05 Exhaust Manifold

[jelag]

I've got the exhaust manifold off my 05... it was whistling and found 2 broken bolts and a warped manifold.....



As we pulled the bolts the manifold had grown so much that the edge of the manifold rounded off the threads of the bolts as they came out... so new bolts will be acquired. .



I've now got the manifold flat, we must have removed . 060-. 080 to make it flat again... but I've noticed that on cyl 4 the bolt holes in the manifold are close to . 420" diameter and the other 10 are about . 525" in diameter...



IT was like a banana touching at 3,4 and loose at 2,5 and really loose at 1,6. .



It's like they want the 2 small holes to be the reference point for the exhaust manifold and the rest to sort of line up and expand and contract... to bare this out the slug or spacer will serve as a clamp to allow the manifold to move as it heats and cools... ...



So the real problem now is that if you line up the two reference holes on #4 and than install the bolts in 3,5 than 6,2, when you get to 1&2 the bolts don't want to thread in... as the manifold is so far out of shape it won't go...



If I loosened all the bolts, and drew them all in... I'm sure you could suck up the manifold and draw it in... . but I'm fearful of that...



What comes to mind is to open the holes on cyl 6 and cyl 1&2 from the . 525" to just about 9/16" (. 565-. 595"), this would allow the slugs (sleeves) to press into the manifold and should hold it...



It seems that it should thread down finger tight, than be torqued... BTW - all the bolts thread in with your fingers without the manifold in place... .



So if I've explained this so you understand... your thoughts...

 

[Andersonville]

I would replace it with an ATS exhaust manifold. I have the 2 piece model. BD and others also make an exhaust manifold. Supposedly, it helps the #6 cylinder and it has an expansion joint built in to it. I would redo the bolt holes to 9/16.

 

[brods]

Do the bolts not line up because the hole bores are no longer perpendicular to the head or because the manifold has changed length?



This was from a car repair site and I assume the car manifolds are thinner and weaker than ours, so it may not be as relevant.

We do not recommend resurfacing a warped exhaust manifold, as the manifold will be prone to cracking.

I’m all for reworking old stuff, but for the effort involved and without any guarantee of a successful long term repair it would seem easier and give more peace of mind to just replace the manifold.

 

[jelag]

We've surfaced exhaust manifolds for years on cars and light truck. . on a gas engine we've always fitted the manifold to the block and let it go... and we just assumed we'd do the same with this...

Think of this as a big banana... it's out of shape...

The manifold has changed length and as we pulled the bolts out of 1 & 6 the threads on the bolts were rolled over and you could see the manifold try and pull as the bolts were loosened... In other words it was under stress as it was bolted to the block and broke 2 of the bolts from this stress...

This truck has to leave for a trip on Wed, there is not time to order in a replacement other than stock (dealer)..... This was not a planned repair...

The bolts are 10 mm which is a little larger than 3/8" so there already is a large gap between the side of the bolt to the side of the hole. . does this make sense...

I'm going to proceed with the repair even if I have to take it apart later and replace the manifold because of the trip... I was looking for input from others... to sort of mull over before I make the decision to do it all over again later or let it go. .

 

[MMeier]

Jim, do what you have to for the trip... then plan on replacing it with a 2 piece. My . 02

 

[p-Bar]

Ya I resurfaced my pontiac cast iron header manifolds and never had problems. the 2 piece units make sense. Problem as you explained these 1 pc grow to much due to the length.

 

[steved]

Fix as needed, pick up a low-mileage manifold from someone that has replaced theirs or by the multi-piece aftermarket...

I've got a spare for just this problem (low mileage takeoff). I knew about the 2nd gens, didn't know the 3rd gens were plagued by it too.

 

[Grizzly]

Sorry to hear you're having this problem Jim. The truck seemed to be just fine when you were here last month. Is that a common problem with 05's?

 

[jelag]

OK, plans have changed... I've ordered an ATS Manifold... it will be here tomorrow...

I'll post photos of the problem with the old one for you guys that tow hard...

 

[jelag]

Photo's

OK, we took it apart because of exhaust leaks and 2 broken studs... we can only assume its because this truck has pulled hard... up to 22K lb trailer early on in its life... it is STOCK, nothing to add HP...

Here are the 2 closeups of the manifold after the 2 bolts in cylinder 4 are installed... as I mentioned above cyl #4 bolts are there to reference the manifold to the block... as you can see on Cyl #2 the port is at least 3/16" off the machined tab on the block and in the next photo you can see how really far off the bolts are... remember that in Cyl #1 and 6 we have opened these holes to 9/16" and see how far off they still are... .

At least the mating surface is now flat... but the manifold is really scrap... you can see that in fact it is warped in 2 directions, not only are the holes drawn towards the center of the block but they are warped down as well... Cyl 6 looks just like Cyl 1... We think we could have pulled this out but were afraid of the miss match to the ports in the block and changing the exhaust flow...

This is really cra* as far as I'm concerned...

So the new ATS will be here tomorrow after Next Day Air. . than I'm off hunting...

 

[Bob4x4]

This is an old issue. The 3rd gens just take longer to have the same issues the 12v's had. The guys that don't use the 3rd gens hard or do the hi miles may never experience your situation

 

[p-Bar]

This is an old issue. The 3rd gens just take longer to have the same issues the 12v's had. The guys that don't use the 3rd gens hard or do the hi miles may never experience your situation

Chinese castings:-laf

 

[MLee]

So is there a way to keep from breaking the bolts upon removal? would it help to remove the outside bolts first #1&6 and then the rest? From looking at the picture that is alot of shrinkage on #1.

 

[jelag]

The bolts on #6 were broken, that was the reason for taking it apart in the first place... Also #3 and 4 were leaking... .

As the bolts came out of #'s 5,1,2 the threads were rolled over from the edge of the manifold. . so it meant new bolts...

We were able to make the manifold flat again but the ports had shifted so far to the center we scrapped the manifold and installed an ATS... We really like the 1/2" thick block between the ports to keep this new manifold from moving. . We also noticed that the torque spec on the stock manifold was 32 ft lbs and the new manifold is 55 ft lbs...

We think we made the right choice but are waiting now to see that the 2 piece seals... when the exhaust brake comes on, all it does is hiss...

The next day air was a killer... but this truck is now ready and will leave town today. .

 

[Grizzly]

What can be done to prevent this from happening. Would it help to install a small fan and direct air over the manifold to help in cooling. The exhaust manifold must have gotten red hot too many time to cause that much warp.



If the truck didn't have the exhaust brake, could this have happened?

 

[rscurtis]

My truck must lead a charmed existence. It still has the clear coat on the front 3 runners.

 

[DGamelin]

Nice pictures!

I guess I have this to look forward to?



_________________________

93 250 2wd xc 354 auto 266k

04. 5 3500 4wd cc dully 373 6speed 90k

 

[MMeier]

My truck must lead a charmed existence. It still has the clear coat on the front 3 runners.

Let me have it for a day... . I'll burn that stuff right off !!!!:-laf Sounds like a buddy of mine, traded in his 46k mile '04 and still had paint on his manifold !!!!

 

[MMeier]

Nice pictures!

I guess I have this to look forward to?



_________________________

93 250 2wd xc 354 auto 266k

04. 5 3500 4wd cc dully 373 6speed 90k

You see what 'can' happen, fix it beforehand when you have time , avoid the issues .

 

[Prairie Dog]

If the truck didn't have the exhaust brake, could this have happened?

An EB wont causes high exhaust temps. They only come on at 0% throttle and my EGT gage has always shown very low EGT temps with the EB on no matter how steep the hill is I'm going down ~ usually around 3-500 Degrees.