I'd like anyone to post if they have had a problem with a tick / knock that they've sucessfully fixed. From reading on here, a lot of the problems are caused by the common cracked exhaust manifold. Another reason is the 4.0 is just notoriously loud. I'm talking about a tick / knock that is loud enough to be heard across the parking lot, or in the jeep at 30 mph. So, let's rule out the exhaust manifold and the natural noise of the 4.0. Has anyone had a problem they've found and fixed?
The 4.0L Engine Ticking / Knocking Thread
seabass2020
1 - 20 of 74 Posts
Joined
·
508 Posts
I'd like anyone to post if they have had a problem with a tick / knock that they've sucessfully fixed. From reading on here, a lot of the problems are caused by the common cracked exhaust manifold. Another reason is the 4.0 is just notoriously loud. I'm talking about a tick / knock that is loud enough to be heard across the parking lot, or in the jeep at 30 mph. So, let's rule out the exhaust manifold and the natural noise of the 4.0. Has anyone had a problem they've found and fixed?
Joined
·
429 Posts
Mine ticked for a couple months, it was something in the cylinder. I thought it was a lifter, but i dont think it was. My jeep is at the shop right now getting a new engine. Word of advise: do not wait. It is costing me alot of money now.
Joined
·
508 Posts
Do you know what the cause was? Did a piece of the piston break off in the cylinder?
Joined
·
898 Posts
I had a sticking lifter on a few cold mornings, oil change fixed that pretty well.
Joined
·
508 Posts
I changed the oil in mine, and it didn't seem to help. The ticking / knocking is pretty loud when I first start it up, it calms down a little after the engine warms up, but it's always there. I think it's been getting louder also. It's definitely not an exhaust leak or the "normal" noise of a 4.0.
Jeep Diagnostics: Vehicle Noise
Ticking or tapping sound from the engine:
This typically occurs when the vehicle is cold, at start up. Once warm, the noise usually subsides or goes away. This indicates a valve tappet going bad. It can go on for months or even longer. It means eventually you'll need to replace the tappets (and keep an eye on your valves). You can get to most tappets by removing the valve cover.
Many Jeep vehicles (mostly those with the 4.0 engines) have tappet sounds that owners just live with (or add a little extra oil to reduce the noise). You won't hurt the engine running it with this sound. If it's an older engine and you're getting more and more tappet sound, I'd suggest keeping an eye on your compression (to know if the valves are going bad).
Once the noise seems to not go away as quickly, I suggest you get it to the shop or pull the valve cover and make the necessary repairs.. Keep plenty of oil in the engine, and consider using supplements like oil additives (Lucas, STP, etc.). These thickeners will help the valve parts continue working smoothly until you can get them fixed. Change your oil often - every three months or 3000 miles.
I hope this helps
Ticking or tapping sound from the engine:
This typically occurs when the vehicle is cold, at start up. Once warm, the noise usually subsides or goes away. This indicates a valve tappet going bad. It can go on for months or even longer. It means eventually you'll need to replace the tappets (and keep an eye on your valves). You can get to most tappets by removing the valve cover.
Many Jeep vehicles (mostly those with the 4.0 engines) have tappet sounds that owners just live with (or add a little extra oil to reduce the noise). You won't hurt the engine running it with this sound. If it's an older engine and you're getting more and more tappet sound, I'd suggest keeping an eye on your compression (to know if the valves are going bad).
Once the noise seems to not go away as quickly, I suggest you get it to the shop or pull the valve cover and make the necessary repairs.. Keep plenty of oil in the engine, and consider using supplements like oil additives (Lucas, STP, etc.). These thickeners will help the valve parts continue working smoothly until you can get them fixed. Change your oil often - every three months or 3000 miles.
I hope this helps
Joined
·
3,919 Posts
Joined
·
508 Posts
Thanks for the link. An interesting thread, but definitely not what my problem is. Mine does it at idle, WOT, and anywhere inbetween constantly.
Joined
·
520 Posts
I had such a knock. Loud when cold, then would go away. Over time it became louder and would become worse on acceleration. I thought it was the lifters. So I took the engine apart and replaced them, the sound was still there. (all pistons looked good from the top)
I then used a long screwdriver to pinpoint the knock to cylinder #1. I then dropped the oil pan and found these...
![Image]()
![Image]()
![Image]()
Luckily there was no scoring to the cylinder wall. I replaced the piston and all has been good. :2thumbsup:
I then used a long screwdriver to pinpoint the knock to cylinder #1. I then dropped the oil pan and found these...
Luckily there was no scoring to the cylinder wall. I replaced the piston and all has been good. :2thumbsup:
Joined
·
508 Posts
wow, so it was running fine with your piston in that condition? I don't feel any power loss at all.
Joined
·
508 Posts
Using the screwdriver, could you hear the knock from the top of the engine?
Joined
·
508 Posts
Well crap, I just dropped the oil pan really hoping to find a piece of cylinder laying in there, but nothing! Anything else I could / should check while it's down? Any other ideas on where the knocking could be coming from?
Joined
·
39 Posts
I too have the infamous knocking problem. I have been using Mobile one in the engine since I bought it used. Luckily I also bought an extended warranty and will be taking it to a shop with a good Jeep Mechanic there. I'm hoping they can find the problem. 
Joined
·
8,854 Posts
The 4.0 in my MJ had pretty severe piston slap for the last 100,000+ miles of it's life. Then a valve keeper broke and caused an ugly mess. Good reason to build a stroker. My point being, if your top and checks out good you may just have to live with it unless you want to replace and/ or rebuild your bottom end. I pulled my head and oil pan when it started getting bad and when I saw what it was I decided to run it until it died. 100,000 later it wasn't even the loose piston to cylinder clearance that killed it...
Same problem as poppy .... only had 2 pieces of piston skirt and ring area was still intact ... ran fine ... only 2 hours of driving after knock/ticking started ....
I put all new pistons,rings & bearings in ....
How is your oil presure ?? less would indicate bearing problem ...(mine had not changed)
Knocks can also come frome water pump, alternator, timing chain. which would be heard from the front.
Take the fan belt off & run it .. also ...
I put all new pistons,rings & bearings in ....
How is your oil presure ?? less would indicate bearing problem ...(mine had not changed)
Knocks can also come frome water pump, alternator, timing chain. which would be heard from the front.
Take the fan belt off & run it .. also ...
Joined
·
123 Posts
My 4.0L had been making a light ticking for a long time and I always just chocked it up to rocker noise, as every other Jeep my family has owned has had the same ticking and that has always proved to be the problem. Then someone stole my oil about a year ago (engine didn't burn oil before and doesn't now; but all the oil mysteriously disappeared overnight with no leaks) and I probably drove at least a 100 miles like that before I fueled up (check the oil when I get gas and the engine didn't run or sound any different).
That said, since then the tick got slighter louder and louder and now its downright blaring loud. Sometimes the engine doesn't do it at all, sometimes only when cold, sometimes it'll do it regardless of temperature or rpm. When it does do it though, it'll instantly stop if you give the engine just enough gas to not accelerate but not let it engine-brake either. If you throw it in neutral or push in the clutch, it'll start ticking again.
The ticking is distinctly different from knocking and I would almost call it a stuck valve, but I've heard a stuck valve and it is deafening; this is loud but not that loud. If it gets any worse, I'm afraid I'll have to tear the head down.
How hard is it to replace the rockers and tappets and anything else that may be the culprit in the head? I can't afford the time (if I do it) or money (for a shop) to completely tear down the engine or even remove the head. But if you can replace the parts from the top of the head (just remove the valve cover) then I can handle that just fine.
That said, since then the tick got slighter louder and louder and now its downright blaring loud. Sometimes the engine doesn't do it at all, sometimes only when cold, sometimes it'll do it regardless of temperature or rpm. When it does do it though, it'll instantly stop if you give the engine just enough gas to not accelerate but not let it engine-brake either. If you throw it in neutral or push in the clutch, it'll start ticking again.
The ticking is distinctly different from knocking and I would almost call it a stuck valve, but I've heard a stuck valve and it is deafening; this is loud but not that loud. If it gets any worse, I'm afraid I'll have to tear the head down.
How hard is it to replace the rockers and tappets and anything else that may be the culprit in the head? I can't afford the time (if I do it) or money (for a shop) to completely tear down the engine or even remove the head. But if you can replace the parts from the top of the head (just remove the valve cover) then I can handle that just fine.
1 - 20 of 74 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
