May Be Time for Rebuild or Swap

AndrewLJR

AndrewLJR

TJ Enthusiast
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Apr 1, 2020
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Ft Lauderdale
From the sounds of my 227k mike engine, she’s not happy. I’m not sure if it’s lower end or a valve issue cause it’ll knock when it’s cold and get quieter up to temp. No drivability issues but I’m not going to risk it. So I’m debating on rebuild, stroker or LS swap. No real desire for the Jeep to be down for the time it’ll take to do an LS, but it’s on the table. I like the idea of a stroker cause it’s cheap, can be done easily as kits are available and swap right in. And I don’t care about running premium. The reman unit would be the quickest route but where’s the fun in that. Sooo, here’s the video

 
Babygools99 said:
My 4.0 is at 232k miles and its starting to sound more and more like that everyday when it starts up.
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Yup, Im undecided on what I want to do. Weird part is it goes away when its up to temp, which makes me believe its a valve issue. But, throwing a few hundred here, few hundred there, mine as well rebuild
 
AndrewLJR said:
Yup, Im undecided on what I want to do. Weird part is it goes away when its up to temp, which makes me believe its a valve issue. But, throwing a few hundred here, few hundred there, mine as well rebuild
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It's a big decision to say the least. I'm pretty back and forth as well. I DD my jeep and would hate to have it sit for the time it would take me to fund a proper LS swap, but once it's done, i know i would love it. It all depends on the timing i suppose.
 
If the noise goes away at temperature, you may have some gunk that holds up a valve rod or lifter. You could try taking the valve cover off and inspecting everything to make sure it's all torqued correctly and clean it up or put an oil cleaner like seafoam in and change the oil. With the second you risk getting a leak somewhere else since it's removing gunk from everywhere in the engine. So any other gunk that's pretending to be a gasket or seal will disappear too.

https://seafoamsales.com/knowledge-base/how-to-add-sea-foam-motor-treatment-to-crankcase-oil/

I'd add 1/2 a can of seafoam to the oil and suck the other 1/2 of the can through your throttle body using a vacuum hose upstream. I pull the stuff in quickly and time it to kill the engine at the end of the bottle. Wait 20 minutes and start up; but do it in a place were a huge cloud of white exhaust smoke won't bother anyone. The cloud will look like something is on fire in a neighborhood. It removes deposits on the valve seats after soaking and typically spits black specks out of the tailpipe.

Drive it 100-200 miles and change the oil. If that didn't stop the tick, I'd take the cover off and evaluate.
 
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Doesn't sound terrible to me. Pull the valve cover and check the rockers for wear. You can replace all the rockers and pushrods for about $100. Dont think its bottom end from the video, sound like valvetrain.
 
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InOmaha said:
If the noise goes away at temperature, you may have some gunk that holds up a valve rod or lifter. You could try taking the valve cover off and inspecting everything to make sure it's all torqued correctly and clean it up or put an oil cleaner like seafoam in and change the oil. With the second you risk getting a leak somewhere else since it's removing gunk from everywhere in the engine. So any other gunk that's pretending to be a gasket or seal will disappear too.

https://seafoamsales.com/knowledge-base/how-to-add-sea-foam-motor-treatment-to-crankcase-oil/

I'd add 1/2 a can of seafoam to the oil and suck the other 1/2 of the can through your throttle body using a vacuum hose upstream. I pull the stuff in quickly and time it to kill the engine at the end of the bottle. Wait 20 minutes and start up; but do it in a place were a huge cloud of white exhaust smoke won't bother anyone. The cloud will look like something is on fire in a neighborhood. It removes deposits on the valve seats after soaking and typically spits black specks out of the tailpipe.

Drive it 100-200 miles and change the oil. If that didn't stop the tick, I'd take the cover off and evaluate.
Click to expand...


Im a fan of Amsoil oil flush and am thinking this is the method I might try first since I have it already. Im thinking its a lifter or rocker but we will see. Maybe Ill go get some seafoam and give that a try, Im familiar with it
 
I can't really hear too well from the video, but that doesn't sound terrible to me. My Jeep has had a slight tick for 40,000 miles at least. That sounds slightly different to mine, but it doesn't sound like the end of the road quite yet. If you don't need the Jeep to be super reliable, I wouldn't be worried to drive it until it dies.
 
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For an old Jeep TJ 4.0 that doesn't sound that bad to me. i would just drive it like that for a while and experiment with different oil filters and oil brand and viscosity and various additives before I rebuilt or swapped the motor. Mine has 245k and doesn't sound quite that bad, but almost that bad on certain days at start-up.
 
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AndrewLJR said:
Im a fan of Amsoil oil flush and am thinking this is the method I might try first since I have it already. Im thinking its a lifter or rocker but we will see. Maybe Ill go get some seafoam and give that a try, Im familiar with it
Click to expand...
Toss a half pint of Marvel Mystery Oil in there and see what happens. Should clear that right up.
 
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jodomcfrodo said:
I can't really hear too well from the video, but that doesn't sound terrible to me. My Jeep has had a slight tick for 40,000 miles at least. That sounds slightly different to mine, but it doesn't sound like the end of the road quite yet. If you don't need the Jeep to be super reliable, I wouldn't be worried to drive it until it dies.
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Its a third car, until my M6 is gone then it'll be a daily until I get another vehicle. Worst case, can rent something. Im not terribly concerned. Im going to try some of these suggestions and go from there. Id like to get more power in this thing eventually so I may plan for a rebuild down the road, prepare for it, so Im ready when its needed.

mrblaine said:
Toss a half pint of Marvel Mystery Oil in there and see what happens. Should clear that right up.
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Ill give that a try. I assume Id want to change the oil after running it?
 
One of my 99s has 197k and makes a similar noise. Starts about 45 seconds after I start it and then goes away about 2 min later.

Surprsingly, when I started it yesterday, I didn't get the sound at all. Only new thing is some fresh gas. Not saying this is empirically the fix, it may have finally blown thru a clogged lifter or something else in the valve train. If it comes back, I'm gonna run it like this until I kill the motor. If that happens, I'll rebuild or replace it. Maximize the value, right? Who knows, may still have 100k left in the motor. Either way, we are gonna find out.

How old is the fuel in your tank?
 
heck, that's about what mine sounds like at 115k. With twice the mileage you're not doing too bad.

Though, a PO of mine did swap a worn out junkyard Dana 35 in to replace the original 44, so i can't rule out that they blew the motor and dropped in a junkyard motor from the same donor the 35 came out of.
 
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So far, the sound is gone when up to temp but still present when cold. I added 1/2 pint of Mystery Marvel or whatever its called. I also run it hard when its hot, hoping to get some good flow and loosen up whatever is stuck. Will see how things go from here.

As far as plans, Im thinking a nice rebuild is in order at some point and possibly doing a boosted application. I have access to a good dyno, builder and fueling options. Should make a fun adventure
 
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I'd check the timing chain just in case. Put a breaker bar on the crank and firmly push the engine both directions, you will feel the slack in the chain if it's worn. 4.0s don't rattle at the chain like allot of engines, the chain doesn't hit the cover. Instead the chain allows the cam to jump in what sounds like a diesel knock as the lobe goes from pushing down to getting pushed up. As the chain goes from pulling to getting pulled it snaps the cam as the slack switches sides. That sound is at the cam which is the length of the block making the noise difficult to diagnose. It might not be the only noise but it can add to the sounds. It is more common once the engine is fully warm but it's still really easy to check and change compared to the alternatives.
 
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AndrewLJR said:
So far, the sound is gone when up to temp but still present when cold. I added 1/2 pint of Mystery Marvel or whatever its called. I also run it hard when its hot, hoping to get some good flow and loosen up whatever is stuck. Will see how things go from here.
Click to expand...

I ran marvel for 1000 miles before an oil change a while back and it didn't do much for me, Now I'm trying the same thing with seafoam, which seems more aggressive to me. Put some in last night, drove about 15 miles, hung out at a buddies house for about 4 hours to let the seafoam soak in the oil passages and then did an "Italian tuneup" on the way back home, with several WOT pulls to 4500+rpm to try to blow things out. I might do one more before I drain the oil out.

What's interesting about mine is it doesn't seem to be a function of temperature, but of how long it's been running. It'll quiet down within about a minute of starting up, even when cold, and if I shut it down to buy gas the noise will be back when I start it up even though the engine is still at operating temp. Then just like after a cold start, disappears again in about a minute. I posted in another thread how 2 cylinders have poor compression but leakdown test is pretty good, which points to a collapsed lifter and indeed most of the startup noise comes from around the cylinders with low compression. The engine shows zero other signs of excessive wear - runs great, never misses, catalyst is working (about a 200° rise from inlet to outlet), averages 15.4mpg with 32's and a 4" lift and it doesn't even use half a quart of oil in 4000 miles.
 
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