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Lighting Guru!
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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.
 

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Lighting Guru!
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Discussion Starter #2 (Edited)
To remove the pulley, it is best to do it in steps. First, we backed the bolt out, which holds the pulley onto the crank shaft as far out as we could so that it was still threaded. We then pulled the pulley as far as the bolt would allow. We then removed the bolt and put a socket in the pulley hole. The socket was small enough to fit through the hole in the pulley but larger than the threaded hole for the bolt. This allowed us to pull the pulley the remainder of the way off. It was hard to determine if the shaft the pulley went on was actually tapered or it was simply a 0 tolerance fit, but either way, it was on there tight. Be careful with the pulleys as they are rather brittle around the edges and we broke small portions of metal off of the edges during this process (see photo).

Once you get the pulley off, take a deep breath as you are almost to the timing belt and other areas to be changed.


The next step is to remove the front timing belt cover. It is the thin metal sheet on the front of the engine. It is held on by a number of fasteners around the perimeter of the cover. Most are typical bolt heads but 2 by the power steering pump are torx bolts. Once all the fasteners are removed, pull the cover off and you can now see the timing belt, water pump cam and crank sprockets and tensioner. This is where the fun begins.

At this point, we put the bolt that held the dampener pulley back into the hole at the end of the crank shaft.
This is the only way you can turn the assembly. The next step is what the scariest to me and that was rotating the crank and cam shaft. The service manual calls for the loosening of the rocker assemblies on both headers. I did not do this and from what I read, it is not necessary if the existing belt is intact. The loosening is necessary when you need to rotate the cam shafts independently of the crank, which is not required when doing a job such as simply replacing a working belt. With the timing belt and tensioner still in-tact and untouched, rotate the crank shaft clockwise until the timing marks on the cam shaft sprockets and on the crank shaft sprocket all line up.



The crank shaft rotates twice for every one revolution of the cam shaft sprockets. Once all of the marks are lined up, I highly suggest marking the teeth on the existing belt that line up with the timing marks. This is the only real way to make sure the new belt is installed properly as there is no way to adjust the belt once it is in place. To properly install the new belt, you need to have a certain amount of teeth between each timing point and marking the existing belt allows you to simply transfer these marks to the new belt, so you can install it properly the first time.

If you do not mark the belt, you may install the belt one or two teeth off. Being a tooth or two off will screw up the timing since the tension in the belt will not be correct. Sadly, this may not be entirely realized until everything I put back together and you fire it up for the first time. Therefore, spending a few minutes before you remove the old belt to mark those three locations is very important.

Once the belt is marked, I then removed the tension from the belt. This was done by removing the two screws that hold the tension cylinder in place. This is a cylinder that pushed on the tensioner pulley to keep the belt tight. By removing the screw, the tensioner cylinder backed away from the pulley and allowed removal of the belt. You are supposed to then remove the cylinder and compress it so that you can install it with the new belt. I was unable to get the cylinder out as there is a coolant hose directly below it and this made it impossible to remove.

Undoubtedly the cylinder was installed with the engine out of the car, thus allowing access. Not removing this cylinder was not an issue though because there was enough play in the cylinder to install the new belt and pulley and then simply reinstall the screws to apply tension to the new pulley assembly.

Once you have marked the old belt, and removed tension to it, you can remove the old belt. To my surprise, the old belt really did not look that bad, albeit having well over the suggested amount of miles on it.

The old belt is on top and the new on the bottom. With the old belt off, transfer the marks you made onto the new belt.

You can then remove the old tensioner pulley assembly as well and install the new one. It simply bolts in with one bolt.

You can then remove the old water pump, which is in the center of the engine.

This is held on with a number of bolts. When I removed this part, a good amount of fluid came out, so having a catch can below the vehicle is helpful at this point. The old pump did not look all that bad but I still replaced it anyhow. The new water pump was a slightly heavier metal and a thicker gasket compared to the preexisting one I removed.

Be careful not to pinch or fold over the gasket when reinstalling the pump. It is also critical to make sure you have torqued the bolts to the proper spec. It is somewhere around 10-15 ft-lbs.

Once the tensioner and pump are installed, the belt comes next. With the marks transferred onto the new belt, it should be rather easy to line everything up. Be careful not to rotate the cam shafts as they are most likely in between rotations and can snap back to the last quarter turn point. With your marks line up, the belt should be rather snug all the way around. Then reinstall the tensioner cylinder and the belt should be tight all the way around. If there is any slack for any reason, make sure correct this. A good test is to rotate the crack shaft clockwise again at least 2 revolutions to see if the timing marks all stay on point together than that the belt is positioned properly. If it rotates easily and the timing marks have remained without any teeth on the belt jumping sprockets, you have done well. From this point, you can them begin making sure that you tightened all of the bolts in the timing belt housing and being reassembling the engine.


To put the dampener pulley back on, you will need to pound it on with a hammer until to reach the point that the threads of the bolt will now reach the shaft. From this point, you can simply use a socket to tighten the bolt to pull the pulley into position.

From there, it is really as simple as doing everything you have already done in reverse. I highly recommend taking pictures and making sure you organize the bolts and screws you remove in a fashion that you will remember where they all go.

Once the engine is reassembled, remember that you will need to replenish or completely flush the coolant system. This is due to the fact air has most likely gotten into the system and that you lost a good bit replacing the water pump.
Once you are satisfied everything is back in proper place, the most nerve-racking part is turning the key to start your vehicle. Mine fired up right away and ran great.
 

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Khaki Nitro Nut
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What a great in-depth How-To! :rep: :rep: :rep:
If I could...
Thank you very much for taking the time to do this.
How-To's are very time consuming and this one is great!
BTW what is the crack sprockets? LOL ;)
 

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Lighting Guru!
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Discussion Starter #4
Thank you very much and good catch on the typo! :D
 

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Khaki Nitro Nut
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I thought your ride had some special drug Mfg plant inside it. :))
Despite what some folks think, I do actually read everything. There was one other, but I can't remember where is was. Them/then fat finger, I think somewhere...
But that really does not matter.
IT IS A GREAT WRITEUP!
Thanks again for the time and effort you put into it. :appl:
 

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Discussion Starter #6
Im sure over time ill read through and find them.
As is ever big job on the Nitro anymore, I go into it with making a thread in mind.
 

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Wow! great job on the write up. Can I ask how many miles are on your rig? I'm only at 41k but just trying to figure our what I can safely run to before I have to do all that work....
 

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Lighting Guru!
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Discussion Starter #9
Wow! great job on the write up. Can I ask how many miles are on your rig? I'm only at 41k but just trying to figure our what I can safely run to before I have to do all that work....
I originally purchased my Nitro at 2.5 years old with 79K on it. The previous owner drove from Florida to North Carolina almost every weekend, so a ton of highway miles in a short period of time. Hence, not as much stress on the timing belt presumably.

I have owned it 3 years and now have close to 130K on the clock. I was very surprised to see the condition of the original belt. Seeing as it was in good condition, I assumed my assumption about highway miles not being as hard on the belt was correct.

I disregarded the manuals 100K limit, but I think it depends on how you use your Nitro more than anything.

Now, can you do this for a 3.7?

:cool:
Haha, I am going to do it on my Tiburon this summer, but I think I am done with the Nitro, haha.
 

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Very nice writeup!! I particularly like the tip about marking the old belt and transferring the marks to the new one. This would have made life a LOT easier when I did the 3.0L in my old mini-van... took me a couple of shots to get the belt positioned just right. We've currently got about 106km(68k miles?) and with the miles we put on, a few years away from this but will keep this how-to in the back of my mind.
 

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Lighting Guru!
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Discussion Starter #11
Thank you,

I actually read about marking the belt minutes before I started the job. It definitely was a huge help. Considering the amount of work necessary just to get to the belt, you surely don't want to find out it was wrong once you put it back together.
 

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4.0 Timing belt

That is exactly the way mine came off. Great job with the details. My Question. Did you replace the cam and crank sensors? If so, where in the devil are they? I'm being told to replace 2 cam sensors and one crank.

Thanks,
Papabear
 

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Discussion Starter #13
I did not change the sensors when I did this job. I looked through my manual and it appears that the crankshaft position sensor is actually located on the Right side (passenger side) of the front of the transmission bellhousing.

The cam shaft position sensor, once again according to my manual is located at the top of the timing belt cover directly below the generator. It does not mention anything about a sensor on the other side cam shaft.

One thing that I found useful was using Youtube and searching for this stuff for the 3.5L engine. The 4.0 is essentially the same engine as the 3.5L, just bored and stroked. There has been a lot more people work on the 3.5 than the 4.0, so there are a lot of videos on there about it.
 

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Awesome! Looks like a lot of fun. Which manuals did you refer to? I was at autozone and they now carry cd's and online downloads. Thanks for all the info!
 

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Discussion Starter #16
I got my information from 2 different shop manuals I have. One a PDF and one is on a CD I got from eBay.
Sadly, the CD version only runs on an older version of IE, so I am limited where I can use it anymore.
 

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I used this thread to help me replace the timing belt and water pump on my 2007 4x4 R/T Nitro, thanks for all the tips and step-by-step instructions.

Before I install the timing belt cover and the damper pulley, I am going to look up the exact torque recommended for the water pump bolts though, as your suggestion of 10ft/lbs to 15ft/lbs seems too high for those 10mm bolts into an aluminum engine block.

If I had not marked the original timing belt and transferred the marks to the new belt, I doubt that I ever would have gotten the new timing belt installed correctly (at least not without a ton more of trial and error). Even with the marks, it was difficult to get the belt installed correctly the first several times I tried. I finally used clamps to hold the belt on the camshaft pulleys in the correct spot and then backed the crankshaft up about equal to one of the teeth on the crankshaft pulley, because when the belt tensioner is installed, it was throwing the timing off by about that amount. I finally succeeded in getting the new timing belt installed to match the original belt and turned the crankshaft over several times to make sure that all 3 timing marks stayed lined up.

Any of you will most likely get it right much sooner than the number of attempts it took me to complete. I was being super cautious and with my back condition, I could not work bent over into the engine bay for more than 1 hour at a time per day.

Edit: Found the torque specs for the water pump bolts. 12N/m or 105in/lbs is the correct torque for those M6 bolts.
 

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Khaki Nitro Nut
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Edit: Found the torque specs for the water pump bolts. 12N/m or 105in/lbs is the correct torque for those M6 bolts.
12Nm = 8.8 Ft Lbs. Where did you find the specs? Neither my hard copy or my PDF files have these for the 4.0.
 

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I used this thread to help me replace the timing belt and water pump on my 2007 4x4 R/T Nitro, thanks for all the tips and step-by-step instructions.

Before I install the timing belt cover and the damper pulley, I am going to look up the exact torque recommended for the water pump bolts though, as your suggestion of 10ft/lbs to 15ft/lbs seems too high for those 10mm bolts into an aluminum engine block.

If I had not marked the original timing belt and transferred the marks to the new belt, I doubt that I ever would have gotten the new timing belt installed correctly (at least not without a ton more of trial and error). Even with the marks, it was difficult to get the belt installed correctly the first several times I tried. I finally used clamps to hold the belt on the camshaft pulleys in the correct spot and then backed the crankshaft up about equal to one of the teeth on the crankshaft pulley, because when the belt tensioner is installed, it was throwing the timing off by about that amount. I finally succeeded in getting the new timing belt installed to match the original belt and turned the crankshaft over several times to make sure that all 3 timing marks stayed lined up.

Any of you will most likely get it right much sooner than the number of attempts it took me to complete. I was being super cautious and with my back condition, I could not work bent over into the engine bay for more than 1 hour at a time per day.

Edit: Found the torque specs for the water pump bolts. 12N/m or 105in/lbs is the correct torque for those M6 bolts.
Marking the belt was for sure a huge help in putting the new belt back on. It was a little tip I found online shortly before beginning to do the job. It really is a life saver when you think of what the alternative is, being putting it all back together just to find out your timing is off.
 
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