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

__________________
85 300D 305K miles WVO(105K so far), Mine
82 300SD 235K miles BIO-D, Wifes
96 F250 SC PSD 4X4 285K MILES BIO-D, Ours
89 BRONCO 182K MILES sold
Finally Compression Ignition Only!

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

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71 220D 169K wrecked
83 240D 118K sweet 4 speed
91 350SDL (one of the 60% good engines) 156K
84 300d (loaner to my sister) 189K
79 300SD (partswagen)
86 420SEL partswagen
70 220d (partswagen)
68 280s GASSER!!! under construction now
85 300sd 310K miles winter beater car retired
93 300d 2.5 turbo 168K wife's car
83 280SL euro 5 speed 155K
69 250S newest project 54K

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

__________________
85 300D 305K miles WVO(105K so far), Mine
82 300SD 235K miles BIO-D, Wifes
96 F250 SC PSD 4X4 285K MILES BIO-D, Ours
89 BRONCO 182K MILES sold
Finally Compression Ignition Only!

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

__________________
85 300D 305K miles WVO(105K so far), Mine
82 300SD 235K miles BIO-D, Wifes
96 F250 SC PSD 4X4 285K MILES BIO-D, Ours
89 BRONCO 182K MILES sold
Finally Compression Ignition Only!

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

__________________
85 300D 305K miles WVO(105K so far), Mine
82 300SD 235K miles BIO-D, Wifes
96 F250 SC PSD 4X4 285K MILES BIO-D, Ours
89 BRONCO 182K MILES sold
Finally Compression Ignition Only!