VJBernard

Hey Folks, My 1994 XJ Cheerokee Sport has been sitting for a while (about 9 months) and was cranky with me for letting her sit so long while I drove another vehicle. 😜 Anyway I've installed new plugs, rotor, cap, wires, battery, as well as changing the oil and filter. Starts up fine, showing a nice charge on the gauge, but after a couple of minutes every time I come to a stop, the gauge goes into the discharge side. A quick stop to a couple of auto parts stores and they check her out both running and off. They tell me the alternator passes, but all indications tell me that I should be replacing the alternator. Hope it's not a short, they take forever to find and is costly for a cheap fix. Any advice will be appreciated.

Tbone289

Check your belt tension.

VJBernard

Thanks for the quick response, tension seems ok, it's not loose and when I press on it, it moves maybe an inch......

PatHenry

Check all your grounds are clean and tight. I'd also double check that all the wires and plugs to the alternator are clean and tight as well.
It could be that when you're coming to a stop something moves a little and disconnects or something like that.

Belt tension is best measured with a proper tool, but a good simple test is to twist the belt about 4 inches or so to the left and if you can twist it more than 90 degrees it's too loose.
It is often said that the belts on these need to be tighter than you'd think is tight enough.

VJBernard

PatHenry,
thank you, I will check it all out. Not to sound dense, 4 inches to the left of what or where?

PatHenry

If you're looking at the engine compartment, locate the Power steering pump pulley. The belt adjuster is just below it. From the top of the PS pulley, along the top of the belt, go about 4-6 inches or so to the left. Sort of where the belt starts to have a bit of "slack".. right about there is the tension test point. That's where you attempt to twist the belt. If the belt is super loose you'll be able to almost turn it 180 (so the inner ribs are pointing up to the hood. You want to try to twist it so the ribs point towards you, or 90 degrees.

This is only an approximate test. Use this technique only as a temporary measure until you can properly check and adjust the tension.

Tbone289

It requires a surprising amount of tension. 140-150 lbs for an old belt, 180-200 lbs for a new one. I had mine too loose for a while and had the same issue as you VJBernard--the alternator would drag due to belt slip under load at low (idle) RPM.

Bugout4x4

Know what T Bone? I'm thinking that if he can can even move it an inch when pressing on it... it is definitely too loose for these?

Tbone289

I agree. At the correct tightness, it's tighter than a bull's a$$ at fly time.

I've heard people say they wish the 4.0 had a spring-tensioned idler, but I can't imagine how strong that durn spring would have to be...

PatHenry

My 2000 TJ with the 4.0 DID have a spring tensioner. It was really nice just cranking the thing down with a breaker bar and slipping the belt on or off.

PatHenry

I feel like an inch is a lot of slack.

Tbone289

To each his own. To me, there's very little difference between a bolt tensioner and a spring tensioner, convenience-wise. If the bolt tensioner is loose, I don't have to hold anything while I slip the belt on. I've had to replace weak spring tensioners, but I've never had to replace a bolt tensioner. Unless there's a disparity in convenience between designs, I will usually opt for the more durable one.

Bugout4x4

The first time I adjusted mine up, I did it a little at a time until the power steering didn't slip at full lock. When I got done and pushed on it all I could think was that it was a wonder it hadn't snapped. For the first few months of driving it I just knew it was going to snap at any moment but it never did. lol

Pretty sure these are the tightest belts I have yet to run across, to get the right tension with a tensioner I think you would need a 2 foot breaker to install the belt.

Tbone289

I know, right? You would think we would be wearing pulley bearings out constantly.

Bugout4x4

For sure, and the water pumps are much stouter than I would figure considering. I was plucking it like a cello string and getting great tone quality out of it. Lol