engine noise

Slightly over 1 year ago i replaced the fuel filter. I was paying attention when i tried to start it for the 1st time, since I remember years and years ago some fuel injection vehicles sometimes were tricky or hard to start after the line was open during filter replacement. Toyota does not list this as a maintenance replacement part. Well, it started right away. however, there was a clicking noise after the engine started. It clicked 6 or 8 kinda rapid clicks, then the clicking stopped then another noise started. that other noise was just a regular standard sounding engine noise, but it was absent when the engine 1st started until the clicking stopped. Its about 3 to 5 seconds of clicking before that stops and the other engine noise starts. The pause between the last click and the noise indicates to me that the additional noise is not drowning out the clicking sound.

Additional noise might be a vacuum pump?

The above noise has continued to this day.

Its clicking is absent when starting hot or even if i just run the engine for 10 to 20 seconds then turn it off and on again. However, if I shut it off right away after just a second or two and start it again I might get the clicking and noise afterwards a time or two, but maybe just 2 or 4 clicks instead of 6-8.

I need to say this too. That this may have always been like that. Its just once I was specifically paying attention because it might be hard to start, I was listening carefully so more likely to hear this and its been on my mind ever since. So most times I start the truck, I now hear it. I have lent the truck to others in this time and asked them if they heard anything unusual when starting and they all noticed nothing. However, when I point it out, then start the vehicle in their presence they notice it and each has their own idea of what it might be.

I went on a long trip a month after replacing the filter and Im planning another long trip in a month or two.

2.4L

Ideas?

thanks,
paul

Interesting. I'm not much help but it sounds like you've got an interesting situation. I've got a fuel filter sitting on the work bench waiting to go in and this caught my eye. I've got a 3.4 but I wonder if the same could happen with mine. I do get some clicking from the emission boxes on the driver side fender but they are constant and most audible when it's very hot outside. With the hood closed you can't hear them.