Is this rod knock?

BrunoPizz97

BrunoPizz97

TJ Enthusiast
Joined
Jul 11, 2019
Messages
408
Location
Long Island
Short story
Woke up this morning warmed ik the Jeep and drive to work 20 miles No problem
Had to drive up north about 150 miles
Cruising at 70-75
Then I get to my destination and I hear a knock/slap sound... check out the video
Knock/slap happens when I’m off the gas in gear and out of gear
When I’m in gear and I’m 4th or 5th no knock/slap
Is this rod knock
https://drive.google.com/file/d/1AzJrhY3-Vx4_WKXL2vvS-xz6NJGsGvMz/view?usp=drivesdk97 wrangler
140k miles
 
Could very well be a rod knock. I've been down this road a couple times on different cars. Don't run it much till you find what it is or you risk grenading the motor.

If you pull the oil pan, you will be able to see all the rod connections at the crank. You can grab them & try to shake them. If the bearing is bad, often times it will click when you shake it. Then if you pull the nuts off the rod & remove the rod cap, the bearing will come out too.

An exhaust leak can sound a bit like that too. Make sure your exhaust manifold bolts are tight.... both at the head & at the exhaust pipe.

You can see the thread where I was searching for the knock on my Jeep engine here. This was about a year ago & I ended up rebuilding the engine.

Good luck
 
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X2 to what he said.

Other possibilities include an exhaust leak (usually in the header), but those are constant and can be heard all the time or lifter tick.

I'd say it's time to pull the oil pan and check. You can also test the compression which could be very telling.
 
Update:
I took my chances and I got stuck on the side of the road. (Got it towed thank god I wasn’t far from my girlfriends parents)
But anyways pretty sure a piston fell into my oil pan. It sounded like a bunch of nuts and bolts in a tin can rolling down a hill.
Motor swapping with a 99 xj which is in very good condition.
 
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Damn, I’m sorry to hear that.

Be careful on the XJ 4.0 swap. It will work, but there are a lot of differences that make it far from a plug and play affair.
 
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Chris said:
Damn, I’m sorry to hear that.

Be careful on the XJ 4.0 swap. It will work, but there are a lot of differences that make it far from a plug and play affair.
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It’s totally ok things happen, and you’ve seen me on the forums a number of times asking for answers to mysterious sounds and stuff so I’m pretty sure this engine failure might have been related to those sounds. But anyways I am aware of the differences such as the intake manifold, my Jeep guy is very good I believe in him. I don’t think it’ll be a bad swap just not ideal. Just wish I were able to just buy a 4bt to swap in there but it would be much more than what I will be paying for labor and the motor combined
 
BrunoPizz97 said:
It’s totally ok things happen, and you’ve seen me on the forums a number of times asking for answers to mysterious sounds and stuff so I’m pretty sure this engine failure might have been related to those sounds. But anyways I am aware of the differences such as the intake manifold, my Jeep guy is very good I believe in him. I don’t think it’ll be a bad swap just not ideal. Just wish I were able to just buy a 4bt to swap in there but it would be much more than what I will be paying for labor and the motor combined
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Oh good, as long as you know what you're getting into. However, if he knows his stuff, it shouldn't be an issue.

The good thing is that the 4.0 is a relatively cheap engine compared to some of the other stuff out there.

Also, as far as 4BT goes, I drove a Wrangler once with that swap. It's annoying, obnoxious piece of shit. That engine has no place in a Wrangler whatsoever IMHO ;)
 
Chris said:
Oh good, as long as you know what you're getting into. However, if he knows his stuff, it shouldn't be an issue.

The good thing is that the 4.0 is a relatively cheap engine compared to some of the other stuff out there.

Also, as far as 4BT goes, I drove a Wrangler once with that swap. It's annoying, obnoxious piece of shit. That engine has no place in a Wrangler whatsoever IMHO ;)
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Really wow that’s the first I’m ever hearing about the 4bt being a pos. Well everyone’s entitled to their own opinion I’m not gonna stand here and argue saying it’s the best swap but you are right they are obnoxiously loud.
 
BrunoPizz97 said:
Really wow that’s the first I’m ever hearing about the 4bt being a pos. Well everyone’s entitled to their own opinion I’m not gonna stand here and argue saying it’s the best swap but you are right they are obnoxiously loud.
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It's louder than holy hell, it weighs a metric shit ton, and it's several underpowered for any sort of practical use. Again though, just my opinion after having driven one. The 4.0 is a good engine, so I think putting another one in it's place isn't such a bad thing ;)
 
Chris said:
It's louder than holy hell, it weighs a metric shit ton, and it's several underpowered for any sort of practical use. Again though, just my opinion after having driven one. The 4.0 is a good engine, so I think putting another one in it's place isn't such a bad thing ;)
Click to expand...
Chris said:
It's louder than holy hell, it weighs a metric shit ton, and it's several underpowered for any sort of practical use. Again though, just my opinion after having driven one. The 4.0 is a good engine, so I think putting another one in it's place isn't such a bad thing ;)
Click to expand...
Having owned a 98 dodge with a Cummins I totally understand, I can’t imagine a 4bt in a Jeep without a stiff front suspension setup. That I cannot argue on at all and for power you can just take a 6bt Cummins turbo and slap it on that motor no problem just have it tuned and you’ve easily gained an extra 50- 60 hp and a shit ton of torque. I’ve even seen twin turbo setups that are very reliable.
 
I had a magic box that connected between the distributor and the spark plugs. 8 toggle switches. Turn them off one at a time and you found your rod knock. Done by killing the spark to the cylinder. Removing the load. Also loosen the tensioner pulley to stop the knock on the crank pulley. Fast and easy check.
 
Mjv said:
I had a magic box that connected between the distributor and the spark plugs. 8 toggle switches. Turn them off one at a time and you found your rod knock. Done by killing the spark to the cylinder. Removing the load. Also loosen the tensioner pulley to stop the knock on the crank pulley. Fast and easy check.
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No need to check now, I know it won’t make a 3 hr drive back to NY.
So now I’m going to tow it back to my guy and swap a good motor into it.
But thank you for the advice I really do appreciate the tips.
 
I purchased a 99 XJ Classic years ago with a blown motor that I ended up doing an engine swap how-to on for a different (now defunct) forum.

Bought it as a 'no start' Jeep. Tested the starter and hand cranked the flywheel. When I cranked, I heard the telltale 'clink clink' of metal hitting the bottom of the oil pan. Pulled the pan and chunks of piston sleeve were at the bottom. Very similar issue to yours. Engine had 150k on it. I swapped it with a junkyard find from the same year that had 50k. Took it out with a cherry picker. (set it on a tire in the alley and it was gone the next day) Put the junkyard motor on a stand. Checked everything out and replaced all of the peripherals while it was easy to get to them, and put it in the Jeep. Took me and another guy about four hours to do the job. Hardest part was lining up the splines to mate to the transmission.

I never understood how this could happen so easily. Doesn't happen often, though. In my case, the freshman college girl that owned the Jeep prior no doubt neglected regular maintenance. Not sure if your PO had the same characteristic or if it is a design flaw.
 
ejay said:
I purchased a 99 XJ Classic years ago with a blown motor that I ended up doing an engine swap how-to on for a different (now defunct) forum.

Bought it as a 'no start' Jeep. Tested the starter and hand cranked the flywheel. When I cranked, I heard the telltale 'clink clink' of metal hitting the bottom of the oil pan. Pulled the pan and chunks of piston sleeve were at the bottom. Very similar issue to yours. Engine had 150k on it. I swapped it with a junkyard find from the same year that had 50k. Took it out with a cherry picker. (set it on a tire in the alley and it was gone the next day) Put the junkyard motor on a stand. Checked everything out and replaced all of the peripherals while it was easy to get to them, and put it in the Jeep. Took me and another guy about four hours to do the job. Hardest part was lining up the splines to mate to the transmission.

I never understood how this could happen so easily. Doesn't happen often, though. In my case, the freshman college girl that owned the Jeep prior no doubt neglected regular maintenance. Not sure if your PO had the same characteristic or if it is a design flaw.
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No clue what this jeeps maintenance history was. All I really knew was that It was owned by a father who bought it for his son to drive to college and that he didn't drive it often when it wasn't driven it was garage kept and that's that. No further information, But my mechanic who will be swapping my motor will be swapping a newer generation 4.0 from an XJ into my tj and I believe that motor will hold up. In the meantime I have his TJ with 300k miles on it and it ran better than the motor that blew up in my TJ.
 
Also a little update, went to start my car yesterday morning to see if I were able to drive it up on the trailer and the motor was ceased.
 
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