Car exhaust joints leaking

[Mikey D]

Fitted a middle and back sections but it's leaking a bit on the joints ,I only had some fire cement to seal the joins , (one section slides inside the other and is secured with a clamp ) car needs an mot so am worried it might fail cos it's blowing a bit... hoping it might "take up" after a while
Any advice welcome from the collective...

 

[Wozzaaah]

Where on the slot did you fit the clamps? Fit them in the wrong place and they'll often blow.
And no, if it's blowing now it won't suddenly magically stop blowing, you'll need to sort out the leaks.

 

[pedrobedro]

Open the joints up again and get some mastic in there then clamp them up again and run the engine to warm it up.

 

[slim_boy_fat]

Some old-fashioned Gun Gum will fix it.

 

[Trevorleach]

Used silicone many times, works well and lasts, how I have no idea, normal cheap stuff not the high temp stuff, got the idea as was told the guys who make fancy stainless exhausts use it.
Obviously that is applied as you assemble, not dobbed on the outside.

 

[Moose McAlpine]

Used silicone many times, works well and lasts, how I have no idea, normal cheap stuff not the high temp stuff, got the idea as was told the guys who make fancy stainless exhausts use it.
Obviously that is applied as you assemble, not dobbed on the outside.

Yep, seen lots of modified cars with expensive stainless exhausts sealed with normal clear silicone. Works really well.

 

[wristpin]

Doesn't using silicone upset the o2 sensor?

 

[Wallace]

Doesn't using silicone upset the o2 sensor?

OK after the sensor.
I have been using silicon sealant for years, particularly on bike exhausts as disassembly is easier than the horrible water based pastes. Envirograph flue sealant is amazing stuff on manifold to head faces and downpipes on older stuff providing no O2 sensors are present.

 

[Mikey D]

Cheers for all your replies , I didn't realise you could use normal silicone sealant I have plenty of that ,I'd already sorted it with more fire cement we'll hopefully it will pass mot tomorrow . If not I'll be siliconing

 

[Trevorleach]

Doesn't using silicone upset the o2 sensor?

I am not sure, but most modern silicones are what I call rubbish as they no longer make your eyes water when you open the tube.

 

[steveo3002]

also use silicon here...havent dared try it upwind of the o2

 

[PhillipM]

Some of the non-acid cure silicones are fine upwind of the o2, permatex, 3m, etc, do versions.

 

[Mikey D]

Well it failed on exhaust leak (and a few other things ) but at least there were less things than last time
Anyway exhaust joint liberally pasted with some expensive PU adhesive and sealer . So I'll let that harden overnight .......
So please don't tell me only silicon will work

 

[My Old Landy]

I've just purchased a new rear exhaust system for my P38A and I also (£4 delivered on Amazon) purchased a tub on Gun Gum after reading your thread I do have silicon but a tube of that is more expensive than a tub a Gun Gum

 

[Mikey D]

Good luck , damned exhaust has been my nemesis

 

[Moose McAlpine]

You need to put it in the joint, not on the joint.

 

[ajlelectronics]

Well it failed on exhaust leak (and a few other things ) but at least there were less things than last time
Anyway exhaust joint liberally pasted with some expensive PU adhesive and sealer . So I'll let that harden overnight .......
So please don't tell me only silicon will work

No, but you need to re-assemble the joint, you can't just slather compound over the top.

 

[Mikey D]

It's in the joint .its definatly in the fekking joint

 

[PhillipM]

Well it failed on exhaust leak (and a few other things ) but at least there were less things than last time
Anyway exhaust joint liberally pasted with some expensive PU adhesive and sealer . So I'll let that harden overnight .......
So please don't tell me only silicon will work

Why do you think we recommended silicone?

PU will soften at about 100c, decent silicone is good for 270...

 

[Mikey D]

Well it's good for -40 degrees to +80 degrees have just read wots on the tube , think I'll go a darkened room and cry