timing belt

[brine]

So I have a 93 pathfinder se 4wd..When it runs i love it..But within the last couple months I have had some problems and I am looking for some advice..Hope someone can help..First of all it had a weird noise that was kind of loud..I took it to a mechanic and he said it was the oil pump..My friend listened close to it and he didn't hear any noise coming from there..Is there any other way to trouble shoot if it is the oil pump? Also i changed the water pump thinking it was that because it had a weird noise when i spun it by hand..Well with changing that I had to take the timing belt off..When i did this i marked the wheels and bottom crank shaft, i guess its called where the harmonic balancer sits on..Both top wheels moved slightly but the bottom one did not..After changing the water pump I put the two wheels where they went by the marks I had..Now the truck runs pretty bad..It shifts at like 3000 rpm's or a little higher and it does not have that much power when I press on the accelerator..Not at all like it had before..One of my friends mentioned it sounds like i didn't match up the harmonic balancer pulley over the tab..and Its not sitting on there correctly..Would this cause the power problem..I changed the water pump once before and put it back together and everything was ok..But I did have a friends help that time..or could this be because the bolt was not tight enough? It does seem to vibrate a little..Just looking for some advise..I have taken it apart more than a couple times and am just a little frustrated now..Also, I read a earlier question and saw you could use a chain wrench..It worked taking off..But broke the second time I took it off..So I know I sound unexperienced with this,but I am so close and dont want to have to get rid of my pathfinder..Any advise would be greatly appreciated..Thanks..

[jj big shoe]

Having the cams a tooth or two off would definately cause a loss of power like you described. The valves aren't open/closed at the right times.

Check out the link below:

http://www.nissanpathfinders.net/forum/index.php?showtopic=12828

It's a good guide and should cover most of your problems.

 

Other tips:

 

TDC is actually pretty easy to determine. Just pull the #1 spark plug, put your finger over the hole and turn the crank. When you feel air blowing your finger off the spark plug hole, you're on the compression stroke. At that point, put a pencil or a stick or something that won't harm the piston head into the spark plug hole and rotate the crank until the stick is at its highest point. Voila, TDC.

 

When the belt is installed under tension, you should just be able to twist it by hand about 90 degs in the center between the cam pulleys,if you can twist beyond that, it is too loose, less and may be too tight. Feel the old belt first it should give you an idea of how tight it is, as well, loosen the belt tensioner and remove tension before removing the tensioner, take note of the position of the tensioner before you move it. The olkd belt is likely looser than it should be as it has been in use for a while and stretched.

 

Hope this helps.

[brine]

Having the cams a tooth or two off would definately cause a loss of power like you described. The valves aren't open/closed at the right times.

Check out the link below:

http://www.nissanpathfinders.net/forum/index.php?showtopic=12828

It's a good guide and should cover most of your problems.

 

Other tips:

Hope this helps.

Thanks for your help..My first problem might be that its too tight..I thought the tighter the better so it wouldn't skip a tooth..And my friend thought with it being tighter it might help the performance..Sounds like not so much..With it being too tight would that make it run poorly and shift at a higher rpm because of the strain of the belt being too tight? Also I marked the top two wheels, and the bottom crank..When i took the timing belt off i heard the gears dropping,shifting, when they moved..But it looked like the crank on the bottom didn't move at all..Is this normal? Or could it be it spun a 360 on me? also when i look for the tdc..I do this with the belt on correct? with a wrench on the crank? and just doing that I will feel air coming through the # 1 spark plug? If its off a couple teeth do i get one at tdc and then count off the teeth to get it right? Sorry for all of these questions..When my roommate and I did it the first time there were no problems like this when we marked everything..Quess i must not have noticed one of the wheels turning more than I thought..Or belt too tight..With the Harmonic balancer pulley..Does it only fit on there one way on a notch? Or does it just go on there and tighten the bolt..Sorry for all the questions..Last time I had help and it went smooth...Now my friend is kinda busy to help out..I parked it though so I dont mess up my truck till I get it right..Thanks alot for your help..this has been a huge learning process..

[jj big shoe]

Too tight could snap the ends off your cams. Don't do that.

 

Also I marked the top two wheels, and the bottom crank..When i took the timing belt off i heard the gears dropping,shifting, when they moved..But it looked like the crank on the bottom didn't move at all..Is this normal? Or could it be it spun a 360 on me?

Are you saying the cam gears spun when you removed the timing belt? Normal stuff, no big deal. The cam is under load from the valve springs. Some valves are open, some closed and the valve springs pushing against the cam lobes will make it spin around when in the right spot.

 

First, find TDC.

Remove the #1 spark plug (passenger side closest to the radiator). With the timing belt removed, turn the crank clockwise (CW) until you feel the air pushing your finger off the #1 plug hole. That's the compression stroke. Do NOT use a paper towel or rag. You could suck part of it into the cylinder - very bad. Once the piston comes up a bit, put a pencil, a straw or something that won't scratch the piston head down into the #1 hole and feel for the piston. Now turn the crank CW until the pencil is at its highest point. That's Top Dead Center. (Your harmonic balancer's zero degree mark -furthest to the left- would be at the 12 o'clock position. Use that for reference when you remount it if needed).

Now line the marks on the cam gears up with the dimple marks on the cover and slide the belt on. Put it on the crank first, then the left cam, then the right (IIRC, fitting the left cam before the right is easier for some reason. But maybe its the other way around). Be sure to only put it on 1/4" or so. If not, it'll seem like the belt is too short. Don't pry it or force it on. It'll take a little finesse, but it will fit. And if your cams move during this step, don't panic. Just turn them so they line up with the marks again and try again. Check other posts for the correct tooth count between gears to be sure.

Now mount the idler and tighten per the previous link instructions. Check tension by twisting the belt 90 degrees between the cam gears or measuring deflection - 10mm @ 22ft.lbs or something like that. Just do the twist deal.

Before you're ready to button it all back up, turn the crank CW a few times and make sure nothing bangs into anything else. BTW, Once you turn the crank the lines on your belt won't line up to the marks for the next 22 revolutions or so, don't worry about it. They're only reference for the initial install mounting.

 

It looks harder than it is, don't be skeered.

 

*Disclaimer:

I'm not a mechanic and I smoked a lot of pot in high school, but I have done this a few times. Your best bet is to follow instructions in previous posts and ask questions if you have a problem.

Edited October 14, 2008 by jj big shoe

[brine]

Too tight could snap the ends off your cams. Don't do that.

Are you saying the cam gears spun when you removed the timing belt? Normal stuff, no big deal. The cam is under load from the valve springs. Some valves are open, some closed and the valve springs pushing against the cam lobes will make it spin around when in the right spot.

 

First, find TDC.

Remove the #1 spark plug (passenger side closest to the radiator). With the timing belt removed, turn the crank clockwise (CW) until you feel the air pushing your finger off the #1 plug hole. That's the compression stroke. Do NOT use a paper towel or rag. You could suck part of it into the cylinder - very bad. Once the piston comes up a bit, put a pencil, a straw or something that won't scratch the piston head down into the #1 hole and feel for the piston. Now turn the crank CW until the pencil is at its highest point. That's Top Dead Center. (Your harmonic balancer's zero degree mark -furthest to the left- would be at the 12 o'clock position. Use that for reference when you remount it if needed).

Now line the marks on the cam gears up with the dimple marks on the cover and slide the belt on. Put it on the crank first, then the left cam, then the right (IIRC, fitting the left cam before the right is easier for some reason. But maybe its the other way around). Be sure to only put it on 1/4" or so. If not, it'll seem like the belt is too short. Don't pry it or force it on. It'll take a little finesse, but it will fit. And if your cams move during this step, don't panic. Just turn them so they line up with the marks again and try again. Check other posts for the correct tooth count between gears to be sure.

Now mount the idler and tighten per the previous link instructions. Check tension by twisting the belt 90 degrees between the cam gears or measuring deflection - 10mm @ 22ft.lbs or something like that. Just do the twist deal.

Before you're ready to button it all back up, turn the crank CW a few times and make sure nothing bangs into anything else. BTW, Once you turn the crank the lines on your belt won't line up to the marks for the next 22 revolutions or so, don't worry about it. They're only reference for the initial install mounting.

 

It looks harder than it is, don't be skeered.

 

*Disclaimer:

I'm not a mechanic and I smoked a lot of pot in high school, but I have done this a few times. Your best bet is to follow instructions in previous posts and ask questions if you have a problem.

Thaks for all your good advise!! I really appreciate your patience with me..One last Question..So if i didnt mark the harmonic balacer..It has to go to the far left? Is there a mark on there to help me with that? Does it just slide over the tab inside the cover when I do that? If so it should be pretty easy to tell when its on there right? If it does not fit on a tab..What makes that throw everything off?

thanks again for your help...

[jj big shoe]

Does it just slide over the tab inside the cover when I do that?

Not sure what you mean here.

If it does not fit on a tab..What makes that throw everything off?

Or here.

 

The crank pulley has a series of marks along the edge. These are timing marks and are used to adjust the ignition timing for your engine. Going clockwise, the first mark is zero, then the next is 5*, then 10* and so on in five degree increments.

The timing belt is for valve timing (so they open and close at the right time in relation to the pistons) and the timing marks are used as a reference for ignition timing (when each spark plug will fire).

But the end of the crankshaft should be cut in such a way that the balancer will only fit on in the correct position anyway, but if your balancer is like mine and can be separated from the pulley then you could set your engine at TDC and install the balancer so that the timing mark furthest to the left (0*) lines up with the pointer on the belt cover.

Edited October 18, 2008 by jj big shoe

[Terrano1992]

So if i didnt mark the harmonic balacer..

You don't need to mark it. Crankshaft has a key, balancer has a key slot inside. So it can be set only one way.