4-2-1 exhaust - sealing the primaries...

[Nick Bassett]

Hi all,

Recently fitted a 4-2-1 SL-R exhaust to my 1.4 SuperSport - really pleased with the result but one thing is niggling me... where the 4 primaries go into the first collector, a couple of them are blowing ever so slightly which makes a slightly odd noise when the engine is under load and I suspect I might be losing a little power as a result.

What are my options?

I've bought some high temp stove sealer which I am planning to use, but my brother (a mechanic) suggested just using normal exhaust sealing paste. However I want to be sure that I can remove the centre section without too much effort at any time (particularly at MoT time to fit a Cat...)

Any thoughts on what I should do?

Many thanks

Nick

[Paul Deslandes]

I've just used Intumescent Acrylic sealant from Travis Perkins (builders merchant) on a non 7 classic exhaust and it works a treat, at least for the short time since I did it.  Its the stuff used to seal around fire retarding door frames etc.  It doesn't seem to set rock hard like the old Firegum or Gungum so should be reasonably easy to get apart.  I put some around both mating surfaces and pushed them together before clamping.  One caution, if it's upstream of the cat I have no idea what affect, if any, it might have on the cat life.

Paul

[Mankee]

I run the same system. You could an exhaust pipe expander to make the offending leaky primaries fit a bit more snugly.

[Ian Mackenzie]

Loctite 5920 Copper RTV Silicone is your friend.....

[OliverSedlacek]

Ditto the RTV silicone sealant, almost all of them are good for 220C.

[aerobod - near CYYC]

This is the copper RTV silicone I used to seal my exhaust, operating range to 371°C http://www.permatex.com/products-2/product-categories/gasketing/gasket-makers/permatex-ultra-copper-maximum-temperature-rtv-silicone-gasket-maker-detail Seems to be available in the UK on eBay: http://www.ebay.co.uk/itm/RTV-Silicone-Permatex-Ultra-Copper-Gasket-Maker-Sensor-safe-Permatex-81878-/321085655159

[michaelf]

Copper RTV silicone for me, Dave Andrews recommended I use it to seal around the pipes in the collector, just push it into any gaps you can reach.

[Nick Bassett]

Thanks all - I shall be popping out this weekend to purchase some Copper RTV! 

Cheers

Nick

[virden]

 I find that silicone gets everywhere, so to keep things neat, before gluing, I mark up the edge of the join where the pipes meet the collector and put masking tape around the "male" tube ends at that point.  That way you can use a Stanley knife to neatly cut off the excess that will occur when you  mate the pipes to the collector.  

[6speedmanual]

Nice tip, Virden

[StevehS3]

I had assumed that the connections were simply one pipe pushed inside the other - hence could leak. I have taken mine apart and see they are sleeved. Although mine fit together quite loosely I am thinking it is unlikely to suck air in.
Any thoughts? 
 

[Seabea23]

Not sure the early K series had the luxury of the sleeved collector.

[StevehS3]

I have probably posted this on the wrong thread. There was another about leaking exhaust connection and MoT emissions being lean but I couldn't find it. 

[John Vine]

#13:  Was it this thread?

At my last MOT, the tester reported a high lambda (> 1.03), and suggested the exhaust stream might be drawing in air at the collector. As it happens, the car passed once I'd pointed out that the applicable lambda range for an R400D was 0.95-1.09 rather than the 0.97-1.03 of the Basic Test. 

My collector is sleeved too, and so far I've not used sealant, although I do have a tube of Permatex 81878 handy just in case.

JV

[StevehS3]

Thanks John, yes it was that one. I too bought the sealant and I am doing mine today. If nothing else it should stop them rattling as mine are a loose fit. 
 

[Toby S]

I agree with copper silicone - I used Permatex 81878 Ultra Copper Maximum Temperature RTV Silicone Gasket Maker on my VHPD exhaust fitted to 1400 Supersport and it seems to work OK

 

[StevehS3]

Reporting back after sealing my primaries with Permatex. My primaries were perhaps a looser fit than most (see here 

 ) but sealing them has made a noticeable difference. Firstly the pops and bangs on overrun have been toned down and secondly it seems to be using noticeably less fuel, although I can't quantify that because I never checked before. Presumably it was drawing in air upstream of the lambda and hence causing it to run rich. I will be interested to see the emissions test at MOT time. 
 

 

[PlastererPete]

SteveS3, what was your application process for the permatex? Did you glob it up and connect the collector? Or wait for it to go off a bit first? 
Only reason I'm asking as I currently have my exhaust off so I can wrap the primaries on my CSR (hot tootsies problem and melting cables), and the collector on mine has always been a thought as it has no clamps or springs, plus the car runs rich aswell.

[SM25T]

I would spread thinly it on the male pipes, starting about 10mm from the end and apply a band about 25mm wide. Slide them home immediately and wipe off any external sealant. 

[PlastererPete]

Thanks SM25T. 

[StevehS3]

When the pipes are separated you can see a line where the collectors end. I applied masking tape at the join to make cleaning up easier afterwards. I didn't want to apply more than necessary in case I need to separate them in the future. I applied a bead about 5mm wide. It is fully sealed and doesn't rattle. 

[PlastererPete]

Thanks Steve. I'll use the same method but with some Loctite 5990 which from all accounts is the same stuff.