Hi all,

Literally just took delivery of my second Defender 90 X Dynamic SE P400. I had a 2022 same model that I sold 8 months ago. I notice a rapid light tapping noise at idle coming from the drivers side rear quarter panel wheel well area. You can hear it easily inside or outside of the Defender, definitely coming from the drivers side rear wheel well or rear quarter panel area. Any idea what this could be? It's quite disturbing even with music playing quietly. Only 48 miles on the Defender.

Thank you and Happy Holidays to you all

 

So the sound I'm hearing is in all Defenders...well at least the P400's. Went to my awesome dealers this morning and it was confirmed immediately by their master tech, and we listened to another P400 that made the same tapping sound in the area of the drivers side rear wheel well. It is the DMTL pump. At some point I might try suppressing the tapping sound with Dynomat to see if that helps.

 

At some point I might try suppressing the tapping sound with Dynomat to see if that helps.

It seemed only for the NAS and China. I think you don't have to remove the innerwheel liner completely.
Start from the rear and work to the front. You can isolate the motor, I suppose this one isn't getting hot in
normal circumstances, but what if you isolate it ? You don't want Vapor Lock to occur.




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I suspect it is not your DMTL pump making this noise because the DMTL pump should *not* run constantly and it only runs its test if the engine is off.

Perhaps there is another fuel related pulsing noise / purge valve?

You said your noise is at "idle" ie engine on which in theory should rule out the DMTL pump. DMTL runs only when certain test cycles / conditions met.

It's part of the evap loss system / fuel system. DMTL = "Diagnostic Module for Tank Leakage"

A couple points from the service manual:

- On North American Specification and China market vehicles, there is an additional DMTL system. The DMTL system allows the fuel vapor system to be pressurized and therefore allows detection of a leak.
- The DMTL pump only operates when the ignition is OFF

 

Thanks guys.....well now I don't know what it could be, but the tapping noise is coming from the precise location of the DMTL pump without a doubt.

 

The area I circled is exactly where the tapping noise is.

 

Bumping my post for any more ideas on what is making the rapid tapping noise heard inside and outside of the Defender in the drivers side rear wheel well area. My dealer is also researching this. My 2022 did not make this noise, my 2023.5 is.

Above docs showing official LR diagrams state the DMTL only runs with the ignition off, so that totally negates the DMTL because I hear the tapping noise only with the Defender idling. Could it be the fuel pump?

Thanks

 

This is a good mystery indeed!

You may not be wrong about the fuel pump ? In high school I was a car jockey (court jester? valet parker?) at a Saab dealer -- and early 9000 Turbos were coming back with a rapid fire tapping noise somewhere in the firewall area. Took SAAB and the dealers a moment figure it out and issue a bulletin. It wasn't an "unpleasant" noise per se, sort of comforting in a way, but it was very noticeable at idle. Turned out it was a fuel line that needed to be damped -- pulses from the fuel pump in a hard line. Only affected certain VINs...