Citroen DS4 Exhaust Manifold

Most of what we supply here is good used original stock through our network, because new manifolds for the older engines are scarce and expensive locally. Tubular upgrade manifolds are also available for the applications where someone wants more than standard flow. The engine code decides everything — manifolds changed within the same model as engines were revised — so send the VIN and engine code rather than the model name.

A cold-start tick that fades with warm-up is the classic, along with an exhaust smell under the bonnet, lazy turbo response on an HDi or THP, and a P0420 code triggered by air leaking in upstream of the oxygen sensor. On South African cars with real mileage, the cast iron manifolds on the 1.6 HDi and 1.6 THP are the frequent offenders. Listen at the flange on a cold start — that one test separates it from valvetrain noise.

It can be welded, and specialists here will do it, but cast iron is difficult to weld well — it needs preheating, the right rod and a controlled cool-down, and even done properly the repair often fails again under the same thermal cycling that cracked it in the first place. On a high-mileage 1.6 HDi or THP we generally recommend a good used original or a tubular replacement instead, because a second failure costs the same labour all over again.

That is the signature of a cracked cast iron manifold and the physics behind it are neat: cold metal has contracted, so the crack is at its widest, and exhaust pulses escape past it audibly. As the manifold heats and expands, the crack closes up and the tick fades. Owners often assume it has fixed itself. It has not — the crack is still there and will keep growing. Listen at the manifold flange on a stone-cold start to confirm it.

For a short period, with reservations. The serious risk is carbon monoxide, which is odourless and can reach the cabin through the bulkhead, and that risk is worst in winter with the windows closed. There are mechanical consequences too — on a turbo diesel the turbine is not receiving the gas energy it was designed for, and unmetered air ahead of the oxygen sensor can push the catalyst into overheating. Get it sorted before a long trip or a roadworthy.