924Board.org

[Eliza]

Good afternoon all,

my Euro-spec 1981 931 is going to be MOT'd tomorrow ( or so I hope ).

IF the mechanic has any time to spare, I would love to replace the sealing ring between the charge tube and the inlet.

We tried a few weeks ago to loosen the upper-to-lower charge tube bolts to no avail, and stopped for fear of breaking one without having a replacement bolt. I now have both bolts, only..

I understand that the longer of the two regularly breaks/shears which I'd rather avoid. Murphy's lurking, I already see the bolt shear inside the thread of the lower charge tube and needing drilling out <eek>.

A few questions:

Does anybody happen to know the torque specs for these two bolts? I can't find them. Depending on torque specs, we might estimate if or not applying any more torque will spell problems.

Do the two pipes absolutely NEED separating, or might we leave them bolted up, and take them out in one after loosening the support bracket?

If that's no option, is there anything, anything at all I can do to make loosening the bolts easier? I tried WD40 but it hardly seems to seep in, still standing on the washers...

Any words of wisdom are MOST welcome!

Thanks in advance and be safe!

Eliza
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1985 924 NA RoW
1981 931 S2 RoW

[924RACR]

Good lord, they shouldn't have much of any torque on them... they're just tiny little things!!

I'd guess that you have bimetallic corrosion from steel bolts into aluminum, which is a drag.

Removing the entire charge tube as a unit is probably a good idea; in particular, if you do need to take extreme measures to remove stuck bits of bolt, you'd be a lot less likely to feed shrapnel into the turbo with the charge tube on a bench!

On the plus side, if you rip the heads off the bolts, the tubes will separate regardless and you'll be left with a lot of bolt material to work with, vice-grips or the like.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Eliza]

Thanks Vaughan!

Corrosion would be my idea - although the charge tubes were separated shortly before I bought the car 18 months ago when valve clearance was checked. I had thought corrosion wouldn't set in so quickly, but there's a lot of heat, and then cooling off in that spot of course.

And would the heads of the bolts shear off first? My internal Murphy horror scenario is that the bolt shears off just inside the thread of the lower tube, with exactly NOTHING to grab at. I saw that happen when the outside mirror on my 924 wouldn't come off, the holding bolt sheared within the door skin and the needed drilling out from the outside. Ugh. NOT pretty.

That's the downside of half-knowledge - I know just enough to worry myself into a right state, but not enough to stay calm and find a workable solution when something goes wrong. Which it WILL

Anyway, thanks again and I'll report back. Just in case some other drama queen faces the same thing

Cheers,

Eliza
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1985 924 NA RoW
1981 931 S2 RoW

[Fasteddie313]

A used replacement lower charge tube shouldn’t cost all that much, worst case..

Lefty loosey..

If you really think their gonna break, put a good amount of lefty torque on them and then at the same time, while torque is applied, whack the head of the bolt with a hammer to shock it..
Turn hard and smack it..

I’ve had these bolts off and back on 100 times.. Never a problem..


Break em if you have to.. Really the lower charge tube should be like a $30 part..
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80 Turbo - Slightly Modified

[924RACR]

Yeah, I'm really surprised to think that they stuck - like Eddie, I've had mine apart countless times.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Eliza]

They came out, and in one piece! Apparently, WD40 did the trick after all.

Phew, that was a relief. And although both o-rings were still pliable, the large one on the inlet side was quite twisted, so with a bit of luck the new ring will put an end to the oil vapour around that area. Feels good to have that sorted.

On a side note, owner's manual advises these o-rings be changed every 20.000 kilometers.

Car is MOT'd as well, with no niggles

Next thing is to get the rear fog(s) working, and to sort the quite strong raw fuel smell in the cabin after sharp, fast cornering. I'll finish my coffee and then down to the garage!

Enjoy your weekend, AND your cars

Eliza
_________________
1985 924 NA RoW
1981 931 S2 RoW

[924RACR]

Oh, that's good news!

Have a good weekend!
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype