6.0 Exhaust Manifold Thread Repair

[2kvrt]

2500hd with the 6.0 lq4. Had the common exhaust manifold bolt problem (who hasn't) ? Had a shop fix it next to nothing due to the under engineered bolts that had broken off flush with the head. Got the truck back I noticed the shop used the same M8x1.25 bolts with the 10 mm head that were originally on there. Gm came out with a revised bolt in 04, M8x 1.25 with the 13mm head. I put the new and improved bolts on myself. Everything went well until i got to the very last bolt. The furthest bolt forward on the passenger side. It was stripped out and the guy had loctited a stud with a nut in there as a cob job.

 

If i cant get away with cleaning up the threads with a chaser or a bottom tap, can i get away with drilling a hole and putting the proper helicoil in there? Am i too close to the water jacket to drill a hole that big?

 

Thanks in advance

[jwhuber]

I'd have to see a pic of the hole to judge whether or not your too close. In reality your not increasing the hole size that much, maybe .040"-050 at the most and re-tap to accept the heli-coil. If the hole is drilled straight you should almost still see the old threads.

[04JJHD]

you try to get the remaining stud out of there by building up a weld on the stud then weld a nut on the end that works well from what I hear

[2kvrt]

The Stud came out no problem, the reason the mechanic loctited it was because he gummed up the treads pretty bad and it was his way of making it work. I took the stud out and i got a M8 x 1.25 Tap and very carefully chased the threads. That seemed to take care of the problem.

[04JJHD]

I got a question for ya, you said the new bolts had a 13mm head. The reason I ask is I have the 13mm bolts on my truck and have 2 of them broke

[2kvrt]

I got a question for ya, you said the new bolts had a 13mm head. The reason I ask is I have the 13mm bolts on my truck and have 2 of them broke

hmmm what year truck 04? I know GM came out with revised bolts in 04 with the 13mm hex head. Maybe they got loose and flexed? I know the very last bolt on the drivers side closest to the firewall was notorious for breaking. atleast your truck didnt have 4 broken like mine. So far no problems with my new bolts.

[markw8]

I got a question for ya, you said the new bolts had a 13mm head. The reason I ask is I have the 13mm bolts on my truck and have 2 of them broke

 

Yep, the new ones will break too.

Just maybe not as many.

 

Mark

[04JJHD]

So is there any unbreakable bolts maybe grade 8 ones? It just seems weird that there are so many

[Doug_Scott]

I think you need to find out why they are breaking in the first place. Can't believe there is that much stress on the exhaust manifold to cause it to break attachment hardware. If is due to overtorque, then you should only need to use the proper torque for that particular fastener. A stud with nut uses less torque than a bolt in the same location if I recall correctly.

[markw8]

The driver side rear has way too much heat. Thats the one that broke on mine after repair.

 

Mark

[monstermarlin]

How common is this? Should I be checking my truck regularly? Thanks

[markw8]

How common is this? Should I be checking my truck regularly? Thanks

 

Not uncommon. When mine broke the end one again, I drove the truck a year then traded for my current truck. It never did leak. I wasn't going to fixit till it did.

 

Mark

[searay220]

I've got 2 broken ones. Both are up front one on each side. If I left those alone I tried to replace the good ones now would that be causing more problems?