Anyone Heard or Experienced a Leak at the Throttle Body Spring?

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Mar 21, 2025 | 12:50 PM

Mac Allan

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From: California

Anyone Heard or Experienced a Leak at the Throttle Body Spring?

Since the AJ34 engine was used across so many Jaguar models, I thought I would post the question here (car in question 2004 VDP 4.2 135K miles).

A couple years ago I had the dreaded lean codes and chased down a lot of leaks including replacing the eight upper plenum ring gaskets, the two lower intake manifold gaskets and other gaskets, o-rings etc. to finally get it sorted and running well again. However, lately it started to run poorly when started from cold, but would run normally once warmed up. When started cold, fuel trims suggest an intake or vacuum leak.

I set up my smoke machine to look for the leak, and it took a few attempts of starting the smoke machine looking for leaks, stopping to let the smoke clear, repeat, etc. to pinpoint where the smoke was originating. It's coming from the Throttle Body spring. In order to see it clearly I had to actually be staring at that spot when the smoke machine first started.

Before I spring for the cost of new Throttle Body, I wanted to check if it makes sense that there would be leak at the spring?

Thanks for your help!