I just bought a van not long ago. I didn't noticed this noise till today and after a oil change. Its not as loud when I rev it up like it does on his. If I put my ear on the intake manifold its louder. Wondering is these noises are common on caravans with high miles or should I start saving for a engine? Seems to run good otherwise. It sounds like this(video I found online).

 

I suspect that it is something out in the open, like on the serpentine belt, maybe the idler or tensioner. At over 100K mi (as in my case), those should get replaced anyway. Probably all original. I have a sort of muffled "diesel engine" racket at idle that is mostly drowned out by the "normal" sound of the engine. When accelerated, it is not perceptible. It too sounds like it might be coming from the intake manifold, but a stethoscope tells me it isn't. I haven't confirmed since I don't want to go near the serpentine belt with a stethoscope and the engine running. I just need to find the time to repair it, but for me it is currently a low priority issue. How's your engine performing? Anything else unusual happening?

 

When cold the sound is more noticeable from the rear valve cover. I don't see the sound being something on the belt side but I'm new to these engines so you could be right. I looked at 4-5 caravans/town and country's on youtube where the user was giving a tour of the vans. I think he was selling(auto place?) and everyone of them had this noise(sort of a tacking sound).

I am betting the previous owner put thicker oil or some additive to quiet the noise down. It definitely wasn't there until I changed the oil and drove it some. I'm taking the rear valve cover off soon to change the gasket what should I look for under there? Other than the sound the engine seems to perform good.

 

This is a direct quote from the 2007_RS_Caravan.pdf document (520 pages). It might cover your vehicle since we both have 4th generation vehicles.
I'll have to listen to the rear valve cover on mine too. I was in a hurry before when I did my preliminary listening. The front valve cover did have a rhythmic type of sound, but much quieter and more sparse pattern from the constant diesel-like clatter. I'll have a listen to it this evening and post back, now that the weather is getting nicer.

 

Just an update to my last post. I got an actual automotive stethoscope from NAPA yesterday instead of trying to use an old medical one. The biggest difference is that it has an 8" long metal probe which screws into the drum. It could still get dangerous if something got caught in a moving part, but most likely it will just yank it apart if something gets caught. Still a much better option and safer than listening with a solid object such as piece of wood, a broom handle, etc. Just be sure to use eye protection, work with a bright light and use a steady hand, and be sure not to stick it onto any moving parts or near any holes. ** such as with the generator**

** As a side note, I was startled by some very loud sounds that it made as the probe scraped past some stationary objects. This might startle you and cause you to jump if you don't expect it. Just be forewarned. **

Anyhow, to get on with my listening. So far I only tried to reach things from the top. Here are the parts that checked out so far (I didn't remove any of the air intake parts):

front valve cover
intake manifold
rear valve cover
gen
A/C
idler
PS pump

so that leaves me with things I can reach more easily from the underside:

water pump
tensioner
engine underside/oil pan
harmonic balancer area

I will need to get it up on a lift to check those. I would suspect though that it is the water pump, just due to past experiences with motor vehicles.

 

I don't know myself. I changed the rear valve cover gasket and nothing seem loose, cracked or broken. All I know is it sounds like my bro inlaws cummins diesel but not as loud. Above 1200 rpms it about goes away. It didn't do this till I changed the oil to 5w30 Pennzoil. I don't know what the previous owner used since I haven't had the van that long. They probably used 2 quarts Lucas 3 quarts oil.