Good evening,


I have a 2016 F-350 and trying to diagnose a cooling issue. I am going to give a bit of backstory of the last few weeks and make sure I am not overlooking something simple.

-On a round trip from Houston to Dallas and back a coolant line going to the turbo busted and of course coolant went everywhere on the side of the road, truck immediately overheated and I had it towed back to Houston. Not the end of the world, life happens. I thought it might have been the water pump but it was this coolant line for the turbo and the leak was fixed. I pulled over at the first exit and it did not run hot for a long period at all. They fix the coolant line, replace CCV filters, a new thermostat, and look over the entire vehicle with no other issues.

-About 3 days later, I am going from Houston to Big Bend and go for about 5-6 hours and the truck starts to run hot. Pull over immediately and check for leaks but don't see anything. Oddly enough temps return to normal and I thought it might have been an "air pocket" and kept driving. For the rest of the 9-hour drive (about 4 hours left), it would get hot for about 1 min. and the gauges would shoot up super high, and then return back to normal. You could go another hour sometimes and the temps would be normal with no signs of running hot. However, in the morning I noticed that the coolant is pretty low, and top it off with about a gallon and a half. Throughout the rest of the trip, I keep looking for leaks but don't see any, but can smell coolant. I get back to Houston and take it back to shop.
-Shop determines it is an oil cooler issue, and that the coolant was actually burning, which is why it wasn't leaking but smelt like burnt coolant. They replace oil cooler, flush coolant system, replace the reservoir, and send me on. They mention this is why it was intermittent and there was oil in the reservoir.
-12 hours later ( and about 50 miles of highway driving) it is a gallon and a half low on coolant and starts to heat up like before. -Take it back to shop and they do a coolant pressure test, and it passes. They also do a compression test and do not think it is a head gasket issue. They have three mechanics search the entire truck for leaks or issues and they don't see anything. They are thinking it is sucking the coolant down and just top it off in a day or so.
-Since this work was done last week I have had to keep adding coolant to the system. (About a gallon every couple of days). This seems odd to me, and the system is still "consuming" coolant and much more than just "settling".

The truck has had "certain exhaust mods" and running an SCT Tow tune, which it has had on it for years without any issues. The EGR system is still in the truck under the hood, just not electrically connected, however, the mechanic mentioned that coolant would still be running through this system. He would like to bypass it all together eliminating messing with it.

Are there any ideas on what might be going on with this truck? There is a decent amount of pressure on the reservoir tank when checking coolant levels if that matters. This is my first diesel, so I am new to all of the lingo and still trying to learn these things.

Thanks!

 

It’s going somewhere. You’re not losing 1 gallons of coolant every couple of days and it’s going into thin air.. You may of blown a head gasket or cracked a head with the initial overheat on the turbo cooling line and its all going out the exhaust and most likely burning up in the DPF ….they need to do a leak down test and check the coolant for exhaust gases if it’s not leaking where it’s visible. I would also throw some dye in the coolant and look over everything with a IR light. your truck could be running hot enough that a small coolant leak may evaporate as it’s leaking. At 16 psi coolant is easily lost at the rate you stated. In some cases coolant may only leak when the car is running and give little to no indication of a leak

 

Yeah agree a second opinion on a compression test is needed. Classic sighs of heads/block issue.

 

Blown head gasket.

— Dave

 

blown head gasket due to the over heat. As I understand it the DPF fell off.

At the tail pipe with it running does it smell sweet or notice alot of moisture?

 

have them do a leak down test. A compression test gives you the momentary reading of max psi which may not help in this case unless it’s a damn big break in the gasket. A leak down test tells you the cylinder hold pressure over a given amount of time which is a better test of the cylinder health. Two different tests. A competent shop should have no issue doing both.



You may not always get that typical sweet smell as the leak maybe very small and gets burned up in the DPF. And diesels run hot so it simply gets vaporized to nothing. I would have them do a coolant system test for exhaust gasses in the coolant. It’s a pretty simple test. I had a dodge Dakota that had a blown head gasket but it showed no signs of the typical milky oil or additional vapor or smell from exhaust. I have one of those test kits that you put that blow liquid in and if it turns yellow it means it’s seeing combustion gasses in the coolant.

 

Picking up from the shop this morning and will be dropping it off at another for a further diagnosis next week.

Is there a possibility the EGR cooler is leaking causing all of this?

 

Thanks. I'll check it out.

 

I do not see any moisture or get that sweet smell near the tailpipe. Would a blown head gasket be intermittent like this?

 

I have seen a head gasket hold compression till hot then leak.

EGR cooler actually leaking I have not seen.

CAC leaking has happened to a few folks. Look at yours and see if you can tell.

 

a possibility. . Have the shop do a test for exhaust gasses in the cooling system. I’ve also seen coolant leaks only happen when driving and disappear when stoped. I had a Truck that the recovery bottle was cracked on the bottom. When the car stopped the coolant housing contracted and sealed up. When it was driven and had enough pressure it leaked. . Same with a radiator side tank. Only leaked when it got hot and enough pressure built up.

that’s a huge amount of coolant to lose with no trace. It’s goof somewhere for sure

 

As already stated, you have a blown head gasket. Any decent shop with a 5-gas analyzer can confirm this.

— Dave

 

that just confirms there is exhaust gasses in the coolant. There are other places where the exhaust gas can enter the cooling system besides a head gasket. . They need to do a leak down test to really get a blown head gasket diagnosis.

 

The shop did a leak down test and confirmed a bad head gasket. They said it failed it twice.

Here is the million-dollar question, while I will be getting things fixed (and by a different shop), what else would be beneficial to have done while everything is apart?
1. CP4 Disaster Kit?
2. Upgrade to ARP head studs?
3. EZ Link tuning, currently have SCT but every single person says they are much happier with EZ link?
4. Cold air intake? - Is this worth the money on these trucks?

I am new to the world of 6.7's but trying to learn these things. Thanks in advance. If anyone is in the Greater East Houston area, any shop recommendations?