Hey guys,

So I have been having some serious pressurization and overheating issues with my truck. It all started when I was pulling my truck/trailer up to ND from Texas during my move a couple months ago. The truck wouldn't overheat, but coolant would come out of my degas bottle when it was pushed hard. It stopped when I didn't have a load on the trailer so I just forgot about it. After a couple weeks of driving the truck daily, coolant started coming out of the degas bottle even when unloaded and driven very conservatively. This was with a completely stock setup.

While I was trying to find out where I was losing coolant, I noticed that the top of the stock radiator had some cracks in the plastic that weren't all the way through yet but were concerning, and that the water pump looked original to the block. I decided to go ahead and replace the whole cooling system at once with an Alliant waterpump and a Mishimoto all aluminum radiator, gates hoses, and a new thermostat housing and 192 Motorcraft thermostat. I was still getting pressurization/leaking issues, so I looked farther into it. I pressure tested the truck with the injectors out and narrowed it down to cylinder #1 or #2 as the problematic hole. I stuck a paper towel down both and #1 had coolant in it. AHA problem cylinder identified. I replaced the cup with an OEM motorcraft and thought that would be the end of it.

I reinstalled some brand new stage 1s from Rosewood, and took it for a test drive. Overheated and pressured up the system, about a gallon of coolant was lost out the degas cap and it was on the "H" within 5 miles.

I drained and refilled the coolant system with the thermostat off, and then the top rad hose off, and then idled the truck for four hours with the cap off to try and burp the system. Took it on the test drive, same thing happened.

All these times, the radiator was cold and no flow was coming from the water pump.

Upon googling the symptoms, the two things that came up time after time were head gaskets and cups, both of which are much easier done with the head out. This fact plus having another set of hands for the weekend (Byron) led us to pull the Passenger side head last night. Pictures:








The second pic is where we are thinking the compromised head gasket is. There were some signs of exterior coolant leaks next to the dowel pin hole in question, and the head bolt that went through that hole was pitted and had some surface rust.

So now for questions..... Do y'all think that was my problem the whole time? I have cups left over so I will be changing all four in this head, just in case using loctite 620.

I know this engine was rebuilt about 15k miles ago. If this head gasket was compromised, I probably should pull the other head just to make sure as well right? I really don't want to do both but I am feeling that I am going to need to do it. I was planning on getting this head back on, driving the truck and seeing if it fixed my problem.

 

Wow. I'll be honest, I don't see anything glaringly wrong with the head gasket. And a leak between a coolant passage and the dowel pin wouldn't cause the system to be pressurized and overheat.

I almost hate to ask, but did you have any coolant in the oil? May be hard to tell now whether it was from pulling the heads or from something more....serious.

 

And how long after you started driving it did it take to have it heat up and blow coolant out of it?

When you say you idled it for hours trying to burp it, did you get any bubbles out of the cooling system while it was idling?

I don't think it's an injector cup issue because that just results with fuel in the coolant, not combustion gasses (which cause the overheating).

 

Did you ever pressure test the system before pulling it apart?

 

All throughout this journey there has not been any coolant in the oil, oil in the coolant, or smell of coolant out of the exhaust. There was, however, some white crystallization on the glow plug tip in the cylinder whose cup I changed that we saw after pulling the head.

While it was idling, it bubbled a couple of times but nothing major. After that, it would have a constant stream of small bubbles, especially while hot. I put 6 gallons in after only pulling the bottom radiator hose, so I doubt that there could be a big enough bubble to cause the trouble I was having.

One more thing I forgot to mention is that I would loose heat out of the vents and it would immediately start to over heat.

I pressure tested it several times beforehand and it always passed the test. It even held 15psi overnight twice.

The system would also stay pressurized for a week after I shut the truck off, to the point that it overflowed almost a gallon when I opened the cap to show Byron. I parked it on Monday and pulled the cap on Friday.

 

To recap, there was pressurization, random loss of heat through the vents, a rust stream and white residue on the block at the spot where we thought the gasket might be compromised, and the dowel pin is rusted. There was also a white ball of residue on the end of the glow plug in that cylinder like combusted coolant residue. Also, we did replace the thermostat with a new MoCo good one (192*) and the truck would go the O and the R and stay there. You could watch the cooling cycles for about 15-20 minutes of driving....until....then it would go to the H, lose all heat, rad would go cold, heater hoses would go cold, and it would start pressurizing to the point of pushing out the overflow cap and overheat. All of these symptoms, as Jarrett said, were either cup or gasket related based on all of the research.

We didn't go *****-Nilly and just pull the head. There was a TON of discussion, changing thermostats, test driving, and talking back and forth before deciding that seemed like the only next logical step. Cups or gasket...and it seemed....SEEMED like the symptoms were pointing to the gasket. I certainly don't know exactly what's going on with it, butI will say that I don't think it's an air bubble. I have done 4 water pumps and umpteen coolant flushes on these trucks. They have never given me an issue upon refilling them. In fact, I found the 7.3 trucks to be the easiest to fill with no bubble problems....just dump the coolant in and go...unlike the Dodge or the Dirtymax. If anyone has had a different experience, please chime in. Maybe I just got lucky?

Anyways, I don't think we forgot anything. I will say we had that head off in 2.5 hours....that was with a supper break. It was kind of a thrash of sorts....pretty fun!! I won't mention my oil cooler took 5 hours, but that was due to beer and slower movements based on lack of motivation. LOL! Thanks for your help guys.

 

I think it's either the head gasket or cavitation made a hole in that cylinder wall. Clean that cylinder out real good and run the piston to the bottom of the stroke then watch for a drop to form in the cylinder wall. If you don't see anything, put it back together with a new gasket and hope for the best.

The heat going cold just means it was losing the coolant. I think the little constant stream of bubbles you were seeing in the degas bottle was combustion gasses escaping through a leak somewhere. I really hope it was the gasket!

 

Thanks Nate! I have never seen a head gasket that was real obvious. It always seems like you had to REALLY look. Has this been your experience?

 

The majority of the ones I have seen blown have been pretty obvious. Especially when you have combustion gasses leaking, those tend to leave a mark. That's what has me kind of questioning whether it was the gasket.

Then again, if it were cavitation, I would think you would have either hydrolocked a piston or had coolant in the oil. The cooling system stays pressurized when the engine stops so the leak generally continues and the coolant either goes into the cylinder or onto the crankcase. If you didn't see either of those, then maybe (hopefully) it was the gasket.

At any rate, I'd clean everything up real good, inspect it carefully, get all the mating surfaces clean and if you don't see anything, put it back together. What else is there to do but try it?

 

Thanks for the input, Nate. I will be changing out all four cups because I have the head out, I have the cups, and I have the sealant so why not.

I am really hoping it is just the head gasket. I will continue to update this thread as I am able to get work done. We have a pretty full schedule so hopefully the truck is put back together before December.

I am assuming that the only head gasket I would want to use would be OEM?

 

Agreed Nate...can only go forward at this point. Hopefully no cavitation since it's a fresh rebuild. Yikes.

 

Would there be cavitation if the truck always passed a pressure test?

Maybe it was at the very top of the stroke so it would pressure up the cylinder?

 

you would need to pressurize the cylinder to over 400 psi and see if leaking past the cylinder wall and make sure there is no oil in there or it could ignite

 

I doubt it was a head gasket, could of been a bad coolant cap and air locked in the coolant system.

 

Well guys, this is a head scratcher. If I read everything correct at one time you only lost about 1 gallon of coolant and had no flow through the radiator or heater core? That just doesn't seem right. Every blown head gasket I've experienced the heater always worked, very well. Why in the wold would the water pump just quit working?

I'm just going to throw this out there but take it for what it's worth. Most of you are a lot smarter than me on these rigs, I'm a electronic expert, and just a fair backyard mechanic.

I know you replaced the water pump and thermostat. Are they the correct combination, short stem vrs long stem thermostat? Short stem will fit in any water pump but long stem is required in Ford OEM water type pumps. If short stem is put into a long stem water pump overheating can occur in the rear cylinders due to the bypass disk. Here is an explanation from the 203 diesel site I believe ...

The thermostat in the Powerstroke not only controls operating temperatures, but properly directs the flow of coolant through the engine. As the thermostat opens, it proportionally closes the bypass. With the thermostat fully open, the bypass is mostly closed, and vice versa. With the International (Pre-96 Ford) thermostat, this cannot be controlled properly because of the shorter bypass stem. The shorter stem of the IH(pre-96 Ford) thermostat allows the thermostat to be fully open while the bypass is fully open. This means the coolant can travel in any direction available -- whatever direction it chooses. It can either travel through the radiator or simply make the shorter, less restrictive path back through the front of the engine. This will cause uncontrolled overheating in the back cylinders of the block

FYI, here is a old picture of the 203 long stem stat showing the dimensions that I dug up before installing years ago. I would think running the rig with no stat would also cause overheating issues.



Once again, take this information for what's worth, you guys know what your are doing, but it might help some new member out in the future.

And, OH ... maybe the other HEAD?