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(Very) slow moving project, rebuilding a DJ with fresh cylinders, pistons, rods, GoWesty prepared AMC heads, a W110 cam and T1 solid lifter conversion. The old engine is more than probably on its last knees now, oil pressure is getting low-ish with 5W-40 oil and it has run 300.000km+ in a Syncro. Sort of waiting for it to grenade since I am so slow rebuilding the spare engine. Daily driver, of course...

The case halves will fit into my ultrasonic cleaner if I can get all the stud bolts out, hence the need to remove them. The case-to-head studs were "easy" to get out, only took a bit of heat and a few attempts each to get them loose. But these ones, the main bearing clamp studs are proving to resist persuation. I have tried heating, then it struck me that that may not be the way to go about it due to the fine pitch threads. Does anyone have any tricks to share?

To ensure we are talking about the same bolts, here is a picture of the first of the stubborn ones.

I don't think in this case heat is a good way to remove bolts in this case. They used to have coils that went around a stud to heat them in a controlled manner but you probably have a dissimilar metal issue included here.

There are now sprays that are designed to loosen up things in this type of situation. Look at some of the WD new products; there are others out there too. They have had to come up with this stuff with all the new designs and materials now being used together.

Lee

I was sort of suspecting that differential thermal expansion was causing more problems than it was solving, I will make another attempt while everything is cold tomorrow. The idea of heating was to try to break the bond between steel and aluminium, all 28 years of it.

Will look into the WD range to see if they have something of interest.

As a rule:
Hit it the day before Kano Kroil or a 50/50 mix of acetone and ATF.
Little bit will do, to much makes a mess when you...

Give it a rinse with clean 90% alcohol to remove any free oil. Blast dry.
...or run it though the dishwasher.
THEN
Heat the case in an oven to ~250F-ish.

Then hit it again Hit it with Kano Kroil or a 50/50 mix of acetone and ATF.
(Per Consumer Reports, and my experience trying it, the dirt cheap mix is as good or better than anything)

A torch can produce uneven heating, even though aluminum sucks it up like a sponge.
Freeze spray the studs may help.

To be honest I have never pulled the case main studs on a T1 or WBX, (didn't know they came out)
...but this works on exhaust studs etc on other aluminum bits.

Aluminum expands ~10X what steel does when heated, so the holes get bigger.

I don't know for sure they come out, but they must have been installed at some point... The only logical way of attaching them blind like that is threading them in. But AFAIK they may have been installed with heat resistant Loctite?

Will try the Acetone + ATF tomorrow, have both on the shelf.

Being kind of silly here but heating AL (expanding) and freezing steel (contracting) can work in cases (not necessarly engine cases that is) but not easy to do. When dissimilar metals have been together for a long time funny things do happen. Am I seeing rust on that stud?

It will be interesting to see what does cause their grip on life to let go.

State of the problem right now: the three lower bolts came out quite easily an hour after I doused them with acetone/atf mix. The top three are still stuck, so will let them sit for a few days to see if that changes anything.

The case end of the main bearing studs is identical to the head stud end, i.e. coarse threaded and with a cone tip.

And yes, there's some minor rust on the top three, but not bad.

I really wish I had some tool to hook up to the impact wrench, that usually frees things up in seconds.

Seek, and thou shalt find!

Sealey AK718 Impact Stud Removal Tool looks to be just the ticket, ordering one right now. It looks like it will be able to pass over the larger threaded section of the studs and clamp onto the shank without any thread damage.

In use: https://www.youtube.com/watch?v=sO10HC0HmK8

I like impact wrenches, they make life so darn much easier. Even rusted rear axle castle nuts are easy with the right impact wrench.

Just be careful using the impact wrench which is why I did not suggest it. In the past have seen fasteners pulled that still have parts of the adjoining threads attached.

Because of dissimilar materials and what can go on with the reaction of the two materials together there is the distinct potential of tearing out threads in the block. You have used chemicals already that may alleviate the potential problem I see but still... be careful.

Will be careful, but I'm not that worried since the lower three came out easily once they let go with a distinct "ping". But I don't really understand why the lower three came out easily and the top three won't budge. I'll just have to wait and see.

Heat the case before hitting the top 3, even if its just with a halogen lamp.
(don't let it get >~250F, unlikely with even a 1000W lamp due to the huge area)

Received the Sealey tool yesterday, had to put it to work immediately.



To no avail...

Back in the house, had a run and a brewsky, then it dawned on me that the drive is 1/2" inside and 24mm hex outside. And I have a deep 24mm socket in a drawer.



That was much better! Two out of three came out in seconds, the last one (between #3 and the flywheel) is still stuck. But I keep hitting it with the impact wrench and various rust dissolvers. A large amount of gunk has come out of the hole so far, hopefully the bolt will let go soon.

Piledriver wrote:Heat the case before hitting the top 3,

x2.