If you have owned a Cummins long enough, you have either broken an exhaust manifold bolt or you know somebody who has. It is one of the most common headaches on these trucks, and it comes down to basic physics. The cast iron manifold heats up and expands, the bolts heat up and expand, everything cycles like that thousands of times, and the factory fasteners eventually fatigue and snap. Sometimes they back out. Sometimes the head breaks clean off and leaves the rest stuck in the head.
Once one lets go, you get an exhaust leak, a tick that gets worse, and a manifold that is no longer clamped down flat. Ignore it and you are loading the next bolt, then the next.
Why the Factory Hardware Fails
- Cast manifold expands and contracts hard with every heat cycle
- Factory bolts fatigue and either back out or snap at the head
- A broken bolt loads the remaining ones and they start to follow
- The leak only gets louder and the fix only gets harder the longer it sits
The Fix: A Stainless Stud Kit
We put together a stainless steel exhaust manifold stud kit that replaces the weak factory bolts with proper studs. Studs let the manifold expand and contract without working the threads loose the way a bolt does, and stainless handles the heat without seizing into the head. You clamp the manifold down evenly and it stays clamped.
If you are already in there chasing a broken bolt, do not put the same factory hardware back in and wait to do it all again. Do it once with studs.
When to Do It
Best case, you do this as preventive maintenance before anything breaks, especially if you are adding power or a bigger turbo that puts more heat through the manifold. Worst case, you do it the day a bolt finally snaps. Either way the answer is the same hardware.
While You Are In There: The Turbo Studs
The bolts that hold the exhaust manifold to the head are not the only fasteners back there that give up. The studs that hold the turbo to the manifold see the same heat and the same cycling, and they strip and snap right along with the manifold bolts. If you are already pulling things apart to fix the manifold side, do the turbo side at the same time with our FSD Cummins Stainless Steel Turbo To Manifold Stud Kit. Stainless studs back there once means you are not chasing the same broken-fastener job twice.
Shop the Exhaust Manifold Stud Kit →