Need Help/Advice on Caravan 2.4 Timing Belt Please

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e50095

e50095

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So I did a semi-stupid thing and bought a non running 07 Caravan with 112k. I assumed it was the timing belt, and although I haven't done one before, it didn't seem beyond me. Start taking it apart, and come to find the previous owner had taken off the crank pulley, lower timing cover, and the timing belt, all of which are gone. Given the top timing cover is still on, I believe he either concluded it was beyond his capability, or incorrectly decided since the belt was bad or broken the motor was bad because the valves were likely bent. Problem with that is these motors are not considered interference motors. My local u-pullit should be able to cheaply provide the crank pulley and missing lower cover. My question is, when the timing marks are lined up on both the crank gear and cam gears, is it possible for the timing to be 180 off? The crank gear is so small in comparison to the cam gears, it seems it can turn multiple revolutions in the time the cam gears make one revolution. Am I off on my thinking on this? Any advice will be helpful. The old me would have scrapped this project when I saw someone else had monkeyed with it, but this van is at less than half of what I would expect it's lifespan to be. Thanks guys....
 
All I can suggest is YouTube videos backing up a ink on paper service manual.
 
If it is the same dohc cam as in the pt cruiser then yes it is possible. There is a mark on the block for the crank pulley and two different marks on the cam sprocket. On the cam sprockets there should be a notch that is painted white and one on the opposite side that is not. When the crank is aligned to its mark the white notches on the cam sprockets should be facing each other and then the tensioner be adjusted. Then the motor should be turned over by hand several revolutions by hand with a ratchet and verify the marks are still good after the tensioner adjustment. You really should have a manual for this so you can read and look at some pictures for this. There is also youtube. Good luck
 
racerdan80 said:
If it is the same dohc cam as in the pt cruiser then yes it is possible. There is a mark on the block for the crank pulley and two different marks on the cam sprocket. On the cam sprockets there should be a notch that is painted white and one on the opposite side that is not. When the crank is aligned to its mark the white notches on the cam sprockets should be facing each other and then the tensioner be adjusted. Then the motor should be turned over by hand several revolutions by hand with a ratchet and verify the marks are still good after the tensioner adjustment. You really should have a manual for this so you can read and look at some pictures for this. There is also youtube. Good luck
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Thanks Dan, I've reviewed the online videos and have a service manual. I'm clear on the alignment of the cam sprockets, what I'm worried about is that when I have those aligned, is it possible the crank gear is not always at TDC so to speak every time it's marks line up.
 
Didn't run into that issue. What I ran into was the camshaft itself wanted to move due to the valvesprings when I was installing the timing belt. The variance that can happen is when dealing with the adjustable tensioner. Too loose or too tight can throw the marks off after a few revolutions. If the marks are still good after the tensioner is adjusted and was turned over by hand a few revolutions and the marks re verified start the vehicle with the covers off for a short time. The crank position sensor and the cam position sensor on the forward cam have to talk to each other and be in sync. Otherwise it won't run
 
racerdan80 said:
Didn't run into that issue. What I ran into was the camshaft itself wanted to move due to the valvesprings when I was installing the timing belt. The variance that can happen is when dealing with the adjustable tensioner. Too loose or too tight can throw the marks off after a few revolutions. If the marks are still good after the tensioner is adjusted and was turned over by hand a few revolutions and the marks re verified start the vehicle with the covers off for a short time. The crank position sensor and the cam position sensor on the forward cam have to talk to each other and be in sync. Otherwise it won't run
Click to expand...
sounds good.....I'll get in there and we'll see what happens. Thanks so much for the info....
 
Not a problem bud. I just hope for your sake the motor doesn't run hot. They were notorious for that and that is why i'm getting rid of that pt. it was a 2005 2.4 dohc non turbo. I know they did some improvements later on, but not sure of the differences. Keep in mind the water pump is driven off the timing belt. Might not be a bad idea to change it while the motor is opened up
 
I think the question being asked (but not directly by the OP) might be: Does the crank stay in phase with the cams, and the answer is yes.

The cams ALWAYS run at half speed of the crank. Every Otto cycle four stroke ever.
Because of this, the crank makes 2 revolutions to bring the cam one revolution.

It does NOT matter if the tensioner is loose or tight. The number of teeth on the crank and cam pulleys does not change, so the ratio between them stays the same. Stretch that belt to the moon and back, and the ratio stays the same. The tensioner makes sure that the belt slack doesn't allow change between the two while running.

Then, the next question seems to be: What keeps it timed correctly to the crank, on assembly? (Y'know, so it can't be 180 out)

The crank doesn't care if it's on the first or second (or third or thirteeth or millionth) of those two revolutions, because the cam timing isn't established when the belt is out (in other words, if the cams aren't connected to the crank, the number one piston at TDC is always the same as far as the car is concerned, no matter how many times you turn the crank. Bring it to TDC where the timing mark on the crank is, and it's always the same). There's no intake or exhaust or compression stroke, because the cams aren't hooked up yet. There is NOTHING on the crank to tell the motor if it's on an intake or exhaust stroke, because it those strokes don't even exist until the cams are installed and connected via belt.

The cam sensor is what tells the motor whether it's on intake or compression stroke, and THIS is why there's a certain orientation for the cams when you assemble. The crank is just at it's TDC mark (which is what the crank position sensor measures), and the cams have to be lined up to time everything (so the cam sensor can tell the motor if it's TDC-overlap or TDC-Fire). If you put the notches in the wrong direction from the service manual, THEN it's 180 out. (I do not not know if they orient to center or outboard on that motor. Your manual will confirm that)

Also, buy a factory water pump, NEW, NOT REMAN. Trust me. The parts store stuff (including the CHRYSLER/Mopar reman) will not last and when it goes....
 
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A note about "new". All new parts are not created equal. my 96 Camry is perfect example. Buying individual parts gets expensive. So on ebay I find I can buy complete package, Water pump, oil pump, belts, both idlers, everything, at huge savings.
My problem was in how the china man positioned this oil pump casting for machining. I had to egg shape the bolt holes to get this pump positioned properly to the block.
We may or may not get exactly what we pay for. Good luck
 
No you can not put it 180 out. It is a fairly simple timing belt to do. Replace the tensioner pulls and water pump while you have it apart. I have seen them bend valves and not bend valves. Cross your fingers. If you fire it up and it misfires due to compression you will take the head off for new valves.
 
jos51700 said:
I think the question being asked (but not directly by the OP) might be: Does the crank stay in phase with the cams, and the answer is yes.

The cams ALWAYS run at half speed of the crank. Every Otto cycle four stroke ever.
Because of this, the crank makes 2 revolutions to bring the cam one revolution.

It does NOT matter if the tensioner is loose or tight. The number of teeth on the crank and cam pulleys does not change, so the ratio between them stays the same. Stretch that belt to the moon and back, and the ratio stays the same. The tensioner makes sure that the belt slack doesn't allow change between the two while running.

Then, the next question seems to be: What keeps it timed correctly to the crank, on assembly? (Y'know, so it can't be 180 out)

The crank doesn't care if it's on the first or second (or third or thirteeth or millionth) of those two revolutions, because the cam timing isn't established when the belt is out (in other words, if the cams aren't connected to the crank, the number one piston at TDC is always the same as far as the car is concerned, no matter how many times you turn the crank. Bring it to TDC where the timing mark on the crank is, and it's always the same). There's no intake or exhaust or compression stroke, because the cams aren't hooked up yet. There is NOTHING on the crank to tell the motor if it's on an intake or exhaust stroke, because it those strokes don't even exist until the cams are installed and connected via belt.

The cam sensor is what tells the motor whether it's on intake or compression stroke, and THIS is why there's a certain orientation for the cams when you assemble. The crank is just at it's TDC mark (which is what the crank position sensor measures), and the cams have to be lined up to time everything (so the cam sensor can tell the motor if it's TDC-overlap or TDC-Fire). If you put the notches in the wrong direction from the service manual, THEN it's 180 out. (I do not not know if they orient to center or outboard on that motor. Your manual will confirm that)

Also, buy a factory water pump, NEW, NOT REMAN. Trust me. The parts store stuff (including the CHRYSLER/Mopar reman) will not last and when it goes....
Click to expand...
You completely cleared it up for me brother. My malfunction was the old way of thinking where the crank is attached to the valves by pushrods, so I now understand if I have the cam sprockets lined up correctly, and the crank gear lined up with the mark on the block, I can't blow this unless I screw up the amount of tension. The cam and crank position sensors will tell the computer when to throw the spark and where. I reviewed the Haynes manual, and i feel good about it. Thanks so much for the input...
 
I'm glad I could help.
This motor doesn't have automatic tensioner in it?
 
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