HELP with Tapping sound!!!
 

My SD started making a funny knocking sound yesterday. It reminds me of loose valves a little but not quite. Also it is loud enough that I didn't want to just keep driving it. It is kind of like a double tap one louder than the other once or so a revolution.

So I pulled off the VC checked all the valves and all are good. I also thought it might be the chain stating to come apart but it looks fine also. With the cam marks lined up it reads ~3.5deg. at the crank.

However I got it to recreate the sound while manually turning it over. It is coming from the area of the vaccume pump and IP.

As I slowly rotate the motor it makes a creaking(something being conmpressed?) sound for about 20 degreees of rotation and then a light knock followed by a louder knock within another 5 degrees of rotation. It seemed to do it at least 2X per revolution.

I'm a little worried and wont drive it until I have it fixed.

Any help will be greatly appreciated!

Thanks,
Stephen

did you experience anything funny before the knocking noise started. you haven't given enough information

I forgot to say that there are no other problems other than the sound. The car is running exactly the same as before the sound started.

I am thinking it is something in the vacuume pump. Is it even possible for it to make a loud tapping noise?

Thanks,
Stephen

Also can the IP be having a problem that is causing the noise. I don't remember reading of this type of symptom on an IP failure.

Stephen

That vacuum pump can breakup and if you are very lucky will give you some advance notice, like noise.
Other times it starts throwing parts around. Not to common, but it does happen.
Take it off and look at it now. Could save an engine later.

Old Dies is right on. A tapping sound coming from the vacuum pump is a warning. If it fails, it will probably take out the timing chain with a resultant catastrophic failure when valves meet pistons. Check the vacuum pump before you go anywhere with it.
(Don't ask me how I know....)

Cheers,
Wes

OK, now I have a starting point!

Is there any reason to leave the valve cover off when R&R ing the Vacuume pump?

I know nothing about the process so It's off to search the archives I go. I still have vacuume but I guess that may not be indicative of pending failure?

Thanks Much,
Stephen