I rebuilt my 4.0: bored, decked, crank grind, etc. Just about everything is new except the camshaft and lifters. I was nervous about a new cam and lifters because I've read they don't last; lobes get wiped and lifters get concaved. I also reused the rocker arms and push rods. The 4.0 has a small lifter tick/tap noise but when I get on highway speeds 60-70mph then exit and come to a stop I notice the tick/tap has gotten louder versus driving around town. Then I let the jeep sit for a bit then i start it up and the tick goes back to mild to non existent. Then after highway speeds the louder tick happens again. Then it's all a cycle over and over. I replaced the rockers, pivots, bridges and push rods, didn't seem to help much. It's still doing the loud tick after getting off the freeway, and then goes away when parked.

Why could this be happening??

 

Did you make sure you put each one back where it came from?
Sounds like a lifter is collapsing. Could just be old and worn out.... Or maybe some snake oil engine flush would help, or Valvoline Restore and Protect might be worth a try.

I just got mine rebuilt with new cam and lifters. I wasnt super excited about it but thats what the rebuilder wanted to do... Hopefully if something happens its still within warranty lol.
The main thing is proper breakin with high zddp oil. I think the lifter problems from about 5 years ago have been taken care of now.

 

All lifters were pumped up without being able to compress the centers. I disassembled every lifter, one at a time and thoroughly cleaning them out. Then one time, something happened and two lifters got loose from there numbered pods and unfortunately I didn’t numerically paint mark them…so I might have two lifters not in their original locations. I contemplated for a long while on new cam/lifters but didn’t know which would be worth it; Crane Cam, Comp Cams (these were always mentioned during the failure stories), OE cam regrind with Melling lifters. So out with the assembly lube, I installed each lifter, push rod and rocker, and saw each lifter was spinning in their bores when I rotated the crank. I convinced myself “it’ll work and if those two fail THEN I’ll look into new cam/liters.”
So yes I can agree maybe they did get swapped, maybe that’s the problem. But I never jump to conclusions and ignore other possibilities. I haven’t seen any shavings yet. Also yes, maybe some of the lifters aren’t pumping up entirely. I run Rotella and avoid synthetic oils but thank you.

How many miles does your 4.0 have after the rebuild? (1,250 miles on mine) No diesel like tapping sounds? I would appreciate if you could ask your builder which cam and lifters were used so I could start some researching.

 

I dont think lifters in the wrong position would cause ticking unless they were already wearing into the lobe, and to me it sounds like a problem with the lifter itself since it comes and goes.

Why? Im not totally against the rotella, but theres way better gasoline engine oils out there. And why no synthetic?
I used to run rotella too till I learned better.

About 275. No noises except something in the belt drive. It was a melling cam kit and I did a breakin at 1800rpm for half an hour with JD Breakin oil and a bottle of lucas cam additive.

Also, are you sure it isnt the purge solenoid on the firewall making noise? It scared me after I got my engine back in, I thought I had a lifter tick.

 

Did you replace/recondition the heads as well? Just trying to get an idea how far you went in this rebuild.

 

Yes it was replaced with a rebuilt 7120 head versus rebuilding the old one. The engine is a 1994.
The engine was cleaned, decked, bored .020 (if anyone’s curious, I didn’t want to remove anymore material than necessary, so .020), crankshaft rod and main journals turned. New cam bearings. Lifters taken about and cleaned. Cleaned camshaft. Sealed power pistons. It was a pretty good rebuild.
I’m curious know if I actually need a different cam duration for the .020 increase in the combustion chamber, or different timing advancement.

 

Mostly from reading and some experience. I used to run synthetic on the 4.0 then read they need higher zddp for the flat tappers which Rotella has. Also I became skeptical about after I ran synthetic gear oil in an old school 3-on-the-tree transmission and found out it wore the gears down to sharp points.


I’ll need to find a Melling kit too eventually. I heard TOO much zddp in break-in oil can actually prevent the cam and lifters from breaking in properly.

Im sure. I can put my ear to the valve cover and hear it.
Yeah when I first test drove about 3 miles, I was at a light and heard an ugly knocking, sounded like a rod knock. I was heartbroken but found out the water pump bolts backed off, one was missing entirely. I forgot to torque the bolts, but that was the issue for the knocking noise.

 

Sounds like mine. Head was shaved .015, deck .005, .030 bore, new pistons, crank, cam, lifters, bearings, etc. Still runs the same as before, including the low idle and slight miss lol (not the reason for the rebuild)
Ive never heard of anyone doing this on any engine just because of a bore job, .020 is a pretty negligible increase in displacement, like 1% or something.


Yes flat tappets need more ZDDP and diesel oil has it, but diesel oil also has really aggressive detergents that clean off the ZDDP quickly. So they kinda fight eachother. I dont really have any advice on what to run, and if you like the rotella theres no reason to quit using it, but there may be better options.

I run pennzoil platinum in my 05 crown vic with 330k on it, and unless I find something better thats what I plan on using in the jeep after I get the first few oil changes done.

This may be a symptom of oil chemistry or something. Some gear oil attacks metal (especially yellow metals) in old gearboxes. Possible it was because of the synthetic oil but who knows without proper testing.



Mine was part of an enginetech kit. The guy who rebuilt my engine says enginetech reboxes a bunch of melling parts, so if you cant find one in a melling box, maybe that is an option.
I havent heard that about too much zinc, I will have to look into it.


Well that sucks.

 

I’ll research more and more but just the tapping is disappointing so I had to ask for some thoughts and opinions. My issue is probably as simple as needing new lifters and cam. They have to have at least 300,000 on them, so I guess it makes sense to replace them. When the time comes I’ll replace those parts of the valve train.
That’s interesting about companies reboxing other brands. It seems like a roll of the dice on what you’re actually getting. I’ll look into oils as well.

 

Im guessing so too.

From what I was told, my enginetech kit had King bearings, Melling cam/lifters, and Silvolite pistons. Good enough stuff for a stock engine, for 700 bucks Theres tons of reboxing and rebranding in auto parts.

 

I'm surprised whoever rebuilt the engine for you didn't demand a new cam and lifters...Anyhow, yes that's probably your problem...There's nothing wrong with todays cam and lifters if you get a QUALITY set...There's nothing wrong with Comp cams ,crane, etc...The 4.0s spring pressure at a stock type rebuild isn't going to wipe out the lobe it's usually high spring pressure and bad break-in procedure...... Coat the cam and lifters with a good cam assembly lube and add a bottle of cam of break-in oil {high zinc content} and just keep the RPMs up so the lifters spin freely the first few minutes...
OK now for the technical aspect...Trueing up the head and block surfaces usually doesn't take much off the mating surfaces...Stock length pushrods usually get it done...If there was an unusual amount taken off the block or head you may need to check the rocker contact pattern across the valve to make sure it's not riding too close to the edge of the valve where a shorter push rod would be needed...Not sure what you've got going on just throwing this out there...