Still with me?

I purchased a 1993 Cherokee Sport, 4.0 HO, last week. Friday the PO, a coworker, drove me to his place to pick it up. I swapped on my plates, we shook hands, and I drove off. Everything seemed fine, merged on the highway great and hit 80mph without a shimmy.

Until later that evening when I realized the temperature gauge was getting pretty close to the Red. Red = Bad, I knew this, so I turned on the heater and went full blast on the fan. The temperature dropped immediately, and once I got moving again, I didn't need the heater. This morning I added maybe half a quart of coolant to refill the overflow bottle, and haven't noticed any issues with temperature since then... but then, I haven't spent much time sitting stopped with the engine on.

What concerns me, though, is the nasty black... goop... in the overflow bottle. The oil looks clear, not milky, and there was no sign of oil in the coolant at the radiator. Just this black goopy crap in the overflow. Any idea what the heck this junk is? It almost looks like tar. I know the high-pressure line on the Power Steering pump exploded back in 2007, maybe somehow it contanimated the coolant reservoir?

I'm a little concerned about the alternator as well. The voltmeter seems to be holding steady at 12v, I know my little brother's '96 5.2L runs closer to 14, as did my last two vehicles. I've heard that the ground on the early 90s XJs is pretty weak, and that I might see an improvement if I add a second ground line from the alternator to the frame? Anyone try this?

I have this massive pile of receipts for repairs since day 1. It seems like they replaced the transmission tail shaft seal quite often, at 103k (1997), 126k (May 1999), 143k (Aug 2000), 150k (May 2001), 159k (April 2003 and again in May). Apparently they fixed it in May '03, or at least gave up on fixing it. How concerned should I be about this? Is it a weak point on the 4-speed auto that I need to worry about? It doesn't appear to be leaking, but I probably should crawl underneath to check.

The spark plugs were... nasty. They had a pretty bad buildup of white/gray deposits, not enough to bridge the gaps, but enough to surprise me. They were last replaced at 169k (Jan 2006), as was the ignition coil. The wires and Cap/Rotor are older, 164k (Nov 2004). They were also severely out-of-spec, none of them was anywhere close to the 0.035 gap recommended in the Haynes manual. The closest was 0.040, the furthest was 0.050. I wire-brushed them clean and regapped them, which solved the slow-start condition when cold, and smoothed the idle slightly.

Speaking of idles, my idle seems to be off. It's a little rough, some of which I attribute to the crappy condition of my ignition system (new plugs, cap, rotor, wires, and coil next pay). I'm also running some Lucas injector cleaner through, and plan on doing a Seafoam treatment just before the next oil change to de-gunkify the engine. However the idle just seems wrong, it seems to be loading the transmission quite heavily. Is this normal? Shifting is smooth and appears to be at the right time, so I don't think there is anything wrong with the transmission (unlike the wonky OD one in my brother's Grand Cherokee that refuses to shift out of first when cold).

Right now the engine has 5w30 in it (178k, June 2008), which I believe is a little thin and may be making my minor valve-cover leak appear worse than it is. Regardless I'm replacing the valve cover gasket, but what oil should I be running on an engine with 184k miles? I'd think maybe 15w30? Oil pressure is about 20psi at idle, when warm. I know it's due for an oil change, which is surpising since it looks clean and is dead-on at the full line. Perhaps it was changed and I just don't have a receipt for it.

Anything I should check on the AC? The compressor, dryer, and Expansion Valve were all replaced in 1996. However it's been refilled several times since then, in 2003, 2006, and 2007. It's working fine.

Any other items I should be looking at?

 

damn....sounds exactly like the 94 I just bought. To a damn T! Waiting patiently for an answer......

 

I would agree that the tar in the coolant system sounds odd. Maybe a flush is in order.
10W30 oil would be the oil of choice in Florida. Doesn't get cold enough to need 5Wanything.
See if your idle improves with the Seafoam. Yes it sounds like a complete ignition tune-up is also due. The PO took good cosmetic care of the Jeep but looks like he qualifies for a in the maintenance category.
The alternator should have 14.4 volt output at the battery so check that with a meter. The dash gauges are ballpark gauges not very precise.
Well that should fill your weekend (what's left of it) Let us know what that accomplishes.

 

Congrats on the purchase! Now that's a laundry list...I've owned two of these and there's always a list I'll throw in my .02 on some of these.

Temp - At a minimum, you are due for a good coolant flush. Do some experimenting to see if you for sure have the temp creep at idle issue. If so, start with a thermostat since it's cheap (stay with stock 192/195* IMO). If that doesn't fix it, then you're looking at water pump, fan clutch, or radiator (in my case, it was all three ). My reservoir was pretty goopy too..think it was just years of buildup never being cleaned.

Idle - X2 on the Lucas injector cleaner and Seafoam. If that doesn't do it, you can try taking off the IACV and cleaning it with some throttle body cleaner and a toothbrush as a cheap next step.

Oil - Oil is a matter of preference, but I would at least dump the 5W30 and go back to the 10W30 that is called for. I throw in a half quart of Lucas oil stabilizer for good measure and mine still hangs around 40psi at idle when hot. I'm at 133K, but I think you'll find that lots of others here with close to your mileage are running less than 20psi.

Sorry, I'm not of much use on the other items. HTH

 

x2

The problem with Multi-viscosity oils is that people in climates that don't need the protection in cold weather are running them. When you look at Multi-viscosity oils the number before the w is the cold weather viscosity and the number after the dash is the vicosity at operating temperatures. So when its cold(think under 40 degrees) the oil is in the viscosity range for an oil of that weight. Example: a 5w-30 at 0 degrees would be in the same range as a SAE 5 weight oil. But at operating temps that 5w-30 is in the viscosity range of a SAE 30 weight oil, but our SAE 5 weight is still only in the viscosity range of a SAE 5 weight oil.

In warm climates(like Florida,Texas, So Cal, AZ, etc.) The first number will have VERY little bearing on your oil performance. So concentrate on the second number. But 10w-30 is going to be available everywhere. Go ahead and run it. But it won't do anything to slow a small oil leak. For you a 5w-30, a 10w-20 or a 15w-30 are all basically equal except in the coldest part of the year.

 

Actually, the PO did halfway decent in maintenance. The problem was that he's not a mechanically inclined person. When I first looked at it he pointed out the "bad head gasket" because it was leaking oil. He pointed right at the valve cover gasket. So basically stuff only got fixed when it broke. I need to do a compression test, but I expect it'll come out fine, since it seems I still have plenty of "GO" when I push the fun pedal.

I'm hoping it just needs a coolant flush. The whole cooling system was overhauled no that long ago. The Thermostat, Water Pump, Upper Radiator Hose, and Heater Control Valve were done at 178k (June '08), the Radiator and Cap were done at 177k (December '07).

Yeah, that's right on the oil... I keep forgetting that the first number is the cold-weather viscosity. Heh. I've been running Mobil 1 0w40 in my old car, but that was fairly expensive. I'm not really looking to thicken up and stop leaks, since the only leak seems to be the valve cover gasket I'm about to replace. I'm more concerned with wear on the engine internals, and wonder if running a slightly thicker oil might not be better for the engine at this point.

Oddly enough, I thought he'd said that alternator had been replaced, but I can't find anything about it in the documentation. I'll have to get it checked, he put two battery's in it over 32 months, which seems excessive. How hard is it to remove?

 

An alternator... not a bad job. But where it is located at the bolts get alot of crap flung on them if the vehicle has been wheeled.

A heavier viscosity oil is not necessarily the answer to less engine wear. Just make sure the oil is API-SL rated rather than API-SM rated. SM doesn't contain enough Zinc and Phosphorous for our motors. You want a bare minimum of 1000 ppm in your oil. SM oils have a maximum of 800 ppm.

 

I didn't see the fan clutch in that list. Check it with the engine hot. Pop the hood and watch the fan when you shut the engine off. It should stop immediately when the engine stops when the fan clutch is hot. If it spins for a few seconds, it's bad.

 

Good advice, I'll take a look at it. Man, the clutch fan on this thing is tiny. It's almost, dare I say it, cute.

Question: In my mad rush to get the freaking valve cover off, I broke the temperature sending unit off the back of the head. It had one wire going to it, there is another sending unit on the thermostat housing with, I think, two wires. According to my Haynes manual, the engine might have both, but only one is used (one is for an idiot light, one for a gauge).

Provided this thing doesn't leak (I think I just broke the connector off), how screwed am I?

 

im not a genious at the newer h.o. motors but i do believe that back sender is for both idiot lights and full sweep gauge. i know on the old renix engines that sender is what controls the gauge it just depends which one you buy at the parts store they list them as idiot light or full gauge. hth

 

That appears to be right, the gauge doesn't work at all now. So until it's fixed I'll be running my heater whenever I'm in traffic.

At least the valve cover gasket isn't leaking now. Doesn't look like the sender will be a PITA to do, either. Man, totally different working on this than my car.

 

yeah the sender unit is an easy fix and if i remember right they are cheap to.

 

I had the black goop in my recovery bottle as well when I purchased it. But since I've flushed my cooling system, have had no recurrence of it in a month. And the Jeep runs fine, and the radiator coolant looks perfect.

 

Ok, my voltmeter is now rock-solid at 14v. How'd I fix it? Funny story... my cell phone was just about dead and I was on my way to work, so I pulled the cigarette lighter (never used). As soon as I removed the element, the voltmeter jumped to 14v. I've since left the lighter element out. Easy fix!

And yes, it stayed at 14v even though I was charging the cell. The only thing I can think is that there is some sort of short either in the lighter element, or in the lighter assembly housing. Since I don't smoke, I'm not concerned with not having a lighter.

 

For your constant tail shaft seal replacement, check the trans mounts, and make sure you dont have a frozen u joint in the driveshaft, causing the shaft to prematurely wear out the seal. also check the mating surfaces between the transmission and the t case