The BEST exhaust manifold bolts?

[jz57]

With "10.9" mark on the bolt hex-head, which is high strength material.

Topping: The hex-head should be flange style, which gives easy installation with a deep socket.

Back in wintry 2018 I replaced both exhaust manifolds and all the associated bolts. Well a year and a half later and I have an exhaust leak again. 2 bolts have sheered off again. What is the best option for these damn bolts? Also had anyone use the thick graphite based exhaust gaskets that watchjrgo used on the old ford pickup?

 

[Rocket Man]

You did say what’s the best. ARP is the best there is. Their exhaust manifold bolts are chromoly. But of course not just any chromoly:
ARP manufactures fasteners from a wide assortment of materials ranging from popular stainless steel and 8740 chrome moly to exotic alloys that have been developed to handle space travel.

You should also know that there are grades within specific alloys. For example, 8740 is available in four grades:

1. SDF (guaranteed seamless and defect free).
2. CHQ (cold head quality).
3. Aircraft.
4. Commercial.

ARP uses only the first two (SDF and CHQ), even though they cost more than double “Aircraft” quality.






https://www.summitracing.com/parts/arp-134-1102

 

[Rocket Man]

With "10.9" mark on the bolt hex-head, which is high strength material.

Topping: The hex-head should be flange style, which gives easy installation with a deep socket.

Why would you attempt to use a deep socket in an area where the manifold is in the way? There’s barely room for a normal socket, usually need a wobble extension with it.

 

[George B]

A big part of me wants to change my bolts before they break.

Another part of me says don’t F@$k with it.

 

[Rocket Man]

A big part of me wants to change my bolts before they break.

Another part of me says don’t F@$k with it.

If I could go back to before I bought my 02, before the bolts were broken, I would have done that. But it depends on the age I guess, and by that I mean how many hours on the engine. I just installed shorty headers on my 08 Silverado with 65k and they all came out fine which was a relief. I’m not sure if they’re really holding much if they break when you remove them, and there are clamps to fix the situation if you can’t get the bolts or broken studs out.

 

[iamdub]

Yeah I know... But at the same time I acknowledge that tolerances weakened over the 13 years of its life..... So I figure these allow some 'error'.... I figure 50 bucks for a full set of these gaskets and some proper bolts, I feel like it should be good for quite a long time.

I didn't mean to sound like I'm against aftermarket stuff. I said all that to reinforce that if you had stock manifolds and gaskets and the bolts snapped after such a short time, then I firmly believe the problem was human error and not materials design.

Having stronger bolts gives us humans a much wider margin of error. For the relatively minimal investment, I would've gotten ARPs for mine. At that time, I wasn't planning on headers and the original bolts weren't broken and all backed out just fine so I would've been at peace going back with factory/factory equivalent bolts. Since getting the headers and already having the regular bolts, I decided I'd give 'em a shot just to see if special bolts are even mandatory for headers.

 

[George B]

If I could go back to before I bought my 02, before the bolts were broken, I would have done that. But it depends on the age I guess, and by that I mean how many hours on the engine. I just installed shorty headers on my 08 Silverado with 65k and they all came out fine which was a relief. I’m not sure if they’re really holding much if they break when you remove them, and there are clamps to fix the situation if you can’t get the bolts or broken studs out.

67,580 @ 2252.4 hours. Lots of idle time or short trips. Guessing it’s idling.

 

[iamdub]

You did say what’s the best. ARP is the best there is. Their exhaust manifold bolts are chromoly. But of course not just any chromoly:
ARP manufactures fasteners from a wide assortment of materials ranging from popular stainless steel and 8740 chrome moly to exotic alloys that have been developed to handle space travel.

You should also know that there are grades within specific alloys. For example, 8740 is available in four grades:

1. SDF (guaranteed seamless and defect free).
2. CHQ (cold head quality).
3. Aircraft.
4. Commercial.

ARP uses only the first two (SDF and CHQ), even though they cost more than double “Aircraft” quality.






https://www.summitracing.com/parts/arp-134-1102


View attachment 251021

Buuuut... What does he mean by "best"? Strongest? Best for the application? Least likely to gall?

I agree with you but you know I had to troll.

 

[Rocket Man]

67,580 @ 2252.4 hours. Lots of idle time or short trips. Guessing it’s idling.

If it was me, I would replace them with ARP bolts. They should all come out ok at that mileage/ hours, I would soak them with PB Blaster for a couple days first. If one or two break you have options like I said. But of course there’s always a chance you’ll break a couple and it’s also pretty much guaranteed some will break on their own if you do nothing. Damned if you do, damned if you don’t. If they all come out like mine did, it’s one less thing to worry about.

 

[iamdub]

67,580 @ 2252.4 hours. Lots of idle time or short trips. Guessing it’s idling.

Use a punch and hammer to tap inward on each bolt head a few times. You just wanna shock it, not crack the head. Then use a small impact while barely pulling the trigger and easing into it to slowly shock 'em loose when backing out rather than just torquing on them with a socket or wrench. If you don't have such an impact or (likely in this case) cant fit on in there, a box end wrench and a small hammer works great.

Either way, I'd take advantage of the low mileage on them to replace/upgrade while your chances are better.