1999 4.0 ticking

[tarock]

1999 4.0 with 280k miles. Purchased with a known piston slap noise that was fairly quiet and would go away once warm.
I daily drive, and it was parked with no issues on Monday. Tuesday morning, it starts fine, but immediately has a very loud and consistent ticking noise. The noise is higher pitched and louder than the previously heard piston slap sound.

I did not let it idle for more than 20-30 seconds, but it does seem to idle fine and it started fine. The ticking pace will rise and fall with rpm. I was told it could be the timing chain has jumped. I have a couple videos on my phone, but I’m having difficulty getting them to upload. Any suggestions on where to start?

 

[Chris]

Upload the videos to YouTube and then copy and paste the link here.

 

[tarock]

Good call on the videos uploaded to YouTube. The noise is hard to pin down on the motor. Under the hood it sounds like top and bottom end. Where the previous piston slap was very much more of a bottom end noise, and not nearly this loud.

 

[macleanflood]

Check out DeXJ on YouTube. Great videos on quick 4.0 refreshes.

-Mac

 

[Bammo68]

Check out DeXJ on YouTube. Great videos on quick 4.0 refreshes.

-Mac

I agree. You can do an in-frame refresh on that motor and put new pistons and bearings in without a full rebuild. Is it going to last another 280K? Nope, but for $150 worth of parts and a day under the car it will probably give you another few good years out of that motor.

 

[Bammo68]

'course what you are better off doing is pulling the motor and doing a complete rebuild on it (assuming nothing substantial is wrong). Its not as hard to do as you think...

 

[rweathers2001]

This sounds very similar to what mine did last year when the number 3 piston skirt broke. I was able to do an in frame refresh and get it back going. This job can be done in a weekend easily. Agree with @macleanflood to watch the videos from Dex XJ and he has great price on new pistons and rings already pressed onto rods.

 

[Bammo68]

Pressing the wrist pins into the rod ends looks really scary when you watch it on YouTube. I made up a little jig out of some scrap bits of steel so that pins could be pushed all the way down and they would centre and put the pins in the freezer overnight. Used a propane torch to heat the little end of each rod and they all popped in dead easy. YouTube is an awesome resource, but ironically it can sometimes make it look harder than it actually is to do this stuff. I'd order the bits from RockAuto, make sure you have a torque wrench and a gas torch and give it a go. Oh you will need something like a small press too to get the wrist pins out but they are dirt cheap.

 

[tarock]

 

[tarock]

Three pistons had cracks. I was expecting more based on the sound. What is everyone’s opinion on the bearings? The kit I bought comes with new bearings…just put them in?
Would these cracks make sense for the amount of noise I was hearing?

 

[macleanflood]

I'd use as many new bearings as you can.

You replacing all six or just three?

-Mac

 

[tarock]

I'd use as many new bearings as you can.

You replacing all six or just three?

-Mac

I’ll do all six. There is a full AMS racing pistons, bearings and gaskets on eBay for reasonable price.

 

[ColoJeep]

I’ll do all six. There is a full AMS racing pistons, bearings and gaskets on eBay for reasonable price.

Be sure to check the bore to piston clearance. cast pistons and "Racing " pistons if Forged , have different specs.

 

[tarock]

Update
I got the pistons replaced. Runs well other than a slight knock or tapping. Even when warm. It’s random. I’ll mainly hear it at idle. Some stop lights it’s there, others it’s not. When I heard it, I reved up the engine and it sped up with RPM, but then disappeared.