Chevy/GM Broken Exhaust Manifold Bolts

hcoles · 06-06-2017, 07:40 AM

Yesterday while replacing spark plugs and spark plug wires in my 2006 Tahoe 5.3L I saw an exhaust manifold bolt that looked loose. Well it was completely loose as in broken. Apparently this is a very common problem and there are a number of ways to get the manifold off to get at the piece remaining in the head, this includes the pieces left in the head you create while removing the bolts that were intact. The two methods to get the broken bolts out that can't be grabbed include stacking welds until you can grab something and drilling then using an easy-out. That's all fine and good.

My question is what should be done or can be done to avoid this happening again?
For example:

1 - replace with new bolts from the dealer (I believe there was a bolt improvement in 2011?)
2 - install better bolts or studs and nuts e.g. ARP or Stage 8
3 - drill the holes in the exhaust manifold a bit larger combined with items 1, 2 above. This is supposed to reduce the side loads on the bolts with the heating and cooling between the AL head and steel manifold. I read Caterpillar came up with this.
4 - replace the manifold with an aftermarket header
5 - installing Dorman brackets that bolt to the side of the head - I think these can't be used in all 4 locations - the most common broken bolts are on the ends of the head.

Thanks for any suggestions or comments.

hcoles · 06-07-2017, 07:44 AM

Well - almost made it to 100 reads and no replies.
I decided after reading many threads/etc. to try the Kral Auto Parts solution which is a bracket.
Different brackets cover different corners.

gizmofixer · 06-07-2017, 07:54 AM

We do a fair number of these jobs (GM dealer parts dept.)
Replace bolts, studs and gaskets.
All these items have been updated/improved.
We have never had a return with the new parts.

Arizona_928 · 08:35 AM

Easiest method I have done was to remove the manifold, and weld a nut to the top of the stud.
Drilling it out is the last resort. I don't recommend it unless all else fails. And then I would leave it alone unless you're having a severe exhaust leak.

I replaced my cast headers with tube. Should have kept my cast as I am playing with forced induction.

mikehinton · mikehinton's Garage

I agree that drilling out is the last resort. If the EZ-out bit breaks in there, it's game over.

hcoles · 06-07-2017, 10:19 AM

Quote:

Originally Posted by gizmofixer

We do a fair number of these jobs (GM dealer parts dept.)
Replace bolts, studs and gaskets.
All these items have been updated/improved.
We have never had a return with the new parts.

Thanks Paul, good to know.
That's approximately what the mechanic was saying.
I'll try the bracket because I can DIY and see how it goes.

Bob Kontak · Bob Kontak's Garage

Did this on a 2002 F250 with a smallish V8 that had pinged three or four bolts off. Noisy.

Dorman hard parts.

Extracted old without issues.

Repair in 2008. Still service same truck in 2017. All good so far.

hcoles · 06-12-2017, 12:22 PM

Update - The bracket from Kral Auto Parts arrived and I installed it. The only issue so far is the hole for a connector to a sensor in the head is a bit too small or needs to be offset. I ground the hole bigger and got things together. Hopefully the hot bracket (connected to the exhaust manifold with the pinch bolt) will not melt the connector and/or sensor in the head. We'll see how it goes. I think with a few simple modifications to the design this issue could be eliminated.

nota · 06-12-2017, 02:13 PM

studs not bolts

then to remove use a nut cracker

Porchdog · 06-12-2017, 02:31 PM

I just finished extracting the studs on a salvage 2001 Ford 5.4 to swap into my son's truck. One was broken before I started, I snapped two.
Is there any advantage to changing the manifolds? The old ones look OK...

hcoles · 06-13-2017, 09:29 AM

Quote:

Originally Posted by AZ_porschekid

Easiest method I have done was to remove the manifold, and weld a nut to the top of the stud.
Drilling it out is the last resort. I don't recommend it unless all else fails. And then I would leave it alone unless you're having a severe exhaust leak.

I replaced my cast headers with tube. Should have kept my cast as I am playing with forced induction.

The welding-nut-on method seems to be the best and safest method listed in the places I've looked. Unfortunately I don't have a welder and haven't welded in some time (40+ years ago). If I try to get the manifold off and break too many bolts I'm afraid I won't be able to put things together enough to drive it to the mechanic who has done a lot of these. Hence, as noted previously I'm trying the Kral bracket on the one (drivers - front) bolt I found broken. Thanks for your note.