Common Problems: Manifold Mishaps

July 2020 Tech Corner Colin Peterson

This article originally appeared in the October 2019 issue.

Are you fed up with issues with the exhaust system on your 6.7L Power Stroke? You’re not alone! So many folks who own diesel 2011-2014 Ford Super Dutys experience problems that stem from the exhaust, especially if they cover a lot of distance on a yearly basis. The truck we’re focusing on in particular is a 2012 F350 dually flatbed chassis cab that developed an exhaust manifold leak and lost its muscle as a result. On top of that, it created a situation that wreaked quite some havoc for its operator and everything surrounding it. The truck has also seen a lot of use in a stop-and-go city environment by different people, granted that it’s owned by a busy landscaping company. That’s a major contributor to these common exhaust issues, and we’ll explain why. We spoke with Jordan Johnson, a technician at PowerTech Diesel, LLC., in Idaho Falls, Idaho, for some insight on this issue.

EGTs

Yes, that dreaded exhaust abbreviation is the root of the problems that happened to this truck. As you’re well aware, emission-regulating components on the newer trucks do put backpressure in the exhaust, especially in a heavy stop-and-go driving scenario. Backpressure heats up the exhaust gas temperatures (EGTs) and the system components start to buck, warp and even melt. On the 2012 Ford, the stainless steel bolts broke as a result of the overheating exhaust manifold.

“Stainless steel bolts break easily,” explains Johnson. “As the manifold heats up and cools down, the components expand and contract.”

That’s exactly what happened to the bolts in this case: the warping caused them to snap. The manifold itself warped out of shape as well. Johnson and his colleagues at PowerTech put a measuring stick flush against the manifold inlets, and they were uneven all the way across. The specified clearance limit between the exhaust manifold ports and gaskets is .010 inches, which this one was well in excess of.

“This truck also has a baby turbo,” Johnson says, and it’s true that a smaller turbo can also contribute to higher EGTs. Though they do spool up more quickly, they also restrict airflow as they have a smaller area.

“The 2016 and newer trucks don’t have issues with this, mostly because they have the bigger Garrett GT37 turbo,” adds the tech. Another component that can drive up EGTs is an exhaust brake, which this truck is equipped with. Driving so many miles (the flatbed has rolled over 130,000 miles) with that contraption in regular use will definitely put some more wear on the exhaust system, and subsequently, the engine over time. As the load being carried increases, so does the exhaust brake workload and wear on components.

“This is the first time I know of this truck having this issue, but I know this truck hauls a lot of heavy loads,” Johnson remarks. The truck even has a small engine tune on it; that performance jack-up also jumps the backpressure.

Awareness & Good Driving Habits

Although they don’t guarantee smooth sailing with these engines, the best tactics 2011-2014 6.7L owners or operators can employ to mitigate or prevent the risk of backpressure-triggered issues involve diverting a little attention to EGT levels. The first place to start is driving habits. Johnson recommends driving more conservatively and trying to only drive the bare necessity in regards to mileage to get to and from places. That really comes into play when on the clock in construction, landscaping, or other similar trades. However, of course some things are simply out of our control.

“If a truck is just being used as a daily driver, this issue is not as common,” the PowerTech technician claims. That makes sense, as the truck won’t rack up as many miles so quickly. More within our control, however, is curbing habits of harsh accelerations and stops when driving these older 6.7L-powered trucks. Jackrabbiting at stop signs and red lights is very tempting when you’re navigating on the clock, but we all need to be more mindful of it. It doesn’t matter if the truck is a chassis cab or regular pickup, they’ll all go through the same wear and tear with the same driving habits.

PowerTech’s Fix

To repair the failed exhaust system, Johnson ordered a new manifold, manifold gasket, and studs. He installed those components on the truck, but with that of course, he brings some wise advice for owners of these trucks. “I definitely recommend getting some kind of EGT monitor for your truck, especially if you have any tunes on it,” Johnson says. “This is so the guy driving sees what’s going on with the exhaust so he can prevent this from happening again.”

PowerTech endorses EDGE and AutoMeter as top choices for brands of devices that can read EGTs. “EDGE is usually what we use,” Johnson adds.

He also brings up the importance of workers taking responsibility for their own actions with a company truck. However, since any given operator with a company might not know much about how truck engines work, the truck’s owner should take more responsibility and take the time to explain to others the issues of a finicky exhaust system.

Conclusion

The bottom line is if you own a 6.7L Power Stroke older than the 2015 model year, it helps to be more mindful of what you do with it, mainly due to the smaller turbo on the older engines. However, if you feel you can make a larger aftermarket turbo work on your 6.7L, you could certainly invest in one. We fully agree with Johnson that driving habits come into play too, and modifying those is an easy solution, but a bigger turbo offers plenty of other perks, too. Hauling heavy loads and work assignments and responsibilities are among the factors out of our control, but perhaps changing driving habits and getting a bigger turbo simultaneously will improve an older 6.7L exhaust system’s performance in the best way possible. After all, who says you can’t do both?