I thought I had my coolant issues resolved but not so fast. I just don't get it. I towed 520 miles last wed and didn't lose a drop. Towed 400 on Thursday and it went down like 6 ounces. I left it that way and towed 350 or so and the next morning it was down to the bottom of the Cold fill lines. Took 12 ounces to bring it to the top of the cold fill area. Drove 400+ miles and it was right on the mark this morning.

Today I towed I 90 from Butte to Missoula and the pig roads up to Glacier NP. Three different times going over the passes the truck got hot to the 230 degree level. All three times the fan came on and the truck defueled (according to the tuner) for boost. Boost was in the 37-38 area, coolant at 225-230, oil just a bit hotter. All three times the truck performed like I would expect it to. Had I not had the tuner I wouldn't have known anything happened. However, the tank is just about empty after cooling for an hour or more and there is evidence of the cap letting coolant out on to the tank. Not splatter but runs down the front and side of the tank. It just got cool enough to open and the coolant level is at the bottom of the tank. I'll wait till morning and see how much it takes.

There is no evidence of external leaks, no white smoke, no coolant in oil that I can tell. Just had an oil report and no coolant in oil then.

When I top it off I fill to the top line of the cold fill mark with 50/50 gold and distilled, is that too high and it forced some out when very hot?

Can anyone explain why it holds the level perfect one day and another in identical circumstances it eats 6 or 12 ounces?

The truck is running great. The temperatures (oil, coolant and tranny) went back to normal after each event today.

Sooooo, anybody have a good suggestion? The truck was out of my control for a month while the tranny was built. Could someone have drained coolant and added water only? Or maybe the wrong coolant? Would the wrong coolant cause these problems?

Could it be thermostats, the coolant/ oil temperature spreads go as high as 15 or 16 degrees but they seem to stay mostly on the 5 to 10 degree range. I don't remember what they were during the high temp events today.

Would the defuel cause the coolant to over flow the system?

Anybody????

 

I don't tow but I would start with a new cap. The thermostat question is a good one. Seems to me I remember reading somewhere that overheating can toast a thermostat. But what is considered overheating in a 6.4 and what are the stats rated for.
Which degas bottle do you have, I would fill it tonight and refill if needed in the morning just to keep the chance of air out of the system.

Your last question is good, it probably defueled from full throttle say 3,300 RPM's to an idle, something to think about.

 

Cap...get an updated cap. If I recall you already have but the spring in the gets weak.

 

I have the stock degas and the updated cap. I'm not sure how much it defueled but it was not to idle or anything near that. The truck continued with a very slight loss of power but plenty to get that big azzed trailer over the hump. Then in short order everything went back to normal. Had I not had the tuner I would not have noticed the defuel.

 

I reread your post again and again wonder which degas bottle you have and if the new bottle holds more than the old one. The reason I ask is I've seen my (old style) degas bottle within a couple of inch's of the cap with coolant when my temp gauge has never gone over 197 degrees. I ask this just because of the thermal expansion of the coolant. If mine rises that much under normal driving I would find it very conceivable to run out of expansion room when running that hot.
Would be a good use for one of those relatively inexpensive camera's hooked up to a laptop with a LED light source.

 

Good thought. A cheap thing to try but yes I do have the new one. If I was home I could get one or test mine but up here unless I get an idea that I am doing serious harm to the truck all I plan is to keep it full of coolant. I think it's a couple hours back to the ford dealer. Isn't there also a new model degas tank, maybe I should try that. I'm also thinking about having the system drained and coolant replaced. I can get that done at the bottom of the mountain in Missoula on the way home. I just did it a few months ago at 60,000 miles but it bothers me that the truck was away from me and came back with air in the cooling system. The tranny guy said he didn't drain it but there were others working in his shop.

 

Bubba, by the time I got that much technology figured out the truck would be obsolete LOL. But yes, my coolant gets very close to the top when hot and I plan to upgrade the tank. What just drives me nuts is that it will stay at exactly the top line (after cooling) some days and then will lose some on very similar days.

 

Well, when in doubt read the owners manual. I did, mine says that the following may cause the truck to over heat: "Towing a heavy load in hot weather conditions". I guess I should have read that before I bought because that's what I bought the truck to do. There are a number of things in the list but this one seems to apply.

I guess on the way home I'll tow over the passes at a lower speed. I was doing 60 or a little under that.

 

i hope you figure it out stanley ive similar issues since we got our truck. its good for long time then i need to add a quart.

 

A couple things;

1st, I know of at least 1 guy that blew his head gaskets 100% stock, it can happen.

2nd, I made mine puke on a big tune once, 60 PSI of boost and heavy fuel did it. Haven't run over 40 PSI in the last year, haven't lost a drop of coolant. So it seems gaskets are fairly resiliant.

3rd, When I did that, I ended up with an air lock, and it took weeks to figure out. Logic and engineering tells you that shouldn't happen, but it did. Mechanic found hot spots on engine with laser thermometer, drained coolant, changed it again, then everything went back to normal.

 

so maybe the tranny shop had fun with the truck? was the tuner left it in the truck?

 

Have you had your cooling system pressure tested Stanley? Hook a pump and gauge up to the degas bottle and run it up to 16 psi. Look for leaks or a pressure drop. Do you still have the EGR coolers on the truck?

 

I don't think the degas bottle or its capacity is the issue. I have been towing the southern route at about or close to 16K and my coolant has been spot on.

The coolant will rise to close to the top but does not try to go up the inlet.

When cold or as cold as overnight can be it was right at the full mark.

 

I have not ruled out that the air has been in the system since before the tranny job. I did a very thorough flush and fill at 60,000 but I don't remember how much coolant/water it took.

As to HG causing the puke, I'm doubtful. Never got past 37-38 lbs and was defueling, coolant never got past 230 degrees. Every thing was very normal. Temps went right back to normal each time. Truck should not puke at those numbers, should it?

 

yes, I tested it before I did the flush and fill 60K miles. The cap failed and I replaced it, system was OK. EGR coolers are on but they may be gone soon. I hate to remove them as it takes so much more work to get the truck back to stock if I decide to sell or trade it but if they turn out to be failing I'll kick myself for not removing them sooner.