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Exhaust Gasket & Popping

Jjc2020

Jjc2020

Accelerating Away
Hi there,

Looking through here I've seen that the probable cause of the popping from the exhaust is an air leak where the cast manifold meets the downpipe. That 3 stud junction. Its actually fully loose and wobbles.

What do I use to seal it? I've been on Paddock and other parts suppliers and they don't have (that I could see) a triangular exhaust gasket for it. Any suggestions on what to use and where to get it? Also any tips on undoing the studs gratefully received as I guess they'll be a pain to undo....

Thanks!
 
Jjc2020 said:
Hi there,

Looking through here I've seen that the probable cause of the popping from the exhaust is an air leak where the cast manifold meets the downpipe. That 3 stud junction. Its actually fully loose and wobbles.

What do I use to seal it? I've been on Paddock and other parts suppliers and they don't have (that I could see) a triangular exhaust gasket for it. Any suggestions on what to use and where to get it? Also any tips on undoing the studs gratefully received as I guess they'll be a pain to undo....

Thanks!
Click to expand...
On my petrol 2.25 there is no gasket .
Will the nuts not just tighten up . If they’re rusty be careful as those studs like to snap .
Alternatively you could try undoing them after a good soak of penetrating fluid , clean the threads up and use new nuts , Brass nuts would be better but don’t over tighten them .

My 2.25 diesel had nuts and bolts with the studs drilled out , a pain to do as you had to hold the top and bottom .
 
Fulltimedad said:
On my petrol 2.25 there is no gasket .
Will the nuts not just tighten up . If they’re rusty be careful as those studs like to snap .
Alternatively you could try undoing them after a good soak of penetrating fluid , clean the threads up and use new nuts , Brass nuts would be better but don’t over tighten them .

My 2.25 diesel had nuts and bolts with the studs drilled out , a pain to do as you had to hold the top and bottom .
Click to expand...
Ok, I'll give that a go. I just assumed there would be one, but maybe not. If I can get the nuts to turn then if I can't close it up, then at least I can ease it off to get some high temp compound in there. Thanks
 
Jjc2020 said:
Ok, I'll give that a go. I just assumed there would be one, but maybe not. If I can get the nuts to turn then if I can't close it up, then at least I can ease it off to get some high temp compound in there. Thanks
Click to expand...

There is no gasket, the end of the down pipe is domed with a corresponding rounded recess in the manifold. It allows the exhaust to be adjusted a bit so everything lines up before being tightened.

In my experience they are very difficult to keep tight. The studs corrode rapidly because of the heat, so if they have been on there long the threads have often disappeared. If you use ordinary steel nuts they will hold well but be near impossible to remove later without breaking the studs ( best way is to heat the nut but even then no guarantee) . I have tried stainless and brass nuts with moderate success but they tend to work loose after a while.

It is possible to replace the original 5/16" UNF/UNC studs with M8 ones which are very easily available, in fact it's probable that someone will already have done that.

I am considering, during the imminent rebuild of my 109, replacing the whole manifold and downpipe with an aftermarket 'performance' upgrade if only to get rid of that annoying joint! David
 
Many (unsure if all) Defender downpipes have a bracket from the downpipe to the side of the block to help prevent this...
Must have been a lesson learned from earlier vehicles..?

tuyau-d-echappement-avant-defender-90.jpg
 
Thank you all. Sorry for the slow reply, but it's taken me a while to be able to get at it because of the rain. Now I have had a go over the weekend, it is now absolutely not moving. I've tried heat on it as best I can with a blow torch, but couldn't get it cherry red.

Honestly though I'm being more delicate than I might be because I am trying not to strip / break the stud. I can live with a popping exhaust, but summer with no exhaust and therefore no roads because the studs broke is not an option.

If the stud does fully let go, what are my options, and how painful / expensive are they? I might make it a winter job, rather than take the car out of action during 'summer' if it is a nightmare.
 
Jjc2020 said:
Thank you all. Sorry for the slow reply, but it's taken me a while to be able to get at it because of the rain. Now I have had a go over the weekend, it is now absolutely not moving. I've tried heat on it as best I can with a blow torch, but couldn't get it cherry red.

Honestly though I'm being more delicate than I might be because I am trying not to strip / break the stud. I can live with a popping exhaust, but summer with no exhaust and therefore no roads because the studs broke is not an option.

If the stud does fully let go, what are my options, and how painful / expensive are they? I might make it a winter job, rather than take the car out of action during 'summer' if it is a nightmare.
Click to expand...
Well i inherited my 2.25 petrol with 2 broken Manifold to exhaust studs and one bent one.

I tried for a few days on and off the free them . I heated , soaked , welded a nut on there , hit them with a hammer to break the rust seal . I hit one stud a bit hard after heating and soaking it and the casting by the stud cracked 😡

So yes it can be painful .

From memory a new exhaust manifold was not that expensive 🤔
 
LightweightV8auto said:
Just a thought... stainless studs and Aerotight nuts. They won't come loose, regardless of temperature or wiggling.
Click to expand...
I beg to differ, I tried that combination on the middle box of a V8 exhaust. Didn't make the slightest difference, Still worked loose as did double nuts and various options in the way of spring washers, star washers, wave washers and pretty much every other thing I could think of. Only thing that prevented the joint from working loose was a combination of castellated nuts and split pins
 
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