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Discussion Starter #1
Got a bunch of seemingly unrelated events occurring and thought I would check it with you guys before I jumped in head first.

Late last year my truck started blowing white smoke so I put in new EGR and oil coolers from Sinister. Problem solved. As long as I had everything pulled apart I threw in new injectors. About the same time, my A/C was acting up so I had it "fixed" because I ran out of time doing the above work. New pressure switch, condenser, compressor, and clutch later, I discovered it was a simple fix as recommended elsewhere on this forum. But I digress.

Shortly after all of this nonsense, I started noticing a coolant leak. Subtle at first, but getting more aggravating. It has now been some 25,000+ miles since the above work and I have some weird symptoms as follows:

- Code P0683 Glow Plug Control Module to PCM Communication Circuit Code
- Pressure test reveals coolant leak at right rear head gasket.
- Pretty intense vacuum in overflow tank when opening cap to refill coolant.
- Significant delta between oil and water temps.

I haven’t had a chance to chase wires for the code, but I’m assuming there is simply a short somewhere. There have been plenty of wandering fingers in the engine bay and something very easily could have been left partially unplugged. Even assuming the module is bad, it should have no bearing on the other symptoms.

A leaky head gasket is pretty normal for these engines, but no coolant has been found in the oil (though, admittedly, it has been a few miles since I looked at the oil). There is typically a fairly large leak under the right side engine bay after it has had a chance to cool down.

Obviously related, when opening the reservoir to refill, there is a very noticeable vacuum as the cap is removed. Even with a quite hot engine the vacuum exists. Which doesn’t make sense to me. Is there some deeper meaning to this I’m missing?

Finally, the stupid water and oil temps. Would a leaky head have something to do with high deltas? Do I need to chew some ass at Sinister Diesel due to a faulty item? Obviously if something is not working I’ll want to swap it out as I put in a new head gasket.

Any help or feedback would be MUCH appreciated!!


2007 F250 6.0 w/~170,000
 

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You will never find coolant in the oil of a 6.0; that's not how the HGs leak. They leak from a coolant passage through the combustion seal of a cylinder, so the coolant goes into the engine and gets burned off, until pressure in the cylinder exceeds pressure in the cooling system at which point combustion gasses and pressure enter the cooling system.

Your new OC is clogged. If there's no coolant filter on the truck that's going to keep happening. If there is, then flush the cooling system with the bad OC in place and replace the filter and OC, and it should be good to go from then on.

Also, NEVER use an aftermarket OC on a 6.0. Motorcraft only, all others are spotty at best. Auto Nation has them for $270.
 
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Discussion Starter #4
You will never find coolant in the oil of a 6.0; that's not how the HGs leak.
Must be tired. I meant the other way around. No oil in coolant. I hear this happens from time to time.

They leak from a coolant passage through the combustion seal of a cylinder, so the coolant goes into the engine and gets burned off, until pressure in the cylinder exceeds pressure in the cooling system at which point combustion gasses and pressure enter the cooling system.
This makes sense, but it doesn't describe what I'm experiencing. If exhaust gases were escaping into the cooling system, there would be positive pressure at the reservoir instead of negative pressure as I'm getting. It is the negative pressure which has me befuddled.

Your new OC is clogged.
This also makes sense and I initially thought that, but I can't believe that it clogged so quickly. I did a full chemical flush and replaced with Zerex ELC and have a coolant filter I've been replacing every 3k. I find it difficult to believe that the OC would clog up after 20,000 miles with these precautions, yet last 140,000 miles on a stock setup. I may look into an air-to-liquid oil cooler if this is truly the case.
 

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Oil in the coolant in a 6.0 is a sign of a ruptured OC. There are no areas of the head to block interface where oil is under pressure, so a blown HG is not going to cause oil to get into the coolant.

Have you verified negative pressure through the use of a pressure gauge? Frankly I'm not sure what could cause a vacuum in the cooling system. Pressure below atmospheric would seem impossible.

During the flush a lot of stuff is kicked loose. If all of it isn't removed, which is almost impossible because when you drain the coolant from a 6.0 you get about half the system capacity, it clogs up that OC again. Most coolant filters are just bypass filters, the are not filtering all the coolant all the time. This is why I always recommend installing the filter, changing it twice, and then flushing. Even then its still somewhat of a risk. With no filter I've seen guys clog a new OC in 1,000 miles. The bottom line is that the deltas don't lie. If they say is plugged; its plugged.
 

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Discussion Starter #6
Yeah... I suppose I'm just trying to avoid changing that stupid thing again. I'm sure you know how much of a PITA that is. Grr... Oh well. Thanks for helping me see the light.

To be perfectly honest, I'm not sure how I would get a pressure gauge on there. I'd probably have to put it inline somewhere and heat the bugger up for some time before reading it. I don't think I have a gauge that is beefy or cheap enough that I'd want to expose it to that sort of abuse. That said, it is pretty obvious when there are hot gases escaping because your hand will burn if you're not careful. I can warm the engine up and pop it loose without a hint of gases hitting my hand. Perhaps I'll run by Harbor Freight and see what I can come up with.
 

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You can just rig a test tee and tee into one of the small lines going to the degas bottle. Just buy a cheapie pressure gauge. Check Harbor Freight, etc. and you can usually find them for less than $10.
 

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The cap has a 16psi relief, so get a low pressure gauge.
 

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Sounds like you're hearing the hiss from the pressure escaping and thinking it sucking. It's physically impossible for a cooling system to develop that kind of vacuum. If you flushed the cooling system with the new cooler installed it will clog very quickly. Plus aftermarket oil coolers don't last. I replace them all the time. Good luck.
 

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You will never find coolant in the oil of a 6.0; that's not how the HGs leak. They leak from a coolant passage through the combustion seal of a cylinder, so the coolant goes into the engine and gets burned off, until pressure in the cylinder exceeds pressure in the cooling system at which point combustion gasses and pressure enter the cooling system.

Your new OC is clogged. If there's no coolant filter on the truck that's going to keep happening. If there is, then flush the cooling system with the bad OC in place and replace the filter and OC, and it should be good to go from then on.

Also, NEVER use an aftermarket OC on a 6.0. Motorcraft only, all others are spotty at best. Auto Nation has them for $270.
You will never find coolant in the oil of a 6.0; that's not how the HGs leak. They leak from a coolant passage through the combustion seal of a cylinder, so the coolant goes into the engine and gets burned off, until pressure in the cylinder exceeds pressure in the cooling system at which point combustion gasses and pressure enter the cooling system.

Your new OC is clogged. If there's no coolant filter on the truck that's going to keep happening. If there is, then flush the cooling system with the bad OC in place and replace the filter and OC, and it should be good to go from then on.

Also, NEVER use an aftermarket OC on a 6.0. Motorcraft only, all others are spotty at best. Auto Nation has them for $270.
Never coolant in the oil on the 6.0 not how the HG works . I purchased a new rebuilt 6.0 from a company called RPM Powerstroke ran by Ashley Hanes and Keith Proctor after installing the new engine and putting in the fluids I checked the oil level and it was over filled . Went to drain some off and 2 gallons of coolant came out . They refuse to Warranty the new engine no specific reason they keep blowing me off ETC .
I was told HG , the engine is studded as well , with no delete equipment everything brand new .
Can you expand on the no coolant in the please ? PS I apologise for highjacking this thread I was looking for solutions in it .. Thanks
 
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