My 95 1500 v6 has a "ratteling" noise coming from the bottom end of the engine. It seems loudest at the front passanger side of the engine, but is also quite noticable from the front driverside of the engine. It has done this since I recently got it, but is now louder since putting seafoam in with the engine oil. Prior to the sea foam, it sounded more like a heat shield or something rattiling around. Now it sounds like someone shaking a spray paint can. The sound doesn't increase with engine speed, and actually becomes less frequent with the engine revved a bit.

Here is what I know:

Sounds like someone shaking a paint can

Loudest from front passanger side of engine

Also loud from front driverside

Does not increase with engine speed

Got louder when I put a can of seafoam in the oil

PO had oil changed at Wal-Mart, and they used 5w-30 and a crappy FRAM filter

I recently did the plenum repair, and took the oppurtunity to check under the valve covers...everything was tight and looked great.

During the plnum update, everything in the lifter valley looked good, and wasn't unusually dirty, bent, worn, etc

I changed the oil pressure sending unit will I had the manifold/plenum off, and I appear to have good oil pressure (I know factory gauges aren't great)

Anyone have any suggestions where to start? I don't know if the timing chain has been replaced before, but based on the fact that its loud from both the front corners, I have a suspicion it might be slapping the cover? I also JUST finished changing a leaking water pump, so that would be just my luck.....lol

 

Have a look at the damper as well. They can exhibit some odd behavior.

 

did it just start or are you just now getting around to it? i have owned 3 3.9's over the years and all make a similar noise. most responses i ever got from mechanics was "its a dodge" so i am interested to see when yours started.

 

could be a bad cat rattling around, at first i thought the sound was my engine, then i thought it was my trans, finally found out it originated from the cat and echoed off the ground.

try to crawl under the passenger door and hit the cat with a solid object (hammer, 2x4, ect) if you hear that oh so familiar sound then you found the culprit.

 

It started doing it before I purchased the truck from a family member that knows nothing about cars (don't know exactly when it started). It sounded like a loose heat shield to me at first, so I put it of unitil now. I put a full small can of sea foam in the crankcase, because I get a couple of taps on startup sometimes. The tap is probably just due to the crappy FRAM oil filter, but I figured I would clean the crankcase, change the oil, and use a better oil filter. I wasn't expecting the ratteling sound to get louder, but it did. It sounds like someone spinning an empty spray paint can around in a circular motion. The cat was recently replaced due to the oil getting into the plenum, so that shouldn't be a problem. I have heard of the material on the damper spinning loose, but mine seems to be solid. I have been doing a lot of internet reasearch, and the 3.9 is notorious for timing chain slop. From what i've read, as long as the chain doesn't phisically break it should be OK. I know there is a method for checking the timing chain slack without removing any parts, so I may have to give that a try. Sure would be a lot easier if the dizzy was mounted at the front of the engine though.

Although its a fairly loud noise, it doesn't sound like a rod hitting the block or anything that severe. The sound is more of a mettalic rattle than a knock.

 

cant swear it it timing chain slop but have read many things about it as well. also have read a few internet postings regarding the installation of a tensioner. looking at a few parts houses it appears a tensioner can be purchased for around 50 bucks. i may consider this and replace the timing chain if i can resolve my other issues.

 

I just found several videos on youtube of 3.9's with the timing chain noise, and mine sounds just like it (though not as loud...yet). I guess now I need to determine how much slack it has and decide if its something that can wait for awhile. It sounds like plenty of people are willing to live with it, and the only danger is if it actually snaps and destroys the valvetrain.

 

Or wears a hole in the side of the timing cover.......

 

From what i've read, the updated version with the tensioner doesn't always sovle the problem either. A few things I read even suggested that the tensioner can contact the cover itself. Apparently the only way to solve it once and for all, is to dish out the cash for a quality, double roller set. I just spent all afternoon yesterday replacing the water pump, so i'm not eager to rip it all apart again. Even worse, the pump was fine when I was replacing the plenum gasket, it waited until a week after I had it all put back toghether to start leaking. Getting all the stuff off the front of these trucks is a real pain.

 

Well i've been looking around, and many people think that a double-roller timing set is the best answer to this problem. I was expecting the cost to be 200 bucks or more, till I found this at Summit http://www.summitracing.com/parts/CL...n/?prefilter=0

It says it works with the 3.9, and its a true roller, double roller set. Should I go with this or the updated factory part that many claim doesn't work? I know how to change a timing set, but i've never actually done it yet.