Broken studs on turbo...what to do??

[billseph]

Hey guys I got myself into a bit of a mess. I bought a used turbo that had originally been on a Z31 and started working on getting the downpipe/wastegate assembly off the turbine housing so I could get it setup for swapping over to my L28ET setup. Bolts were all seized up so I got out the rosebud torch to put some heat to them and successfully got less than half of them out, with the others backing out partway and eventually shearing off.

 

 

So I'm wondering what would be the ideal way to go about solving this dilemma of getting these out or tapped. I'm under the impression that I can drill these out carefully in a drill press in a couple stages and as long as I am well centered can hopfully just tap out the rest of the bolt and essentially clean out the existing threads. I'm also wondering if getting a kit to install Helicoils would be better than banking on being able to tap out the existing threads. I really don't want to have to pay a shop to do this since I have access to a nice large drill press and taps to ream out these holes, a fair amount of confidence in my light fabrication skills, and plenty of time.

any thoughts would be much appreciated. Also while I'm at it...Being just plain dumb at the moment I was trying to see if the bolts on the center section were any less seized up and with (what I thought to be) not much torque and effort I accidntally broke the head off one of the 6 center section bolts.

 

 

Will I end up kicking myself for taking the easy way out and just leaving it this way and have oil or coolant leakage because of this?? I'm worried because of the bad experience I had with the downpipe studs and bolts that it will just end up happening here too and have that much more work drilling out and tapping or Helicoil-ing.

Thanks guys.

[dan5138]

Simple, if you know someone who is half way decenent with a mig welder. Just have to weld a nut onto whats left of the stud/bolt, and they usually come right out. You might want want to drill a small hole at the end of that crack and pin it shut to stop it, don't try to weld it though.

[rayaapp2]

Hate to be the bearer of bad news, but if you were able to get them 1 thread out and then they seized and sheared the bolts you may be in a pickle. There is a slight possibility with the older stuff that the shanks were just fatigued, but likely the studs started to strip in the threads and then seized. The expansion and contraction from heat cycling will distort the threads and when you go to pull them out they will strip on their way out. The ONLY thing that helps prevent this is a very good penetrating oil that can be applied while using that rose bud tip. See Exhaust Heat Valve penetrants for older engines for the most common stuff available.

So my advise is to take it to a machine shop for a quote to remove and repair. IF you can buy another turbine housing for less then you have your answer correct?

 

Good luck with the Heli-Coils. Maybe Thread/Time-Serts. Maybe. I measure 2100* F at that housing in indirect flow at relatively low boost levels.

 

No you will not have an oil or coolant leak at the inner broken bolt head. You may experience long term issues with warpage and leakage of exhaust. I dont think the clearance on the back side of the turbine is small enough to create an interference between the housing and the turbine during a small warp like that with one bolt head missing. Just a thought though. More than likely it warps the other way anyway. Been a while since I overhauled one of those T3 units.

[billseph]

Thanks for the replies guys. Dan 5138, I wish it would be that easy, but I'm thinking those babies are STUCK.

Rayaapp2, your explanation seems like the likely case based in what I observed while getting them out. It seems like there's only about 1/4"-3/8" of threads actually "in" the housing when it's all bolted together...I'll have to check in a bit how deep the entire hole is before bottoming out. What are your thoughts on drilling out the old bolts and just stepping up the smallest size (maybe from standard to metric even) OR just reaming out the threads once I get most of the bolt drilled out?? Something some common sense and patience can accomplish??.

I don't want to drop too much more on this turbo...I'm only into it (t3/t04e) $250 right now. Also I have a machinist at work that would gladly perform the operation for me for a small fee (way less than a machine shop charging big $/hr. locally) but I really think I could tackle it myself.

The biggest concern I have is tapping the cast...but research leads me to believe I just need to do it slowly (1/2 turn, then back out 1/4, and repeat) of course come Monday I'll chat with my shop machinist. THOUGHTS?????

[rayaapp2]

Item number: 230706083836 EBAY

 

Oil cooled only, but Buy it Now for $130

Many more on FleaBay. Price is cheap enough that it doesnt really matter if it only last 30K miles instead of the rated 60+K

 

Im sure you will find oil and water cooled ones if you look hard enough.

 

Why mess around with the old housing with a crack and 4 broken bolts/studs in it.

There are also a lot of used housing out there if a china turbo wont do for you.

Edited November 26, 2011 by rayaapp2

[billseph]

Well I went ahead and attempted to fix this broken stud issue on my own and was quite successful so I wanted to share what I did in case anyone else finds themselves facing this issue. It turned out to really not be that difficult at all, just took a little thought and patience to get it done right.

I started by cutting off all the broken studs and flushing them with the surface of the housing. No pics of this step but you get the idea. I tried to just center punch in the middle of the broken and studs after they were ground down but was not too successful getting a "perfect center" so I thought about it for a while and made up this "guide" with a bunch of holes the size of the drill bit I'd need, I had some 3/4" thick steel laying around at work which worked great to help guide the bit in and keep everything centered. Here's the guide...

I was able to visually center up the guide over the studs I needed to drill out and then clamp the guide down in several places to hold it in place VERY tightly.

This ended up making easy work...though it took a while to reposition each time. I chocked up the whole turbo in a drill press vice and shimmed it here and there within the vice to keep it level (no pics, but I just clamped the compressor inlet into the vise and shimmed around the "body" of the compressor because I couldn't tighten the vice enough to keep it from wobbling around...once I put the shims in place it was rock steady for drilling.)

So after leveling evertything up on the drill press I drilled out the holes I needed. I wasn't sure if I'd be able to chase out the existing threads with the appropriate tap so I went the next size up (from 5/16" to 3/8" fasteners) and drilled out the right size hole to be tapped. Tapping the metal didn't turn out bad at all...in fact I used a cheap Harbor Freight set I've had and not used in years and they worked just fine. I just had to be careful tapping...Once i was started I would go 1/2 rotation then back out 1/4 turn, lube with cutting oil, then repeat til I bottomed out or had enough threads.

Here's the finished product after I took a file to it to flush everything up (the tapping process "pushed up" the metal around the edges of the holes. (I put some bolts and the tap in for effect...those aren't the bolts that'll stay.)

Last thing I did was make sure everything lined up...so i had to enlarge the bolt holes on the Z31 downpipe since the bolts were now larger diameter. Everything lined up great so although I don't have the L28ET wastegate assembly to line up (it's still on the motor and it's been WAY too cold out lately), I know that all I'll need to do is enlarge the holes slighty and bolt it on.

So that's what I was able to come up with...got to keep all my original stuff, and didn't have to spend a dime, just had to spend a bunch of time on it, but it was actually a fun project.

I do have one more question now though...What fastener would be better for reassembling this, stainless or grade 8??? I figure stainless because of the heat it'll see, I just want a quality fastener so in case I ever have to take this apart again I may avoid having the bolts break again.

[ModernS30]

Weld a washer onto the stud, weld a nut to the washer.

[NewZed]

I really like that guide you made. Something similar would work great for drilling out the typical broken intake or exhaust stud in a cylinder, with the head still in the car. Use the other cylinder head studs or holes to clamp it down and drill away without the constant checking to see if you're still centered and perpendicular.

[jacob80]

This reminds me of a couple months ago where I broke off a stud that fastens the turbo to the manifold. Better yet, I thought using an easy out on a drill press would be an awesome idea. That was one of the biggest mistakes I've made in my time working on automotives.

 

I was told I was SOL and that only a machinist could help me dig out the cobalt bit that was broken off in my stud, which was stuck in the exhaust manifold. I was determined, however, and decided to strap the manifold onto my drill press and use a lot of oil and time. This task required a couple DeWalt cobalt drill bits, about 6 hours of drill time, and a lot of patience. I didn't think I was going to get through the cobalt bit but when I did, GREAT SUCCESS! From there on, drilling through the steel was like drilling through butter. The best feeling was when I stuck my easy out through the hole I had drilled through the stud and applying such small torque, it simply came loose.

[rejracer]

I drill a hole throught the bolt then put either penetrating oil or muratic acid in the hole (iron/steel parts only), and let it work on the rust for a few days. I can usually get them out fairly easy once the chemicals have worked.

 

also I use snap on screw extractors. The cheap ones (squarish design) are junk imo. I also have a reverse pitch drill bit.

 

When removing I quickly heat the bolt until it glows, when it's still hot insert the cold ez out and slowly tap the tip of the tool as I'm turning it out. It may require several cycles to get it out. The temp of the bolt in relation to the housing and the tool is important.