Discovery 2017

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  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    Inlet Manifold coked up!

    Hi All,

    Just had the throttle body replaced as the butterfly had seized up.

    Whilst doing it, dpf guy pointed out that the manifold inlet was chocka with soot and should be cleaned out!

    On speaking to a local LR engineer he said they are all like that and best not to touch!

    Having a look at the new throttle body (two weeks old), it is filthy inside with soot.

    What everyone's thoughts on it, clean out the manifold inlet or leave it be?

    Phil
    18th Oct 2025 6:43 pm
  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    That's the inlet on the left of the throttle body, from the front

    It's a td6, one turbo and egr.
    18th Oct 2025 6:45 pm
  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    I'm a Pratt, I meant the inlet on the right, not the left!
    18th Oct 2025 6:46 pm
  • Mole HD
    Member Since: 18 Nov 2024
    Location: Orkney Islands
    Posts: 525
    Scotland 
    2017 Discovery Td6 HSE Fuji White

    I don't overly fuss about a bit of soot or carbon build up unless it's excessive or clogs the boost sensor at the back of the throttle body... or makes the butterfly valve in the throttle body stick. You'll know if that happens though as it'll cause a turbo overboost fault and the car will go into limp mode usually with a 'DPF full' message on the dash.

    The soot and carbon build up in the inlet manifold is an unfortunate (but deliberate) consequence of the EGR's fitted to modern diesel engines as manufacturers forever chase politically driven, stricter emission controls Neutral

    All those emission control systems, specifically EGR's, have the same effect on diesel engines as sticking a rubber hose up your ar*e, shoving the other end in your mouth, then running around all day breathing in the fumes...


    Last edited by Mole HD on 19th Oct 2025 7:35 am. Edited 1 time in total
    18th Oct 2025 7:39 pm
  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    Thanks Mole,

    That's what caused me to replace the throttle body, stuck butterfly and over boost message.

    Now I'm wondering if that will happen again quite quickly as I haven't dealt with what caused the problem.

    The bus has done 60,000 and I'm guessing it's the first throttle body replacement.

    What do you think. Leave it alone or have a go at clearing some of the soot?

    Phil
    18th Oct 2025 8:03 pm
  • Mole HD
    Member Since: 18 Nov 2024
    Location: Orkney Islands
    Posts: 525
    Scotland 
    2017 Discovery Td6 HSE Fuji White

    I'd leave it be if you've replaced the throttle body to be fair, certainly at that low mileage. The throttle body is easily cleaned though if you remove it and spray it with brake cleaner (or the expensive alternative of a branded carbon cleaner).

    In the mouth of the inlet manifold itself, you have to be careful when cleaning as you don't want any lumps of hard carbon falling off and down to the turbo or EGR. You can carefully pull or wipe out as much as you can...but never just spray it with cleaning fluid and wash it inward down the manifold Thumbs Up
    18th Oct 2025 8:11 pm
  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    How about removing the throttle body and setting about inlet with an old vacuum cleaner, do you think that might be effective without causing any damage?
    18th Oct 2025 8:21 pm
  • Mole HD
    Member Since: 18 Nov 2024
    Location: Orkney Islands
    Posts: 525
    Scotland 
    2017 Discovery Td6 HSE Fuji White

    Yup, the Henry hoover is a mechanic's best friend in that case, they're great for sucking up damp soot or carbon deposits without blowing up. Don't go using the wife's posh Dyson though, starvation, radio silence and celibacy don't go well together...Ask me how I know that and why I've now got a yellow Henry hoover in the garage Laughing

    As for the root causes of excessive soot or carbon build up...short distance stop/start town driving is a common culprit. Turn your auto stop/start off unless you feel it's necessary...your engine will thank you in the end. Once a week, go for a blast up a motorway or decent A roads for a bit to get the turbo working and put the engine under a bit of load at higher RPM Wink
    18th Oct 2025 8:24 pm
  • Chillyphil
    Member Since: 07 Jul 2025
    Location: Paignton
    Posts: 22
    United Kingdom 
    2018 Discovery Td6 HSE Lux Silicon Silver

    Thanks Mole,

    I'll get on it next week and let you know how it goes.

    Phil
    18th Oct 2025 8:51 pm
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