Noisy 4.0

MrBClark

MrBClark

TJ Enthusiast
Joined
Mar 30, 2019
Messages
300
Location
Montoursville Pennsylvania
So I know I have asked this many times on this forum, but I am still dumbfounded by how noisy my 4.0 is in my Jeep. It's only loud in the morning for like 5 mins and then it makes the noise for like 2-3 mins on a warm startup. It's pretty noticeable if you are kinda near the Jeep. It runs fine. You guys have said its completely fine, but just trying to settle my nerves a bit. I also put it on another forum and they said its normal. Here is another video.



 
Well, it sounds like the infamous lifter tick. That tick is very common on 4.0s during cold starts, but typically it goes away after a minute or so once the engine warms up.

If it's not going away it may be time to replace your lifters and such.

It could also be rod knock, though that is probably less likely. Still, a compression test would be a nice thing to do, just to see where you're at.
 
Sounds like you found your lost bag of marbels. The noise is like many i've heard. They are not a quiet motor by any means.
 
Chris said:
Well, it sounds like the infamous lifter tick. That tick is very common on 4.0s during cold starts, but typically it goes away after a minute or so once the engine warms up.

If it's not going away it may be time to replace your lifters and such.

It could also be rod knock, though that is probably less likely. Still, a compression test would be a nice thing to do, just to see where you're at.
Click to expand...
It definitely goes away. Doesnt get louder when warm like most rod knocks. I definitely should do a compression test. As a side note, I plan on dropping the oil pan once I change the pre cats. Gonna make sure it's all normal looking.
 
MrBClark said:
It definitely goes away. Doesnt get louder when warm like most rod knocks. I definitely should do a compression test. As a side note, I plan on dropping the oil pan once I change the pre cats. Gonna make sure it's all normal looking.
Click to expand...

Yep, do the compression test just to see, but if it goes away once it's warm, it's happened on almost every 4.0 I've ever owned (and I've owned A LOT of them).
 
  • Like
Reactions: Feralkid
Every 4.0 I've had makes this noise, including my Cherokee with 255k and my TJ with 101k. It's the lifters. I don't think about it.
 
Thanks for posting this video, MrB. My 1998 Wrangler 4.0 (145K miles) sounds *exactly* like this under the *exact* conditions you are describing.

That "rattle" sound is what I was concerned about, and I was wondering if this was normal or not for these engines.
 
TJRick said:
Thanks for posting this video, MrB. My 1998 Wrangler 4.0 (145K miles) sounds *exactly* like this under the *exact* conditions you are describing.

That "rattle" sound is what I was concerned about, and I was wondering if this was normal or not for these engines.
Click to expand...
From what I've been told, it's normal. I personally do not like it, but I've been told it's fine unless it doesnt go away. I suppose time will tell, but I'm just gonna let it go.
 
MrBClark said:
From what I've been told, it's normal. I personally do not like it, but I've been told it's fine unless it doesnt go away. I suppose time will tell, but I'm just gonna let it go.
Click to expand...
Install a mechanical oil pressure gauge and record the reading during the noise and after. See if there’s a difference.
 
I’m going to throw out something quite controversial but I bought an ‘06 with 110k on it that had a lifter tick until it warmed up. I changed oil and subbed 1 quart of marvel mystery oil, drove about 1000 miles, changed oil again and ever since I have added a couple ounces of MMO per oil change. Tick is completely gone, huge improvement to say the least. An old school approach that might not work in every case but certainly is very safe and can’t cause any damage to try it.
 
The Mystery Oil has worked for me also. On several engines. Another trick is to add a quart of diesel fuel to the crankcase. Drive around for 5-10 minutes making sure the engine is up to temp. Then drain, change the oil and filter. This can often clean out the lifters and get a lot of crap out of the engine. Diesel has lubrication in it so it is easier on the engine than Mystery oil (which is mostly ATF). If the lifters still make a racket then add a 1/4 qt of the Mystery Oil to the new oil and call it good.
 
  • Wow
Reactions: Ephry73
Aviatortroy said:
I’m going to throw out something quite controversial but I bought an ‘06 with 110k on it that had a lifter tick until it warmed up. I changed oil and subbed 1 quart of marvel mystery oil, drove about 1000 miles, changed oil again and ever since I have added a couple ounces of MMO per oil change. Tick is completely gone, huge improvement to say the least. An old school approach that might not work in every case but certainly is very safe and can’t cause any damage to try it.
Click to expand...
How long can I run MMO in my oil? I run Rotella T6 5w-40 in my Jeep.
 
Goatman said:
The Mystery Oil has worked for me also. On several engines. Another trick is to add a quart of diesel fuel to the crankcase. Drive around for 5-10 minutes making sure the engine is up to temp. Then drain, change the oil and filter. This can often clean out the lifters and get a lot of crap out of the engine. Diesel has lubrication in it so it is easier on the engine than Mystery oil (which is mostly ATF). If the lifters still make a racket then add a 1/4 qt of the Mystery Oil to the new oil and call it good.
Click to expand...

Drain first and then 1 qt diesel + fresh oil to full?
 
Chris said:
Yep, do the compression test just to see, but if it goes away once it's warm, it's happened on almost every 4.0 I've ever owned (and I've owned A LOT of them).
Click to expand...
My first jeep was a 95 Rio grande yj, 2.5l, shittiest engine ever made. It was simply inappropriate, only slightly better mileage than a 4.0, but with absolutely no power, even at 4k rpm.

Then it was a 97 xj manual 4.0 ax15. 78k miles when I bought it. It had the lifter tick bad, when it warmed up it got quieter. I think it was overheated by a previous owner. It had pure rust water in the radiator when I bought it. Which I flushed out the right way...... with a leaking garden hose in the barracks parking lot. Then I replaced the water with green flavored antifreeze twice within the next year. Ran fine, ticked, got used to it until I stopped noticing. Tried many different grades of oil, nothing changed.

The 4.0 is a strong engine that can take abuse to the point of damaging the valve train without dimishing performance or lifespan. That's what makes it a classic. Too bad it's no longer in production.

I also had another xj, former police vehicle, engine and transmission were well maintained, the rest of it was beat to shit tho. 160k no ticking.

And my current, 2006 rubicon. No noises. Runs great, 140k
 
  • Like
Reactions: Chris
MrBClark said:
So I know I have asked this many times on this forum, but I am still dumbfounded by how noisy my 4.0 is in my Jeep. It's only loud in the morning for like 5 mins and then it makes the noise for like 2-3 mins on a warm startup. It's pretty noticeable if you are kinda near the Jeep. It runs fine. You guys have said its completely fine, but just trying to settle my nerves a bit. I also put it on another forum and they said its normal. Here is another video.



Click to expand...
It won't cost anything to slip off the serpentine belt, mine had a bad idler pulley. Made lots of racket especially when cold
 
joelachr said:
Drain first and then 1 qt diesel + fresh oil to full?
Click to expand...
Nope. Just add the diesel to the old oil. You won't damage anything for the short time you have it in. I have even seen this boost compression by getting the rings cleared of some varnish, tho that is very uncommon, requiring an odd set of circumstance to happen. But very good clearing varnish and sludge. The lubricity of the diesel protects bearings and lifters. The new fancy wordings is now called "Stiction" by some marketing experts.
 
  • Like
Reactions: joelachr
bromel said:
Every 4.0 I've had makes this noise, including my Cherokee with 255k and my TJ with 101k. It's the lifters. I don't think about it.
Click to expand...
Do you let your 4.0 warm up at all before you drive it? To let the sound subside a little? I don't want to hurt the engine by driving it with the sound, but not sure if it would hurt anything.
 
  • Like
Reactions: Ephry73
Top Bottom
Back