Self-Removing Manifold Nuts

[stuzbot]

When I got my Syncro a year or so ago, one of the [many!] basic maintenance jobs I had to tackle was the fact that the exhaust manifold was blowing and making a right racket. On closer inspection, it turned out that the gaskets were knackered and no less than 4 of the 8 manifold nuts were missing.

At the time, I blamed it on PO Syndrome as I've found plenty of other missing nuts, bolts, fasteners etc in my tinkerings on the van.

Anyway I replaced the gaskets and bought a set of [supposedly better] long, brass manifold nuts and fitted those.

Fast forward to a month or so ago and I could hear the telltale sounds that the exhaust was starting to blow again [wind the window down and you hear a rattle strangely like that of an air-cooled Beetle bouncing back at you off the buildings, as you pass].

Crawled underneath again, suspecting that some other part of the exhaust was blowing this time [as it's fairly old and rusty] but found, to my surprise, that it was the manifold again and [again!] four of the nuts were missing.

So it seems [on that score anyway] I owe an apology to the PO. It looks like my Syncro has developed self-removing manifold nuts!

I've done them again a couple of weeks back and, this time, double-nutted them to see if that would persuade the buggers to stay put. But I'm sure I can hear that rattle starting to develop again. Very odd. Anyone else been plagued by manifold nuts which keep going AWOL? And, if so, how did you solve it?
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1992 VW LT35 2,4D [SOLD]
1993 VW LT35 2,4D [SOLD]
1992 VW T3 1,6TD Syncro [SOLD]
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[?Waldo?]

Do you have the turbo brace installed? If not then there is no hope. Do you have the proper 'special' 1/8" thick washers/spacers installed under the exhaust nuts? If not, then you certainly should. With both of those items correct along with correct torque on the correct manifold nuts, the manifold will not typically loosen.

[?Waldo?]

I looked at your older similar thread and you said this at the end:

[danfromsyr]

also on VW Turbo manifolds they use a special hardended THICK washer.
this allows the manifold to 'slide' under the nut when it expands from heat (that red glow) and cools instead of unwinding your nuts.

VW used them on all turbo engines.. the I5s the TDs the 1.8Ts (I've never had a TDI to verify).

so make sure you have those hardend washers..

and FWIW I use stage8 racing nuts (with a SS locking tab) to keep my nuts from unspinning
the non-turbo stage8 come with an aluminum tang that won't survive the heat cycles.

Edit: I tried the brass nuts too. and they will unspin quickly as the brass looses it's grip when it all gets near red hot.
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[?Waldo?]

Yeah, I mentioned the special thick washers in this thread and in stuzbot's last thread on the same issue. The special washers should definitely be used but without an appropriate brace used with the JX manifold, all hope is lost regardless of what fastener hardware you use. If you run without a brace and positively prevent the fasteners from loosening (e.g. using the 'stage8 racing nuts with a SS locking tab'), the studs will break instead. The leverage of the mass of the turbo vibrating with the engine is simply too much force levering on the exhaust studs alone with them in two rows 2.5" apart.

IIRC the stock brace mounts between the downpipe flange and the block. If the exhaust is changed then the original brace might not be possible, in which case a custom brace is needed to triangulate to the block.

[stuzbot]

[danfromsyr]

this might get you started, but you might be able to find them a little cheaper elsewhere.
N 900 955 01
£3.12 (Inc VAT)
https://www.brickwerks.co.uk/exhaust-manifold-washer-t3-t4-lt.html

[?Waldo?]

L is the turbo brace. If you cannot use the stock brace you need to add a custom one.

[?Waldo?]

This pic of yours from the other thread shows the brace is missing:

It looks like you are using the stock downpipe, though, which should accommodate fastening the brace.

Here's a quote of my post in your other thread:

[stuzbot]

Strange? I posted a reply before but it seems to have vanished. Maybe I previewed but forgot to send.

Yes. I've not got the brace but I do have the bracketty fixing bit where it attaches to the turbo, so should be able to fit one.
_________________
*****************************
Click to view image
*****************************
1992 VW LT35 2,4D [SOLD]
1993 VW LT35 2,4D [SOLD]
1992 VW T3 1,6TD Syncro [SOLD]
*****************************

[ndorian]

I just ordered the thick manifold washers from eEuroparts. $1.24 each. Now looking into a turbo brace for my set up. Love this site.

[stuzbot]

From my searchings, it seems the brace isn't available –at least from any of the 'usual suspects' I get parts from. So I'll likely knock one up myself.

To anyone who has the brace fitted; is there anything fancy about it or is it just, as it looks from the diagrams, a rigid support between turbo and engine block, to hold the turbo housing from being able to move when the turbo spins up? [presumably there's a fair bit of centrifugal force generated then].

@ndorian –that sounds a fairer price. Although still steep for a single washer.

One thing that puzzles me about the thicker manifold washers is this idea that they can expand and contract with the heat to take pressure off the nuts and studs.

Does this mean that you should fit the nuts slightly loose, to give the washers room to expand or –even more tricky– heat up the washers before tightening the nuts, so that they're at their maximum thickness and thus have room to contract? Either way it seems a bit odd to me. How can the washers expand, if the nuts are tightened down fully? And how can the nuts stay on, if they're left slightly loose, to give the washers expansion room?
_________________
*****************************
Click to view image
*****************************
1992 VW LT35 2,4D [SOLD]
1993 VW LT35 2,4D [SOLD]
1992 VW T3 1,6TD Syncro [SOLD]
*****************************

[ndorian]

Now you've got me wondering...

[Ahwahnee]

Some good advice above, I'll just add that on one of my other cars with a reputation for self-loosening manifold nuts I found these to be very effective:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=351427601718

The brand name version is Nord-Locks, these are generic but well-made.

Note - the eBay link is to the ones I bought, if ordering you will need to determine what size you would need.

[danfromsyr]

nope, you are thinking of heat expansion in only an outward force/motion.
the manifold is expanding side to side more. and that slight side to side motion unscrews the nut like a ratchet.. things never vibrate/expand tight..

the hardened thick washers allow the manifold to slide w/o loosening the nut.
also be sure to only use the specific torque stated in the book for turbo engines.. it's less than you think.. over torqued turbo fasteners will break.
I know they WILL deform softer metals like the brass nuts you 1st mentioned.. I know that from my own learning experiences.. deformed threads will not hold any proper torque value.

[?Waldo?]

Add an appropriate brace, use the correct washers and nuts, torque to spec, and enjoy a manifold that generally stays put.

[stuzbot]

[?Waldo?]

I'm not entirely sure what the mechanism involved is with the thick washers for the turbo application. Regardless of the physics involved, in my experience, if the correct VW washers are fitted to the specified torque and the turbo is braced to the block, the manifold hardware doesn't tend to break/loosen. If either of those first two conditions are not met, the hardware loosens and/or the studs break. I don't find the specified hardware to be particularly expensive, considering it works. I find that the routinely self-loosening manifold with the ruined manifold gaskets is a lot more 'expensive' and the spec'd hardware is a bargain to avoid the failure. Certainly feel free to experiment with whatever hardware you like. Report back your findings. If you get tired of the hardware falling off or breaking you can always just fit the stock pieces and get on to the more mundane task of driving the van.

[stuzbot]

[danfromsyr]

trick to the right washers are they are harder than the manifold to allow the manifold to slip/slide underneath.

they are thick to not deform from the heat and pinch the manifold.

soo some hard thick washers.. think Machine washers maybe.
or
drill out the center of a hardened bolt
then cut into segments with a hacksaw.. cut straight/square though.

should only take an ~hour.. plus a bolt..

money in the bank.
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