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Langdog
Novice
Apr 25, 2013, 6:32 AM
Post #1 of 17
(2103 views)
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2008 Jeep Wrangler - 3.8L V6 - 6 Speed Manual Trans - 50k miles
A few notes about this engine - These are notorious Oil-Eaters. They have been in production since 1991 and have been used extensively in Chrysler mini-vans and from 2007-2011 in the Jeep Wrangler. The engine design is a pushrod 60-degree V-6 layout with an iron block and aluminum heads. It has a camshaft-driven oil pump that is located inside the front cover. Since I've owned the vehicle, I have noticed a high frequency of dry starts, independent of which oil filter brand I choose.
A little over a month ago, my engine developed a strong, metallic ticking sound. When checking the oil level, I found it about two quarts low - stupid me. After topping off, no change in the sound. After talking to a few mechanics, we determine that a collapsed lifter is likely the culprit. With the engine idling, the sound is roughly half of the idle speed. There is no loss of engine peformance.
My first step was to switch from conventional 5w-20 to synthetic to try and break loose any sludge or deposits that might cause the issue. I also used an oil additive for an extra cleaning boost. No results...
Assuming it's a permanently damaged lifter, I pull the valve covers off and check the rocker assemblies and pushrods. Everything on top of the heads was clean and lubricated. I rotate the crankshaft to all degrees and check for equivalent play in all the rockers and pushrods. One of the lifters offers a significant amount less resistance than the others and I think I've found my problem.
For an extra step, I perform a compression test and all results are normal.
A friend and I pull the exhaust manifolds, fuel injectors, intake, manifolds and heads off in order to access the lifters for replacement. All the camshaft lobes look decent and none of the lifters display abnormal wear patterns. I disassemble the culprit lifter, but see nothing alarming at this point - strange.
As I'm cleaning the combustion chambers, I notice some abnormal dings in one of the exhaust valves (see picture). I consult a mechanic, but he sees nothing terribly abnormal, especially since my compression results are good.
[URL=http://s1103.photobucket.com/user/LtDanPup/media/8ACC8FF4-4048-4657-A5CD-447D59753AA5-3181-0000046E401CA0C4_zps2c69a627.jpg.html]
I replace all the lifters and pushrods anyway and reassemble the engine. I add an oil pressure guage while I'm at it via an oil-filter sandwich plate. We refill with coolant, change the oil and start things up - same exact tick as before. My oil pressure reads 12psi on idle once the engine is warm and around 45-50 psi under load at about 2,00 RPM.
Now I'm worried that it's something in the bottom-end. The sound isn't getting worse, but it is always present - moreso once the engine is warmed up to full operating temperature. The sound is much less apparent under heavy load, but is still slightly audible. I've now been driving the vehicle for over 600 miles since the noise became apparent. There are no performance losses. The noise is loudest near the oil pan towards the rear of the engine. The video below is one I took to help identify the sound.
http://youtu.be/vjVFsOZVd6s
(This post was edited by Langdog on Apr 25, 2013, 6:38 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 25, 2013, 7:07 AM
Post #2 of 17
(2079 views)
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How did you determine which cylinder it was?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Apr 25, 2013, 7:12 AM
Post #3 of 17
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Recording noises are still somewhat tricky. That sounded awful! if this really is doing the "dry start" AND the 12PSI oil pressure, warm at idle I'm guessing but you have some real damage not just lifters. Check that oil pressure with a mechanical gauge - it's too low.
Bearings can take a real hit and initial start is probably trying to catch up with excessive leak down before oil can get where it's needed.
I can't be sure but bet this engine is in trouble,
T
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Langdog
Novice
Apr 25, 2013, 7:32 AM
Post #5 of 17
(2062 views)
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Others who have installed pressure gauges have similar hot idle readings as mine. On a cold startup, I'm reading 70-80 psi on the gauge.
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 25, 2013, 7:35 AM
Post #6 of 17
(2058 views)
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If you can't change it by killing cylinders that would tend to indicate something in the valve train. I would but a vacuum gauge on it and see how it acts. See if you are getting any bouncing in the needle.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Apr 25, 2013, 8:18 AM
Post #7 of 17
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That video to my ears made it sound like a rock crusher! I still don't like this oil pressure thing but not there checking myself.
As Hammer Time just said if noise go away or drastically change by taking out one cylinder at a time it helps for figuring out just what as does the vacuum gauge. I could be wrong but seeing 80 PSI isn't right either to me. Too high and shouldn't be able to get that high IMO if all is right which it isn't,
T (off line till later today)
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Discretesignals
Ultimate Carjunky
/ Moderator
Apr 25, 2013, 5:34 PM
Post #8 of 17
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Sounds like a rod bearing. Probably due to the dry starts. That engine is known for ring problems, so if you have to go into the bottom of the engine, you might as well check the cylinder bores roundness, deglaze, and re ring the pistons with some high quality rings.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Apr 25, 2013, 5:37 PM)
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Hammer Time
Ultimate Carjunky
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Apr 25, 2013, 5:36 PM
Post #9 of 17
(2012 views)
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I think a rod bearing would have changed sounds when the cylinder was killed.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Apr 25, 2013, 5:46 PM
Post #10 of 17
(2008 views)
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When the engine is revved in the video you can hear the distinctive rod clatter.
Take another video while holding the rpms up around 2500.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Apr 25, 2013, 5:52 PM)
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Langdog
Novice
Apr 30, 2013, 5:18 AM
Post #11 of 17
(1948 views)
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I pulled the oil pan off last night to take a look at the bottom end. All the piston skirts are intact and I didn't notice any unusual play in the connecting rods/journals.
One thing I did notice was an excessive amount of slack in the timing chain (video link below). Looks like I'll be pulling the front cover off...
http://www.youtube.com/watch?v=fQfGKHAsIGY
Can anybody say they've heard a timing chain make the kind of noise my first video had in it?
(This post was edited by Langdog on Apr 30, 2013, 5:28 AM)
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Tom Greenleaf
Ultimate Carjunky
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Apr 30, 2013, 7:22 AM
Post #12 of 17
(1932 views)
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Should just be a HD chain. Yes they can make noise. You can get some idea of how bad one is by indexing the crank damper/pulley and turn by crank bolt back and forth to see how much it can move till in this case you would just feel some resistance increase. I don't think there are markings for degrees on this damper at all but don't know either for sure.
The noise of a chain would be at that end, more of a slapping but if it uses idler tensioners they could go wild.
I don't think that would have much to do with the problem in general with oil pressure and consumption issues.
BTW - just feeling for free-play in the crank/rod bearings isn't even close. A product called "Plastigauge" and re-torque them then measure how fat it got like squishing a string of plastic that stays squished.
Looked at one of these and forget what year but this engine I think - new. I actually wanted something to use for real work and all they had were luxury stuff with junk I wouldn't want to gave up.
Old phart - they used to sell CJs that only had a driver's seat and just painted floor - not even rubber! No top not just a choice! That's history but they were street legal with nothing for any creature comforts.
How far do you want to go on your own with this job? I tend to think you'll run into some serious stoppers with this engine but not there to second guess either,
T
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Discretesignals
Ultimate Carjunky
/ Moderator
Apr 30, 2013, 7:38 PM
Post #13 of 17
(1914 views)
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That chain does look sloppy. You would think with only 50K it wouldn't be like that already.. There is a procedure for measuring the chain wear in the service information. It requires removing the timing cover though.
Kind of strange the noise is louder near the back of the engine. You would think being a chain slapping around it would be noticeably louder at the front cover. You could pull a couple of rod caps and inspect the bearing half just to be sure they are doing alright.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Apr 30, 2013, 7:45 PM)
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Langdog
Novice
May 1, 2013, 7:12 AM
Post #14 of 17
(1896 views)
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If I remove the timing cover, I'm just going to replace the whole set.
Keep in mind that this engine is an oil-eater. If I allowed it to get a couple quarts low, I can't imagine that the less-vigilant first owner could have done during the first 30k miles. Low oil levels in that phase definitely didn't help the timing set out.
A good note to add here is that I've recently noticed an unusual amount of rough acceleration when pulling out or shifting gears at a low RPM. In layman's terms, the engine/trans 'wobbles' a lot when I pull out. Could this be a symptom of retarded valve timing due to a worn/slack chain?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 1, 2013, 7:42 AM
Post #15 of 17
(1891 views)
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Sorry - didn't re-read whole thread but have you done a basic compression check on this yet? Even apart and cold it could be very telling of problems.
With timing chains by the time you are looking right at them on typical ones that I think this has you probably should just toss it. Famous last words, parts are cheap for many but getting to some is the work. I'm a bit surprised at the mileage a metal chain and gears (I think) would have jumped unless there is a tensioner involved that let go.
Again - I don't feel so good about this engine overall. You just said orig owner may have some unknowns about the thing. Even 30K if it was an oil consumer/burner and allowed to run no doubt ignoring warning lights it would be toast as said back before. Hard to say but perhaps this poor thing got beat to death and cleaned up enough to sell it when you bought it??
You said back up top these were known oil burners? I haven't heard that yet and have read some surreal amount of posts from assorted vehicles for years now. If it consumed without an obvious leak more than a Qt. in 2,000 miles I'd be surprised. Being a Wrangler perhaps something was broken or a filter, drain plug left loose or whole knows in it's history. That would and does take out whole engines if new. Car makers jump all kinds of hurdles to design their stuff to make it off warranty without nasty problems. Sometimes stuff just happens even with new but rare to me for this trouble,
T
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 1, 2013, 8:47 AM
Post #17 of 17
(1885 views)
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If this only has the cliche "Idiot" light I'm surprised. 4PSI isn't anywhere near enough pressure for crap and an engine would blow. Bearings as you probably know are not rolling ball bearings in an engine that I know of older or newer. It's sliding on oil under pressure such there really isn't any measurable metal contact at all on the things that really count. If the 4PSI thing is really true that's delinquent engineering! Any recalls or TSBs on this?
Think like if you ever did it, just water between two pieces of glass they are not touching. I know you get the idea.
Trouble is lack of oil pressure not just oil level which of course will have no pressure when it can't pick up any to pump doesn't take a mile to do wild damage.
If you are well tuned into a Jeep only site you probably know or have more specifics at hand then I could dig up for the assortment that shows up here. Just the basic mechanical internal combustion engine has not changed much since the first ones well over 100 years ago!
Just might come down to a reman engine. To me, way too bad at the low miles. Not sure how many miles you want but just know generally reman engines are no where near as good as a good original unless there are some improvements in doing such. You just plain lose the balance. Unless the world of engines totally changed you can't even mess up bearing caps or put in a used crankshaft without going thru all hell.
Good luck and sorry this is happening. I used to suggest if in fact an engine is toast to find the fully checked out good whole used one, an original with a history and why it's available but with what you are saying I'm not so sure on this engine anymore so a feather of knowledge in my cap if this really is a bum engine design from the get go,
Tom
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Please Help - Knock sound & engine fail
