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pedrocandrade

Member Since: 30 Sep 2022
Location: Rio de Janeiro
Posts: 30

2011 Defender 110 Puma 2.4 SW Epsom Green

~30 second engine note change

Here’s the enigma. Since about a year ago, I noticed that sometimes (once a month) the engine sound on my 2.4 Puma would change to a deeper growl for about 30 seconds before coming back to normal. It happened just after starting the engine, just as I was leaving home. More recently, the deep growl started to happen also in the middle of trips, with a warm engine. And again it also goes away after about 30 seconds. There’s no rattle, no noticeable loss or increase in power, just a change in engine sound. Like a different (deeper) exhaust note.

I searched the posts here in the forum but couldn’t find a similar symptom. I imagine a turbo actuator issue would change engine power. Same for MAP / MAF sensors. And as far as I know the 2.4 doesn’t have a DPF.

Does anyone have a clue as to what could be the culprit?

Many thanks!

1st Feb 2025 12:54am

jim4244

Member Since: 13 Apr 2014
Location: Bedfordshire
Posts: 853

2007 Defender 90 Puma 2.4 CSW Zermatt Silver

Hi

No, you are correct that there is no DPF on the 2.4 just an EGR system.

Is there a dip in engine revs at standstill when you hear the "growl"?

Jim

1st Feb 2025 3:23am

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 634

I have heard the type of noise you describe when working around the engine when running..
I have thought it was the viscous fan operating 🤔

1st Feb 2025 7:23am

Johan_B

Member Since: 20 Sep 2024
Location: Gothenburg
Posts: 49

2008 Defender 110 Puma 2.4 CSW Tonga Green

Do you have an AC?
It would be more frequent but maybe you don’t notice it most of the time.

1st Feb 2025 7:37am

pedrocandrade

Member Since: 30 Sep 2022
Location: Rio de Janeiro
Posts: 30

Hi, thanks for the replies. Here is a bit more detail:

- I do have an AC and it is working all the time. It does make a bit of a noise but it’s much softer.
- I only hear the noise when I rev the engine. Sometimes it’s “there” but unnoticeable because the engine is idling. But as soon as I raise the revs to say 1500 rpm the noise gets quite clear. And it goes away like magic after a few seconds. So there is no dip on the engine revs when the noise happens. No change at all in engine behavior.
- The viscous fan is an interesting idea. But why would it be engaging with the engine cold, right at startup?

Thanks again guys!

1st Feb 2025 10:54am

MK

Member Since: 28 Aug 2008
Location: Santiago
Posts: 2453

2007 Defender 110 Puma 2.4 SW Chawton White

Viscous fan does engage shortly after starting the engine. Do not ask me why but I believe it was mentioned in this forum. Try a search. Puma 110" SW

.............................................................
Earth first. Other planets later

1st Feb 2025 11:12am

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 634

When you park up and the fan has fluid present in the drive portion, that isn't cleared till the fan starts spinning and it will eventually be carried back to the resevoir, and of course won't be replaced until the bi metallic strip is warmed opening the valve to allow the fluid to flow into the coupling..
Having said all that I've heard that air type roar at times when I'm thinking it shouldn't be active....but I can't come up with another explanation for the noise...

1st Feb 2025 11:41am

pedrocandrade

Member Since: 30 Sep 2022
Location: Rio de Janeiro
Posts: 30

That makes a lot of sense. It must be the fan. Thanks a lot for the replies and explanations!

It was the butler after all. 😄

1st Feb 2025 1:13pm

Esben Kold

Member Since: 14 Oct 2023
Location: Horsens
Posts: 27

2008 Defender 110 Puma 2.4 SW Galway Green

Edited [/code]

1st Feb 2025 7:16pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20620

I have found this to be turbo actuation related, when completely cold.
Presumably, it’s more sticky at that point, albeit momentarily, which is enough to spin up more than it normally would do but momentarily.

If that tends to happen, lube those two pivots with light oil and I tend to find it’s a non issue.

The fan does have an affect, but it’s less noticeable.
Presumably it’s the former here, and not the latter.

Depends on whether you’d consider it slightly different, or fairly loud? TheThunder Rolls🇬🇧🇺🇸
⛽️🛢️⚙️🧰💪

1st Feb 2025 10:17pm

pedrocandrade

Member Since: 30 Sep 2022
Location: Rio de Janeiro
Posts: 30

Oh it’s quite noticeable. The engine noise changes quite a bit. I’ll check the turbo actuator as well. Thanks a lot!

1st Feb 2025 11:44pm

ickle

Member Since: 22 Jul 2010
Location: South Vendee
Posts: 1822

2008 Defender 110 Puma 2.4 CSW Alpine White

Can you temporarily remove the fan and see if the noise disappears ?

HTH Keith

2nd Feb 2025 8:08am

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 634

Trouble is it's not a given your always hear the noise..or at least that's my case..but if you removed the fan and never heard it again I'd say that was conclusive..👍
If custom 90 has confirmed it's turbo related then you should be able to see the actuator move as the noise appears and leaves..or if you happened to have access to boost or maf data you should see it...but certainly in my case the noise always catches me unawares..and nearly always just when I'm working on it..given I'm stone deaf that's about my only chance of hearing it 😁

2nd Feb 2025 9:05am

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