Author Topic: "Bolts" on the exhaust manifold, what for? (Read 2623 times)

nomad · « **on:** April 11, 2008, 04:09:55 PM »

Excuse my ignorance but what are the purpose of the "bolts" attached to the outside of the exhaust manifold about 2" away from the flange?

I suddenly thought about this and can't seem to figure out what they are for. O2 sensors? Some sort of diagnostic check?

beegeezy · « **Reply #1 on:** April 11, 2008, 07:56:52 PM »

I dont think many people know what they are for. There has been a lot of speculation as to what they may have been for, but no solid "heres your sign". Would be interested in knowing for sure myself.

colin86325 · « **Reply #2 on:** April 13, 2008, 12:08:48 AM »

I've always understood that they were there for CO monitoring. The S14 manifolds also have similar plugs in each runner. The M20 manifold has a single plug for the manifold for cylinders 1-2-3, and another for the manifold for 3-4-5.

Paul Strefling · « **Reply #3 on:** April 13, 2008, 03:53:59 PM »

I believe they are EGTs; they look like the correct size.