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Unread 10-15-2009, 01:20 AM   #1
ddruker
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4.7 Valve Train Noise - Will thicker or thinner Oil make it better?

I've got a 2000 WJ limited with 110,000 miles on the 4.7 engine. I'm currently running Mobil 1 5W-30 synthetic oil and a Mobil 1 filter. Oil pressure is constant at about 50.

I've developed a case of valvetrain noise - what I assume is hydraulic lash adjuster noise - the noise started about 10,000 miles after I switched from conventional oil to Valvoline synthetic. Once I started hearing the noise - about 3000 miles ago - I switched to Mobile 1 synthetic. I made the switch to synthetic from conventional dino oil to try to improve my gas mileage.

I've also noticed the engine is now consuming oil - about a quart every 3,000 miles. I never noticed this when I was running non-synthetic oil. There are no other signs of oil problems - exhaust is clear, no oil in the coolant.

The noise sounds like classic valve clatter, and it is most apparent when I back off the throttle. It's speed sensitive and sounds like it's coming from the top of the engine.

I've read a ton of posts on this here and on the dodge forums - it seems this noise is real common on the 4.7's and it also turns out some people think Mobil 1 is the culprit on the dodge forums.

Which leads me to my question.

The forums give conflicting advice on what to do about the noise - some say put in heavier weight oil (I presume on the theory it will stay in place and do its thing better), others say put in lighter weight (I presume because it's easier to pump thinner oil through the engine).

I put in a quart of Mobil 1 15 W 50 and the motor indeed is quieter now - not entirely gone away but not real noticeable except at high RPM under heavy throttle.

Any explanation here of what is really going on? I can go back to dinosaur oil but wonder what might be behind this. Also any thoughts about why the motor is consuming oil now and whether I should worry about this level of oil consumption? Or should I look at replacing the lash adjusters?

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Last edited by ddruker; 10-15-2009 at 12:19 PM..
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Unread 10-15-2009, 02:07 AM   #2
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lucas oil treatment makes all noises go away. i've used it on every jeep that i've ever owned. all it does is make your oil thicker tho. i'm on the thicker oil side i guess
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Unread 10-15-2009, 07:51 AM   #3
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If I were the OP I would switch back over to conventional oil or maybe try a synthetic blend?

Synthetic oil is notorious for slipping out already existing leaks, like front seals, rear mains, valve covers, etc, because the molecules are so fine.
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Unread 10-15-2009, 08:01 AM   #4
Double E
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Same engine, roughly the same miles, same year and use the same oil. Been using that combo since 44K miles. Changed every 3000. No leaks, no consumption. (I do use a Purolator Gold filter though.)

The one thing I'd suggest is to have the rocker arms looked at for being loose or even off of their mount. Mine has not had the issue but I've observed others that have and it created the noise you describe. In those cases, removing the valve covers quickly revealed the issue and it was an easy fix.
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Unread 10-15-2009, 10:42 AM   #5
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Slightly thicker oil may help, along with treatments (although these can often add chemicals not approved for a particular engine --> e.g. excess PTFE, chlorinated parafins, both of which have been said to cause filter clogs). So don't go to far out of the recommended range for your 4.7.

However, I seriously doubt that the noise is caused caused by a swap to synthetic mobil 1 or whatever you use. Maybe coincidental engine wear. I agree with Double E, get it checked out. Sometimes engines (even well maintained, young ones, have parts come loose that can lead to failure).


My synthetic experience:

In my experience I have only seen quieter better running engines after switching to synthetic. I have also noticed fuel consumption improvements, and better cold starts. Even my extremely thrashed JD garden tractor, which had developed an extreme clack on standard 10W-30, was virtually silent after 4 hrs of run time on Mobil 1 10W-30. It seems to burn slightly less oil now too. (Maybe 25% less).

The only downside of synthetic (besides cost) is that I have seen a couple cases of increased leaks to the exterior of the engine. It hasn't happened in all of my vehicles. In fact on my WJ, it began a slight seeping out of the oil pan about 1 yr into synthetic, but within 6 months It actually stopped. (Not sure why, but I have read that modern synthetics, and the latest blends of Mobil 1 actually meet or exceed seal conditioning of standard oil). My theory on synthetics causing leaks on high mileage engines is that the oil will eventually remove thin layers of gunk helping the seals to hold oil back. Then the leak will occur, but eventually the leak should subside somewhat. (my WJ, and MB diesel have both had self healing leaks.)

Increased Synthetic Noise info: In the last couple years I have read that extended use of synthetics can actually reduce engine noise signifcantly. One famous guy who had always advocated sticking with synthetics was Marshall Booth (mercedes guys know him well). He for those that don't know was a famous MBCA technical adviser (now deceased). He always told skeptic people to stick with it for about 10,000 miles. Most of the time the oil would reduce and even cure lifter noise. (Yeah I know he worked with MB diesels, but the mechanics of all engines work virtually the same; there is friction, and collisions, and oil dampens and lubricates.)

My experiences have made me a believer. You have to remind yourself, that there are reasons that most modern engines require synthetics: They are far advanced from dino oil (although this stuff has come along way), it works better in the tight clearancs of modern engines, its lasts longer, flows better, cleans better, and provides better fuel economy. And our late model less advanced engines more often then not run better on synthetic.



If it were me, I would remoce the valve covers and look for issues. Then I would continue to run the synthetics for a while and wait.
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Unread 10-15-2009, 11:47 AM   #6
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DDRUKER - same experience here (00 WJ, 4.7, 140K). Mobil 1 = more valve train noise + about 1 quart consumption over about 5-6K miles. Oil also turned very dark (almost black) after about 3k in use. Conventional dino 5W-30 was quieter and consumed 0 oil over comparable periods. Seems odd to me, but it likely has something to do with the Mobil forumulation. After 2-3 oil change cycles on the Mobil 1, I've switched back to conventional.
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Unread 10-15-2009, 11:50 AM   #7
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Quote:
Originally Posted by txtumbleweed View Post
DDRUKER - same experience here (00 WJ, 4.7, 140K). Mobil 1 = more valve train noise + about 1 quart consumption over about 5-6K miles. Oil also turned very dark (almost black) after about 3k in use. Conventional dino 5W-30 was quieter and consumed 0 oil over comparable periods. Seems odd to me, but it likely has something to do with the Mobil forumulation. After 2-3 oil change cycles on the Mobil 1, I've switched back to conventional.
This is true: Many engines raised on conventional, are very picky. My rule is try it for a year and see what happens. There is no harm switching back.
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Unread 10-15-2009, 11:32 PM   #8
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I have a slight tap on my 4.7HO that instantly goes away w/throttle. Anything above maybe 7-800 R's it goes away. Just picked this WJ up the motor was replaced by the dealership and now has 26k on it. Anybody else have this noise? I noticed the dealership I bought it from changed out the oil to 5w30(conventional i'm sure) and I know they recommend 10w30 only for the HO(why is beyond me).
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Unread 10-16-2009, 06:42 AM   #9
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My 4.7 has some very slight valve ticking. Been on conventional 5w30 oil and thought a switch to synthetic might be in order. Just rolled over 100K and debating the switch but having concerns about the potential leaking, etc. Also been partial to Castrol for one reason or another. As far as synthetics go, Castrol or Mobil?
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Unread 10-16-2009, 11:18 AM   #10
ddruker
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All I can offer is that I had pretty bad clatter / noise at first with Mobil-1 5W-30, but adding in a quart of 15W-50 so far seems to have things put back to normal at least from a noise perspective.

As one of the above posters suggested, I'll probably pop off the valve covers and look around in there this weekend to make sure nothing is mechanically out of whack - from the service manual it looks like one side is easy to get off and the other is more involved.
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Unread 10-16-2009, 11:39 AM   #11
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I would drain the oil, and run ATF for about 50 miles.

You could have a lifter that is collapsed due to a piece of debris in the orface of the lifter.
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Unread 10-16-2009, 11:53 AM   #12
txtumbleweed
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I would simply switch back to dyno at your next oil change and see if the noise quiets down.
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Unread 10-16-2009, 03:13 PM   #13
ronsaun
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run seafoam thru your crankcase per the directions on the can then do an oil change immeadiately. it works ive used it on several vehicles and it solved the problem!!!!!!!!!!!!!!!!!!11
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Unread 10-16-2009, 03:24 PM   #14
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Bottom line, I really doubt switching to dino vs sythetic is going to change anything. You have a problem. Fooling around with viscosities and such may quiet it, but the problem is still there.

I suggested ATF to clean your engine. Using seafoam will clean your intake and combustion chambers very well. It will not reach a lifter unless you pour it in the crankcase. And I doubt pouring it in the crankcase is going to do much of anything.

ATF is a mineral oil, with a ton of detergents. It works fine as engine oil for short term and does an excellent job of cleaning away deposits that sometimes produce pour oiling in certain areas.

That all being said, if it were me thinking about it, I would pop a valve cover off and start the engine. I also wouldn't rule out it being an exhaust leak or a cracked manifold. It could even be piston slap. Popping a rocker cover will at least point you in the right direction and requires very little work.
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Unread 10-16-2009, 05:25 PM   #15
txtumbleweed
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Not my intent to go OT, but........

Oil Myths and Facts
Read Myth #12 from Chevron

According to AMSOIL, ATF4 is probably close to a 0W20 oil. If you think OP has valve train chatter now, go ahead and see what it sounds like with a crank case full of ATF. ATF to clean up a gunked engine might have made sense 30 years ago, but oil detergents are pretty good these days.

I have personally experienced what the OP discussed. The 4.7L has a little bit of valve train noise (maybe even a little piston slap) at start up. Once it warms a little, much of that goes away. My experience tells me Mobil 1 synthetic has more valve train noise than dyno (assuming same viscosity).

Feel free to post up an objective study that recommends driving around with ATF as a replacement for oil.
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