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Jeep Wrangler

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  • goducks1goducks1 Posts: 432
    I've never heard of any problems with that tranny. Just making sure the guy knows it has no OD. I wouldn't be happy with the engine spinning for hours at 4000 RPMs on a road trip, it sucks fuel pretty fast and the engine isn't designed for it. I've heard it averages 14mpg on the highway b/c of that issue.

    The 4.0L is a great engine overall though and that mileage is not a big issue for this particular engine, AOTBE. The biggest issue to look for is the exhaust manifold, make sure it was replaced as pretty much 100% of them crack for any of the 1990s Jeeps with the 4.0L. It's an expensive repair, many of us can testify as to that.
  • eltipoeltipo Posts: 21
    Jeepers,

    I drive an '05 Unlimited, auto, 4.0L. I have a daily commute one way of about 1.5 miles with top speeds of 30mph. I live in a hilly area and have been driving with the overdrive off. I feel like I am getting more climbing power. Am I dreaming? Are there any benefits to doing this? Is this a bad idea?

    Thanks
  • mac24mac24 Posts: 3,910
    Am I dreaming?

    No, that's what the overdrive switch is for.
  • jimlw2jimlw2 Posts: 122
    Like Mac24 says, your scenario fits exactly why there's the "O/D Off" switch. Per the manual, I sometimes use it on my '05 Unlimited on high-wind days during my 25-mile commute when I see/hear/feel O/D kicking in and out...though, I also back off the accelerator too since Wrangler's aren't known for their aerodynamic coefficient, especially in high-winds ;)
  • jimlw2jimlw2 Posts: 122
    I just assumed the warmer air through the floor vents was due to engine compartment heat. I often use the bi-level A/C setting to get cooled air through both upper and lower vents...It divides the air velocity so I increase fan speed to compensate. I'm sure the right answer is to open up the top and get nature's A/C ;)
  • wheelsdownwheelsdown Posts: 250
    One little comment. I have a 2000, 4.0 with the "crappy" three speed and 3.07 rear end. It turns a little over 2400 rpm at 65 mph. Not near 4000.

    A lot of things determine engine life. In most cases, number of turns on it is way down the list.

    Like you say, taken care of, it will last a long time.

    I agree, MPG is a downer. :P

    Terry
  • mac24mac24 Posts: 3,910
    I thought I'd wait until someone else chimed in before posting on this again. ;)

    There are many other factors that will have more of an effect on engine life than a small increase in average rpm. Personal driving style and habits are one.

    For me it's 2500rpm at 65mph, and about 2950rpm at 70mph, with a 3.73 and 31" tires. Redline is about 5200rpm, so cruising at 3000rpm is well within the envelope.

    I drive briskly in town and I keep up with, or am usually ahead of, most other traffic. On the highway it's 65-70 mph, very rarely above that. Additionally, the a/c is almost always on.

    I get a return of between 14 and 15mpg, while a manual should get 15-17mpg.
  • eltipoeltipo Posts: 21
    Thanks,

    I was really wondering if this posed additional wear on the car or not. I was also wondering if driving with the overdrive off at low speeds decreases MPG.
  • Hey guys, newbie here to the board and to my Jeep. Just bought (4/23) a '00 SE with 64k miles. Nice Jeep, however when I drove it home on the highway I was going about 70 mph and downhill and it started shaking pretty bad, once I slowed down it stopped. Then today, I was out on the highway again, around 70 and downhill so gaining speed, and started shaking again. Concerned what it might be???

    My two front tires are pretty low on tread (got add'l discount for this), but is there common steering or suspension related problems that might factor in as well??

    Appreciate the help.
    Ryan
  • mac24mac24 Posts: 3,910
    It's not an unknown problem, but it's more common on Jeeps that have been lifted.

    Things to check (in order) are, wheel balance, wear in any of the steering and front end suspension joints, failed steering damper, and finally, wheel alignment.

    However if you need tires anyway, the order changes. Check for wear as noted, then have an alignment followed by new tires and balancing. Finally, if the problem remains (unlikely) check the damper, but don't be tempted to replace it with a bigger one regardless, just to try and mask the problem.
  • jimlw2jimlw2 Posts: 122
    I've got the longer wheelbase Unlimiteds so I can't give you real-world advice on your specific model. However, I can attest to Wranglers in general are not known for their highway speed characteristics. I know test driving the regular wheelbase Wranglers seemed a bit more "choppy" at highway speeds than the Unlimiteds.

    Start by checking tire pressures on all four. New tires certainly would improve your ride/handling and you'd want to have an alignment done with new tires as well which may solve the issue. You also might see if your Jeep has stock suspension parts that are worn. If not stock, previous owner(s) may have changed them out or added a lift.

    Just wanted to give you a few simple thoughts...I'm certain more ideas from the real experts on this forum will get you straight 'n smoothed out. Happy Jeepin'.
  • wheelsdownwheelsdown Posts: 250
    mac, did you have a typo on the 70mph revs? Based on the 65mph number, looks like 70mph should be about 2695rpm.

    While we are discussing rpm. A few weeks back there was a discussion about the valves not rotating until above 3000rpm. The rotating knocked carbon off which helped smooth running. Heck, with my 3 speed auto, 4.0, I doubt mine had ever been above 3000rpm. What is the recommendation here? Run up to 3200 or so for a short period every once in a while? How often? How long?

    I put mine low and ran it up for ten seconds or so. Plan to do it every couple of weeks. My TJ is a run around town car. Darn few road miles.

    Terry :confuse:
  • erickplerickpl Posts: 2,735
    Mine has a shake about 60 mph. At 63 it is gone. Doesn't do it at 70. I'm thinking it has something to do with the 33's I'm turning and their balance.

    TrXuS MT's are a PAIN to balance on a good day.

    -Paul
  • mac24mac24 Posts: 3,910
    mac, did you have a typo on the 70mph revs? Based on the 65mph number, looks like 70mph should be about 2695rpm.

    No, the typo was on the speed. :P

    Should have been 2500rpm at 60mph. Just under 2300rpm at 55mph, 2700rpm at 65mph, and a little over 2900 at 70mph. All figures taken from the tach, so they're approximate.

    Referring back to the original mention of 4000rpm, that would equate to about 95mph. Quite achievable, and even a little more, but not recommended as a cruising speed.

    As for the engine rpm required for the valves to start rotating, I don't know the exact figure but the theory is correct. However, the benefit is the evening of wear on the valve faces and seats, rather than the removal of carbon. You don't have to engage low range, just put it in first or second (after the engine is fully warmed up) and accelerate up to 3500rpm or so, hold it for a few seconds then slip it into 'D'. Do that once a week and it should keep you ahead of the game.
  • wheelsdownwheelsdown Posts: 250
    Martin,

    Thanks for the reply. I have been putting it in 1st gear, not low range. My bad on terminology. :blush:

    Terry
  • goducks1goducks1 Posts: 432
    Boy, I didn't mean to cause offense about the 3-speed. I do remember thinking a 3-speed was unacceptable when I bought my current Jeep new in 1998. My YJ had the 3-speed auto and I hated it. I thought it was cheap of Chrysler and still do. They also had a 3-speed in the Neon if memory serves.

    I get close to 20mpg on the highway with my 4.0L, 3.73 differential, 30" BFG A/Ts. It seems to me if I ran in 4th gear only I'd run close to 3000rpms vs 2500rpms. I don't know. Good to know about revving it up now and again though.

    Jeeps aren't perfectly designed and I do think potential buyers should know when Chrysler has been less than perfect, as with sticking a no-OD auto in the Wrangler, or the whole exhaust manifold fiasco.
  • wheelsdownwheelsdown Posts: 250
    ducks,

    No offense taken on the 3-spped auto. Many of us have been on this forum since the early days of the TJ. Mine is a 2000, so I missed the manifold problem. My little "crappy" deal was poking a little fun harking back to the discussions on this forum about the crappy 3-speed auto being so bad that those who had the 5-speed (I think) manual just could not understand how we could put up with them. You would have thought crappy was part of the official name. Well, I drove manuals for thirty years. The TJ was my retirement present to myself. I was just tired of shifting. I knew it was my around town wheels and the auto would get the job done. It has not given me any trouble.

    Most of the problem the stick shift guys had with the auto seemed to revolve around not having an overdrive. With the 3.07 dif's, you kind of live in overdrive all the time. A little slow off the line, ( even a little slower since I put 30's on it) but it gets me there.

    True, the manuals are probably more fun to drive. True, you have better control over engine speed and power for up hill climbs. True you can use the engine for down hill braking. Heck, I live in the Chicago area. We don't have hills you can't see over. In fact, most of our pot holes are deeper than our hills are high.

    No problem. :D

    Terry
  • mac24mac24 Posts: 3,910
    No offense taken by me either. :)

    The three speed in the earlier YJs was the basic TF999 without a lock-up torque converter. Revs would have been higher and changes more frequent, so I can see where you're coming from.

    However, when it comes to the number of gears, less doesn't necessarily mean cheaper. Chrysler had some truly awful transmissions available that could have been used to bring an automatic to the Wrangler for the first time, but to their credit they picked a strong, heavy duty but smooth unit that was fully capable of handling off-road duties as well as those on.

    Remember as well, that the Wrangler is a true dual purpose vehicle. If its development had been directed purely at on-road driving then it would long ago have had a unitary body, smaller wheels, two wheel drive, independent suspension and a smaller higher revving engine.

    Virtually all the features on a Wrangler are a compromise of some sort, but right from the early days the vehicle has been in evolution, and continues to be so. The vehicle on which the current model is based was introduced over sixty years ago as an off-road military transport. The vehicle will never be perfect for all people, all the time, but I do think that the introduction of the Torqueflight 999 was the correct decision at that time. Especially considering the alternatives, which were either a much weaker four speed or no auto option at all.

    Oh, and congratulation on your fuel mileage by the way. That really is the top end of what can be expected from an early TJ. You must be a very smooth driver! ;)
  • dctalkdctalk Posts: 6
    I'm seriously considering on of the new 2-door JKs, and trying to decide whether the Rubicon is worth $3k over the Sahara the way I would want them configured. The Jeep would be my daily driver, and my intent would be to use it off-road only on light trails in the Southwest mountains or desert, no heavy duty Rubicon-style boulder crawling or stump-jumping or mud slinging. If I go with the Sahara, the question is do I opt for the rear locker or would the limited slip differential suffice? Another question for the group--how does the LSD react on wet road conditions? Does it help at all on rain-slick roads or hurt? Any other effects on driving that the LSD would have?
  • erickplerickpl Posts: 2,735
    No experience with LSD (either type ;)) but the Rubi/Sahara choice is really up to you. Given how I drive my TJ, I'd opt for a Rubicon if buying one today. The lockers are nice if DO get stuck on those trails. Desert rain can make a trail into a river REAL quick, and having that capability is always nice. Plus, if you decide to sell it later, you have that much better resale.

    I never thought I'd wheel like I do now, so if you know you'll be doing trails and such in the future, it doesn't take much to go that next step and want to do something a little more challenging. :D

    -Paul
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