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Old 08-17-2012, 02:46 PM   #1
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Hello, intro and tech question (yes, another about a rattle sound) ;-)

Hi all,

I'll first introduce myself before i ask my Tech question.

I'm from the Netherlands and i just bought my first Wrangler. It's a 1999 4.0 TJ with 159.000 kilometers and some mods.

4" inch lift Rubicon Express Superflex suspension kit
Quick connects
4:10 axles
Slip yoke eliminator
Offrotec vacuum diff lock
Easylock front diff

here's a picture:





Before this Jeep i drove a 2004 Mitsubishi Evolution VIII quite a change going from that to a lifted Wrangler lol. But you have to keep things interesting.

I am thoroughly enjoying this car and even though i have it for only a week i think this is what i should have been driving from the start.

There's a few minor issues like the front brakes that need a little maintenance, some cleaning and fresh pads & some small spots on the body that need attention.

There is also one other thing i have been doing a lot of reading up on. Surprise, surprise a rattle

Now i have already ruled out the cat, the heatshield & rest of the exhaust (the cat aint there anymore. The exhaust manifold is a aftermarket one with the flex pieces, then a simple downpipe straight to a muffler under the passenger seat, then a higflow cat and a pipe) Today i gun gummed the connection between manifold en downpipe, fixed the last piece attached to the high cat that was loose and firmed up the end pipe connection so it cannot hit against either the shockabsorber or the fueltank.

I felt around the manifold as good as possible if there was anywhere that sooth had leaked out. It's all clean. I checked the manifold studs as good as possible without removing the inlet. Just a thorough look & feel around, with the engine off, and running. And i also thoroughly banged the exhaust to listen for any sounds. But nothing.

Now the (sound) problem i have is the following.

There are no mechanical ticking sounds when iddling, nor are there any when revving the engine manually. There are no such sounds if i rev it with the clutch in or out. However as soon as i start driving and put load on the engine, hey hey. There is a rattle. it is not a pinging or knocking metalic rattle/sound. It is noticable as soon as you give throttle. With light throttle it is hardly noticable, but there. The more throttle the louder the rattling like sound. The best i can do to describe the sound is a cold diesel sound going up and down with the revs.

It's most noticable when cruising at approx. 50-60 km in 3th and then slightly accelerating or cruising along in 5 at 80-90km and then give it some throtle. As soon as you push it hard the rest of the exhaust overrules the sound but it does seem to become less, but dou to the loud exhaust i cant be really sure.

Now, i have done research, and since it is not a metallic sound i for now rule out bearings, also because it is simply not noticable when iddling. If it would be i assume i would hear a ticking sound. Same goes for the valves, there is some slight valve sound, but hardly noticable.

I pulled the plugs and they look good, no signs of either running rich (black) or lean (grey) Just relatively clean and healthy, though i dont know when they have been last replaced,. The plugs are on the to do list anyway (I opt for NGK's? is that a good choice for the 4.0?) so i think it is not Knock either, i only know knock occuring when running high revs and low quality fuel or badly adjusted carburetors, and know it as a soft crisping pinging sound!?

So, after this long story, what do i have left to check (apart from taking of the inlet and very thoroughly check the manifold, but judging from the loudness of the rattle it must be a huge crack i think, but since i cant feel/see anything suspicious i'm at a loss for the moment. Only other thing i can think of at the moment is the timing chain???

Thank you very much in advance for any suggestion

Regards

DutchWrangler

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Old 08-17-2012, 03:26 PM   #2
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Use a mechanics stethoscope and listen carefully around your exhaust manifold at idle. If you have a exhaust port is louder than the rest, you may have a manifold crack or a blown out gasket.

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Old 08-17-2012, 04:05 PM   #3
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Nice wrangler man! I don't know a ton about jeeps yet (I'm still getting there) but are you sure it's from the engine? Could it be related to the driveshaft/transmission/etc? And just out of curiosity, what size are your tires?
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Old 08-17-2012, 04:49 PM   #4
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@Dextreme, I'll see if i can borrow one somewhere and focus on the manifold. Jeep did a pretty good job hiding most of it and making it as inaccesible as possible lol

@ Deepsouthjeeper, thanks, it indeed does look good imho. The tire size is LT 295/75/R16 123/120R BF Goodrich Baja Champions on Mayarosch rims (a German brand), though i'm already looking for Mickey Thompson classics . I'm used to metric so i'm taking a really wild guess here that those tires would be what you would be referring to as 33"-ers???

As for the sound, I dont think it is in the drivetrain. I also need to get to know the Wrangler a whole lot better offcourse, but with such a noise, and my past car experience, i would at least also expect somekind of vibration. It drives very crisp though. No serious wobbling (though i did already have a deatwobble due to a brake pad that hanged) In fact it drives pretty crisp and stiff. Most awkward driving characteristic comes from flex due to the high walled tires, especially when i have to go into the sideditch on a narrow road for oncomers and steer back on to the tarmac. And we have alot of narrow roads over here lol. But i'll get used to it. Better then worrying about my rims and where to find my kidneys back if i had to do that manouvre in the Evo ;-)
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Old 08-17-2012, 11:00 PM   #5
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Nice. I thought they looked closer to 35's personally. My uncle had a set of Micky tompsons on his old CJ7. I'd love to find a pair of them for my TJ. Well keep us posted, I'd love to see how it goes.
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Old 08-17-2012, 11:33 PM   #6
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It kinda sounds like valve chatter to me try running high octang gas in it and see if that helps. Good luck!!!
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Old 08-18-2012, 12:14 PM   #7
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@Firedog327 Valve chatter & higher octane fuel? Are you suggesting to use the higher octane to "clean" the engine from carbon buildup? If so how could Carbon buildup explain the noise under load? I'd like to know and learn the why of it.

Over here in Europe the minimum you can get is Ron95 fuel which, if i'm not mistaken, is premium (91) in the US?? We also have Ron98 (94 in the US i believe??) which is what i already use. I was thinking about using seafoam, problem is it is not sold over here and if you order it in the US it has te be shipped by boat, since no fuids are allowed on planes. However what i can get is E85 fuel. I was thinking of mixing in that to clean the engine out while driving. A ratio of 9/10th Ron98 and 1/10 E85. I read that E85 works even better then Seafoam.

Fuel in Europe also is already mixed with 10% Ethanol anyway (E10) I know it's pretty common to run E85 in the US but it's very uncommon over here. Before i sold the Evo i was planning to go to a full E85 setup (Easy gain of at least 80bhp, and i'd be the first to do so in at least the Netherlands as far as i know (lol ok there's only about 300 Evo's model 1 to 10's over here lol)). I dont know how the 4.0 would take it though and what kind off adjustments need to be done for full E85. In the Evo it was simply a matter of bigger injectors, a Air fuel sensor for monitoring purposes and a reflash by @mail. I highly doubt it is that easy, if possible at all, on the 4.0? Running E85 would solve any carbon build up problems in any engine imho. I use it to thorouhgly clean carburators for instance, works better then any other product i have tried and is out there. Most vehicles from the mid 90's and up dont have problems with the more aggresive E85 eating up o-rings or damaging fuelpumps or lines. They have been running Ethanol for decades in Brazil without al the feared issues.
It's funny how scared people are over here off the stuff and the wild stories going around (even about the E10) it will dissolve your car lol destroy the engine whitin hours after filling the tank with it lol lol lol Even respected technicians sell alot of bullshit about it and seem almost scared to death of the stuff. Judging by what i read on US forums for the Evo conversion, there is nothing to fear at all. Only slight problem could be the cold start in severe cold winter conditions and shorter oil change periods due to borewash.

Ok i'm getting quite a bit offtrack here. There is a rattle in my Wrangler i need to solve first lol I'll throw in some cleaner (Wynns?) and octane booster on the next fill up anyway. Cannot do any real harm i guess.
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Old 08-18-2012, 04:25 PM   #8
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Just had a brainfarth.

could it be floating valves because of worn valve springs?
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Old 08-18-2012, 05:48 PM   #9
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I'm not sure how E85 would *gain* power. Many cars in the US are set up to accept it in any mixture with straight gasoline (E10), but both fuel economy and power suffer. It's only a (very small) cost benefit. Also, in most parts of the US, it's really hard to find. I don't remember ever seeing it in Europe, though my travels there have been fairly limited.

To my knowledge, it does not have any special cleaning abilities. Seafoam is great stuff, but perhaps marginally better than other fuel system cleaners. The magic is that it's also a stabilizer, so for a vehicle that sits often, it's a great product.

Carbon buildup can cause 'knocking' by raising the compression the the cylinder. More carbon in the cylinder means less volume for the air/fuel mixture, so compression raises. Higher compression can lead to preignition, otherwise referred to as knock or ping. Some will use higher octane fuel to mask the problem (also caused by improperly set timing), but if your (stock) engine needs high octane fuel to avoid this, there's an underlying issue. European petrol is quite different from US; additives and cleansers are different, so I can't comment on that. I'm pretty sure you're right on with your octane conversions.
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Old 08-18-2012, 08:16 PM   #10
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Hey dutchwrangler I brought a car from an uncle who replaced the engine in it with a new one during the brake in period he used high octane gas when I got it I used a lower octane and when I got on it or put it in a hard strain the valves would chatter so I hadto use high octane just to keep the chatter quite
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Old 08-18-2012, 08:21 PM   #11
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I really dont know if it had anything to do with it or not but it worked for that car at the time. Anyway hope yyou find the problem let us know
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Old 08-18-2012, 08:28 PM   #12
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There is a product out that helps with carbon build up and it called Z-Max. I haven't used it yet but ppl saids it surposed to be good stuff it anyone has used it let us know how it works
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Old 08-19-2012, 02:14 PM   #13
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I'll look into some carbon cleaning stuff, see what i can get over here.

@Geoff, The power gain from E85 is mostly due to it practically being racegas (Ron100+) this allows for much more turboboost. So, yes, in normally aspirated engine it wont gain you much power. In turbocharged vehicles it's the best you can have.
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Old 08-24-2012, 09:51 AM   #14
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Found the culprit. Indeed the manifold. A rather large crack so obvious i completely overlooked it ahem lol.

Ordered a new one, so next weekend i'll be getting my hands dirty.

Enough time to read up on the howto. Fingers crossed the bolts cooperate.

Thanks evryone for the input
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Old 08-25-2012, 12:29 PM   #15
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Quote:
Originally Posted by DutchWrangler
Found the culprit. Indeed the manifold. A rather large crack so obvious i completely overlooked it ahem lol.

Ordered a new one, so next weekend i'll be getting my hands dirty.

Enough time to read up on the howto. Fingers crossed the bolts cooperate.

Thanks evryone for the input
Glade you found the issue! Keep us posted man.
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Old 08-25-2012, 01:51 PM   #16
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I will. It is cracked an inch or 2 above where the manifold connects to the rest of the exhaust and just beneath where it comes together to one pipe. A neat horizontal crack i thought was a weld. There was no sooth around it, looked clean and almost new. They should shoot the engineer who came up with the idea to hide the manifold as much as possible from view and visual inspection lol Then again, engineers hardly ever have to get their hands dirty and solve technicall issues aftwerwards, so it probably does not even occur to them to design something that is also maintenance friendly lol

This crack imho is caused not by the usual head expansion but simply from the weight of the exhaust hanging on the manifold. Closer inspection revealed that the first support point is from the 1st muffler. So from the engine to under the passenger side there is no support for the exhaust. I think welding on one or perhaps two extra supports for exhoust mounting rubbers should be enough to avoid the same thing happening again.

I did a crude repair with some exhaust putty and aluminium tape and i'm glad to report there are no other strange noises from the engine now that the leak sound is gone. It runs as smooth as silk.
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Old 08-29-2012, 02:06 PM   #17
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And here it is, not to bad, took my time, but had the manifold off in about 2 hours. Tomorrow i'll clean the inlet, take of the rest and make a start bolting it all back:

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Old 08-30-2012, 03:27 PM   #18
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Well it's done, about 6,5 hours in total and a few sixpacks. And no leftover bolts, nuts or electrics lol lol Worst part was the bolt just left of No 3 outlet. Took me about half an hour 45 minutes to get that ^!@%$@^#%bolt in.

It's cracked almost all the way i'd say about 130-150 degrees.

The engine runs smooth as silk no other sounds noticable. It iddles better and drives smoother and silent. As far as silent goes for a 4.0 with one muffler and a highflow cat lol

Thanks again evryone for all the suggestions.

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