Exhaust Manifold to Turbocharger - broken stud

[kenn]

It appears I have a broken bolt stud on one of the four bolts that hold the turbo to the exhaust manifold. After searching through the TMs and finding all sorts of variations, I think I have narrowed it down. It appears I'm going to have to remove the exhaust manifold and then remove the broken stud and replace it. It's pretty darn rusty in there but it appears quite a bit of stud is left as it is barely below the level of the plate on the turbo. I'm wondering if I can drop the turbo and leave all else installed and soak that stud with pb blaster for a "while" then grab it with some vice grips. If it breaks off, I'll have to have a center section of the manifold and start over, I guess. That appears to be quite the uninstall/re-install effort. I'll need a 5 in the diagram below and possible two 3's and one 4 if it's possible to replace that center section on an old manifold that is rusty.

I would not have known about this issue had I not had the engine idling at 1500ish rpms for 30+ minutes three times back-to-back which caused a buildup of unburned (partially burned?) oily residue to ooze out of there. Until that point it had not oozed back there so I'm assuming the 3/4 bolts have been doing their job for a very long time.

This is a 1973 white 465-1C with a 1D turbo on it so I'm guessing some motorpool knucklehead private replaced it, broke the stud, and didn't tell sarge.

Any advice/suggestions on this fix before I jump in? I'm going to drive and enjoy the truck a bit before I tackle this as I'm tired of wrenching without driving and it seems like as long as I don't idle like crazy, there is no wet stacking and no oozing.

 

[patracy]

Should be able to drop the turbo and should be enough stud left to get a stud tool on it. PB blaster or anything is a good idea. A torch to heat it up would also be a good idea.

 

[V8srfun]

Pb and a torch is your friend but is it leaking exhaust. If it is not leaking that is one of those jobs I would let go until it does simply because of the snowball factor

 

[ToddJK]

If I'm not mistaken, these should just be bolts. If these are rusted, I wouldn't even bother with PB blaster. Hit it with a some good heat and a couple taps with a hammer and a punch, it will pop right out. Like Patracy mentioned, you can just drop your turbo. I would use PB blaster on the other bolts and let those soak, just so the nut comes off easier. If you get that bolt out before removing the others, then you don't have to remove the turbo, just put a new bolt on and tighten it up.

 

[patracy]

I think the inner two are studs and the outside two are bolts.

 

[ToddJK]

I think the inner two are studs and the outside two are bolts.

It's been nearly a decade since I tore down a multi-fuel, so you're probably right.

 

[patracy]

Last time I had one off was to replace the C turbo with a D. I'm sure it was that long ago, so I could be wrong. But the pic looks like that's what it is.

 

[fleetmech]

yep two studs, two bolts.

 

[davidb56]

drop the turbo only. weld a nut onto the broken stud , then heat it up and wrench it off (6 point, not 12) ........or not.

 

[kenn]

Thanks, gentlemen! This will be a project to take on soon. I'm still doing all kinds of preventative and safety maintenance. Current order... wheel cylinder, more brake inspection, remote reservoir, axle seals, transfer and trans oil changes...

 

[kenn]

I'm not having luck finding that exact stud or the equivalent. I found the specs in a couple of different places and the part number here:

10935241 Plain Stud

10935241 Plain Stud NSN 5307-00-067-4895

nationalstocknumber.info

It is 420 stainless which is high-carbon. The specs say 416 or 420 which is much stronger than the normally carried stainless hardware. Rockwell hardness is listed in the spec as 33-37 and it will take regular grade 8 hardware to get there but it won't be in 416 or 420 stainless. I assume stainless was called for since the corrosion from the heat cycling would be intense and a hope that if it needed to be removed, it ultimately could be. There are lots of places that will make a 416 or 420, but I can't find anything in stock.

For anyone else looking for this fastener:

It is 3/8", 16 tpi. 1.75" total length with 1/2" of stud thread and 3/4" of nut thread. The closest I have been able to find after a couple of hours searching is:

The closest I have found is a dorman double end manifold bolt model 29146. It doesn't say it is grade 8 so I assume standard steel which is probably not wise. I'll keep looking but if anyone knows where to get the original or a similar in grade 8, please let me know.

 

[gimpyrobb]

I may have a manifold at the barn, if so I can pull one and ship it. Hope your not in too big of a hurry, not sure when I'll be up there.

 

[kenn]

I may have a manifold at the barn, if so I can pull one and ship it. Hope your not in too big of a hurry, not sure when I'll be up there.

Thank you! I'm certainly interested but I'm in no rush at all. The current leak is quite minimal and it's about a dozen or more items down the list as I'm still working through safety and reliability items first.

 

[gimpyrobb]

I checked high and low yesterday. I have intakes all over, but no Exhaust manis. wtf, sorry.

 

[ldmack3]

Going back together should copper or nickel anti-sieze be used?

 

[gimpyrobb]

Do you mean copper or aluminum? I would imagine whichever is rated at the highest temp, but definitely use some! (as a dear mechanic friend once said, any is better than none!)

 

[V8srfun]

I am no expert on this subject but oxygen sensors come with copper type in a little packet for installation. I don’t know what one is better where or why but I would assume copper would be better for exhaust.

 

[ldmack3]

There are several types from what I've read, copper, aluminum and nickel. Nickel is good (depending on brand) up to 2,600F.
Local has aluminum good up to 1,600F.

 

[87cr250r]

It doesn't matter. Anti-seize is highly misunderstood. It's meant to prevent galling during tightening or loosening. It's a poor corrosion inhibitor. Pipe thread sealants would be better suited for most applications anti-seize gets used in. A sealant will keep the moisture out that causes corrosion related seizures. Personally, I use Dow Corning Molykote 111 for most situations.

Whatever you do, never use lock washers, EVER!

 

[ToddJK]

It doesn't matter. Anti-seize is highly misunderstood. It's meant to prevent galling during tightening or loosening. It's a poor corrosion inhibitor. Pipe thread sealants would be better suited for most applications anti-seize gets used in. A sealant will keep the moisture out that causes corrosion related seizures. Personally, I use Dow Corning Molykote 111 for most situations.

Whatever you do, never use lock washers, EVER!

My old shop teacher used to talk about that. Anti-seize was better for parts that were never exposed to the elements or maintenance on a regular basis. Sealants were the better alternative for parts that see the elements but he always said that grease was a poor man's sealant.