As my Nitro begins to get up there in mileage and I just recently paid it off, I want to make sure that it lasts a good while longer. Therefore, I decided it was time to tackle the timing belt replacement on my ’08 4.0L. The timing belt is the one downfall to the 4.0L application but shouldn’t be a deterrent to anyone looking at a 4.0L.
I was quoted at around $600 for the timing belt, tensioner and water pump to be replaced. I was not about to throw this money at something I felt I could do myself.
Therefore, I decided to tackle this job myself. This was the first timing belt job my Father (who helped me) or myself had ever attempted. So there was a good bit of research done before we began this project. I suggest you do the same in addition to what I have written here. It pays off to know what you are working with.
I read all I could from other forums and the 2 shop manuals I have for the Nitro to make sure I could handle this job. I eventually decided it was time to take on the job.
The following is step by step of how we replaced the timing belt, water pump and tensioner. If you choose to do this repair yourself, I am in no way responsible if you mess something up. This is simply how we did the repair and it worked for us, I am by no means saying this is how one SHOULD do the repair. This is a challenging job that unless you have a good understanding of engines and the confidence in your repair sklills, probably should seek a professional to do the job.
Before I did anything, I made sure I had all the supplies I needed. Nothing worse than being in the middle of the job and needing to run to the store. The basic supplies needed for this job are as follows:
- New Timing Belt Kit (Should include water pump, timing belt, tensioner pulley and tensioner shock (optional) I used the Gates OEM kit
- At least 2 gallons of coolant (you should flush entire system)
- Pulley puller
- Belt dressing
- All necessary tools (screw driver, torx bits, pry bar, wrenches, sockets, hammer, jack and jack stands, etc…)
- White felt tip marker (important it can be seen on black surface)
- PATIENCE!
Before you begin, make sure you start the job in a location that you can leave the car for a day or so if necessary. Once you do, block the wheels so that it cannot move and make sure you leave the car in park or neutral. This will prevent any unintended movement of the engine from the wheels.
I then disconnected and completely removed the battery from the vehicle. This was to assure there was no chance of the battery terminals making contact with anything, plus it gives you room to work. The next step was to remove the air intake box and intake pipe attached to the intake manifold. Once again, this gives you more room plus it makes removing the intake manifold much easier.
After the air box and pipe are removed, the next step is to remove the washer fluid and coolant reservoir tank. The coolant line running from the radiator cap attaches to the back of the reservoir and needs to be removed. Then the washer fluid pump also needs to be removed from the side of the washer reservoir. There are 5 torx screws holding the reservoir in place. 3 of them are at the top of the reservoir attached to the top of the engine bay adjacent the grill. The other 2 screws are little trickier to get to. One is on the far Left end below the radiator cap and the other is on the extreme Right end below the washer fluid pump. When removing the reservoir, you may get a little wet from the fluid in the reservoir so try to remove as much as possible before taking it out of the engine bay.
Once the reservoir is removed, the intake manifold came next. See my previous thread on how to remove this “
Thermostat Replacement“.
Along with the manifold, I also removed the plug coils and the spark plugs. I did this to remove compression in the engine if and when we had to rotate the crank to line up the crank and cam shafts. Not sure this was necessary but it made rotating the components much easier. Also, make sure you cover the top of the lower intake manifold once the top portion is removed to prevent anything from falling down into the engine.
The next item to remove is the radiator fan. This is simply held on by 2 bolts at the top sides. There is one screw holding 2 steel lines to the bottom of than fan as well that needs to be removed. Un-clip the electrical connector and the fan should pull straight out.
Once all of these items are removed, the real fun begins!
The next step is to remove the accessory drive belt from the front of the engine. This is done by inserting the square end of a socket wrench into the square on the tensioner and pushing it down.
This will relieve the tension on the belt and allow you to pull the belt off of the pulleys. I marked the belt showing which side was the front so that I could put it back on the same way I took it off. I did not replace this belt.
After the belt is removed, I then removed the tensioner assembly. There is one larger bolt that goes into the engine block and one smaller one that needs to be removed. The assembly should then come off. Next, you will need to remove the entire accessory pulley assembly from the front of the engine. There are a total of 4 bolts present going into the engine that must be removed. There is one bolt that has a nut and is also threaded itself into the engine must be removed
. Once these bolts are removed, there are 2 more bolts that must be removed in order to get the pulley assembly off of the engine entirely.
These 2 bolts are actually on the side of the engine by the A/C compressor. One is directly above the compressor and one is below it. Both of these need to be removed entirely in order to remove the pulley assembly. The bolt below the compressor is challenging to get to, so be patient and take your time.
Once all of these bolts are removed, you can then lift the entire pulley assembly out of the engine bay. You are now left with the following (see photo).
You then need to remove the power steering belt still on the pump and big pulley. This can be done by rotating the crank shaft pulley and using a screw driver to jump the belt off of the pump pulley. This is crude but is actually how the manual says to do it.
The next step was the hardest for us in the entire job, removing the dampener pulley. This pulley needs to be removed in order to take the timing belt cover off. To remove it, you will need a special pulley puller. The one we had, was a little large for this application.
The service manual shows a small jaw tool that actually grabs the pulley from the inside. Ours as is shown, attached to the outside. One mistake we made at this point was pulling on the middle ridge of the pulley. The pulley is actually comprised of 2 pulleys, pressed together. Pulling on the center ridge caused us to pull the 2 pulleys apart. This was ok as we still got the assembly off, but we had to press the pulleys back together when reassembling the engine.
