3 litre inlet manifold crack problems

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Originally Posted by DiscoJeffster

Mmm

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Ha, sorry guys, must have pocket replied.. reading this thread with interest.

I had the same issue with both my manifolds cracking last year on MY12 3.0 D4 110,000kms. Noticed after i came over the Alpine Way towing a caravan using compression braking. Fault light came up Restricted Performance. Got towed to Albury LR and they spent week replacing just one of the manifolds. Got the car returned to me in Newcastle and a week later it cracked the other manifold...luckily all covered under Extended Warranty.
I didn't see the old or new manifolds so cant comment if they looked any different.

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Originally Posted by Hungo

Noticed after i came over the Alpine Way towing a caravan using compression braking.

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Pardon my ignorance, but how do you use compression braking? Understand the idea but haven't the foggiest how to do it. I have a D4 MY13 auto.

Martin

Compression braking - just using the gears manually to hold speed downhill(i.e. hold in 2nd gear), taking some load off the brakes.

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Originally Posted by Hungo

Compression braking - just using the gears manually to hold speed downhill(i.e. hold in 2nd gear), taking some load off the brakes.

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Probably creates a mighty bit of vacuum in those manifolds also!

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Originally Posted by Hungo

Compression braking - just using the gears manually to hold speed downhill(i.e. hold in 2nd gear), taking some load off the brakes.

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Yes, I do that already, but I haven't noticed any accompanying sounds like you hear when a semi does it. I know they have a much bigger engine but assumed that there would be something audible to indicate compression braking. Just sounds like gearbox noise to me. [smilebigeye]

Martin

Truck compression braking actually turns off the fuel and alters the valve timing of the engine and turns it into an air compressor.

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Originally Posted by letherm

Yes, I do that already, but I haven't noticed any accompanying sounds like you hear when a semi does it. I know they have a much bigger engine but assumed that there would be something audible to indicate compression braking. Just sounds like gearbox noise to me. [smilebigeye]

Martin

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Trucks have an Exhaust brake which is quite different to only using the engine compression as a brake [thumbsupbig]

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

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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

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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.