Garth S

I'm attempting, without success, to remove the four 6mm allen head bolts from the thermostat housing - where it bridges to each head: The reason is to get at the oil fill housing to replace it's gasket.
The only tool I can get on three of the four is a 6mm key - and I've forced that just shy of the point of deforming the bolt heads: I'm sure that an impact wrench would work, but the sockets ( in pic) will not access the heads.
This is a very bad area to twist a bolt off, as they are angled to the center and wouldn't allow removal of the housing if they snapped!
They continue to marinate in Kroil penetrant while I regroup, and ask for any sage advice: What tricks have you used to loosen these bolts??

GlenL

Mine come out really easily now but I broke two of four the first time at it.

With steel bolts into aluminum and bathed in the coolent, I'd expect them to be stuck pretty good. The removal can be aided by the regular tricks: penetrating oil, tap with a hammer, twist back and forth, repeat and be gentle.

ILucky is breaking at the cylinder head head. Unlucky is breaking at the bolt head. If you're unlucky then the bolt will need to be drilled out of the housing and then the head. Then comes drilling/tapping/thread insert...

I guess my strongest advice is to consider what you're doing and weigh the risk and benefit. That gasket might be leaky but there's not much pressure so the leak is only a nusance.

You might try removing the oil filler and hope that the gasket comes out easy and in one piece then slide in the new one.

2V4V

Garth,

In addition to the lube/tap advice from Glen, I would recommend the 1/4" drive stubby hexes from Snap-On (or whomever, though that long one in the pic looks to be S-O).

You should be able to get at them and put a little more 'oomph' to it with about a stubby to a ~1.5" to a flex joint to another extension of your choosing to the 1/4" ratchet/breaker.

HTH,

Greg

Vilhuer

Try heat (tiny blowtorch), cold (cold spray from electronics store), witchcraft and voodoo but do not break them in







Pics from relatives '78. Took several days to dig remainings out. Especially because we did broke nose of counter thread tap inside bolt trying to unscrew remainder out. Now new bolt is in on original thread. All it takes to save heads original thread is to eat bolt with diamond bit from inside to so narrow wall thickness that remaining collapses inwards. Don't want to do that ever again.

Thom1

What they said, and PBlaster penetrating oil.

Garth S

Inspiration!
Glen, you echo my thoughts as I left the garage in saying " strongest advice is to consider what you're doing and weigh the risk and benefit. That gasket might be leaky but there's not much pressure so the leak is only a nusance" ... Exactly!! There's an excellent chance of screwing up big-time - all for some weeping oil! Actually, looking at Erkka's pictures ( sorry Erkka, but that is the nightmare I'm concerned about!), I should ask if it is possible to replace the oil filler gasket without removal of the thermo housing?? If it would lift ~1/2", ..... it may be possible to feed one in: Has anyone tried that?
Greg, yes - I have the SO hexes, but only in 3/8" drive - and that is too large, but you guys reminded me that I have a trial can of Wurth 'Rost Off Ice' - an aerosol that claims to break free seized bolts by chilling to -40 deg.
And then, there's the mini butane tourch - and the sharp blow on the end of the bolt ..
But before doing anything else, will the oil filler lift ? Hummmmm .. If not, perhaps doing nothing is the best answer.

Vilhuer

It should lift a little. Can't remember offhand if later cars are different than '78 in that regard. In '78 it looked doable. I would try Wurth also. Longer you leave those bolts stuck, harder they are to remove when you really need to.

Gregg K

Run the vehicle until it's up to temp. Use an impact wrench. That last part is critical. From my experience, impact is what it takes.

You might have to get creative with impact extensions and swivels. The more stuff you add to the stack of items on the wrench, the less effective the impacting becomes. But since an impact tends to do no damage, it's the first place I start, on stubborn parts. Believe me, I've removed the impossible, with an impact. It's a dual action- hammering and slight turning. Both are needed.

Let me just add this- I've done tests where I've used a wrench, and simply torqued a frozen bolt into two broken pieces. Then I've fixed an impact onto that same bolt, and it came off. It was totally rusted, too.

GlenL

The oil filler will come up a little bit once the two bolts are removed. (One is inside the filler.)

An alternative may be to remove the plenum and take the filler out towards the rear. I'm not 100% certain this will work as I haven't done it. Would allow plenty of WYAIT opportunities.

Garth S

Gregg, good advice
"Run the vehicle until it's up to temp. Use an impact wrench"
- but a slight problem: the whole front end ( cam drive & accessories) is stripped off for these repairs - so it won't run for a while. Similarly, both my impact gear and even regular 3/8 drive won't fit: Perhaps if I cut a 6mm allan key and fit the stub in a 1/4" drive socket ......
You are correct: impact tools prevent most breakage of fasteners. I even had two 5mm oil pan bolts nearly shear - and they removed easily via impact.
Hummm .... homemade 1/4" drive hex key - as 2v4v mentioned

Glen - I shutdown the 'weekend warrior in garage' stint for the night by resnugging the two filler bolts. The gasket is the orriginal cork a la pan gasket. I'll take a look at the intake in the AM, provided I can forget about Erkka's 'good news' photos!

borland

A bit of advice.....

Never use a allen wrench that fits loosely inside the socket head. If in doubt, buy a new allen wrench. Sears sells them individually.

On a stuck bolt, always work the bolt out by repeated loosing and tightening in very short increments. If the bolt doesn't break free from the start, use this technique. Otherwise, the threads will gall or gum up resulting in so much friction that the bolt will shear off with excess torque applied.

Gregg K

Here's a trick I've used-

Make your own hex tool. Start with a slightly bigger allen, and file it to fit tightly. And while you are doing that, file it so it will fit into a socket for impacting. In fact, start with an allen the right size for a socket, and only file the business end that goes into the socket bolt.

Files- the poor man's milling machine. It just takes work and time.

Temp isn't that important.

fst951

If it strips, weld a nut onto the bolt. The tremendous heat needed to do this often expands the bolt and breaks the corrosion so the bolt can be remove. Use a 1/4 allen and file it down works as well if you distort the six point hole as well. Bad design by Porsche. There are a few and this is one of them.

Good luck

UKKid35

It is worth replacing the oil filler gasket, if you can. It was the source of all the oil contamination around the cam belt area on my car, and others have suggested that it contributed to my belt failure. Not to mention that it made the whole area a PITA to work on. I don't have any helpful ideas about your siezed bolts, but I would suggest that you change the seals in the thermostat housing once you remove it.

Garth S

Thanks for all the tips! I did find that a long ball-head hex will access 3 of the four, and an impact tool can be used - so I focused on the one in the back right of the pic, which is by far, the most difficult. NO GO! So decision time has arrived ...
- the vee is bone dry
- modest weepage on the front of the oil filler gasket
- the TB and all cam drive gear were bone dry on disassembly
- the filler gasket (cork) snugged up nicely, as the 2 bolts were quite loose
The housing was retightened and the gasket will be left in place until some more urgent need arises: there is a good chance the weeping will be cured, and to go further, there is a better chance of snapping that back stud.
If it doesn't work out, I can always easily go back - and snap that stud later!
Good tips - will file in the 'gems' category.