Mechanics

SERPENTINE BELT PROBLEMS.

1997 Jeep Grand Cherokee • V8 4WD Automatic • 124,000 miles

I have a couple of questions. Basically, my belt broke on my 1997 jeep grand Cherokee. It runs on and across 7 or 8 big and small runner and work cogs.

One of the (runner) cogs broke internally and I have been looking to get a replacement in wreckers yards, etc. But that's a minor problem - however itseems to be the one that caused the bigger problem described below.

My problem is that the belt (i've cut it and tried to pull it out) has jammed itself behind the central spinning cog/wheel, the one that comes out of the engine block and spins the fan behind the radiator. I've tried turning this shaft and having someone try to pull th erest of the jammed belt out from behind but to no avail.
Question 1 then: Is is going to be a big job for a mechanic to take the radiator fan shaft apart and remove the jammed belt from between this shiny cog and the engine block? Would the whole radiator have to be loosened up?

Secondly. I have noticed that when I turn the engine now, nothing moves. None of the cogs. I had assumed that the driving power for the belt system came from the lowest, biggest cog. The one that is directly below the one that I talked about as being jammed. However, if this is the case then that should be moving when I run the engine, but it's not. So, this leads me to assume that the power to drive the belt system comes from the spinning cog which is jammed and sits on the shaft which goes to the fan at the radiator? The thing is that this doesn't look right as this is one of the smooth surfaced cogs which touch the smooth outside of the belt, whereas the cogs which work all the other pumps and alternator, etc, all sit inside the belt where they have multiple tracks and ridges running?
Am I correct in thinking that the main power that drives the belt is transferred to the outside of the belt via the smooth surface of the cog on the shaft that goes to the fan? (It just doesn't seem intuitively right, but it must be since that's the only one that is jammed and nothing else is moving?)

I'm going to have to bring it to someone anyway, but I would love to have the answers to these questions if you can help me? Thnx.

Also, finally, I have been able to lock a wrench onto what appears to be a large nut that sits around that shaft, and slowly turn it whilst having a friend try to pull the belt free as this thing moves and the shaft turns, but we haven't managed to get it out, although it did move somewhat. I could keep trying this, but I am wondering if by manually turning that shaft, is there a direction that might cause some problem inside the engine where it connects?
(Hopefully that questionmakes sense?) Hoefully I haven't done any likely damage by this manual turning of the shaft.

thnx much
KevinBecause if it hadn't broke the belt wouldn't have slipped and jammed elsewhere.
Avatar
Kevinm1
November 28, 2010.



Kevin: I have attached a diagram of the belt. I am assuming you have the 4.0L 6 cylender engine. The bottom pulley is the crank shaft. That should turn when the engine is cranked or running. If it isn't, that tells me the crankshaft is broken (which I doubt). That is what drives the belt. The one above it is the water pump (see diagram). If it is that stuck, what you need to do is remove the fan shroud from the radiator. There are 4 bolts that hold it on. Carefully remove it. Next, you need to remove the fan / fan clutch. Place a large cresent wrench in the large bolt behind the fan, and wedge something behind the pulley to prevent it from moving. Next, smack the cresent wrench with a dead blow hammar. It will take a few good hits to break it loose. Once that is off, the pulley will come off and you can remove the belt.

Let me know if you have other questions.

Joe
PS: If the crank pulley (see diagram) isn't turning when you try to start it, let me know. There could be a sheer key in it that sheered off. And even though the pulley isn't turning, the crank has to be. Does the engine still run?

Let me know.


Hi Joe,
Thanks for the tips. I'll probably end up bringing it somewhere, but what I was worried about was that the jammed cog = the water-pump was running off the main crank-shaft. It's not - so that's not what needs to be dismantled. Now I need to check and make sure that the crank shaft is moving. That willlessen my problems. Mine is the V8 model, so the diagram isn't exactly the same, but I understand enough to get what I want from your answer. Thanks. Kevin. If I have other questions about this, I'll post them.


Tiny
Kevinm1
Nov 28, 2010.
Kevin: I have attached the routing diagram for the Gr. Cherokee (V8). Honestly, Kevin, it sounds a lot harder than it is. If you decide to do it, let me know. I'll try to walk you through it.

Joe


Jacob. Sorry it's took me a long time ot view the response. I won't be doing anything with the car for at least another week, but I may ask for some help then. Can you send the diagram for the V8 again? I couldn't see iut here, or find it? The crank-shaft and its pulley are turning/spinning fine. So, that question-worry is no loonger in my mind.

Thnx
Kevin


Tiny
Kevinm1
Dec 7, 2010.
That is good news. I didn't think the crank would stop turning.
As far as the belt, go to the site listed below. It will show all diagrams for the Jeep Gr. Cherokee serp belts. Identify the one that is for your engine. It's harder for me because I can't see what you are dealing with.

Let me know if you have questions.

Joe