Have a 1996 B2500 van, 3.9 engine, 148,000 miles. It has what I'm sure is a timing chain rattle: it's only at idle, goes away when revved and when driven. Truck runs fine.

I've read through a lot of posts on this forum and it seems the rattle is common. Do these things ever break? Is there an obvious sign that replacement is needed?

Moving from East Coast to California; I have to drive it 3,000 miles at the end of next week. If the rattle at idle is just a common annoyance, I'll replace it later. If it's a sign that the chain will break or slip any minute, I'll replace it myself. Gotta know before I pack my tools: I have a lot of them and they are getting loaded first as I need to load the heavy stuff on the bottom. Having my van roll over because 1/2 ton of weight is on top layer will be worse than having the timing chain slip!

 

If it makes ya nervous, replace it. Not that bad of a job, and with your mileage, you should pick up a bit of power due to the stock unit stretching. Really not such a bad idea.

 

I spoke to my Dodge mechanic: he said that if it's only at idle I can wait until I get to CA and start working. He felt that if the guides were seriously loose it would get louder when revved and driven, not quieter. If I have time I'll replace it before leaving; but half my tools are already packed and I have about a zillion other things to do between now and when I leave.

All I really want to know is if a rattle like that is likely to break the chain or slip on the gears. It seems slipping a tooth can happen if they are really loose, but breakage is uncommon.

Anyone have knowledge otherwise?

 

It's a rare occasion indeed that I have actually seen one that failed, just from being old. (well, the old fords with the plastic cam gears were pretty failure prone.... we don't have that problem though.)

There are no guides in there. The chain is held in place by the gears. That's it. No tensioner, nothing. The chain would have to be REALLY sloppy to be able to slip a tooth. I don't think it can actually stretch that far. Not enough chain in there. Makes your injector timing bounce around though. (the sensor in the dist has nothing to do with ignition timing, it simply controls injector timing.)

 

NO: 09-07-97
SUBJECT: Timing Chain Noise
DATE: Jun. 27, 1997
NOTE:THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 3.9L ENGINE.

SYMPTOM/CONDITION:
Rattling or lifter type noise coming from the front (chain case) area of the engine.

DIAGNOSIS:
Start the engine and bring it to operating temperature. Increase and decrease engine RPM slightly while listening to the front end of the engine for a rattling or lifter type noise. A stethoscope can be used to help pin point the noise location. If the noise is found coming from the timing chain case, perform the Repair Procedure.

PARTS REQUIRED:
Quantity Part No. Description
1 83507095 Timing Chain and Sprocket Package
1 53021057 Gasket, Timing Chain Case
1 02129013 Gasket, Water Pump 1990 - 1991
1 04483757 Gasket, Water Pump 1992 - 1997
1 4897297AA Seal, Front Case 1992 - 1997
1 03830109 Seal, Front Case 1990 - 1991
1 53021195AA Tensioner, Timing Chain



REPAIR PROCEDURE:

This bulletin involves replacing the timing chain and sprockets and installing a timing chain tensioner.

Following the appropriate service manual procedures, disassemble the front end of the engine to gain access to the timing chain and sprockets.
Remove the chain and sprockets from the engine. Discard the parts.
Remove the thrust plate and chain oil tab (Figure 1). Discard the parts.
Install the timing chain tensioner p/n 53021195AA in the position where the thrust plate and oil tab was installed (Figure 2). Torque the bolts to 24 Nm (210 in. Lbs.).
Install the new timing sprockets and chain p/n 083507095. Align the timing marks per the appropriate service manual procedure. Torque the camshaft bolt to 68 Nm (50 ft. Lbs.).
Remove the lock pin that holds the tensioner plate for the chain. Discard the pin.
NOTE:WITH THE TIMING CHAIN TENSIONER INSTALLED, THE CAMSHAFT END PLAY WILL BE 0.051 - 0.330MM (.002 TO .013 IN).

Reinstall the remaining components per the appropriate service manual procedures.

 

in my limited view of the world i've never seen a timing chain break.
i have seen them slip on the sprocket, but usually not till about 250-300K miles.
i've also seen them so loose they slap the cover on one side, and still not slip...

you'll be fine. drive on.

 

If there is a bulletin posted on this for this engine, then get the chain replaced. You dont want it to skip and come off or break. If your timing chain is gone the engine will destroy itself.

I wouldnt say it needs fixed asap but get it done when you can... and FYI look up how to do it.. Believe it or not its really easy to replace them it just takes time, you dont even need special tools except to rent a harmonic balencer puller (assuming the 3.9 has one which i dont think it does ..only the 5.9, but still

 

all engines will have the harmonic balancer.

 

Sorry to get off topic, but I HAD to seeing that HeyYou is now a mod!!! Congrats Bud!!! It couldn't have happened to a better man!!!

 

Thanks.