I was bleeding the hard injector lines on my '79 240D, which of course caused fuel to dribble down the injectors to puddle in the depression in the head where the injectors are screwed in. The bleed was successful, and I started the car, which ran reasonably smoothly (all cylinders firing). On my #1 cylinder this puddled fuel at the base of the injector began to blow up into bubbles at idle. The bubbles would form at the base of the injector, blow up to a certain size (say, about a 1/4" high and 1/2" across) and then pop, repeatedly.

The car is running pretty well, but it makes me wonder if I should pull that injector and replace the heat shield under it? Other possible causes?

Thanks,

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).

About ounce a month someone will past a similar issue.

The Injector threads into the Prechamber Retainer Ring/Collar. Under the Collar and between where the Injector seals on the Heat shield is an empty space around the Injector.

Liquid that gets into that space is going to react to the Heat and the shockway created by the burning Fuel in the Combustion Chamber. When the Engine is still cold but running put your Finger on the Injection Line and go down to the Injector. You will feel a lot of vibration.

So the Bubbles could be caused by the above or you could actually have a leak at the Heat Shelds as you suspect; or even the Prechambers.

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84 300D, 82 Volvo 244Gl Diesel