A quick idiot check - exhaust manifold nut torquing up

[AndrewGP]

Following on from the MOT emissions failure thread my car is off to Northampton Motorsport tomorrow for a stint on the rollers to see what's going on. I'm doing a quick spanner and fluid check of everything today to make sure things (hopefully) go smoothly.

 

Everything so far is fine, however, the exhaust manifold nuts that sit on the studs holding the primaries on aren't that tight. I've checked the archives for the value and 25lb ft seems to be the value, but torquing them up to that value seems to be crushing the gasket. Am I doing something daft or is that right? The exhaust is a 4-1 R500 job.

 

 

[Stationary M25 Traveller]

Torqued one up to just that only three days ago. Didn't seen particularly tight or damaging. Is your torque wrench set ok ?

 

What sort of gasket is it ?

[AndrewGP]

Gasket looks like a foil type of material and I've triple checked the torque wrench

 

I'll go and have another look at it now....

[subirg]

I'm about to replace one of my primaries (Primary number 1 in fact..). Similar exhaust to yours I think - Duratec 2l. The build guide says tighten to 32Nm (24 lb/ft in old money).

 

As an aside - if you change a primary, do you need to replace the gasket too?

[AndrewGP]

All done now, whilst the nuts weren't loose they weren't torqued to 25lb ft by some margin. Looks like I was worrying unnecessarily about the gasket too, all seems good now

 

I guess I'll find out tomorrow if this is contributing to the poor emissions readings....

[Stationary M25 Traveller]

Shouldn't have to change the gasket .... as long as it doesn't look damaged.

[subirg]

^^^ Thanks for that!

[Stationary M25 Traveller]

Out of curiosity .... what made you replace one primary ?

[subirg]

Quoting Stationary M25 Traveller: 

Out of curiosity .... what made you replace one primary ?

 

It developed a significant crack that extended nearly half way round the pipe about 1/4" away from the weld that links the primary pipe to the bracket that bolts into the engine block... No idea why and none of the other primaries have any problems.

[Stationary M25 Traveller]

Is the exhaust supported by the centre mount too, or only by the rear silencer mount and manifold studs in head ?

[subirg]

Only by the rear bracket and manifold studs. Didn't even know there was the option of a mid mount? I have a Raceco silencer and straight through pipe set up. There is clearly decent amount of vibration going through the exhaust as I've also had to replace the rear mounting bobbin.

[Stationary M25 Traveller]

It is between 800-805mm from the centre of the rear bolt hole. You obviously need to attach a bracket to the silencer or inlet pipe too. It does make a big difference.