Idunno

Reading around the internet regarding causes/cures for lifter noise, which I have in my 96, I read that the oil pump should be changed due to reaching it's life limits expectancy around 185,000 miles. Is this fact or fiction? My oil pressure is fine and I'm using a full synthetic 5W-30 oil here in central Florida. Mileage is north of 241,000. The claimant proposing the pump change qualifies it by saying the lifter noise will quiet down with a new pump. I also read that a lifter noise is no cause for concern with these 4.0 engines and a thicker oil could dampen the lifter noise. What's the opinion pool here suggest?

awg

just general comments here

I have heard of XJ with original motors doing well over 300k miles without overhaul

OEM parts show no known weakness ( others with experience may be able to comment on this)

newer replacement parts do not seem to be as reliable as the original factory pumps were

If oil pressure is good, it is good...isn it ?

I use 5-40 in a similar climate, and mileage in my 96s

its true the most common time for a machine to fail, is after you have just worked on it

I do not know whether such a thing as a fully OEM, made in USA oil pump is available ?

BruceB

If you have lifter noise, trying to cover it up with thicker oil or a new pump is not addressing why you have lifter noise. I personally would be more interested in fixing the lifters...

Idunno

Yep. I was looking around for stuff like a lifter/cam kit and pushrods, etc. Not uber expensive but, like awg says, are the parts from shops like Autozone comparable in quality to OEM? I'd hate to kill the engine with good intentions.

dave1123

I'll tell you what. I installed a rebuilt shortblock and refurbished Clearwater head in my WJ. I also used new lifters, rockers, pivots, and pushrods. It was quiet for about 1000 miles, then started the normal lifter ticking. It's just something the 4.0 does, mainly at idle, and you just have to get used to it. They will live forever making that ticking noise anyway. My original engine had 252K miles on it and I replaced it only because of a slight rod knock. I have noticed that right after getting off the highway, it'll be quiet for a short time until it sits and idles awhile.

Melling made the OE pumps for Chrysler for more years than most of us have been alive. BTW, a high volume oil pump doesn't fix it either and it causes a fitment problem with the pan.

You can always tell a jeep have a 4.0 in it just by listening to it idle. It's like a badge of honor in my book.

RocketMouse

X2 on that.... there's just something special about these old 4.0s... you just wouldn't see in a modern engine. it's almost like you would have to intentionally try to blow this engine up in order for it to not just keep "ticking" along for heaps of miles.

NM-XJ

Piling on with a x3. Have yet to meet a healthy 4.0 that didn't have some sort of mild valvetrain noise. In fact, once you know the sound of an I6 and are familiar with the 4.0's "tippety-tappity" you can tell it's one without even looking.

My theory is that they are such a darn smooth and quiet engine the only thing you can hear is the valve train....ha.

318SixPack

The times I've had oil pump failures, and none of them have been in my 4.0 1996 XJ 359,000 miles, you can see it if you have an oil pressure gauge and you can hear it too. It ain't a little rocker tick either. The oil pump in my 1986 Dakota 3.9L would just up and lose pressure. I'd stop and superstitiously add a quart of oil. That went on for years then finally it just quit on I-66 out near nowhere. Wasn't long after that I bought my XJ.

dave1123

I just watched a video where a couple of guys resurrected an old Dodge truck with the 318 (5.2) in it and one guy said "it's so quiet all you can hear is the injectors clicking!" Really? IDK about that.

Idunno

I hear you all and give the 4.0 culture a nod. But, hydraulic lifters were created to keep the valve train in constant contact from cam to valve stem and prevent tapping like the old mechanical lifters that were adjusted to allow for thermal expansion (growth) in the engine as it warmed up. Things preventing that are a lack of oil pressure in the lifter reservoirs, defective push rods (mushed/bent), foaming of the oil (bubbles compress and defeat lifter action), or dirt lodged between the walls of the lifter and internal plunger preventing independent movement. Or, a rocker is binding enough to impede valve spring force but that would be remarkably noticeable in the performance of the cylinder(s). In other words, there's a problem and to say it's okay and just the nature of the engine kinda slays my logic.

NM-XJ

Can't really argue against that from a technical perspective. But let's get pragmatic. I would submit that even if we agree that the light "clickity" valve train noise is technically a "problem", it's repeated demonstrated effect on the motor is very minor and over a very long period of time. While a singular data point, mine has been doing it for 22 years/120k miles. It's ok. I'm not going to fix a non-problematic problem.
I owned a 5.2 for many years. Definitely a quiet engine, at least when compared to the injectors and mechanical fan. Reliable, too. But that didn't make up for blown plenum gaskets and the slushbox 42re it was bolted to.

awg

my approach to noises is to monitor them very closely to see if they are getting worse

In my experience with well worn equipment, and you have already mentioned this, but you would probably be advised to replace the camshaft if you did the lifters ?

...and any other old part, might as well do rings & bearings while you are in there, tank the block, head rebuild etc etc...where does it end ?

dave1123

It's a real PITA to pull the camshaft out of a 4.0 while it's still in the frame. The cam is as long as the engine and must come out absolutely straight, which means pulling everything on the front of the jeep and jacking the engine up enough for the cam to clear the front frame rail. Then there's the question of the cam bearings. Are they any good? Hard to tell unless you can measure them, and they can bleed off oil pressure if they are bad.

I totally agree with awg in the case of where do you stop? I have done a lot of research as to why this engine can't maintain valve lash at idle and there seems to be no definite answer. I heard that the ports that supply the lifters with oil are small and with the reduced flow of oil at idle they starve. I seriously doubt this because they are created by the intersection of the drilled gallery and the lifter bore and are quite large. PLUS the entire engine is lubricated from that one gallery, the mains are full ported, and the rods are timed lubed by the rotation of the crank. It may have something to do with the oil pump design in that it's a gear pump rather than a gerotor pump as is used in many other engines, but that hasn't been proven either.

Anyway, after 252K miles on my engine, the rockers showed no abnormal wear on either the valve stem contact point, the pivot bore, or the pushrod pocket and pushrod length. All new valve train parts didn't change a thing. It was quiet for 1000 miles, then the tick returned, although not as bad. This was with a rebuilt engine with new cam and lifters as well. I made sure the lifter preload was correct.

These engines never sound like a threshing machine like solid lifter engines when the lash is worn do, so I'm not going to worry about.

PatHenry

2 I6's in my family, 400k and 300k all original miles. Both ran perfectly at retirement and as far as I could tell, both would have given a couple hundred thousand more before worrying.

The ONLY engine issue between the 2 was a single broken valve spring in the 300k motor (2000 TJ).

I would not touch the oil pump for preventative reasons. If you are certain you need to replace it, do so, otherwise I'd leave it until you do. Just my opinion.

Idunno

Okay, by the numbers you've checked the entire valve train. Very odd you got 1000 miles out of it only to have the noise return. That had to be frustrating. Not interested in restoring the engine to new. I'm just confounded as to why this occurs. Maybe the lifter hydraulics have become mushy. Never heard a new 4.0 run but I doubt they were built that way. I put a long screw driver against the block but could not pin-point the location of the noise. That said, it sounds like it's coming from down low, like it's a cam-lifter problem where the lifter is not fully following the cam lobe, stopping short and then getting smacked by the advancing side of the lobe. Trying to visualize what's hitting what.