I have a 1999 Jeep Cherokee with the 4.0 6 cyl., I noticed a light valve tick 1st thing in the morning at start up when I got it home(when its been sitting overnight) when cold, its only does it first thing in the morning and then completelly goes away when its warmed up.....??? What could it be?? Sometimes it doesn't do it at all....The motor was rebuilt 90,000 miles ago, it has 165,000 miles. Two very compitent mechanics I know said its normal in Jeeps with the 4.0 6 cyl. engine (as well as a lot of other cars) its just from the oil draining back down to the pan overnight, and its nothing to worry about. could it be just as simple as a valve adjustment?? I'm selling the Jeep to a friend in 2 weeks, and I want to make sure its o.k before I sell it to him....

 

I could be wrong but I don't think you have much to worry about.

If the valve is making noise than at least it's closing all the way, it's the quiet valves that burn up (This has been my experience wrenching on motorcycles). Once the motor heats up the little bit of clearance you have in there is being taken up hence it quieting down.

 

Change it back to standard 10W-30 oil and see if the lifter tick goes away.

 

I would not be concerned about it at this point,it is not that uncommon. you might try a heavier weight oil like 20-50. Other than that you could check the valves and see if they are set right,not needed on hydraulic valves but sometimes it does not hurt to check. It is a simple process in cherokees.

 

Thanks!! I did change it back to regular 10W-40, and it still did it the next (this...) morning...for like 3-4 minutes then once it was warmed up, and "off idle" it went completelly away, and the valve tick goes away comletelly all day/night then (everytime you start it after the 1st time in the morning, its 100% fine no valve tick at all...), untill I start it the next morning (some mornnings it doesnt even do it at all).... If I needed a new head or valve work wouldn't it do that all the time??

Also, it runs friggin awesome!! Its like a tank, has great power and is fast....runs like new (the engine was replaced at 90,000 miles)

Is the valve lash adjustable on a 99 6 cyl. 4.0??

 

How do you check the valves to see if they are "set right" valve lash/adj. on a 99 cherokee 4.0 6 cyl?? Are they hyraulic??

 

The lifters are hydraulic. You have one or more that is losing its prime after sitting.

It takes it a little bit to pump back up after cold start.

The noise you are hearing is the collapsed lifter striking the pushrod. Since the lifter is collapsed, there is a gap between the lifter and pushrod that isn't supposed to be there.

The 4.0 probably has positive stop rocker arms. Once they hit that stop, there is no more adjusting. But I'm not certain of that.

 

Yes they are hydraulic,the way I set mine is to put it at t.d.c and torgue loosen all rocker arms and then retighten to 19ftlbs,I looked up 99xj and they say 21ftbs,they did not mention it had to be at t.d.c. Top dead center. you need to get a manual or find the info that says it has to be at t.d.c. I would not be to worried at this time about the lifter noise,but if you would like to check them that is how it is done.
Once hyd lifters are set they do not need to be readjusted unless you have done some repairs that required you to remove them.