Two Jeeps, Two Questions

crackedhead1crackedhead1 Member Posts: 16
Mr Shiftright and others:
Thanks for your help in the past and i hate to start a new thread since the first topic has been covered quite a bit here in the past -- but I can't seem to pin down a headache with my 82 CJ7, and a newer one with 96 Grand Cherokee.

First the CJ: I can't get it to heat. Engine temp normal, water does circulate, i replaced the heater core (this is fun), bled it to release any trapped air -- there was a little but really not much -- worked on the cables so they all seemed to function well, still no or little heat. Sometimes it will will blow pretty hot for about 1 minute, then cold. Mr Shiftright you have referred to a heater control in a couple threads -- whattheheck would that be in my old CJ -- the cable and knob themselves? I'm fixing this Jeep up since i've had it for about 12 years and the engine still runs great. Anybody got a thot on this??? Water pump is ok but i wonder if the thermostat could be at fault even the engine temp comes up. The heater hose to the heater feels hot, but as you mentioned in another thread, it would be hard to believe a heater core, especially a brand new one could be THAT blcoked. Looks like I replaced the core for nothing -- well, actually about $50 :)

Second problem: My 96 Cherokee has that memory settings thing and although the seat, right mirror and stereo settings always work fine, the LEFT MIRROR resets so low when you unlock with the remote that a gerbil -- if one were were ever to drive my car (normally i just loan it out to a neighboring family of hyenas) -- MIGHT be able to see out safely. This has just started in the last three or four weeks and DOESN'T ALWAYS DO IT but it is occurring with more frequency -- say, 75% of the time. Sounds electrical rather than mechanical which usually means, at least with Jeeps, at least three (seemingly) befuddled yet giggling mechanics and two bills, each roughly averaging $57.60 and $129.28 before the problem is fixed. Any suggestions on an economic repair that i might be able to perform (IQ approximately 88-90)? As usual, THANKS TO ALL!


  • swschradswschrad Member Posts: 2,171
    issue (1), no heat. the bowden cable activates a valve someplace under the hood, that turns the hot water on to the heater core and also turns it off. I strongly suspect that valve. follow the cable, find the tin geegaw it connects to, and bypass that sucker, see if you don't get hot in a hurry.

    issue (2), left mirror. willing to bet any amount of other people's money ;) that it's a couple of wires being pinched under the protection where they enter the door, or in the cable heading in. if you have the wire color codes off a wiring diagram, you could wiggle that open and put a layer of tape (or two or three) over that mirror wire for a quick fix. the better one is probably a new harness section if availiable.
  • crackedhead1crackedhead1 Member Posts: 16
    my Bowden??? Sheesh. The onliest Bowdens i ever heared of were Bobby and Terry. I will check both your suggestions tonight and see. I have the wiring schemes for the JGC and can trace wire, but the geegaw (man, i'm an editor and i had to look that one up) connectin to the cable connectin to a valve under the hood seems complicated. I'll follow it along and see what it finds. Is it possible this valve is under the dash -- or if it's under the hood, you think it'd be closer to the radiator; thermostat, or closer to the heater hose near the firewall? Thanks for responding.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    I think he means following the control cable from the dash to the mechanical valve that lets water into the heater core. Perhaps this valve is sticking or only opening partially. If you have a hot hose going IN to the heater core but a cool one coming OUT, it really has to be that valve. If you have a hot hose both IN and OUT, then the fan motor is not being allowed to blow directly onto the's being blocked by some kind of mechanical or vacuum or electrically operated flap or door. A CJ is pretty primitive, you should be able to see all this happening.

    If you had no hot hose going INTO the core, then I'd suspect a theromstat or some internal clogging in the engine's water galleys (gulp) or perhaps a thermostat problem.

    I presume the engine heat is normal on the gauge.
  • alcanalcan Member Posts: 2,550
    Check the heater hose fittings on the engine for internal obstructions.
  • crackedhead1crackedhead1 Member Posts: 16
    ... i couldn't work on it! Thanks and i do know it's a hot hose in, don't recall temp going out but i'll check. Is this valve at the core? I'd rather have rotator cuff surgery again than go back into that dash :0

    Alcan i'll check the hose fitting at the block and radiator. Yes Mr. S, the engine temp guage shows normal (replaced guages as of last year) and i did a temp check a couple of times after she was up to full temp, bled the cap and put a friends rectal -- er -- whatever that little digital temp guage with a probe in the radiator and she checked in OK both times, just under and just over 200 F. Thanks to you both.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    Yes, the valve is generally at or near the core on most cars, but not all. Some with automatic climate control have them scattered all over the place.

    You could have a pinched or collapsed hose, that's true--hadn't thought about that one.
  • crackedhead1crackedhead1 Member Posts: 16
    .... shouldn't the valve be attached and therefore probably not the source of the problem? Not that something new couldn't be faulty (see Houston Texans) but dropping the dash should be my last resort i should think (hope).

    fyi, i think most all the heat/cool doors and vents i have messed with are strictly cable operated on this old girl, but i might be missing some sort of vacuum apparatus somewhere but there definitely isn't any auto climate control except when the doors are off. : )
  • crackedhead1crackedhead1 Member Posts: 16
    in the course of testing the heater again, i had to warm the old cj up and so i put it in 4wheel and took off in the snow for about 15 minutes. oil, coolant, temp (not heater)all ok before embarking. pretty soon the exhaust started smelling like roasting flesh, frankly, so i spun around, got er home, shut her down. oil, coolant still ok, exhause pipe was emitting a slow, disgusting little plume 10 minutes after i shut it off. i'm no mechanic but if a valve was stuck, wouldn;t it try and burnsome unspent gas and carbon etc out through the engine? There was no knocking or pinging and frankly, it still had plenty of power, i just didn want to runit like that.

    First i am going to pull each plug and do a compression test, then i don;t have a clue beyond pulling the valve cover and having a look-see. Could a ring have burned out or is this like a major blown engine deal? The old girl has almost 180,000 miles but doesnt use or burn oil and has lots of power so i wasnt anticipating this abrupt event.

    suggestions from anyone besides shutting up, getting out my checkbook and being thankful that it wasn't my pancreas that decided to stop functioning?
  • swschradswschrad Member Posts: 2,171
    if a blowing plastic bag whips under your car and melts onto the exhaust pipe, it will definitely catch your attention even if it doesn't catch fire. the stink would tend to be more of a chlorine or an ammonia odor if it was a bag or a dead and cooking critter stuck on the hot pipe.

    if the odor was very sulfurous, it could be you are dumping lots of petroleum into the catalytic, which is a great way to kill it. things like dead rings or shot valve stem seals, a drooling injector overloading a cylinder, no spark in one or more cylinders can all do this.

    I'd check compression and put the values down against the table of acceptable ranges for your engine, put plugs and wires on it, and if you're equipped with 02 sensors, check 'em to see if they work. a dead 02 sensor might not set off the computer's $$$ light, and could force the engine to rich up. the non-compression issues are not expensive to deal with.

    with 180K on the clock, though, this CJ is getting close to needing some cash shovelled at it. if you're lucky and it's just a bunch of sour spark or a bad sensor, merry christmas.

    oh, brand-new tailpipes are pretty rancid for the first week or so of driving, if you replaced one of them recently.
  • crackedhead1crackedhead1 Member Posts: 16
    so i'm sort of expecting the worst, as you say, i've gotten my miles out of it but although i dont mind working on valves and such, the next layer down -- pistons and rods is out of my league tool-wise, time-wise, not to mention skill-wise (and while i'm at it, wise-guy-wise).

    NOTE: i cant find compression ranges in my specs book, i was told it should be around 90. the book lists some freaky numbers like .00075 and stuff like that. do i have to convert or am i lookin at the wrong chart? Both my jeep books seem to say the same thing. thanks once again for your suggestions.
    by the way, the cat. convert on this old dog is shot and i'm replacing from the exhaust man. on back. the smell, seriously though, was like grilled venison, or maybe Venetian (!!!).
  • swschradswschrad Member Posts: 2,171
    I don't have the compression specs, but there are a few good wrenches who prowl around regularly who could get 'em. ".00075" sounds like tolerances we barely get to generally in this country in grinding crankshafts and the like. I would think 90 psi would be the "reject" compression on the cylinders, and would expect something in the 120-140 psi range as a good cylinder number. seem to remember that a spread of over 15% is an indication that you need to start lining up the tools.

    these WAG numbers are from long-ago readings in a 1976 buick manual, are not intended to suggest to anybody that these are the correct numbers for a jeep engine, and are merely illustrating the point that there is a "good", a lot of "OK", and some "dead as last week's fish" numbers. there will be variation from cylinder to cylinder, that is normal, and causes for low compression can range from block wear to broken rings to chipped, worn, or warped valves to cracked heads and blown gaskets.

    any cylinder in the "reject" pressure range is reason enough for a teardown and examination... if it's a broken ring, maybe you can replace it, if it's a burned valve, send out the head and recheck... but to me, that would be the indicator that I needed to order a short block and either get smart fast, or get a mechanic to do that block order and finish the job.

    with the mileage you have on this jeep, I wouldn't even consider fiddling around in the block unless I was going to strip it down and do a complete re-machining and rebuild. that decision depends on the amount of wear in the cylinder bores, meaning you have to mike 'em with an expandable gauge and a micrometer, to see if the block is within tolerances to be remachined. if the bore wear is "oval" and it's near the limit, it's scrap. that sort of thing you can't tell until you pull the head and start checking, but practically, nobody but teens who want to learn seem to do their own rebuilds, it's really all send in the core, and get a warranted short or long block.

    two reasons a catalytic will die... physical damage, or overheating caused by excessive raw hydrocarbon going into it from the engine. a sick engine will kill the new cat as well, which is why I'd save the $150-200 bucks and spend $12-15 on a compression tester and spend an hour screwing it in and cranking the engine.
  • crackedhead1crackedhead1 Member Posts: 16
    as well as the tear-down. A guy at AutoZone who was pricing a new rebuild for me called and told me 150 psi optimum with 75 percent minimum acceptable so your guess was right on, or top ded center i should say. I have a tester so I'll try this. If they check out okay then i guess i'm still lost, but i assume a ring or valve is shot or that burning smell wouldnt still be in the garage, yeccch.

    Since i can barely pronounce micrometer, i don't plan on using one on an internal engine component such as my old cj friend.

    i replaced heads on my old chevy V-8 from salvage and thing ran for years before i sold it, i still see it around town -- but the valves were in good shape and that was my first one. I'm afraid this one is going to be a mess. Odd, it starts up and has power but it definitely has a quiet but clearly audible sound that really sounds more like an exhaust leak, but surely has to be a valve or ring failure. It has coolant and i remember when the chevy head gasket blew (cracked head, my name) it sent lots of white smoke out when coolant got into the head. it was so cold the other night, the exhaust smoke had not calmed down yet so i never knew whether it was a gasket or not. Still, radiator was full last night and there are no leaks or smells under the hood (just at tailpipe) so i guess i'l find out one eway or another.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    I don't think a cylinder will fire very well with 75 lbs compression...maybe sorta. That's a lame reading and a sure sign of a malfunction.

    90 and up would be good. Two adjacent cylinders much lower than the others might indicate head gasket issues.
  • swschradswschrad Member Posts: 2,171
    are not a valve or a ring. your first typed thought, an exhaust leak, is probably right on... that or a vacuum hose is off.

    get a chunk of rubber hose, put one end to your ear, and use the other to fish around the top and sides of the engine until your mystery hiss is identified by the hose almost being dead on top of it.

    if you're in compression on the cylinders, you still have to find the cause of the cat rotting to death on excess dinosaur ooze. the hiss and the cat dead start me thinking about maybe the EGR valve is plugged up or defective, or not bolted on tight, and nonsense in the EGR can cause a rich mixture. 02 sensors can also be at fault, and of course the usual rotten spark, wacky wires, and gutless coils still need to be verified.

    you can find spark wires deteriorated enough to be leaky with a mist-spray bottle of water in the dark. BE INTENSELY CAREFUL OF AREAS IN WHICH MOVING PARTS ARE LOCATED while spraying a little water mist on all the ignition harness. if you get blue coronas or sparks, you have wires needing replacement. that and new plugs will make a difference, absolutely.

    those are a few broom-handle type tests that can narrow down what's going on under there, along with the compression readings from the cylinders. I don't think you have to run the engine (which will pour more raw fuel mix into the tailpipe,) I think just pulling it over manually a couple times from the crankshaft bolt on the isolator pulley should be enough to get the reading on a warmed-up engine.
  • swschradswschrad Member Posts: 2,171
    75 percent of 150 psi is 112.5 psi, and that would be the cutoff point at which you say this cylinder is a dud.
  • crackedhead1crackedhead1 Member Posts: 16
    obviously pros. Yes, he meant 75 percent of 150. I will do the compression test tonight. If they seem to be up to sniff, er, snuff, then i'll embark on these other cool tricks. i can tell you that the plugs and wires are no older than six months, carb was rebuilt at local jeep dealer less than a year ago. pcv new, egr -- i dont remember what that is -- exhaust gas recirculation somewhere on the exhaust manifold?????? It would be good to get this resolved -- after all -- you all were helping me figure out the danged HEATER problem i had before i blew the thing up. I can do this compression test with the engine cold, right? I mean, if i'm just having my kid crank it over until i can record the highest reading on each cyl., i don't need a warmed up engine to get those do I? My manual says if the readings are low, go back and put a few drops of motor oil in there and retest. If the readings come up significantly, it's a sign of, of, something, i forgot. ANyway, it's a BAD thing. Also, the AutoZone guy told me there should be variances from cylinder to cylinder, that's ok, but like you all said, if adjacent cyls are low, it's more likely that the head gasket is blown right there than it would be that valves or rings on cylinders right next to each other would be blown. Does that seem right??

    Thanks as always for your help, and like i said, the catalytic convertor is just shot, you can tell, rust holes coming through from there on back to the tail pipe that i have patched with weird sticky products obviously manufactured with NASA, not Chrysler in mind. Since i'm gonna have to replace that anyway, should i hack it off right there in order to exact some less restricted (and obviously louder) flow from the engine? On the other hand, to do that now would hinder using a piece of hose to listen for vacuum and other leaks after my compression test, wouldn't it?
  • swschradswschrad Member Posts: 2,171
    redoing the compression test with a few drops of oil should check for cracked or carboned-up stuck rings (carboned-up rings should suggest oil is getting by, a good indication that there will be a big "necking" at the top of the cylinder, where the piston will have worn an obvious larger diameter in the cylinder you can measure with a piece broken off a yardstick. in a slant-6 of mine once, that difference was close to an eighth of an inch, clearly not an engine any more at 42,000 miles. the folks I bought it from never changed a filter in 42,000.)

    if the plugs are gunked after 6 months, that's an excellent sign that you have issues.

    ideally, the compression test should be done with a warmed-up engine, I seem to remember, you can pull the distributor cap wire and gig it over a couple revolutions with the starter, or take a big socket and pull the engine over manually from the crankshaft bolt a couple revs to get the reading. note that it might be easier to do manually, as obviously once you hit TDC = maximum compression in the cylinder, and the crank keeps turning, you will open the exhaust valve and let all the compression out.

    if you have perforating rust from the cat back, replace it all from the cat flange where it connects to the exhaust manifold.

    good luck, sounds like a typical 180-thousand miler, and a good hobby project if you decide to do it yourself. again, before you sink bucks into anything else, I heartily and obviously recommend the engine be brought up to snuff, so there's a reason to think you can get your money back out.

    oh, almost forgot again... don't overlook the possibility you can get a "runs or we replace it again" used pullout engine from a junkyard for less than a good rebuilt short block might cost. if you get a bad one, it's a great way to waste a ton of time pulling the second one and putting another in... but if a good short block is several thousand bucks, and you have to send out your heads and get them done as well, it might be more cost-effective. depends on whether you figure you and a pal or two and some rented hoists and stands can get the job done, or whether you have to pay for it. if you have to hire out the labor, don't screw around, get the short block if needed.
  • alcanalcan Member Posts: 2,550
    Compression test: engine warmed up, ignition disabled, throttle wide open, crank engine over 8 times (4 compression strokes). Note 1st and 4th readings. First pump should be at least 50% of maximum achieved. '82 Jeep CJ: minimum 100 p.s.i., maximum variation 25%.

    Cylinder leakage test: engine warmed up, piston at TDC of compression stroke, pressurize cylinder, note percentage of leakage. Should be less than 10%. Listen at: tailpipe = exhaust valve; carb or throttle body = intake valve; oil filler cap or PCV = piston rings; bubbles in rad = head gasket or cracked head.
  • swschradswschrad Member Posts: 2,171
    print alcan's response.
  • alcanalcan Member Posts: 2,550
    LOL those are a couple of the tests we teach our basic level apprentices in Engines practical class. For cylinder leakage the trick is to get the piston at more or less TDC before pressurizing the cylinder. Otherwise it finds BDC in a hurry. That's where the degree'd plate on top of the distributor shaft comes in, if the engine still has a distributor.
  • crackedhead1crackedhead1 Member Posts: 16
    .. dumb questions of you guys but once i warm this thing up, how do i turn it over with the ignition disabled, not that i even KNOW HOW to disable the ignition (pls don't say "TAKE THE KEY OUT, YOU OZARK HICK"). And the "crank over," eight times, note the first and fourth would be for EACH cylinder, correct? Just feel free to hang up on me when i'm gettin too stupid for you, but SWSCHRAD told me in an earlier message that it would help to get smart fast, which is not an option for all of us, knowhaddamean? Your last two messages sort of seem to switch back and forth between English and Klingon, which lowers my comprehension psi to about 40, which i assume, also would be an unacceptable reading. :)
  • swschradswschrad Member Posts: 2,171
    not having gone through the sort of apprenticeship training that alcan runs for his new guys. not trying to sort and grade you and sell you at the front counter here. I don't mind kicking myself once or twice to illustrate a point, but don't want everybody trying to help me with it :-D

    different folks have different experience, different backgrounds in how far they've looked over their manuals or opened up their engines, and thus differing understanding. it's not intelligence, it's training by whatever means. I don't care if somebody has a degree from Hard Knocks or Harvard if they can do what I need at the time I ask them for help... and if they say they can't do it, that's to be respected as well.

    you don't REALLY want the engine to fire when you crank it, you just want it to turn a few times to get the slop out and then stop turning as you approach the maximum compression in the cylinder being tested. pull the coil wire either where it goes into the ignition coil, or where it goes into the distributor, and that's taken care of. if it's an electronic ignition, pull the little two or three wire connector off the magic coil module pack.

    at its base, taking six or eight compression readings is not brain surgery. taking them accurately and repeatedly takes more skill and technique. using a $14 compression tool to run your own quick read on whether you have a paperweight or an engine shouldn't be scary... shoot, if you look real fast and see what the needle bumps up to, more or less, as the engine cranks, that's better than flipping a coin, at the worst case. that's a crappy test, but it should show really gross failures for as sloppy a test as it would be.

    PS -- before we all found out a couple posts ago that (at least a) problem with the catalytic was rust holes, the assumption was that it was melted through and partially blocked or worse INSIDE, on the ceramic block, from excess fuel. that does change the picture. it could be you still have reasonable compression and aren't facing a dead engine for whatever cause. but it would be a shame to fizzle a couple hundred bucks away by redoing the exhaust system, only to find out the car can't get out of its own way due to no power left.

    as long as you screw things in tight, don't get in the way of moving parts and cut something off you would like to keep, and don't horse around but follow your $20 countertop manual, the test is worth doing. If you don't figure on hinking around with heavy engine changing work, cool, you don't need to gear up to parkerize your own crankshafts and cut 'em to size on a lathe. doesn't mean you can't ask a few questions and answer a few of them yourself in an afternoon.

    don't worry about us, only a couple posters bite, and you can generally smell 'em a mile away....
  • alcanalcan Member Posts: 2,550
    No worries, we're here to help and the world's best tech was once where you are. First, a quick primer on the 4 stroke cycle engine operation:

    1. Intake stroke: piston at or near top dead centre (TDC), intake valve open, crankshaft rotation pulls the piston down the cylinder, the resulting vacuum causes air/fuel mixture to fill the cylinder. Piston's now at or near bottom dead centre (BDC) and the crankshaft's rotated 1/2 turn.
    2. Compression stroke: intake valve closes, crankshaft rotation pushes the piston up the cylinder, air/fuel mix is compressed to about 1/9 it's original volume. Piston's now at TDC again and the crankshaft's rotated another 1/2 turn.
    3. Power stroke: spark jumps the plug gap, igniting the mixture and causing a flame front to extend across the combustion chamber. The resulting high pressure of the expanding gases forces the piston down the cylinder. This motion is transferred to the crankshaft through the connecting rod, forcing the crankshaft to rotate. Piston's now back at BDC and the crank's rotated yet another 1/2 turn.
    4. Exhaust stroke: exhaust valve opens, crankshaft rotation pushes the piston back up the cylinder, and the burned gases are forced out into the exhaust system. Piston's now back at TDC and the crankshaft's rotated a fourth 1/2 turn. That's the 4 stroke cycle; intake, compression, power, exhaust, or suck, squeeze, bang, blow. Takes 2 crankshaft revolutions to complete. Also brings the cycle back to intake stroke again. All cylinders will have fired in 2 revolutions.

    Soooo.... to check each cylinder's compression you'll have to put the gauge into each spark plug hole and crank the engine until it's hit 4 compression strokes (8 revolutions) for each.

    To disable the ignition, just remove the coil wire from the distributor and use a jumper wire to ground it to the engine block.
  • crackedhead1crackedhead1 Member Posts: 16
    sheesh, shoulda thought of that. It's two-wire thingie with easy clips. I was just lost on the warmed-up engine thing. I do want to be sure i have that right; should i warm it up FIRST, THEN disconnect the coil wire(s) to do the dry crank sequences on each cylinder. That might loosen things up a little???

    OR, am I dry-cranking from the very start with no fire? Sorry to be so dense. To clarify on the cat covert incase i have mis-described it: this thing is ok, pipe and all from Exhaust man to the convertor -- but rusted through in three or four places from cat. to tailpipe. The tail pipe itself has got an honest-to-goodness 1/8" thick coating of black, mostly granular-looking crap that smells like -- oh let's not go there again -- the stuff looks like what a can of Skoal might look like that someone forgot and left on the dash of an old truck in the mexican sun for six months. When you tap on the convertor with a wrench or, say, a .357 magnum grip, it sounds plugged, full and the outside is the color and barely the thickness of a copperhead skin.

    Unless you all have more Fear Factor warnings, i'm going to do this tonight. Thanks very much again for the insight and understanding, and if you get a chance, i'm not 100% on whether i need to warm it up first or not.
  • alcanalcan Member Posts: 2,550
    The engine should be fully warmed up first to allow the pistons, rings, and cylinders to normalize (expand to their normal running clearances)
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