Once again!! Exhaust breaking

         

for some reason, the backbox is breaking on my Mk1 again! same place as the last 2.. across the weld at the front of the backbox    

now… as you can imagine I'm getting fed up with this happening..

would this be caused if the centre section was fitted at a slight angle? I fitted all new exhaust mounts and had the centre section replaced the first time it broke…. can't think of anything else that would cause it, there's no way 3 exhaust's would break in exactly the same place (all different types) without a common fault somewhere.. I can't be THAT unlucky

any ideas would be great chaps.. because if the next one breaks I'll probably get so stressed I'll give the car a kicking  

time for a very annoyed Mk1 owner to do some internet shopping and to put new injectors on hold once again  

Hey Phil…

You replaced all the mounting points or just the rubbers?

I would say your problem is  excessive exhaust movement either due to missing mounting points around the back/centre section OR excessive play in the engine mounts causing the engine to rock and crack the exhaust at the weakest point…..

Have a good look underneath at the mounting points and visibly check the engine for movement under acceleration……hope that helps
 :dontknow:

Hi DJ, I just replaced the rubber mounts.. thought all the mount points are welded on??  :dontknow:

I've checked the engine mounts by giving it a good pull and push and didn't move at all with 13 stone of weight   so thought they're ok


been looking on t'internet for a new exhaust, but all the big names are 3" tailpipe which I think is a little too big really

anyone used an Ashley Comp. system? are they any good?

choice's I'm looking at are Mongoose (loved the sound of it on my N*va years ago, yes.. I hate N*va's now  :wink: ), Magnex, supersprint

but I'm not sure which to go for

Phil,

Think I have a new standard back box if you need one.

Need to make sure you don't have a missing mount somewhere.  Are they cracking at the top or bottom as that'll give you some clue to where the stress is originating from.

will it fit on the supersprint centre section?

this one started breaking on the top of the weld, so I'd assume the exhaust is being pushed up too much which would suggest the engine is moving wouldn't it?  :dontknow:

just seems strange they've all broken off at the same point.. I must be overlooking something  :roll:

I've had a good look at it and it's still fairly secure, although a bit bendy and blowing lots.. hopefully won't fall off to and from work this week (only about a 1 mile each way).. If it does I'll be on the phone to Rich  :wink:

ordered up a nice new Piper stainless system which I'll get fitted on Saturday (2-3 days delivery)

couldn't find anywhere though a sports system that wasn't 3" tailpipe or bigger  8O should look ok, will get some additional hangers on there somewhere to stop it happening again… hopefully

I've checked the engine mounts by giving it a good pull and push and didn't move at all with 13 stone of weight  so thought they're ok

Phil look again at the above mounts you may have a front mount broken ? Putting stress on the exhaust . There should be a little bit of movement on the mounts same as the exhaust or else it will break under normal use as its to rigid . You should be able to grab the end of the exhaust tail pipe and give it a good waggle with out any stiffness or knocking on the body if not you need to look again from the engine back . Not worth replacing it untill you get it right , stainless is softer and will crack more easily than steel if not correctly fitted    

Cheers……..

Ah I see

well, the original exhaust used to knock on the back panel towards the drivers side, the supersprint never knocked but broke unexpectedly, the current one started knocking towards the passenger side (after all new exhaust mounts were fitted)

I'll have a good look though, when I rebuilt the car I didn't know about the front engine mount and drove a few hundred miles without it… after I found out I put it on  ops: so knowing my luck it's the rear engine mount that'll be worn

if that's the case which dirrection would the engine be pushing? up or down? the weld is breaking from the top so the center section must be pushing up?  :dontknow:

how much play would be normal on the rear engine mount and is it fairly easy to replace?

Does sound to me like something is slightly out of line, my exhaust used to hit at the back because a) I used pattern parts, and not VAG origenal, which are never quite the same, however well made they are, and b) I didn't support the centre section when I bolted the two together, so it slightly sagged in the middle at the join causing the tail pipe of the rear box to angle up, only ever so slightly, but just enough to make it hit the rear panel.

I have had an exhaust go because of excess engine movement before, but they tend to go at the front. Even so the best way to check your engine mounts (in my opinion) rather than to pull at the engine yourself, is to start her up, put the hand brake on securely, then put her in first and see how much the engine moves as you bring the clutch upto the biting point. Obviously don't hold it there long as you'll burn your clutch away!

The engine should move a bit, but if it moves a lot then you've got worn engine mounts. The other thing that shows up on some cars (not sure about mk1s) is the amount the gear stick moves as you accelerate then decelerate suddenly. If it moves a lot then your engine is moving around, and that equals worn or loose engine mounts.

That said, normally the universal joint present on the exhaust system stops this movement getting as far as the rear of the exhaust.

Mike.

well, my Piper exhaust has arrived  :cheer:

bit large for my liking but the smallest performance exhaust I could find was 3"

needs a polish where it's been welded

just wondering, how can I protect the stainless welds from rusting? bit of high temp exhaust paint over the weld?  :dontknow:

The welds should also be stainless phil if the rest of the exhaust is so they souldnt rust

just trying to cover every possible cause for it breaking again!  :wink:

going to replace the rear engine mount as well on friday just to be sure

Sounds like a good idea from what you have said, also worth checking that the front mount is still sound, these are the two that should stop the engine moving forwards or backwards (within reason unless the others are totaly shot), if for some reason the welds are not stainless then halfords do a brush on silver vht paint that i have found good in the past

For anyone interested



that's what it looks like, going to fit it myself tomorrow (if a jobs worth doing right, do it yourself and all that)

Nice an shiny Phil can you post a link up for your supplier please mate ?


Cheers…………..

Yeah it's Motorsport world

had to phone them up after ordering as I didn't get a confirmation email, but the exhaust arrived in 3 days (not bad considering piper manufacture to order!  8O )

all in all I'm very happy with it

couple of bad mobile camera pics




none of the fitting as it started raining  :cry: