Exhaust renewal

[silverbullet]

Always work hot i.e. a well warmed up engine.
If you break more than two I would drop the engine and transaxle as one and get it out in the open.
Yes its more work but then you can get proper access, weld a nut to the broken stump if necessary, put a propane lamp on the relevant boss etc.

[kevtherev]

Ok. Bums twitching. Keep hearing about studs breaking.....

Has anyone ever changed an exhaust with no dramas??
When do they normally break,on removal or can it happen when fitting new ones.

Are the studs a standard length? I am guessing I will need them to be 40mm in length, allowing 26mm to be inserted into the manifold, thus leaving 14mm to screw the nut onto.

I discovered that the new studs will screw in far more than they need.
The flange of the exhaust+gasket can vary.
Other than that inconvenience I had no issues.
Never have, always used heat, patience and a good fitting tool.

[CJH]

Ok. Bums twitching. Keep hearing about studs breaking.....

Has anyone ever changed an exhaust with no dramas??
When do they normally break,on removal or can it happen when fitting new ones.

Are the studs a standard length? I am guessing I will need them to be 40mm in length, allowing 26mm to be inserted into the manifold, thus leaving 14mm to screw the nut onto.

Yes, I did mine a couple of weeks ago without drama. I gently tried shifting each nut/bolt, and once the 8th one moved ok I cracked on and did the whole job. I think it might depend how long the exhaust has been on. My van had an exchange engine about 10 years ago so maybe the studs were replaced then. Although mine all came out easy enough, one of the nuts on cylinder 3 felt like it wasn't going to tighten fully on reassembly, so I suspect the thread in the head has stripped, or is about to. I stopped tightening, and the other bolt plus the rigid geometry of the exhaust has made that joint gas tight, but I think I may tackle putting a helicoil in this weekend. Access is pretty good back there for tapping out the hole.

As suggested in Ghost's post above, I used socket head high tensile studs (yes, 40mm is fine) and brass nuts and washers. Studs are preferred I think (over bolts) because they produce less wear on the threads in the head, but since they're generally not disturbed many times in the life of the vehicle I'd guess this doesn't really matter too much. Whether you use all studs or a mix of studs and bolts depends on the specific exhaust I think - if there's an easy opportunity to separate the exhaust between cylinders 1 and 2 (and 3 and 4) then studs are fine, but if not then the distance between the opposing flanges is fixed, so you'll need bolts on at least one end. Mine has an easy joint between each front and back pipe, so I used studs all round, but the advantage of those socket head studs is you can still treat them as bolts if that 'easy' joint becomes difficult in later life. Also consider access on the inside of the bends - some may be a bit tight for bolts.

[silverbullet]

I favour studs on top, bolts in lower tappings.
Again, use M8 grub screws instead of plain studs: much easier to fit and it gives you the means to loosely hang the exhaust in place and get all the joints assembled with paste before tightening down.
Brass nuts, 70 grade stainless bolts.

[shrig1969]

Tried this to see if I could loosen the nuts/bolts a little easier.
Filled the rubber nipples with plus gas (circled in red) and popped them on all 8 of the fixings.
Can't do any harm, hopefully make a start tomorrow.

[shrig1969]

Ok, as promised I completed my first major renewal work on my bus today...

In the end I decided to leave the existing studs in, and just renew the washers and nuts with stainless. The bolts were replaced with stainless also.
Here is the end result..

Many, many thanks to everyone who contributed with ideas and advice.

Also, can anyone tell me how I access behind the plastic cover( where both pipes enter), so that I can renew the 50mm warm air ducting?

[ghost123uk]

Just for future "searchers", an update on =

I replaced all mine with Hi-Tensile studs, stainless steel washers and brass nuts earlier this year............

suggest you check the tightness of the nuts a couple of times in the first few days after doing it. I didn't and though I thought I had them at the right tightness, two of my brass nuts fell off onto the road somewhere

The update is = they keep coming loose. In fact 3 of the fancy studs (with the Allen key sockets in them, to make insertion / removal easier) have, over time, fallen off into the road and are lost. I have had to replace them with ordinary bolts (for now). Odd as I was confident I had tightened every thing up enough (and I'm not new to any of this). It started blowing a bit again 2 weeks ago and because of the weather I put it off. Two days ago I bit the bullet and on a horrid day got under it with the spanners, only to find that most of them were either a bit loose, or very loose, and one was missing I removed all the brass nuts (and the 3 ordinary (used) bolts ) and fitted split washers beneath them. Perhaps I should have done that i the first place

[shrig1969]

I did follow your advice and re-checked mine about 2 weeks later. To be honest everything seemed ok. There was maybe a little give around 3 or 4 of them, but nothing like the pain you went through. I only tightened them as much as I dare with a standard socket.
( Gurning face = Tighten no more... )

I will continue to monitor mine but would be interested to know the reasons behind your story.

[bigherb]

Also, can anyone tell me how I access behind the plastic cover( where both pipes enter), so that I can renew the 50mm warm air ducting?

Remove the rear light cluster

[ghost123uk]

I only tightened them as much as I dare with a standard socket. ( Gurning face = Tighten no more... )

I know that feeling I get it when tightening spark plugs and sump plugs too

I will continue to monitor mine but would be interested to know the reasons behind your story.

Umm, so would I. I have seen in the past special brass manifold nuts that are kinda crimped at one end, presumably to behave like a locking device. The ones I used were not like that, just plain brass nuts.

Perhaps one of our metal / material gurus might have some idea why mine came loose.

[mshaw1980]

Buy a stud extractor off amazon. About ten quid. Used it to get all the studs out of my 1.9 engine (before realising the engine had had it). Worked a treat, took each one out, cleanly in a few seconds. Mine looks a bit like a drill chuck.

[tobydog]

I only tightened them as much as I dare with a standard socket. ( Gurning face = Tighten no more... )

I know that feeling I get it when tightening spark plugs and sump plugs too

I will continue to monitor mine but would be interested to know the reasons behind your story.

Umm, so would I. I have seen in the past special brass manifold nuts that are kinda crimped at one end, presumably to behave like a locking device. The ones I used were not like that, just plain brass nuts.

Perhaps one of our metal / material gurus might have some idea why mine came loose.

Brass is a bearing type material? Lower co-efficient of friction with steel than steel with steel.