× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network
MOPAR Hemi exhaust manifold stud failures
Posted to Technical Tips Forum on 2/23/2019 44 Replies

I was working with a former automotive & marine engineer when the subject came up about his truck being back in the dealership for another set of heads as the outermost exhaust studs had once again snapped. Now, I know, so long as I am able to get a straight shot at these broken studs that I cab successfully extract them at least 80% of the time, but I learned something new from an old buck!

He had heated the manifold in the oven to measure the overall expansion of the manifold. It literally expanded over .030" =, but most of the expansion occurs at the extreme ends of the manifolds.

Now, he has had this figured out from an issue they had with marine manifolds over 30 years ago, but Mopar didn't want to hear from him. So he insisted that the dealership give hi his manifolds and we notched the last 2 holes so that they're more like a sideways "U" now.

Now he had had this truck since '12 and the studs would average between 65-80k miles. Now he has over 125 k miles on his "notched" manifolds and those outer studs are still in excellent condition and actually will come right off with a socket..as I just had to see it to belief it.

Now, I don't know how many of you may know of this little trick, but the next time your doing cast iron manifolds on aluminum heads, notch the last two holes on both sides of the manifold. With the measurements I saw with my own two eyes, Dave's notes from 25-30 years ago and now seeing his Hemi Dodge with the same manifolds,studs & heads still in great shape with over 125k on them...I think he was definitely on to something!

Whenever I do ANY cast iron manifolds now....the first thing I do is notch the ends. I haven't seen a repeat failure since!

Keep our industry going! Kirk.

PS IF this is already well known, I apologize for wasting your time.....but I try quite hard to stay up to date despite being disabled and know none of the Mopar techs at a dealer near me have ever heard of this and one is willing to bet me $100 that this can't work as he's convinced they only break due to corrosion....So there definitely are a lot of techs unaware of this issue and likely repair.

Kirk Bonanny
Owner/Technician (Retired)
Bonanny Automotive
Forty Fort, Pennsylvania, USA

44 Replies Received (View Replies)

 

car Vehicle Data

2012 Ram 2500 Laramie 5.7L

Engine5.7 L
Trans5-speed Automatic (Electronic)

car Vehicle Data

2012 Ram 2500 Laramie 5.7L

Engine5.7 L
Trans5-speed Automatic (Electronic)