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Discussion Starter · #1 ·
I replaced the timing belt, water pump, thermostat, all drive belts, and all idler pulleys. With all drive belts removed, I've got a noise that sounds to me like the t belt tensioner squealing or the belt rubbing on something, or both. The noise comes and goes and varies in volume. There's a video link below.

I believe I did everything correctly on the timing belt change with the exception of possibly not getting the correct tension. The tensioner was also new so I guess bearings could could be bad of the box. Or am I completely wrong and the noise is the valves being incorrectly timed aka hitting the pistons? Like I said it comes and goes and the motor otherwise runs an idles just fine.

Please help.

Video:
https://youtu.be/jUosVSspYu4
 

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Discussion Starter · #2 ·
I just watched the video again and it isn't as bad or as loud as it sounds in the video. Plus there is some noise from a badly cracked manifold in there.

Seems to go between what I would describe as the rubbing noise in the beginning of the video to the squealing and then no noise at all.

I'm going to take the timing belt covers back off and have a look but I won't get a chance to do that again until next weekend.
 

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Listening to a noise on a YouTube vid is never as good as hearing it live, but it definitely doesn't sound good! Not having seen in-person what you did doesn't make it any easier. I'm assuming this noise didn't exist prior to replacing the belt, so I would suggest you start to turn the engine to TDC and disassemble the front of the engine. One mistake I have seen people make is the very bottom bolt of the lower timing belt cover. This bolt is different in that, unlike the other timing cover bolts, does not have a rubber spacer on it. I have seen people use one of the short cover bolts with a spacer in place of that bolt, which, if done, will grind against the back of the crank pulley. If your cover bolts are okay, I would remove the upper and lower covers and check for any signs of scraping. I would also look at the guide plates that sit inside and outside of the crank sprocket (if you didn't remove the sprocket, the inside should be okay); make sure the edges of the guide plates (when installed) turn away from the timing belt and not toward it. If that's okay, make sure the engine is at TDC #1 by making sure the cam sprocket timing marks are in the 11:00 (right bank) and 1:00 (left bank) positions, respectively. If they are 180 degrees out, turn the engine one revolution.
Here's how I check belt tension: Turn the right bank cam sprocket about three teeth clockwise; this puts the slack in the belt between the two cam sprockets. At the middle point of the belt between the two cam sprockets, take your thumb and forefinger and twist the belt. You should be able to twist the belt 90 degrees, no more and no less. If you can twist it more than 90 degrees, the belt is too loose; if you can't twist it 90 degrees, then it's too tight. I would then remove the tensioner and turn the pulley, checking for any signs of roughness while turning. If it feels good, re-install the tensioner, turn the tensioner in the proper direction and tighten the nut.
The belt should have one dotted or dashed line and two, solid lines and an arrow to indicate the direction. The arrow should point towards the front of the vehicle. The dashed line should line up with the timing mark on the right bank cam sprocket; the solid lines should match up with the timing marks on the left bank cam sprocket and crank sprocket, respectively. Loosen the tensioner nut and turn the right bank cam sprocket about three teeth in the counter-clockwise direction, which pulls the slack toward the tensioner side of the belt and the spring will allow the tensioner to remove the slack. Tighten the tensioner nut to 35 ft/lbs. Turn the right bank cam sprocket about three teeth clockwise, which, again, puts the slack of the belt between the two cam sprockets. Do the twist test and confirm the 90 degrees via the twist test to confirm the proper tension.
Once you know the belt is properly installed and tensioned, install the guide plate and lower timing cover. Install the crank pulley and crank bolt and tighten. At this point, you can start the engine without the upper cover installed to check for noise (since there is no coolant in the engine, you obviously don't want to run the engine but for a brief period to avoid overheating the engine). If there is no noise, you should be good at this point to re-assemble.
 

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Discussion Starter · #4 ·
Thanks for taking the time to post. You are correct in assuming there was no noise prior to changing the belt.

I felt good about the engine being in the right place and all marks being lined up correctly. However I did mess around with the tensioner spring and belt tension wondering if I had that right. I have seen the numbers 13-15mm of deflection when 98N is applied to the belt between camshaft sprockets but I don't have a way to accurately place a load on the belt. Thanks for explaining your method of checking tension, I will use that.

I almost feel like the tensioner is bad or not installed properly and is not turning freely. When I would shut the truck off after listening to it for a few seconds it almost sounded like it screeched to a stop, making me thing the tensioner isn't turning and the belt is sliding over it.

Anyhow, I purchased another timing belt, tensioner, and tensioner spring. As long as it all shows up this week I'll take it back apart this weekend.

On a side note, while looking at it apart today it appears I have a coolant leak back behind the thermostat housing under the intake. If I remember correctly isn't there a gooseneck or something that is prone to leaking?
 

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What he said about the bottom timing cover bolt is very true

If you used a spacer or forgot to tighten it then it will rub the back side of the crank pulley and make that noise. I had that happen, same noise like you have

If your bottom timing cover bolt is tight and proper, then take off both timing covers and run the engine. If the sound is gone then your belt is rubbing the timing cover

If the sound is still there then the only thing left is either a screaming water pump or a screaming tensioner

If your timing is off you definitely wouldn't get a noise like that. It would either be popping, backfiring and misfiring, barely able to run, or not run at all

Other than that the only other thing would be a broken vibration damper. The vibration damper/crank pulley isn't one solid piece - it's glued together. If you used a 2 or 3 jaw puller instead of a harmonic balancer puller then you may have broke it and it is seperated. Same thing can happen if you try to use prybars or screwdrivers to pull the crank pulley. Although you would probably distort the lower timing cover before you break the crank pulley in that case

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His video shows the engine running without the drive belts installed, so that rules out the water pump. The pump is not driven by the timing belt on VG engines.

If running without both covers, just make sure the guide plates are installed as well as crank pulley and bolt. Also, make sure you don't have anything laying around the engine compartment that could possibly fall off and jam the timing belt while running, or you'll have a whole lot more work to do!
 

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Discussion Starter · #7 · (Edited)
To pull the crankshaft pulley/harmonic balancer I used the two threaded holes in the pulley. Is there a better way to pull it off? Also, Is there a way to check it out for damage other than just visually inspecting it (which I will do when I take it off again.)

I will check the bottom bolt out as well.
 

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To pull the crankshaft pulley/harmonic balancer I used the two threaded holes in the pulley. Is there a better way to pull it off? Also, Is there a way to check it out for damage other than just visually inspecting it (which I will do when I take it off again.)

I will check the bottom bolt out as well.
You're right it can't be the water pump sorry about that haha.

Yeah you did it the right way though

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Discussion Starter · #9 · (Edited)
You're right it can't be the water pump sorry about that haha.

Yeah you did it the right way though

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No problem.

Do you happen to know what size those threads are off hand? I know I bought bolts when I did the belt change but I didn't keep them handy and it has been close to a year.

Correct me if I'm wrong but aren't they the same size as the timing cover bolts?

ETA: I think they were 6 x 1.0mm. Sound right?
 

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Discussion Starter · #10 ·
Well I went down to the garage and had a look at the bottom cover bolt. Low and behold, it has the rubber washer on it and is clearly contacting the harmonic balancer! I feel like a doofus and I'm glad it's a simple fix. Still sucks I have to take it all apart again though.
 

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Well I went down to the garage and had a look at the bottom cover bolt. Low and behold, it has the rubber washer on it and is clearly contacting the harmonic balancer! I feel like a doofus and I'm glad it's a simple fix. Still sucks I have to take it all apart again though.
That was my first thought because I made that same mistake and it took a while to figure out

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I can usually get the balancer off by removing the crank pulley bolt, removing the big washer from the bolt, reinstalling the bolt partially (to prevent the pulley from falling on the ground) and then using a prybar on each side of the back of the pulley to work the pulley off the crank. You have to be careful not to break the back edge of the pulley, though, if you use this method because the metal is brittle.

Going back to the coolant question... "Yes," there is a water outlet behind the rear timing cover that connects to the bypass hose. Usually, the hose fails and leaks or the aluminum corrodes and causes a leak. It's tough to replace without removing the timing covers. If you replace the hose, use the genuine Nissan part as the aftermarket versions don't have the proper bend and will tend to not fit very well.
 

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Discussion Starter · #13 ·
Well I had a fun filled day tearing the truck back apart. Having the wrong bolt in the bottom hole actually broke the aluminum tab that contains the threaded hole for the bottom bolt. I believe it will be ok though. That tab was in close proximity to the oil pan seal but it doesn't look like that was affected. There is a potential for dirt to get up under their cover I suppose since there isn't a bolt there so I may seal it around the outside edge at the bottom. Not sure if that's necessary though.

Anyhow, it's all back together and running smoothly. I checked the tension using the 90 degree method smj described and the belt was just right. Thanks for the help

Now to pick what to address next. The spongy brakes or the exhaust manifolds.
 

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Well I had a fun filled day tearing the truck back apart. Having the wrong bolt in the bottom hole actually broke the aluminum tab that contains the threaded hole for the bottom bolt. I believe it will be ok though. That tab was in close proximity to the oil pan seal but it doesn't look like that was affected. There is a potential for dirt to get up under their cover I suppose since there isn't a bolt there so I may seal it around the outside edge at the bottom. Not sure if that's necessary though.

Anyhow, it's all back together and running smoothly. I checked the tension using the 90 degree method smj described and the belt was just right. Thanks for the help

Now to pick what to address next. The spongy brakes or the exhaust manifolds.
You'll be okay without the bottom bolt

If anything it will help you identify a oil leak from cam seals, crank seal, or a coolant leak from the water pump because the opening will allow oil or coolant that would otherwise pool in the bottom of the cover, to come down

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Discussion Starter · #15 ·
You'll be okay without the bottom bolt

If anything it will help you identify a oil leak from cam seals, crank seal, or a coolant leak from the water pump because the opening will allow oil or coolant that would otherwise pool in the bottom of the cover, to come down

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Looking at the cover it appears there is a .5" or so slot where the bottom bot would be to allow fluids to run out instead of pooling. I'm just worried the gap is excessive and will allow dirt and stuff to get up in there.
 

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I wouldn't be worried about it. Keep in mind the opening is hidden behind the crank pulley plus you have an engine cover that will block debris being kicked up from the road.
 

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First off I would like to say thank you to Hertz for starting this thread, and especially for including the video. I was emediatly able to deduce that my post-belt-change noise is identical to that in the video. Secondly I want to thank everyone who pointed out the bottom timing cover bolt as the culprit. You all have saved me a great deal of time and grief. For that I am very appreciative.

Some of you (if not all) probably remember my constant battle with my truck earlier in the year. After finally getting it running perfect-ish, and driving it for a week without issue, it suddenly began making the same noises as Hertz. My assumption was that the timing belt had partially slid off the tensioner and was rubbing against the cover. At that point, after all the previous labor, and compounded by the quickly rising Texas heat, I decided to just leave it until such time as I felt like tearing it apart again. And so it is. The truck has sat abandoned for the past 5 months. And in truth, it may very well have continued to sit, or even been sold off at a loss of thousands of dollars, if not for this thread. I am so relieved right now. Well... sort of lol

As I'm sure you've all figured out by now I have confirmed that the bottom of the timing cover is in fact rubbing against the harmonic balancer due to it not being bolted into place. I'm relieved because this now means I don't need to rip everything apart and mess with the timing belt. Unfortunately... it's not bolted into place because there's nothing to bolt it too. The small triangular part of the engine with the threads on it literally broke off the first time I tried bolting the cover in place. Which I still have a hard time believing, because I hadn't even applied 5 pounds of pressure to it when it happened. In related irony I actually ended up stripping several thread points around the timing cover using almost no force on the ratchet. I've turned a lot of bolts in my time, but never have I encountered such frail aluminum. Still has me a bit stunned.

So I guess the million dollar question now is... How can the bottom of the timing cover be secured without that part of the engine? (I believe it's part of the oil pump?).

*update* I guess I partially answered my own question. It was in fact part of the oil pump that broke off, and fortunately it's a semi-cheap replaceable part. Probably foolish question to ask, but I need to rip everything apart again to install it, don't I? https://www.rockauto.com/en/catalog/nissan,2001,frontier,3.3l+v6,1374522,engine,oil+pump,5564
 

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Dang... No such luck. After an hour under the truck making sure the timing cover is not making any contact with the harmonic balancer the sound is now much worse. I guess it is the timing belt rubbing against the cover after all :(
 

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Discussion Starter · #19 · (Edited)
While taking it back apart to correct my wrong bolt in the bottom hole syndrome, the triangular tab on mine actually fell to the ground when I removed that bolt. At first I was all like, bro wtf is this where did that come from. Then I was all like, oh duh you broke that off when you tightened the harmonic balancer against a bolt that was too long. This revelation came when I was trying to install the correct bottom bolt and it wouldn't start in the now nonexistent hole, go figure.

Josh my recommendation before you take it back apart is to run the engine and with a screw driver, push on the bottom of that cover where the bolt should be. See if the noise goes away. Perhaps the cover is slightly bent and sticking out into to harmonic balancer. My cover, without a bottom bolt, is currently not rubbing the balancer. However, I have not driven the truck at all. I ran it for a little while to refill and bleed the cooling system and all was well though.

Good luck, I don't know how the belt could partially slide off the tensioner and track correctly on the cams and crankshaft. Especially with the washers on both sides of it on the crankshaft sprocket. My assumption would be that if the belt is in fact rubbing on the cover, that the cover is not secured properly, or is bent/damaged somewhere making in closer to the belt than it's supposed to be.
 

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As mentioned already, the only way the belt could slide off the pulleys is if the guide plates before and after the cam sprocket were missing or improperly installed. The upper edge of the plates need to point away from the belt, as opposed to toward the belt. It is usually easy to tell what way they go as the cam sprocket outline is usually on the guide plate when you remove it.

I currently don't have the lower "triangle" on my oil pump, either. It happens more often then you would thing (I purchased mine with it that way). As long as the other cover bolts with their rubber spacers are installed and the lower cover is not bent, it should be a problem as far as contacting the balancer. To replace the oil pan, not only does the front have to be taken apart, but the oil pan has to be removed, as well, which is a real pain if you have 4-wheel drive.
 
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