3 litre inlet manifold crack problems

Quote:

---

Originally Posted by letherm

Well, you learn something every day. I always thought I was using the gears to slow the car down without realising that I was actually using compression braking. In hindsight I presume that the use of downshifting just limits the top speed of the car to the gear selected. One final point, is the noise I hear the engine or the gearbox or a combination of both?

Martin

---

actually no. you still have to watch the tacho. The ability to pass redline is still there. Though without serious weight on the back it would have to be a steep hill.

Quote:

---

Originally Posted by trout1105

I watched/listened to that 10 min ago and am still chuckling [thumbsupbig]

---

Thanks cocko

Quote:

---

Originally Posted by trout1105

I would say Both.
I can remember back a while where the operating manual in auto cars recommended choosing a lower gear on long descents to avoid cooking the brakes.
Most people with a manual transmission usually select a lower gear on big hills But the vast majority of auto drivers don't for some reason.

---

I believe that those that do were probably taught how to drive on a manual. I certainly was, long enough ago to be taught double de-clutching to shift down and could successfully change down in a non syncromesh gearbox without crashing the gears. Yes, I know that makes me old.[smilebigeye]

Martin

Quote:

---

Originally Posted by Pedro_The_Swift

actually no. you still have to watch the tacho. The ability to pass redline is still there. Though without serious weight on the back it would have to be a steep hill.

---

Totally agree Pedro. Very aware of not exceeding the redline and brake well before I get there.

Martin

Sadly too many shove the Auto in D for Dumb and just toddle along!

Not realising The extra functions are there to assist [emoji41]

Sorry I may have used wrong term calling it compression braking, but the theory is there using motor compression and gearing combined...

Like you letherm I was taught how to drive on a manual (inc the old double clutch...) so have always had the habit of using the gears to save cooking brakes on long descents. Referring to my experience coming over Alipne way, I was towing a Jayco Eagle pop top camper with electric brakes. I didn't red line the motor but balanced between gears and brakes to play it safe in mid range revs, well I thought... Reading other threads on forum, I don't think it was a single cause of the manifolds cracking, but it must have contributed to an already weakened part as it appears many SDV6 owners have had similar failures with the manifolds.

Quote:

---

Originally Posted by Hungo

Sorry I may have used wrong term calling it compression braking, but the theory is there using motor compression and gearing combined...

Like you letherm I was taught how to drive on a manual (inc the old double clutch...) so have always had the habit of using the gears to save cooking brakes on long descents. Referring to my experience coming over Alipne way, I was towing a Jayco Eagle pop top camper with electric brakes. I didn't red line the motor but balanced between gears and brakes to play it safe in mid range revs, well I thought... Reading other threads on forum, I don't think it was a single cause of the manifolds cracking, but it must have contributed to an already weakened part as it appears many SDV6 owners have had similar failures with the manifolds.

---

Yes good using the engine to help on descents. As for the manifolds, they’re a substandard quality product unfortunately and are prone to failing no matter how you use the vehicle. No use of the vehicle should cause that issue.

Certainly not caused by engine braking!
The manifold has negligible/no positive pressure under idle or overrun.

Just wondering if any one who has suffered a cracked manifold in their 3.0 D4, did Land Rover provide any support in the form of $$$ for the repair.
A mates D4 (2012) has just been diagnosed with this problem and quoted a hefty amount for repair. As has been reported in earlier posts, Land Rover has acknowledged a manufacturing fault with the plastic manifold.

Ivan

If the belts are nearly due when a manifold needs to be replaced then I suggest a body off exercise and change both manifolds and the belts. Access to the manifolds with the engine in-situ is far from ideal. The manifolds are on their 8th version and having assisted my son over 2 days in changing one of his recently, the only difference is seemingly extra thickness at the edges and improved external strengthening ribs.