I drive a 2002 Tj with a 4.0 and it has had a small tick after a few seconds after a cold start and it comes and goes until it is totally warm. Just recently I started the cold engine and it produced a much more violent tick almost like a knock, the engine ran much less smooth as well. I shut off the engine then started it again and it went away. what could this be and should I be worried?
4.0 engine tick / knock on when cold
- Thread starter rhauseriii
- Start date
This is pretty common for 4.0s, and is almost always lifter tick.
You don't need to worry about it, but if it bothers you a lot, you can always replace the lifters.
In rare cases it can be rod knock, but rod knock doesn't usually go away when the engine warms up. It wouldn't hurt to do a compression test just to see what your numbers look like.
You don't need to worry about it, but if it bothers you a lot, you can always replace the lifters.
In rare cases it can be rod knock, but rod knock doesn't usually go away when the engine warms up. It wouldn't hurt to do a compression test just to see what your numbers look like.
Chris (or anyone) why is lifter tick so common for Jeep 4.0L engines? Is it because of engine design or just a fallacy of hydraulic lifters in general? The only time my Jeep will tick (about 1-2 seconds) is during the winter when the temperature outside drops below low 50's. During the summer with the warmer temps it won't tick at start-up....at least not yet. Ha!
I also had a tick in mine,ended up being this.
https://www.amazon.com/dp/B00NEW6GTA/?tag=wranglerorg-20
https://www.amazon.com/dp/B00NEW6GTA/?tag=wranglerorg-20
Could also be a cracked exhaust manifold, which may explain why it goes away after a few seconds.
ejay
TJ Addict
+1 Very common issue. That, and a intake manifold gasket going bad. Basically the same area and problem. You may also want to try a zinc additive. These 4.0 like their zinc. Helped me years back. There may be others here that say it's a wives tale but it works.
Raymund
TJ Enthusiast
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Excellent post. Don’t forget the 4 pre cat bolts . Notoriously for working loose and freezing that way giving the illusion they are tight .
I'll speak from an old school point of view. If it is a hydraulic lifter, lifter clatter often begins at around the 100k+ mark. They operate on oil pressure and do get deposits of dirt and residue that can build up from age, poor maintenance, lower quality oil, etc. We used to use Mystery oil in the crankcase and fuel to keep the lifters and valves healthy, and then replace the lifters when the clatter got too annoying. Sludge and deposits keep the lifter from fully operating. Not saying that is what is going on here, but age, mileage, wear, and contaminants can take their toll on valve lifters. They can also clatter and complain with these engines for years. The exhaust manifold gasket is an evil ventriloquist that can mimic many frightening conditions just to F with you.
MallCrawlOnTons
TJ Enthusiast
A buddy of mine was convinced to use Lucas oil stabilizer after turning the little marketing gimmick at the checkout at autoZone. You have one? It’s the little vertical 3 gear oil slinger in clear plastic case by the cash register.
It says it took his startup tick away.
It says it took his startup tick away.
Really appreciate the feedback here regarding lifter tick! Here's a bit more information on my Jeep. I'm the original owner as it was purchased new in 2001. When new I was running Castrol full synthetic oil and made the switch to Valvoline High Mileage oil at about 39,000 miles. I changed my oil faithfully thru the years and currently only have 61,500 miles. I will be sure to check what ya'll suggested above regarding cracked exhaust header and loose cat bolts but my tick is so brief...1-2 seconds...seems like if something was loose or cracked it would tick longer AND it would tick during the summer which it never does?
Let me run one theory by ya'll and let me know if this makes sense or could be a possibility....could the cooler temps cause one of my lifters to bleed-down which helps explain why it never ticks during warmer months? Something else I was thinking....if some contaminants were to blame looks like it would tick regardless of outside temperature which it doesn't?
Let me run one theory by ya'll and let me know if this makes sense or could be a possibility....could the cooler temps cause one of my lifters to bleed-down which helps explain why it never ticks during warmer months? Something else I was thinking....if some contaminants were to blame looks like it would tick regardless of outside temperature which it doesn't?
A lifter clacking for a few seconds after start up would not worry me. You rig could do that for another 200K.
BTW, an additive for cleaning and helping lifters is not a bad idea. It is one area a mechanic in a can actually can work.
MallCrawlOnTons
TJ Enthusiast
X2, I had the same issue, be sure its not your OPDA, it will cause significant wear on the cam if not addressed