Timing chains start out pretty tight. After just a few minutes of running they get some slop on the side thats not pulling the cam. A timing chain has to be pretty loose to actully come off the sprockets. W/O actully measuring the slop theres no way to tell how bad it is.

But they are not snug like a belt is.

 

I don't think it is in danger of falling off the sprockets, nor did I hear any abnormal rattles from it, but for how close the cam is to the crank on the 4.0, there seems to be more slop then needed.

 

if your there i would replace it. whats it cost? and considering your already in it.

steve

 

Here is the short video I took of it

 

For anyone that has rebuilt a 4.0 or replaced timing chain etc... Is this normal?

 

thats really not much at all. At work i've seen some start sawing threw a cover there so loose. I wouldnt worry about it.

 

that chain is out of spec. it should be replaced.

i've seen them stay nice and tight till 200k and i've seen them sloppy like that after 30k. luck of the draw.

straight up replacement of a timing set is easy, just buy the chain. only like 25$.

 

That looks like a lot of slop to me. I'd tear the cover off and investigate.

 

I know timing chains aren't normally a problem on the 4.0 especially with only 92k. But my TJ hasn't exactly been the most trouble free vehicle - several repairs needed that, IMO were way too soon mileage/age wise.

Other then helping on engines when younger - my timing chain experience pretty much is with the BMW M42, which was rather complex with crank, intermediate and dual overhead cam sprockets as well as a hydraulic tensioner and plastic guides. That chain ran tight and this much slack would have torn things up.

Since the 4.0 isn't an interference engine, there isn't much to worry about - but if he chain was loose that would have an impact on timing and work against performance/mpg etc...

 

I should also note that I did not turn the engine either way to add/subtract slack from that side of the chain, it is just from simply shutting the engine down, not sure how much, if any slack is on the other side.

 

timing chain is cheap enough, I'm thinking about putting a new one on... Other than the chain and gaskets, anything else needed? I wasn't going to get the set as the sprockets look fine. I imagine it is rather straight forward to replace.

 

Always replace the chain and sprockets as a set. If you only replace the chain the new chain will be worn out in just a few weeks.

 

TIMING BELT/CHAIN AND
SPROCKETS
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove the fan and shroud (Refer to 7 -
COOLING/ENGINE/RADIATOR FAN - REMOVAL).
(3) Remove the serpentine drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(4) Remove the crankshaft vibration damper (Refer
to 9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - REMOVAL).
(5) Remove the timing case cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(6) Rotate crankshaft until the "0" timing mark is
closest to and on the center line with camshaft
sprocket timing mark (Fig. 91).
(7) Remove the oil slinger from the crankshaft.
(8) Remove the camshaft sprocket bolt and washer
(Fig. 92).
(9) Remove the crankshaft sprocket, camshaft
sprocket and timing chain as an assembly.
(10) Installation of the timing chain with the timing
marks on the crankshaft and camshaft sprockets
properly aligned ensures correct valve timing. A worn
or stretched timing chain will adversely affect valve
timing. If the timing chain deflects more than 12.7
mm (1/2 inch) replace it.
INSTALLATION
Assemble the timing chain, crankshaft sprocket
and camshaft sprocket with the timing marks
aligned (Fig. 91).
(1) Apply Mopart Silicone Rubber Adhesive Sealant
to the keyway in the crankshaft and insert the
key. With the key in the keyway on the crankshaft,
install the assembly on the crankshaft and camshaft.
(2) Install the camshaft sprocket bolt and washer
(Fig. 92). Tighten the bolt to 68 N·m (50 ft. lbs.)
torque.
(3) To verify correct installation of the timing
chain, rotate the crankshaft 2 revolutions. The camshaft
and crankshaft sprocket timing mark should
align (Fig. 91).
(4) Install the crankshaft oil slinger.

 

I measured it, probably not the best way as it was somewhat difficult so I measured several times. With all the slack on one side, I kept getting measurements from 1/4"-3/8". Close to the 1/2" I guessed, and also according to the above post, when it is out of limits.

I decided to leave it alone and finish up putting the new oil pan on. If I ever need to replace the chain the only main benefit from having the oil pan already off is about 4 bolts and 2 dabs of RTV.

 

With all the slack on one side, I kept getting measurements from 1/4"-3/8".

That's not much different than a new chain. You don't have a problem.

 

I would definitely leave alone...

 

I replaced oil pan at Christmas time. Mine looked loose too at 107000. I haven't done anything about it. I think it is accessed from front so oil pan I think don't have to come off.

 

The oil pan does not need to come off, but the 4 or so leading edge bolts on the pan go into the timing case, those need to be removed. It was just one of those "While I'm in there..." things that under further thought, is probably better left untouched for now.

 

Well, that's good to know. I don't have anything to compare it to, new or otherwise and my previous engine timing expereinces (belts, and one chain) were very different from the AMC 4.0 so I wanted to verify.

As much as I enjoy my TJ, it sure seems to have a lot of problems much sooner age/mileage wise then I've experienced in the past, and it is my newest, most expensive, lowest mileage vehicle I've owned. At this point, I wouldn't even put it past for the timing chain to need replacement at 92k. It's rather sad when I consider the TJ of which I am the 2nd owner purchased with 40,243 miles when it was 3.5yrs old - to be no more reliable than my '87 BMW 528e, a car which is exactly a year older than I (built in 7/86) nearing 300,000 miles and was one step away from the junkyard before I bought it - totally neglected including a major crack in the oil pump housing that caused low oil pressure - enough to keep the light on until 2,000RPM (this engine is the low RPM, high torque version with 5100RPM redline) for 2 years!. It dosen't miss a beat or leak/burn any oil between changes.

Then if I try to shift the Jeep too fast, or run it to redline - it grinds 3rd unless I double clutch. I've tried every premium fluid in it, I've accepted it as the synchros being worn out. As for the 5spd Getrag that is older than I? Seals leak a little, but I put a short shifter in it with entire rebuilt shifter linkage and the cheapest ATF I could find - shifts like buttah, every gear, any speed. It really is pathetic.

It dosen't end there, the list goes on, but now I'm getting off-topic. I just don't get how a water pump will crap itself at 58k miles, fan clutch at 65k... not to mention the failed OPDA and the mini cats that got plugged (atleast it got a new exhaust under warante) all around the same time... and the old Bimmer came stock with 4-wheel, 4-channel ABS with front brakes larger than the TJ, on a car first sold in 1983. It really is pathetic.

To think I used to be so pro-American and anti-Import too.... it's a good thing I *really* like the TJ, cause I don't know why else I really put up with it...

I took this 2 days ago when I started this phase of work on the TJ... That is Der Panzer! Really is rather pathetic when you compare the condition, age, mileage of each vehicle, not to mention one was totally abused and neglected while the other had top notch preventative maintenace and care.... and yet, which one proves to me, day after day to be more reliable. Heck as much as I really like the AMC 4.0 I6 as well, I can honestly say - BMW builds a better one. While not comparing apples to apples obviously, that old Bimmer gets twice the gas mileage of the Jeep, 26mpg town and 30mpg highway on regular gas.

Then again, if it wasn't for the Jeep, I wouldn't have the old girl! $500 allowed me to save an old tank from an immeasurable about of neglect and filth - I have a sickness with 80s era BMWs - maybe even moreso than the Jeep. Now it made a 2200-mile round trip to NY and back in less than a week without a hiccup at all.

Screw it, I'm so far off topic now, if anyone is actually interested, here is the story on that car. I haven't updated it in a long time... but you can see what I got it as.... and why I get frustrated at Chrysler because I trust it more than the Jeep...

http://www.mye28.com/viewtopic.php?t=84131&highlight=

 

i've worked on too much german machinery to view their products as anything but sub standard.

 

X2. The last thing I think about when I hear BMW is reliable.

As to your timing chain, unless it makes noise I wouldn't sweat it. At least it's not like my 22R that started wearing a hole into the cover at 80k miles.