Broken rear exhaust manifold bolt

[Hipster]

Correct it is a 94 305 tbi. So for the shorty headers they should just bolt on and its done? No o2 sensors or anything right? Im pretty sure the 02 sensors are both in the Y pipe. If thats the case i might just do that.
Ive heard that the spark plugs are harder to remove with long tube headers. Would that be the same case with the shorty headers?
Also yes he drilled out the stud in the flange along with its threads. Would i be able to weld a new stud in there. Im pretty sure its cast iron but just wondering if anybody has done it.
Also if i run long tube headers my check engine light would come on correct? Unless i build a whole custom exhaust for the long tubes to include 02 sensor ports.

Sometimes its better to not open a bigger can of worms than you have to, You went from not removing one manifold for fear of breaking more bolts to both sides and a header swap. What's are the chances the other side comes off clean?

 

[Drunkcanuk]

Also if i run long tube headers my check engine light would come on correct? Unless i build a whole custom exhaust for the long tubes to include 02 sensor ports.

I have long tubes, never had the CEL come on after I installed them. I had the exhaust shop weld a bung into the collector for the 02 sensor when they did the dual exhaust.

 

[Jjbiskup]

How
Many
O2
Sensors
Does
Your
Truck
Have
?

Where
Are
They?

I think theres 2? The grounds wet and i dont feel like crawling under there and i only found 1 forum online stating theres 2 for that year. In the Y pipe

 

[Jjbiskup]

so anyway once i get the manifold off and the bolts and broken pieces removed i should go with an ac delco gasket and arp bolts? Also would i need to get the manifold planed?

 

[Schurkey]

I think theres 2? The grounds wet and i dont feel like crawling under there and i only found 1 forum online stating theres 2 for that year. In the Y pipe

Download the service manual set for your vehicle from the links in the Sticky section of this forum. FIND OUT.
What I'm seeing in the '94 Driveability/Emissions/Electrical book, page 1-10 and 1-11...

1994_NATP-9442_DRIVEABILITY_EMISSIONS_ELECTRICAL_DIAGNOSIS_MANUAL

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...is that a manual trans small-block gets ONE (plain ol' ordinary) O2 sensor in the left exhaust manifold, while an auto-trans small-block gets ONE (heated) O2 sensor in the Y-pipe.

so anyway once i get the manifold off and the bolts and broken pieces removed i should go with an ac delco gasket and arp bolts?

Once the manifold is flat and smooth, and the cylinder head gasket surface and threaded holes are SPOTLESSLY CLEAN, "I" would put it together with NO gasket--metal-to-metal with the cylinder head. Chevy did this for decades. ARP bolts are really nice, but I'd call them an unnecessary luxury on the exhaust manifold. An expense you don't need. Twelve proper-length hardware-store bolts should be fine, in the same grade as what's on there now. Kinda expecting Grade 5, but maybe GM used Grade 8.

But that's me. Others might disagree.

Also would i need to get the manifold planed?

Holy crap, didn't I completely and thoroughly cover this in a previous post?

Machine shop to have it planed flat and smooth. This can be done on a milling machine (expensive) or on a gigantic, glorified "belt sander" (less expensive, not as nice of a finish.)

That's IF the manifold isn't already cracked, and IF you use the manifold-spreaders before you loosen the bolts.
www.amazon.com/Lisle-13000-Manifold-Spreader-Chevrolet/dp/B0009OR94W/ref=sr_1_1?crid=1FR0UQ7CI4PIGsprefix=exhaust+manifold+spreader%2Caps%2C138&sr=8-1

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You'd need two of these. They stay in place the entire time, from before the manifold-to-cylinder head bolts are loosened, until the bolts are torqued.

Without the spreaders, the manifold warps so that the ends twist toward the middle, and then you can't get the bolts through the manifold and lined-up with the holes in the head. This is so common that there was a time when GM cast a reinforcement bar into the manifold to prevent warpage in that direction...but they didn't do that on these vehicles.

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[Erik the Awful]

Also would i need to get the manifold planed?

99.413% of the time the manifolds are warped. It's so bad that there's even a tool to help reinstall them. I wouldn't spend the time or effort to plane them. Either clean and reinstall with Remflex gaskets or replace them outright.

https://www.autozone.com/test-scan-and-specialty-tools/exhaust-installation-and-removal-tool/p/oemtools-exhaust-manifold-spreader/191674_0_0

PRODUCT DESCRIPTION​

This OEM exhaust tool is used for re-installing the manifold on small block Chevrolet vehicles.

 

[LVJJJ]

When I bought my 94 k1500 about 6 years ago it had 2 broken bolt heads on both manifolds, was told that's normal with a 350. Dinked around with drilling etc. finally took it to my mechanic to remove the bolts, turns out the manifolds were also cracked. Bought a couple of new manifolds from Viet Nam and bolted them on. As I tow a travel trailer up a lot of mountain passes, I cracked two more sets as I would go up the passes at about 3700 rpm. Was told I shouldn't do that or the manifolds would crack. Had enough of that crap, bought JBA shorty headers and put them on, had my dual pipes replaced put one O2 sensor in one of the pipes, now much more power and can't crack the headers.

 

[Jjbiskup]

When I bought my 94 k1500 about 6 years ago it had 2 broken bolt heads on both manifolds, was told that's normal with a 350. Dinked around with drilling etc. finally took it to my mechanic to remove the bolts, turns out the manifolds were also cracked. Bought a couple of new manifolds from Viet Nam and bolted them on. As I tow a travel trailer up a lot of mountain passes, I cracked two more sets as I would go up the passes at about 3700 rpm. Was told I shouldn't do that or the manifolds would crack. Had enough of that crap, bought JBA shorty headers and put them on, had my dual pipes replaced put one O2 sensor in one of the pipes, now much more power and can't crack the headers.

Did you do a cat delete or space out the o2 sensor?

 

[Ardyh]

I thought I would share my recent success. I just did this to fix the rear bolt that broke on the passenger side rear after 260k miles. 2000 C3500 with a 350. As others suggested I sprayed every remaining bolt with penetrating oil to at least loosen the rust at the head to manifold and then used lots of feel and long breaker bar to slowly work the bolt heads in both directions as they would tighten up after they stated to move. Once they were all backed off a half turn or more I sprayed more PB Blaster between the manifold and head. This took some time but they all came out and was not as frustrating as mig welding the nut to the flush broken bolt in the iron head. The problem I had was winding up with the nut filled with weld that did not stick to the bolt. Aligning the mig head to the correct angle seemed to be part of the problem. It took six or seven tries to get something to stick. After breaking off yet an other nut I found a stub of weld still attached to the bolt in the head. Vice grips got it to move and with more spray oil it came out without damage to the head. Multi layer soft aluminum gasket and new bolts and it does not leak. Good luck with yours.