Breezy_Pete

You've spent a lot of time and words trying to justify your use of the term 'stainless steel' for fasteners that aren't. I just pointed out that stainless steel is not what you should be searching for. So just get your new bolts (of the correct part number and therefore right material and strength) fitted. Then you can stop worrying.

I give up. Use stainless steel everywhere you like.

Understanding of the failure mode, in order to avoid it? Most people working on cars know that stainless steel bolts if used anywhere tend to only be used for cosmetic, rather than structural functions. Well you'd be calling them by something other than their correct description. I'm honestly not trying to beat you up, just to avoid others thinking that buying stainless steel bolts for this use is a good plan.

It doesn't matter what I think they are made of, cos I'm not suggesting anyone replaces them with stainless steel. If you insist that I speculate, I'd say "Alloy steel"; as described in the link I posted. That covers a very large array of material compositions, probably, many of which may resemble stainless steel in appearance and properties, but aren't referred to as stainless steel. Point is, stainless steel bolts are generally weaker than high tensile ones.

Thing is, you've recommended that people try to source stainless steel replacements of some or other grade for these, yet you don't know that they are stainless to start with. Not a limb I'd like to be wandering out on.

Photo would be good. I don't understand why you're so keen on them being stainless.

In my experience, stainless fasteners usually have grades like A2-70, A4-80 see here for example: http://www.volksbolts.com/faq/basics.htm High tensile stuff, on the other hand, is marked with grades like 8.8 as seen in photos upthread.

How do you know? The first symptom may be the fatigue failure? What makes you think they are stainless steel?

Thanks @Lemto; unfortunately, there's not much visible of the end surfaces. Some similarities with images on page 3 here though: https://www.asminternational.org/documents/10192/20564188/amp17208p18.pdf Overtigthening would tend to cause necking of the threads near the failure point, as I understand it. Perhaps @Eric_DK can request the broken parts from the place mending his car. In this country it is your legal right to be given such parts, if you request them back. Not sure if same will be true in Denmark.

A bit of Loctite might be all that's required. Self-loosening due to vibration may be resulting in fatigue failure, once the parts become free to move relative to each other. An end-on view of both bits of @Lemto's broken bolt might shed more light on this, if still available.

The hard plastic loop of the PCV pipework is just a push-fit into the rubber couplers at each end, so will move in/out without huge effort. If it was loose enough to leak, I think you'd hear hissing when wiggling it about. Add a cable-tie or two to snug it down if it seems too loose? Brake servo hose is looking unusually intact!

https://www.ebay.co.uk/itm/Brake-Caliper-Guide-Bolt-Thread-Repair-Tool-Kit-Set-Ford-GM-VAG-VW-Audi/282434033532?hash=item41c261577c:g:K7kAAOSwpkFY8cyQ Good find that, please let us know how it goes. 🙂

Can you post a photo or two of the non-return valve in the brake servo line, one from topside, one from underneath. You're looking for this kind of thing:

It may be even simpler with a standard helicoil, since you haven't oversized the holes like the OP in that thread.

Best bet is to repair the threads. See posts by @sepulchrave and @rum4mo about halfway down the page here: https://www.briskoda.net/forums/topic/480872-stripped-thread-on-brakes-help/

I'd be surprised if that isn't leaking, in the circumstances.

You've checked the brake servo hose, right? At the point where the rigid plastic hose sections join onto the one-way valve, either side of it. Just near the ECU.

That's the PCV valve, no EGR on a BMD.

No, the thing to do is just flex that shiny bit of pipe upwards, if it's leaking at the same point, you'll hear a pronounced hiss of air entry, and the engine will stutter/bog down. I think the trouble is, due to the design of the joint, oily stuff will sit at the bottom of that rubbery coupler piece all the time, gradually softening and rotting it out. Then with a bit of engine vibration, it just cracks through and starts to leak.

Check this:

Bet that's the thermoswitch. If you mean right as viewed from standing in front of car.

Other way round, pollen filter is after fan, so if blocked, the fan is trying to pump into a dead end.

You don't need to do anything with those rivets, they are something to do with the electric window mechanism. What you do need to do is to take the two large plastic/rubber grommets out, lower the window glass until you can see the bolts to release the glass. Do that, tape the window up fully once it's detached from the carrier, then you can remove the carrier.

Good stuff Colin. 👍

Check earth connections, I think there's one near the offside engine mount that causes trouble on these when it corrodes/breaks. If that seems OK, look for a broken wire going to the starter motor solenoid (thinnest wire going to starter motor).