1991 Jeep Cherokee- General questions on my first Jeep...

aislinmmhaislinmmh Member Posts: 1
edited August 2014 in Jeep
I just bought a 91 Jeep Cherokee Laredo, 4.0L 6cyl, 168,000, no rust, no paint chipping, just a little front fender dent and a end piece of the back bumper being loose...The engine sounds strong, from what I can tell, not that I know a whole lot about motors. I know it has an oil leak, most likely the valve gasket (?). But I had a few questions about other stuff since my manual was missing.

*The last (and only other) vehicle I owned didn't really have an oil pressure gauge (if it did, I don't really remember, it was 3 yrs ago)...just a light that came on if it got low. The gauge in my Jeep usually starts at 40 when I start it, goes up to 60 when I start driving. After a little while, it goes down to 20-ish or a little lower when idling, and 40 when Im driving. I haven't seen it get much lower than that. Is this normal?

*When I apply brake pressure after going maybe 30 mph or above, there's a clicking that sounds like it's right under my feet. Someone told me it may be the U-joint, but again...I am automotive-challenged.

*I got the jeep up towards 55/60 mph today for the first time. After about 20 minutes, there was a squealing sound any time I hit 55 or over, but only if I was pressing the gas pedal. And at about 60/70 mph the motor starting shaking kinda roughly. Should I have flipped the transmission switch...or whatever that thing was....from "comfort" to "power"? Again, it came without a manual, so I have no idea what half of these switches are for.

*I have heard THREE different opinions on what kind of oil to use. The oil change sticker from the previous owners last oil change listed 5W30. A mechanic friend of mine told me to use 10W30. The guy at Auto Zone, said 10W40. Again, no manual to actually look up what it's supposed to be. Anyone know what kind I'm ACTUALLY supposed to use?

*There was a recall issued in 94 or so for...something having to do with the brakes. Based on my VIN, it was never taken care of on my Jeep. Is it possible to take it to a Jeep dealership or something and have it replaced under that recall? I've never had to deal with recalls before, so I honestly don't know the "rules".

Any help/ideas would be greatly appreciated. Like I said, I know nothing about engines in general. I've heard some pretty bad stories about mechanics in the area, and really don't want to get screwed over just because I don't know what's going on, or panic over things that are normal in a larger vehicle/Jeep in general...all I've ever driven is fairly compact cars.


  • 5213252132 Member Posts: 62
    The 4.0L I6 engines are notorious for oil pump failures. If your oil pressure gets below 30 pounds at idle then you have a bad oil pump. By the way, your Jeep takes 10W30 oil (don't listen to people who tell you to put in 10W40 or synthetic!) If I were you I would sell it due to signs of neglect.
  • jacemtjacemt Member Posts: 1
    This is a very old post, but wanted to put in my two cents for anyone who ran across it later. I have to disagree with the previous post. For the notorious oil pump failures I have owned 4 Jeep Cherokee's with the 4.0L engine, 2 that I ran well over 200,000 miles and none of them ever had an oil pump failure. On the oil pressure, I was looking in the shop manual for a Cherokee that was a year or 2 older and in the shop manual it said that at idle (600rpm) that the oil pressure should be around 13psi and at operating (2000rpm) that the oil pressure should be between 35-75. On the oil it depends on the temperature that you will be driving the vehicle in, 10W30 (I believe) is what the manual recommends for all around weather.
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