Sealing Primary to Collector Exhaust Joints

[revilla]

I will be fitting a replacement exhaust with four long primaries into an external 4-into-1 cat collector (the standard Caterham VHPD system). I intend to fit a lambda sensor into the cat collector section and ECU runs closed loop. Would people recommend fitting the primaries into the cat dry or sealing it with something (and if so, what)?

[SM25T]

You can use a smear of clear silicone sealant around each primary an inch or two from the end .. ..... but not enough to leave any inside the collector. There is also an orange loctite (?) silicone sealant.

[Ian Mackenzie]

Only use O2 sensor safe silicon, or it may harm the sensor. Readily available, the last tube I think I got was from Halfords...

Cheers

Ian

[ECR]

If you don't seal it, the Lambda probe is seeing more oxygen than it should .....

And yes, sensor friendly sealant should be used.

[john milner]

Silicone bath sealant works and is cheap. But use sparingly as the curing fumes can kill lambda sensors and harm cats.  I believe it is safe once cured.

[revilla]

Thank you gents.

Loctite 5920 looks like a good RTV to use. High temperature and sensor-safe. And at £2.99 it's not exactly expensive either.

[SM25T]

That's the stuff.

[apjenkins]

If you use a large (100mm) Jubilee clip around the four primaries where they fit into the collector it will stop the two unsecured primaries vibrating and rattling in the collector thereby allowing a consistent seal from the Loctite 5920.

@

[revilla]

Thank you.

[Bottrill]

To state the obvious only lightly smear around the outside of the primaries and not inside the collector tubes. That way you can remove any excess sealant and not have it pushed into the CAT. They are a relatively tight fit. I did mine last weekend to cure a slight gas leak.

 

Lee