Got a TD5?  Is it chipped?  If it is then you’ve more than likely experienced this problem sooner than those non-chipped owners...

If your not chipped, and use your TD5 offroad, in sand, or tow, then you’ll experience it some time as well.

You’ll be driving, press the accelerator and hear a ‘whistling’ sound - Like Sonny Hammond calling Skippy on a Gumleaf :-)

Whats happened is your Manifold is leaking, and most likely its towards the rear 5th cylinder.

If you look under the turbo shield with a torch, you’ll notice soot.  And possibly some missing studs or Nuts that should be holding the manifold in place.

Number 5 Cylinder - Notice the soot!

So what can we do about it?  Well, theres several schools of thought on this one.

- Open the holes for the studs on the end ports is one.

1. -Re-tap the head for 10mm studs
   

2. -Just remove the manifold, face it and bolt it back with a new gasket
   

3. -Refit with 2 gaskets
   

Or, try to find a permanent fix that solves the issue.

I have searched for the later option when the manifold on my Discovery started whistling!

One way is to remove the webbing or stress relieve the webbing between the ports.

Your still required to re-face the manifold, but you’d do that anyway (wouldnt you).

Left: Stock Manifold                                    Right: Warped Face on Manifold

Die Grinding the Webbing from Between the Ports removes stresses under thermal load

Or go the very expensive route and go full custom stainless Manifold

So what did I do to fix mine?

Unfortunately I wasn’t able to get photos of my manifold prior to being installed but here are some details and images showing my solution.

Manifold coated with HPC Ceramic Coating.

Close Up - Visible is the 3mm Slot between the ports, this acts as a stress relief point allowing the manifold to expand and contract a little under thermal loading.

Another shot of the manifold, a slot between the ports is visible in the background.

The coating is called ‘HyperCoat Extreme’

Rated to 1300 Celsius its exceptionally well suited to turbo manifolds and comes with many benefits.

The coatings help maintain exhaust gas temperatures, increase flow velocity, aid cylinder scavenging and assist in preventing damage to hoses, belts and wiring harnesses.

Testing has shown as much as a 30% reduction in underbonnet ambient temperatures and a 50% reduction in component skin temperature. HiPerCoat™ Extreme achieves this by creating a thermal barrier that retains heat, which in turbocharged applications assists to increase turbo boost and spool-up.

Link to HPC Coatings here

The manifold was then refitted with new studs and gaskets.

After running the engine up to temperature and being allowed to cool down again the tensions were checked.

This time we should have sorted the problem.

OBSERVATIONS since the upgrade

Engine bay appears to be cooler after a long hard run

Engine appears slightly more responsive

In the near future I plan to pull down the Turbo and have it coated as well.

Then I’ll move on to the Exhaust Dump pipe.