Scyry

Pretty sure I am having this issue on both sides. Both started, different times, after coasting downhill for long periods of time while towing our travel trailer. I was wondering if anyone else had similar? Like 30 minutes of 20-35 mph of engine braking heats up this area too much? Truck was in tow haul mode, sitting at 2500-3500 rpm, and I was just letting the truck do as it wanted. My trailer weighs out at 5,700 ish loaded, checked on a scale. I'm worried I do this fix and will be right back here again. Truck is a 2016 and just over 62,000 miles.

Alohacomputer

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2nd time, right side. About a year and a half ago I replaced the stock manifold with a NAPA brand and had it done. Now the dealer says it needs to be replaced again on the right side.
The design is crap. Each exhaust port should have two bolts the last port has one bolt where the turbo attaches. Very weak at that point, either snaps the bolts off, the vibration from the turbo.

Scyry

Confirmed, truck is waiting on parts, $2,600 estimate both sides at once. Talking to the mechanic (friend of a friend) sounds like this is very common and he sees it more with people who tow regularly. As much as we tow our travel trailer, I'm thinking it may be time to move on from the truck when the market settles down..

rockfossilman

Just had both exhaust manifolds replaced--cost just under $1700. One stud on each manifold had broken, possibly in the way you described--we took a 9,500-mile trip towing our 7,000-pound trailer from PA to the Pacific Northwest and back. Had multiple circumstances where we were in to haul mode--uphill and downhill in the unusually high temperatures of June and July in that area. I wish I could be as specific about when the studs likely broke.

The mechanic told me the new manifolds were redesigned with different stud locations than the original design. I asked him how that could be--he said Ford had extra holes in the engine to accommodate the new manifolds. Makes me wonder if Ford knew the problem might occur. I have read that removing the broken studs is sometimes a problem. Mechanic told me he has done same job on others and they seem to be holding up well. I will post again if the problem reoccurs.

Alohacomputer

They would have to have extra tapped holes in the head as well as the exhaust manifold which they do not....

rockfossilman

So you're saying he lied to me?

Alohacomputer

I'm just saying my 2012 f150 3.5 EcoBoost did not have such a thing....
IDK if later generation of that engine might have had. One of the problems is where the manifold mounts to the Head is only one bolt so the vibration from the turbo causes vibration that can break off bolts.

needadiesel

I just took my 2010 5.4 back in to the shop because the exhaust manifold they replaced on the driver side last year is leaking. Luckily that side is covered under warranty, but they said the passenger side is leaking as well. The passenger side was replaced 3 years ago by a different shop (no warranty). They're going to do both sides and charge $950 with the one side covered under warranty. Now both sides will be under warranty for about another 25k miles. Sounds like a good deal if I need to have these replaced every 10k... What year did Ford get this issue fixed? Has anyone actually had engine problems based on these leaking? I have 175k miles on it and tow a 8500 lb camper about 100 miles every few weeks in the summer. Pretty flat terrain, the engine brake rarely kicks in. Probably time to upgrade to a diesel when these prices settle down a bit...

Scott91370

The holes are already there on the, for sure, 2015-2016.

Corrected from mass-hole's reply.

mass-hole

Wrong years. 2011-2016 3.5 has 11 holes drilled and tapped but only 8 are utilized on the original manifold design. The new design uses 9 of them and repositions some of the studs.

The 2017+ 3.5 manifolds are completely different and dont seem to be an issue.