80SC RoW rebuild: 8 broken lower head studs! 200K KM

[Ed_914]

Hi Tom,

I didn't have any problems but make sure you clean the sides and the top to bare metal ,so the weld will be penetrating the stud and the nut. Using a non galvinised nut is best(gives less splatter and toxic smoke). The washer is for protecting the spigot. The biggest trick was to get the washer and the nut level. I did hold the washer straight with pliers and made a small spot weld onto the stud and then placed the nut over the stud. I started filling up the gap around the stud and the oversized nut and then filled the nut till the top. By the time the socket fits over the nut, expansion from heat gone enough, I backed the nut with the stud out of the case. It worked well for me on my 8 broken studs so I did also all the other ones this way but higher up the stud. I also heated the spigot up with a torch for 15 min before starting this. You mean concern is to protect the cylinder base.

[boosted79]

When heating the case for stud removal does the heat damage the thru bolt o-rings near the heat? Necessary to replace them individually after doing the studs? Maybe a wet rag around the nut or bolt head to prevent damage to the o-ring?

[Ed_914]

Good point, in my case it was a full tear down.

[safe]

I did one headstud like that, welding a nut on. Actually I have done several stud removals like that, but only one headstud.

The biggest problem is getting the weld to bite on the stud. It helps to make a spot weld on the stud first so there is a good base to weld on to. Othervice the puddle likes to just attach to the nut. Drilling out half the nut with a large drill bit to get a big v-shape groove around the stud is another tip.

You may have to repeat this procedure before having success.

[NEWFIE 69 911E]

Hi. Update via pictures below: Made a wrist-pin puller, removed all cylinders, and pulled piston from the scored cylinder (#5, as per above) with no broken rings






Also able to extract some broken lower studs with my Titan stud extractor with no heat



Next: welding of nuts to studs broken close to case, in order to attempt removal.

[boosted79]

Good news, put the piston back in and run it.

[NEWFIE 69 911E]

Success! Milestone achieved! All remaining broken head studs removed by MIG welding a nut on.

First we cleaned each broken stud to bare metal, then placed a cylinder base gasket to protect the surface, then a washer, then a nut with washers positioned to level the nut.

Note my favorite blue dress shirt positioned to protect the case etc

Welding generated enough heat to help break the bond and success; all studs backed out easily with little effort and threads intact

I big thanks to mhicks for expert welding skill!!

[boosted79]

Great, hopefully that shirt isn't the one your wife or GF gave you for Christmas

[NEWFIE 69 911E]

Hi all,

Been a while since I posted! In August/September I shipped all 6 cylinder heads to Ontario for inspection and machining. Inspection revealed that head surfaces required only a minor (less than 6 thou) resurfacing, but valves needed replacement. So, heads were completely rebuilt, resurfaced and returned home to the stable in late September. Then I started a long business trip, then various other life items consumed my time but now I'm back at it!

I'm about to order the parts required for rebuild; studs, gaskets, chain ramps, etc.

Question: I was planning to replace the timing chains, but can I do so without replacing the chain sprockets?? Please note: I did not split the case

Thanks!

[Flat6pac]

I d leave the chains alone if you're not willing to split the case. Snap ring on the chain will make you worry.
I was always told, if the chains are worn out so is the rest of the bottom.
Install new plastic guides as the old are brittle.
Bruce

[NEWFIE 69 911E]

Hi again all,

As mentioned, the sealing surfaces of all 6 heads were in decent shape; only needed to remove 0.006" to clean them up. This said, should I be concerned about the sealing surfaces of the top of the cylinders? They look fine to the naked eye...

Thanks,

Tom

[NEWFIE 69 911E]

Hello,

Well, after a winter of clearing snow, and acquiring parts, I'm ready to tackle the rebuild! First step is to install new studs, but should clean the threads in the case first - I know I should not use a tap - any good posts on how to make a thread chaser from out studs? A search did not provide instructions; just pictures of finished product (stud cut with dremel). Thanks!

[Flat6pac]

Use one of the whole dilivars and cut across the threads to have a place for the junk to go to when you run the stud in. Blow the holes out, spray carb cleaner, blow dry. Use thread lock.
I install the piston units first then install the studs. It gives you more room to get in the snap rings.
Measure depth of the stud from top of the piston.
Bruce

[NEWFIE 69 911E]

Originally Posted by Flat6pac

Use one of the whole dilivars and cut across the threads to have a place for the junk to go to when you run the stud in. Blow the holes out, spray carb cleaner, blow dry. Use thread lock.
I install the piston units first then install the studs. It gives you more room to get in the snap rings.
Measure depth of the stud from top of the piston.
Bruce

Thanks Bruce, all is nice and clean now!

When installing the new (steel) head studs, is there a torque specified? Cannot seem to find a good thread about that, although I do see lots of info re deck height...

Tom

[NEWFIE 69 911E]

Hi all.

As per above, I have cleaned the bores and am now ready to install the new steel head studs. Most of new studs can be installed all the way (until bottomed) easily by hand; no tools required. Is this normal? Considering this, I am thinking to use red thread-locker instead of blue. Thoughts? Thanks and happy motoring!

[NEWFIE 69 911E]

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