This would happen just after Christmas!!!

[Porschemaniac]

The MOT for my dear old Jeeaaag is looming (due on 13th January). And so, with this in mind, I set about a bit of a pre-MOT today.

Structure - all good. Shocks and general suspension - yep, not too bad; no split gaiters, not too much play in all of the rubber bushes and barely preceptible play in the wheel bearings. Brakes all good - flexible lines not perished, discs look OK and plenty of meat on the pads. May need two new front tyres - but was expecting that.

In short, it was all looking good.........until...........

Over the last couple of months, I have been hearing a little chuf, chuf noise on startup - which sounded very much like an exhaust problem. Decided to give the system a once over.

Happily, the central section (with two very expensive Cats) all looks OK. I know the back boxes are OK, so I decided to have a look at the front downpipe - all looked good.

Then I saw it - laying on my back, looking up into the engine bay, I noticed what looked like a small crack in the underside of the rear exhaust manifold. These cars are actually know for this, so it was not a copmplete shock. However, just to get a better handle on the condition of the manifold(s) I removed the heat sheild from the engine bay. Here is the sight that greeted me:









In short, both front and rear manifolds have cracked. The parts (new) are about £300, so with tyres, I'm in for £500 (ouch!)

There are a couple of second hand ones on the bay for about half the new price, but I guess it's probably worth buying new (can't imagine used ones would be particularly long-lived; so it could be a big flas-economy).

With the heat sheild in place, these cracks are not visible and, truth be told, the chuf, chuf isn't that loud - so I'm hoping that the MOT tester may not spot it (giving me a little longer to sort it).

These are cast manifolds, and I did think about getting hold of some Stainless wire and having a go at MIGing them - but that in itself could be a costly 'experiment'.

So, all things considered, I guess I'll just bite the bullet, buy the parts and do the job.

If you want to run one of these wonderful old cars, then I guess you have to be ready to accept the cost. I'm estimating £500 for this year's MOT and whilst that hurts, this car is a keeper, so over the remaining life, it'll pay for itself.

Could have done without it, though

 

[Justme]

Would mig brazing work?

What do you have to loose by trying either the brazing of stainless migging?

 

[weldingscotty803]

drill each end if the crack with a 3mm bit. carfully V the crack with a thin cutting disc, then mig it, or get some cast rods and arc it. you will need to pre heat it though before welding

 

[shenion]

If it was me, I'd look for aftermarket headers. Always better to up efficiency

I have MIG'ed cast with SS wire and it did work. I would use nickel arc rods on a manifold.

MIG brazing might work. I have used regular brazing on bike headers and it did not last as it oxidized in the high heat.

 

[john224]

jag

Hi what i would do is replace the manifold back on the engine carefully wire brush the area round the crack to clean then use exhaust sealer paste and smother it round the manifold then wrap with some exhaust heat shield rap will hide the crack and help with the cooling tempererly? ,,, If they carnt see the crack or hear the blow they carnt fail it ?? It should last a few weeks/months,,,,

 

[hotrodder]

Impecible timing, cars always know the right time to cry for some attention! Middle and back box both started blowing on my w124 just before MOT. As someone had 'been there' before a proper welded repair was pretty much out. Got it through the MOT with 2 coke cans, a piece of sectioned tube some (alright a lot!) exhaust paste and several jubilee clips. Worked so well it got kinda forgotten about then it got properly cold and snowed so of course perfect time for it fall apart properly! Currently running sans back box with an aluminium tailpipe until i can face lying on a cold floor swearing at it or can borrow a mates 4 post.

Brazing will probably stand more chance of working long term on a car manifold (relatively low state of tune) than a motorbike i would think. Stainless more likely to crack due to different rates of expansion. Both would make a proper repair with cast O/A filler or a nickel filler much harder to impossible

If you can only hear it 'chuffing' when cold may be worth giving a garage a drink to stick it on the gas analyzer when hot to see what the emissions are like. Or just it take it in early to give you time to fix it. Might be closing up enough when hot to get it through which'd give you some time to look into alternatives

 

[scarecrow]

had the same problem this year myself nothing as nice as your car replacement only cost €40 secondhand so didn't bother Welding here is the few options for you 1 2 3
the hardest will be figuring out exactly what type of cast it is you don't really have anything to lose if it probably needs to be replaced anyway

 

[Porschemaniac]

Thanks very much to all for the replies.

Truth be told, I reckon it should make it through an MOT - it's not very noisy and you'd have to remove the heat shield to get the view in the photos (which an MOT man can not do).

Once it's got it's ticket, I think I will have a go at welding it. Unfortunately, I don't have arc, so it will have to be MIG. I know that MM do a half kilo reel for about £17 - so even if it doesn't work, it's not too much money wasted.

I know that I'll need to pre-heat, but only have a butane torch - will this be sufficient, or will I need to invest in a MAPP setup (or similar)?

May also need to find a local machine shop to machine them flat for me afterwards.

But I reckon that will all be worth doing - rather than consigning them to the scrap bin.

 

[Weldingartisan]

If you've got access to oxy-acetylene those cracks will bronze weld, no problem. V prep 60 deg to a 1mm root face, warm up the whole manifold, weld up and allow to cool. MIG will not last, MMA with nickel rods requires more skill. W/A

 

[Paul.]

I did a similar repair to a mates BMW 2002, I intended to stick weld it with a copper nickel electrode but it was a bit thin, so knocked the flux off the electrode and used it to TIG braze the crack, it was only intended as a temporary bodge until he found another manifold, 3 mot's later its still a sound repair,

 

[Weldingartisan]

I did a similar repair to a mates BMW 2002, I intended to stick weld it with a copper nickel electrode but it was a bit thin, so knocked the flux off the electrode and used it to TIG braze the crack, it was only intended as a temporary bodge until he found another manifold, 3 mot's later its still a sound repair,

I've not tried TIG brazing cast iron, always thought the heat to be too 'intense' if you know what I mean. From your experience I'll give it a try next time. W/A

 

[Justme]

1, I know that MM do a half kilo reel for about £17 - so even if it doesn't work, it's not too much money wasted.

2, I know that I'll need to pre-heat, but only have a butane torch - will this be sufficient, or will I need to invest in a MAPP setup (or similar)?

1, Dont forget the right gas as well.

2, You will get a lot of pre heat buy running the engine.

 

[Porschemaniac]

Just a thought, but could I braze this, using a carbon arc attachment for a small arc welder? A bit like this.

The manifold will probably be off of the car (owing to limited space around it), so I think that pre-heating will need to come from my heat gun and blowtorch.

 

[Porschemaniac]

Following my earlier post, I found this.......and these.

Possibly a better bet?

As always, your wisdom will be greatly appreciated.

Cheers,

Ian.

 

[scarecrow]

might be even a better bet to maybe get another forum member too weld it for you as there is a few good ark welder from Essex here

 

[Porschemaniac]

Thanks Scarecrow - yes, that does make sense.

As it goes, I have been thinking about getting a little buzzbox anyway, to learn the noble art of Arc welding - so (if I'm honest) I am probably just using this to justify the purchase

Having said this, it will get use after this job, also. So rather than pay for a one off job, I would prefer to invest in something that I can use going forward, also.

 

[gavuk]

Not an easy first project PM,i understand your reasoning and you have convinced me you need an arc welder ......i'd recommend saving for an invertor .......personally i would think you could get scrapyard manifolds a lot cheaper than e-bay items ,port match and improve the jeeag breathing at same time?....or get a fellow essex member to stitch it up for beer tokens ....what age is jeeag? s/father has just bought one

 

[scarecrow]

cast welding rods are notoriously hard to get a decent weld with I have only use them a few times with very limited success it's really about getting the feel for them as they don't behave themselves have you anything to practice on before you try as it's not the easiest way to learn ark welding
the other way to look at it even if you have to pay someone to weld it you will still be quids in if you manage to save the manifold

 

[Porschemaniac]

Not an easy first project PM,i understand your reasoning and you have convinced me you need an arc welder ......i'd recommend saving for an invertor .......personally i would think you could get scrapyard manifolds a lot cheaper than e-bay items ,port match and improve the jeeag breathing at same time?....or get a fellow essex member to stitch it up for beer tokens ....what age is jeeag? s/father has just bought one

Cheers Gavuk. Yes, I suppose in the long-run an inverter does make more sense (maybe even one that doubles up for TIG). So, as tempting as this price is (and, having shopped around, it really is a good price - with next day delivery thrown in free) I will probably leave it.

The car is a 1995. This manifold issue is well known among owners. Unfortunately, it is also well know among breakers too - so even the non-specialist ones know what they can get for a pair of sound manifolds.

 

[Porschemaniac]

cast welding rods are notoriously hard to get a decent weld with I have only use them a few times with very limited success it's really about getting the feel for them as they don't behave themselves have you anything to practice on before you try as it's not the easiest way to learn ark welding
the other way to look at it even if you have to pay someone to weld it you will still be quids in if you manage to save the manifold

Thanks Scarecrow. No, nothing to practice on, unfortunately, unless I got an old manifold (a cheap one) from a breakers - which kind of defeats the object!

All things considered, I'll probably give the little SIP Buzzbox a miss and see if I can either get them repaired - or swallow the cost of a new pair (ouch!)