ATK 143 1 Cars Posted April 5, 2020 Fitted a new Bosal backbox today. Have the correct two piece clamp and some holts firegum. Tried twice now and still have a slight escape of gas from the join, can just about feel it by putting fingertips on one part of the join. This is despite using a little paste in the clamp and around the join to help. Any tips to get a good seal? my car is phase 2 so olive style joint. Share this post Link to post Share on other sites
DamirGTI 344 Posted April 5, 2020 Personally , i'd weld the joint and be done with it . New clamp (don't reuse old one) of the correct dia. , proper flange alignment and some exhaust paste on both sides prior to clamping together usually works .. If the pipe flange (on either side) is bent , crooked or otherwise surface damaged it'll be hard to seal the joint with just the clamp and exhaust paste . Or could be mismatch in the dia. of the main pipe flange and silencer flange .. Might try with some copper sealant instead of exhaust paste .. and see what happens . D Share this post Link to post Share on other sites
ATK 143 1 Cars Posted April 5, 2020 Whats the correct size clamp?69mm? Share this post Link to post Share on other sites
DamirGTI 344 Posted April 5, 2020 Yes , OE is 69mm ... Some aftermarket exhaust parts (mid sections , rear silencers ..) for the 205 with olive type joint comes in 66mm , so beware . D Share this post Link to post Share on other sites
ATK 143 1 Cars Posted April 5, 2020 Its an aftermarket generic pipe and bosal backbox so should this be 66mm? Share this post Link to post Share on other sites
DamirGTI 344 Posted April 5, 2020 Can't say really , need to do some measurement . But by this : http://www.bosal.com/en/catalog/exhaust/69786985364855/SYS09312 Bosal seems to be 72mm ... D Share this post Link to post Share on other sites
welshpug 1,666 Posted April 5, 2020 get out there and measure it I prefer the single piece oem type clamps from the later vehicles even though they are an arse to get on and off they tend to seal very well. https://www.clampcouk.co.uk/french-one-piece-exhaust-manifold-clamps.html Share this post Link to post Share on other sites
Kitch 4 Posted May 3, 2020 This stuff. Follow the instructions, don't rush to start the engine, however tempting. It's brilliant stuff. Really is. The only other exhaust paste worth any kind of recommendation is STP Bloseal, which was this blue/grey stuff that used to come in a cartridge. Was brilliant - I sealed open holes in silencers with this stuff, with no reinforcement whatsoever. Sadly, I don't think it's made anymore. Share this post Link to post Share on other sites
SweetBadger 94 Posted May 4, 2020 (edited) I had loads of trouble getting an olive fit bosal backbox to seal - turned out to be the aftermarket clamp was the issue. It was bending / deforming and so not holding the joint tightly and doing the bolts up tighter just stretched the clamp further. I bought an OE clamp from Peugeot, and problem was solved. The OE clamp was much better made, far sturdier than the aftermarket one. I'd give a genuine clamp a try if they're still available. Edited May 4, 2020 by SweetBadger Share this post Link to post Share on other sites
steve@cornwall 100 Posted May 6, 2020 Try fitting the rear box with all of the exhaust hangers disconnected, I have found this gets a better seal as the joint can be dead straight Share this post Link to post Share on other sites
