Exhaust sealant

[Julian B]

Would you ordinarily use a white exhaust sealant (Gun Gum in the UK) when re-fitting the exhaust? I have just dropped mine to try to sort out a small leak (fairly sure it was on the LH side manifold) - I have x4 new gaskets, but not sure whether to also use the sealant.

Also, the straight "in line" join between the exhaust downpipe and the silencer box; that just has a "U" clamp, and not sure whether to seal it or not.

TIA

[heinkeljb]

The use of sealant on any of the exhaust joints really depends on how "Knackered" they are. If they have been apart a number of times, they are not likely to seal very well without some sealant.
There are two main sorts of sealant in use in the UK. One is called exhaust assembly paste and is a relatively thin more runny paste than the other sort which has a trade name of Gum-Gum - this is thicker and along with some other mechanical strengthener like a sheet of metal and a jubilee clip is designed to fill and cover holes.
The assembly paste is designed to fill smaller holes, like the leak you get when you slide one piece of exhaust pipe into another piece (assuming they are designed to go together snuggly)

Both sort dry out from the heat of the exhaust and become hard and brittle which is why Gum-Gum requires extra support. If you used assembly paste on two pipes and they are subjected to vibration / movement between the two, the assembly paste will also give up after a while.

Both work well in the correct places and with the correct preparation - i.e. remove all loose rust / dust - wipe the surfaces with a damp cloth before put either paste on metal, it will stick better.

Pin holes and slightly bigger holes can be covered with Gum-Gum after the surrounding area has been cleaned up. Just try and work some of the Gum-Gum "in to" the holes and then put about 3 ~ 5 mm of Gum-Gum over the top of the hole(s) and about an overlap of about a centimetre onto good metal round the hole(s). If you have a blow torch or a hot air gun, use that to dry the Gum-Gum rather than running the engine. The exhaust gasses tend to push out the Gum-Gum from the inside before it has had a chance to harden.

John

[Julian B]

Many thanks - I will use it today.

[gren_t]

As a side note, for exhaust assembly I use "Loctite High Temp Exhaust Silicone Sealant Copper 5990" for assembling exhaust joints
It doesn't breakup like Gun Gum and is great for gap filling.

Linky: https://www.halfords.com/tools/garage-e ... 99712.html

[heinkeljb]

That stuff has some blurb Quote "Temperature resistance: -55°C to 350°C intermittent" Unquote - it won't last long on an exhaust system, particularly near the headers.
I notice you have some blocking a common joint leak area on your Carb block heating pipe. The only real fix is to take the manifold off and put some Braze in there.
When it happened on mine, I ended up heating the joint up, pulling the old piece of pipe out an putting a new piece in there. If you find my post you will see I also managed to get it a bit squiff and had to do a strange cut and shut to get the pipe and the flange to line up.

John

[AustHaflinger]

This is what I use on all my joints - works really well as it expands when it sets and seals everything up. I guess you cannot get it where you are.

https://www.repco.com.au/en/car-care-pa ... p/A5179300