Replace exhaust manifold bolts?

[seattle gmc]

Hi All,

I recently purchased a 2007 silverado 1500hd classic last december, with 61,000 on the odometer its my first full sized truck, besides the 70 wich dosn't count since its my hobby truck, as my pops calls it and not a daily driver. I was looking up some info on the 6.0 thats in the truck and see that broken exhuast bolts are quite common on these truck engines. So i weent out poped the hood and saw that all the heads of the bolts are still there, so thats good.

Should i replace all of these bolts? Im a bit concerned that i will end breaking some of these in the process if they are as bad as whats reported on the web. What would you guys do im my situation. I do pull a small camping trailer from time to time, which is one of the reasons i bought this truck. On that note will say i thought i would have more power and ease pulling the camper since i have 6.0. Im not sure since im new to full size trucks and towing stuff, but it dose seem like power is lacking.MPG is 10.5 average, lots of city driving, i never reset the calculator so i have no idea what i get on the highway, or pulling the trailer?

Here are some pics, engine still looks clean with only about 63,000 on the odometer. Oh yeah, is the passenger side manifold supposed to have that split in the flange?

[47 Fasttoys]

If it was mine (I have a 2003) I wouldn't replace any of them at this point. I go with the old saying "if it ain't broke, don't fix it". That split is normal in the manifold. As for power that 6.0 should pull just fine, it may be time for a little fuel injector cleaner and some new filters. At 60K miles that engine is just barely broken in, these things are good foe 200K plus with very minor maintenance. If you do decide to replace the bolts, have the engine at operating temperature before you loosen them. A common mistake is trying to break them loose on a cold engine.
Just my 2 cents,
Rob

[69gmcc10]

I wouldn't worry about it right now, but it is something that you may want to get around to on a lazy afternoon for a few dollars.

Sorry to hear about your mpg. The 3.73 gears in most 1500hd trucks make them a little slow off the line but when the get rolling they move and get a little better economy than the 4.11 rears. My 1500hd was lazy until I got my computer flashed by black bear performance, the efficiency went up as well. Take a look at my build thread for more info on what can be done to optimize your truck and what results I got.

[seattle gmc]

Hey thanks for the replys. I do have 4.11's in the rear, and the truck has had some seafoam ran through a couple of tanks of gas. i have been wanting to get a black bear tune for the truck, but money is one of the issues putting that on hold, plus i don't have a pc so i think that i will have to go with the standard tune offered.

I was expecting to the truck to have more power and pull our little trailer with a little bit less effort. One thing that dose bother me, is that even in the tow haul mode, the truck is slow or lazy to down shift out of OD, unless i really put the foot into it.

With these exhaust manifold bolts, do they become weak and break on their own. Or are they likley to break from removal or re-titening?

[69gmcc10]

if you keep the air box and the stock exhaust the standard tune would be great for you. Also that hesitation in the down shift you mentioned will go a way.

[CubFanMan1]

I have an 03 2500 HD with the 6.0 and had the two rear bolts on the driver's side shear off at 97K miles. What a pain to remove the rest of what was left from the head. I decide to replace all of the bolts just to be sure it didn't happen again.

[Truck Guy99]

Why do you have to remove them? Is it leaking?

[seattle gmc]

Originally Posted by Truck Guy99

Why do you have to remove them? Is it leaking?

Technically i don't have to remove them, and not they are not leaking. I was doing a little web searching last weekend, and it seems like they have a tendancy to fail and break on there own. Leaving you with the end of the bolt stuck in the cylinder head. So i think that i will be proactive on this one and change them out. I am worried that when i do go to replace them, is when they will break, which will make me wonder if i should have just left them alone.

Do you have any additional info on this TRUCKGUY99

[Truck Guy99]

Originally Posted by seattle gmc

Technically i don't have to remove them, and not they are not leaking. I was doing a little web searching last weekend, and it seems like they have a tendancy to fail and break on there own. Leaving you with the end of the bolt stuck in the cylinder head. So i think that i will be proactive on this one and change them out. I am worried that when i do go to replace them, is when they will break, which will make me wonder if i should have just left them alone.

Do you have any additional info on this TRUCKGUY99

I have heard of bolts on these falling out on there own but breaking on there own is not common and is very unlikely. If yours is good and not leaking, I'd leave it alone. My brother has a 05 silverado and it still has original manifold bolts at 230k miles.

That 6.0 will have no trouble pulling a camper, but be prepared to pump a lot of gas. Overall they're great engines and will last a long time if you keep it maintained.

If you do have to remove them, here's my experience. I have an 88 Ford with a 460 and I had to remove the manifold bolts and studs because the old manifold was leaking do to a bad gasket. I found put it has the original gasket and that means the bolts had been in there for 26 years. Twice a day for a week I'd spray pb blaster on every bolt and stud. Right before you start to take them out, give them a few firm taps on the end of the bolts with a hammer. This helps to break loose rust scales that have clustered together around the threads. Before you start on the bolts, let the engine run for about 20 minutes. This will cause the metal around the bolts to expand which helps in more ways than you can imagine. Also, use a hex socket. If you get one with more than 6 points, there is a very good chance it will round the bolt off because it only grabs the very tips of the hex he'd corners and getting out a stripped bolt is tough to say the least. I did use an impact wrench but it was adjustable. I set it to its lowest setting which put it at less than 80 ft lbs. I used an extension and a deep socket and slowly backed it out. I've learned to turn it back and forth if your doing it manually. So if you turn it to the left half a turn, turn it back to the right a little and repeat until it's out. This will keep you from snapping the bolt and could save the threads. This is what an impact wrench does but at a different rpm. I did this exact method with mine and didn't break a single stud or bolt.

[GASoline71]

Happened to me in my '06 Silverado 2500HD with the 6.0L... here is the thread I posted about fixing it:

http://www.67-72chevytrucks.com/vboa...d.php?t=587659

My 6.0L pulls a 30 foot 5th wheel trailer, and it isn't any more thirsty than any diesel I've owned over the last 15 years. Great engines with a lot of power.

Gary

[seattle gmc]

Originally Posted by GASoline71

Happened to me in my '06 Silverado 2500HD with the 6.0L... here is the thread I posted about fixing it:

http://www.67-72chevytrucks.com/vboa...d.php?t=587659

My 6.0L pulls a 30 foot 5th wheel trailer, and it isn't any more thirsty than any diesel I've owned over the last 15 years. Great engines with a lot of power.

Gary

Thanks for the reply GAS, and i have already read your thread on this issue, TWICE. Im going to change the bolts out, i have allready ordered another set. I just hope nothing breaks when i go to remove them. I don't know how to weld or have a welder. Fingers croossed that those bolts come out with out breaking.

Got any tips for removing these, espcially if they are brittle?

As far as the engine power is concerened i guess i just need to hammer down on the gas pedal more.

[Truck Guy99]

Originally Posted by seattle gmc

Got any tips for removing these?

Did you read post #9 in this thread?

[95 S_Trucker]

Originally Posted by Truck Guy99

Did you read post #9 in this thread?

Aluminum heads are a different animal than iron heads.



I highly doubt you will have issues getting the bolts out. The bolts snap off on their own when the manifold expands. The problem is not with the threads in the bolts or the heads. I would use a quality penetrant, And a small breaker bar. Avoid constant pressure until you are confident the entire bolt will come off. And use common sense, If the bolt feels like it is going to break, It probably will.


Worst case scenario, They are fairly easy to drill out. I have drilled out several of broken of manifold bolts on these 6.0s

[seattle gmc]

I did read that post (#9). Thats whats good about these forums you get all kinds of tips from people that have accomplished the same job, but in a different manner. Then you can chose something to try that might better suit you situation. I apreciate all the replys and, everyones advise and tips. thanks.

I will be getting replacement bolts soon, they have already been ordered.

[GASoline71]

A tad bit of heat from a butane torch on those bolts will help to keep from snapping them. They are "glued" in from the factory with loc-tite. Don't need to heat it up cherry red... but just enough to help loosen the "glue". The heat from the weld I did really helped out in that respect. Of course, remove the plug wires and anything else that can be burnt from the torch. And be careful!!!

I actually put a small dab of anti-seize on the threads of the new grade 8 bolts when I rieinstalled them. No problem to report as of yet, and my truck does a lot of pulling between a 5th wheel and an 18 foot salt water boat.

Oh, I also never changed out the stock bolts on the other sdie. They are just fine. Truck has 125,000 miles on it.

Gary

[seattle gmc]

I finished replacing all of these bolts today. Split each side of the engine between a few days to i wouldn't get so burned out. Bolts came out supper easy and nothing broke.

[68C15]

Originally Posted by Truck Guy99

Why do you have to remove them? Is it leaking?

in hard use the manifolds grow and stretch the bolts. Then the heads snap off and you have all kinds of fun ahead of you. I've done a few of these and it is NOT cheap. I bought a $400 jig kit and it makes it a bit easier. The last one I did the customer left with a $600 repair ticket

I'd spend the money and replace them now. Warm the truck up good, give each one a good rap on the head with a pointed air hammer bit to rattle any rust loose, spray them with penetrant, and let it sit until cool. Then remove them one at a time and torque to specs (13 ft/lbs IIRC)