coolant blowing out the degas again, but this is indeed coming out the cap. I immediately threw up lunch and then executed a deliberate "what the ***k"? When I popped the cap there was a lot of pressure in the system. Took it back out and did a "torture test" on it and brought it back and plugged in the AutoEnginuity and checked EOT and ECT. Oil and coolant temp. were within two degrees of each other (191/191.5). Of course more coolant had spewed. Looking at the coolant level with engine running and cap off was at the Max level (relative to the yellow tape). Maybe to much coolant in the system perhaps, but it hasn't done this before and I have purposely dogged it to see if it would hold together. Guess I got my answer. I did turn my heater switch on and off and did notice a slight drop in coolant level, but also noticed with the heater on, I had a pulsation in the tank. Kinda of like a pump draining a bucket of water, but not constant flow. I have never changed the thermostat, but I can't rationalize that causing the spitting of coolant out the degas. Maybe the pulsation flow in the tank when I turn the heater on... Anybody have any ideas? If not, anybody have any C4?

 

Yea mine has been doing the same thing. It was coming out of the cap and then it stopped for a while, now it's coming out again. Got it pressure tested and that turned up okay. Just put a new thermostat in and completely flushed the cooling system. To my surprise it is still coming out of the cap. Got the pressure test done from my buddy(Diesel tech) from the dealer. He has no idea either and I'm definately lost to what it could be. Oh and the degas bottle level always says the level is okay even though there was a puddle of coolant running down the driveway twice before i flushed the system. Anyone have any clue what is going on. Just getting tired of smelling coolant everyday!!

 

Well what does a pressure test tell us? It says the cap and tank are good. If the headgaskets are blown, it is OVER-pressurizing the system and pushing coolant out again. So the pressure test doesn't really tell us that. If your gaskets are blown, please be sure to use OEM Ford gaskets this time. I've heard a lot of bad things about black onyx as of late.

 

Yea I'll be sure to do that. The way he talked though, the pressure test was a sign for the gaskets. He even took it for a spin with the gauge coming in the window and said the pressure stayed the same throughout the ride, but I'm just going from what I thought I understood he was saying.

 

Check your water pump. I had basically the same problem with mine,My truck is a f 550, dominator service body,5000# imt crane, welder,torch tanks, etc... This thing is heavy! I checked the pressure in my cooling system under a load and my cap was poping off just as it is ment to do (over pressureization of the cooling system) Then i pressure tested my cooling system with the engine warm and lost no pressure, this told me the system was tight. Everyone i spoke with told me head gaskets, even the dealer, i just couldnt buy what thay were selling (so to speek) I checked my thermostat and it was bad, installed a new one and the same problem, i removed my water pump and my impeller was broken, almost in half. Installed a new pump and problem solved, what was happening was lack of coolant flow when pushing the truck, causing it to overheat, heat = pressure in a pressureized system, too much pressure then the cap starts to work on the tank relieving pressure. Its not allways the head gaskets. I hope this helps

 

Ok, that makes more sense. I've seen some of them just pressurize the system with air to 16psi and see if it leaks. Sounds like he did it the correct way and I just misunderstood what you meant earlier.

Definitely might be worth looking in to. The impellers on our pumps suck, they crack and break quite often actually. Bulletproof diesel is developing a billet impeller wheel now.

 

Ok. I'll look into that one. In the book I have, it says i have to remove the fan shroud, fan, and radiator. Do I really have to remove the radiator so I can get at the water pump?

 

Yes its the best thing to do ( remove radiator) If not you can damage it, once you remove the shroud it comes out real easy.