Valve train noise after head rebuild swap

[optmaxx]

So I had a used head rebuilt because the one I had on cracked, and I know that the head I had rebuilt had some work done in the past like a light resurfacing to get it straight, and this time it had a light clean up because it didn't need much to get it flat according to the machinist. It also had a 3 angle valve job, new guides, seals, seats and they were able to reuse the valves and springs from the old head since it didn't have many miles and were in good condition, but the valves had some work done to make sure they sealed.

After installing the head I just torqued the rockers to spec, but that caused my valve train to sound clattery. So I went and did the zero lash procedure while having all of the cylinders in their compression stroke, and that seemed to show that I have excessive preload on all cylinders using the counting the bolt turns method pictured bellow. All ranged over one turn, and some even going to 1 1/3 turn to reach 21-ft/lbs after zero lash, so that puts me at around .063-.077 of preload through out.

After doing the zero lash procedure the noise did improve a lot at idle, but it would get clattery after driving it on the freeway, or for a long time and I have really good oil pressure. The weird thing is that if I turn off the Jeep, wait a bit and then turn it on the clattering improves a lot so I'm not sure if the lifters are still trying to adjust...also, I changed all of the rocker arm assembly thinking it may help, and it did-a little.

So I'm thinking that I need pushrods that are .020 shorter or close to that, so I was hoping that I can get pointed to the right direction on where to get those pushrods. Can I shim the rockers as a test to see if that'll fix anything first?

Here's the method I used for checking preload.

[optmaxx]

Also my head is from a '92 4.0, and the pushrods and rockers are for those 4.0s as well. So the pushrods are 9.639 in, and I used the thicker Fel-Pro 530SD Head Gasket.

[optmaxx]

Also, I think I should point out that the lifters aren't spongy when you try to push on them hard, there's no play on that end.

[Cheromaniac]

So I'm thinking that I need pushrods that are .020 shorter or close to that, so I was hoping that I can get pointed to the right direction on where to get those pushrods. Can I shim the rockers as a test to see if that'll fix anything first?

This, though you could try the 30 thou shims under the rocker pedestals first.

[Rustywolf]

Wow, this is quite interesting.

I had always thought there was no adjustment on the valve train, and to order the push rods the length needed after using an adjustable push rod tool.

Where was this lash picture from? I don't remember seeing this in my manual.

BTW OP, as far as I know, push rods are just push rods. There are companies that make them any length and even different thicknesses. The thickness is if you're really gonna be winding out some RPM's, maybe if you have stronger valve springs, etc.

ETA: I wouldn't go by year for push rods, either, especially if it has been decked. At this point? I don't even trust rebuilt heads from Autozone or the like. Maybe they measure to make sure it hasn't been decked before build? But I would wager probably not, just deck it if it is warped. So 2 deckings after a cylinder head has been touched twice over 20 years- as an example- can really change the geometry and specs.

[Russ Pottenger]

Comp Cams and others make a fairly inexpensive adjustable pushrod length checker that you can use for mock up purposes that greatly simplifies the measurement process.

They typically make Pushrods in .050 increments. With the correct preload you should expect to see something close to a 9.600 length pushrod. Order them in a 5/16 diameter made out of .080 chrome moly.

[optmaxx]

Wow, this is quite interesting.

I had always thought there was no adjustment on the valve train, and to order the push rods the length needed after using an adjustable push rod tool.

Where was this lash picture from? I don't remember seeing this in my manual.

BTW OP, as far as I know, push rods are just push rods. There are companies that make them any length and even different thicknesses. The thickness is if you're really gonna be winding out some RPM's, maybe if you have stronger valve springs, etc.

ETA: I wouldn't go by year for push rods, either, especially if it has been decked. At this point? I don't even trust rebuilt heads from Autozone or the like. Maybe they measure to make sure it hasn't been decked before build? But I would wager probably not, just deck it if it is warped. So 2 deckings after a cylinder head has been touched twice over 20 years- as an example- can really change the geometry and specs.

I found it while doing an online search for Jeep 4.0 zero lash procedure.

[optmaxx]

Thanks guys, I did put .020 shims with some change in noise, and at first I thought that it worked, but the clacking comes back after driving it for a while. The problem is that it sounds great at startup with no clacking or anything, but it starts to make some chatter or clacking after going for a drive...I don't know how to explain it, it's not a knock for sure, and it might be coming from two sources after I dropped the pan to change the rod bearings thinking that it might be that, but no.

So I noticed that my timing chain looks loose, so the chatter could be from that, and I also have sealed power lifters and I've read some bad reviews on those saying that they tend to be noisy or fail prematurely. My Jeep is running great though, it's just chattery, and there is a faint tapping noise that fades in and out that I believe is a lifter, so some time down the line I'll swap out the cam, chain and lifters.

The noise sounds like it's coming from the bell housing though, which seems to plague '96+ 4.0s, or 4.0s in general, and I have a '96 block with the girdle on so I don't know if it's just a Jeep thing hahaha. I also have a tf999, but I don't know if those tend to make any noise, but oh well.

I was thinking that 9.600 rods might be the right size too, but for now I'll keep driving it and try those size rods later. Oh, and I ended up putting a .040 shim on the rockers just to see what will happen, and the rear lifter started to make that tapping noise that fades in and out but much louder. It started to fade as it adjusted but it didn't quite go away while the other lifters sounded good...I wonder if that means anything.

I've also read somewhere that shimming rockers vs getting correct rod length gives different noise results. Like shimming would sound more like a diesel, while getting correct push rods length would sound more quite, but both would fix lifter ticking and tapping. Is that true?

[optmaxx]

Here's a video of my Jeep after driving around doing errands, again it's much quieter on cold start up and I'll get a video of that too.

Recap: -Changed rod bearings after dropping pan to see if that was the cause, but it's not.

-Timing chain had slack that seemed excessive

-Everything else looked ok from visual inspection from underneath

-Added .020 shims with no real change in noise, but it did seem to affect performance so I removed them

-changed the oil pimp was well

-Some have told me that it might be the wrist pins, or lifters, I'm kind of leaning towards lifters and timing chain

-I haven't drove it much

https://youtu.be/hJ35zvBWiWI?si=m4s5MroKee-rv78B

[optmaxx]

Here's what it sounds like on cold start up.

https://youtu.be/ZDltjLu2hUk

[Cheromaniac]

I think you might be on to something when you mentioned a slack timing chain. It sounds like it's slapping against the timing cover. Pull it and see if there are any witness marks.

[optmaxx]

Comp Cams and others make a fairly inexpensive adjustable pushrod length checker that you can use for mock up purposes that greatly simplifies the measurement process.

They typically make Pushrods in .050 increments. With the correct preload you should expect to see something close to a 9.600 length pushrod. Order them in a 5/16 diameter made out of .080 chrome moly.

The closest size I was able to find was 9.594 that was fairly priced at $4-5 a rod. Would that be close enough to try cause I'm only able to find size 9.600, but cost around $9-$17 a rod, and I just to test something out. Hesco sells that size as PR-301, but Melling makes the same one as MPR-301, but other than that, the only other size I'm able to find is 9.622.

[optmaxx]

Noise improved a lot after changing to smaller pushrods, and I used pushrods for a 1977 CJ5, length 9.594, part number MPR-30. I think I'll call this fix done for now cause the noise doesn't seem to be terrible and maybe it'll improve even more after more driving. Preload seems to be in the .025-.050 range, the .025 preload is on one rocker.

This is after taking it for a drive, where before the clacking would be way louder. Oh, and there was a difference with shimming and getting smaller pushrods with this project. Shimming didn't seem to fix the noise, and it affected performance like it couldn't breath very well, while getting smaller pushrods didn't seem to affect that.

https://youtu.be/vTfJ9zPv1ic?si=WRftCg0MSI59-DG0

[optmaxx]

Here's another after video.

https://youtu.be/OpQFRmw-e1Y?si=cxbCWqGEQhMrgD-t

[optmaxx]

Before, there used to be a pretty obnoxious tapping noise, it's still there, but way more faint. I suspect the other noise, which almost sounds like a rattle could be from the loose timing chain.