[Kimano]

Let me preface this by saying I don't really know if this is the type of forum to put problems like this in, but I figure it can't hurt to get an enthusiast second opinion. Also, I'm not that much of a car guy, so some of my terminology might be misused or off; take what I say at face value.

Firstly, the car. It's a 97 Jeep Cherokee XJ, 4.0L I6 engine, AW4 transmission. (Don't know if that's enough information to assume or not, but it's also NOT 4WD.) Everything is stock, no real work has been done to the car.
It's also been in a few collisions, mostly minor cosmetic/trim damage except one front end that did some frame damage, wrecked the AC condenser and did some other (mostly minor) damage to front end components. Due to money, I did most of the repair work myself, minus the radiator repair. I can list out all the things that were damaged and what I worked on, if it's relevant.

This car has been an awesome car, and driven it since high school (thus the wrecks. ) Now, I know it's never going to be totally fixed and I accept that, but over the past year it's had a couple of issues that worry me. I'm basically just trying to keep it running as long as I can, and I need to know which of these issues are ones that warrant serious attention and that I need to get looked into, and which are minor issues that won't impact the car for the maybe 1-2 years of life it has left. If the fix is easy and/or cheap then I'm happy to do it, but I don't want to put a bunch of money into a car that won't last much longer anyway.

First issue: Sometimes when driving, the car won't shift into Overdrive/4th. I can usually fix it by shifting to neutral or parking and shutting the engine off, then turning the car back on. I haven't really been able to narrow it down to cold or warm start, since sometimes the issue can persist through the first restart. I should also note that sitting idle for short (~10 minutes) of time doesn't fix it either. It's easy to tell when it happens if I'm driving on the interstate, because the rpm sits 500-1000 rpm higher than normal for that speed and I can shift from 'D' to '3' with no gearing changes.

Second: Sometimes the car acts like the battery is dead when cranking, even with a brand new or freshly charged battery. It only does this on a cold crank and if I restart the car after a few minutes of driving, once it's warmed up, it cranks flawlessly. I can hear the starter turning the engine over, but it's really slow to catch and start, almost like it's starting in slow motion. The issue is constant, but how bad it is seems to change from day-to-day. Some days it'll only take 2-3 seconds to crank, others it'll take almost 10 and it sounds like the engine is in slow motion, though it usually tends towards the former.

Third: Lately, I've been hearing what I assume is spark knock from the engine during any kind of acceleration, even if it's just maintaining 30 mph. It's a really light pinging, almost like someone hitting a metal pipe with a plastic bar. It's off and on and doesn't have any discernible pattern or cause, but in general it happens consistently. I *think* it started right after I filled up, so I'm hoping it's just bad gas.

Any help or advice I can get on any or all of these would be awesome, thanks in advance. (And sorry for the wall of text.)

Edit: I should add that I've already used my Google-fu and have some info I'm going off of. Just looking for second opinions and any extra helpful advice.

[Holder350]

That my friend was a mouth full.

Originally Posted by Kimano

First issue: Sometimes when driving, the car won't shift into Overdrive/4th.

This is hard to diagnose online. Do you have a CEL or the like? It may be due to a bad shift solenoid


Second: Sometimes the car acts like the battery is dead when cranking, even with a brand new or freshly charged battery.

This is indicative of a bad connection, most likely at the battery or the starter.

Remove connections clean till shiny then reconnect and see if the problem is fixed.

If not then your starter might have some worn brushes and be on its way out.

Third: Lately, I've been hearing what I assume is spark knock from the engine during any kind of acceleration, even if it's just maintaining 30 mph.

Run some injector cleaner thru it and next fill up go with 92. The pinging is caused by carbon buildup in the cylinder which is getting heated and causing pre-detonation of your fuel air mixture.

Search for "seafoam" and do a treatment on your motor. This should help.

[xjfever]

X2 on all the above. It sounds like your torque converter isn't locking up as it should in overdrive. This could be from a bad solenoid.

[Kimano]

Thanks for the answers.

I can clean those connections pretty easily, but if the starter does end up being the issue is that an easy replacement?

Also, is that solenoid something I can get to and replace myself? I'm an engineering student, so I've got the general mechanical knowledge, just no specific car experience. The check engine light hasn't been on in several months, though I did have issues with it staying on for weeks at a time, but that just stopped randomly some time ago, and I didn't think much of it.
If it's relevant, my car has the shaking issue at 60+ mph, which I'm assuming is from the driveshaft. Could that vibration have somehow affected the transmission, since the shaking would all be taking place in 4th gear, maybe damaging it?

I'll pick up some of the cleaner in a bit. I have an hour or so drive this afternoon, so I'll put it in then? Is it good to use that kinda of stuff right before that type of single, long drive?

[Glion]

dont do it in the street. unless you poor it in the gastank. if pouring into the vac hose you will have lots of smoke that will hang around.

[Holder350]

Starter is a simple replacement, 30min or so.

The solenoids arent bad and you get to do a filter and fluid while you do it.
http://www.jeepforum.com/forum/f11/aw4-solenoid-replacement-write-up-no-56k-717206/


Does the vibration come in then go away after you accelerate thru it? Or is it constant after you hit 60mph? The vibe should not damage the transmission.

The cleaner really doesnt matter, if you have ANY room left in the tank I would put some 92 in on top of your fuel.

[Kimano]

The vibration is pretty minor, and hangs around until I decelerate. Figured I'd mention it just in case it was a symptom of a larger issue.

I have room to put in some premium, then do I just pour the cleaner in after it?

[Holder350]

Any time I see a vibration under power I change Ujoints first, and check trans output and pinion input for excessive play.

I would throw some injector cleaner in, then top it off with premium. After you get back from your trip I would do a seafoam treatment to it tho.

[Kimano]

So when I get this sea foam stuff, do I have to pour it into a vacuum line, or can I just pour in however many ounces I'd need for my gas tank right before I top off?

[Holder350]

I prefer running it thru a vacuum line, I think it works better and pulls more carbon out of the cylinder.

[Kimano]

Update, the only problem I've really had time to work on was the knocking. So after I ran the cleaner for a little while, the knock didn't go away, it got worse. Also, I had done a bit of research on spark knock, and what I was reading wasn't really making sense with what I was hearing, it sounded too metallic. Also, it started happening while the car was idling sub 1k rpm. So earlier yesterday when I had some spare time I started the car and popped the hood. After spending a couple minutes searching for the noise, I found it. Some of the blades on the belt-driven fan are scraping against what my rough interpretation of the belt routing diagram tells me is the Crank.

Now I'm trying to figure how that's happening. Are the blades on the fan bending? Or is the engine shifting forward or tilting in it's mount somehow? I turned the car off, spun it manually and it only seems like 1 or 2 blades are clipping it, the others are passing it with maybe a 1/4 to 1/2 inch clearance. Can I get a pair of Vice grips and bend the fan blades back into position? Or does something need to be done professionally?

[Holder350]

The fan blades should all be the same length...

I think I would pull the fan and get it out where you can see whats going on, and if it is bent, you can simply bend it back

[FairlanePhil]

I would be more concerned your harmonic balancer on the crank is coming apart and hitting the fan. Could explain some of the vibes as well. Anyone agree?

Check all the bolts on the fan and look the balancer over carefully. On Fords its a metal ring fused to the center with elastomer then bolted to the crank. The elastomer wears out.

There was a guy on here recently with a similiar issue

read on:

http://www.jeepforum.com/forum/f11/fan-blade-hitting-pulley-1015923/