3500rpm Vibration culprit -> VIDEO!

[barnum]

In a recent post, I off-handedly mentioned I experience engine vibration in the 3500-4500rpm range. It occurs in all gears as well as neutral. I decided to pop the hood, manually rev the engine while keeping an eye on the RPMs via the Torque app on my phone and video the belt drive and see what is going on. Well, I think I found the culprit. The fan clutch bearing of all things! Not sure how to imbed a Youtube video so sorry if it's messed up. Maybe someone can fix it?

[youtube]http://www.youtube.com/watch?v=ZvZnEHleg-k[/youtube]

I initially thought it was the harmonic balancer separating from the crankshaft pulley since both the fan blades enter a harmonic mode and the A/C belt flapped in a short rpm range at the same time. However I finally noticed that the clutch appears to begin vibrating first by going out of balance and fluctuating in a sinusoidal manner while its base is steady, which then of course puts the fan blades out of balance and also into a crazy vibration. I imagine the vibration as intense as it is translates to the A/C belt via crankshaft pulley and causes the flapping in it's longest pulley-to-pulley stretch. Above ~4500rpm it straightens itself out since it cannot sustain the amplitude of its vibration at the higher engine speeds (higher angular velocity -> higher radial acceleration -> greater centrifugal force -> clutch and fan mass settle vibration with respect to central shaft shaft).

I'm going to pull of the serpentine belt this weekend and make sure the vibration is not present when the pulley is stationary before I purchase a fan clutch. Otherwise, I'll be looking at the crankshaft pulley, harmonic balancer, crank (say it ain't so), or flywheel imbalance. I know the connecting rods are pretty short in the VQ35DE's (relative to its successor) which causes greater horizontal forces on the cylinder walls and have been known for various minor engine imbalances. Nissan's marketing made a nice little brochure about it acting as if it is only a performance improvement over a good design rather than admitting poor design in the first place.

Anywho, anyone have experience with aftermarket fan clutches? I've seen some reviews that aftermarket clutches end up being louder than the stock and the viscous fluid breaks down fast causing the fan to spin all the time. Any suggestions? I've been looking at Hayden.

[Towncivilian]

I've fixed your YouTube video in your post.

I'd lean toward Beck/Arnley or OEM myself, I'm not sure of Hayden's quality. Do be sure to use a 5% off discount code at RockAuto if you order from there.

[barnum]

Thanks for the info towncivilian, as well as embedding the Youtube video. After some more research, I'm not finding any positive stories of replacing a fan clutch, regardless of brand. Each brand seems to crap out after 13ish months (when most have a 12mo/12000mile warranty go figure) and often people have to get a 2nd, 3rd, or 4th replacement from the manufacturer before they get a "good one" that lasts a year or so. On top of that, they appear to be louder than the stock clutches.

Well RockAuto has a Hayden clutch for $33, the Beck/Arnley is $99, and a OEM clutch is $150 ouch. So I could get 3 Hayden's for the price of a Beck/Arnley or 5 Hayden's for the price of OEM. I hate being a cheapskate. Almost seems worth it to go to an electric fan setup, but not sure how to tie that in since the thermostatic fan clutch is not ECU-controlled.

[Towncivilian]

An electric fan conversion has been done before: electric-fan-conversion-t455221.html

Also, there a thorough guide for WD21 Pathfinders, it may be helpful: http://www.nissanpathfinders.net/forum/ ... us-38-fan/

I've used Beck/Arnley parts before and the quality is generally comparable to OEM, and they tend to have good quality control. If you do end up getting an OEM fan clutch, give Rob a call at 1-866-742-0297, he will have the best price in the country for the part. Have your VIN ready.

[barnum]

I'm glad I found this forum. Seems like there's a lot of good info on here.

Well the belt tension gauges come in today so I may pull the belt tonight and see if the vibration is there or not to make sure it is indeed the fan and not some other vibration setting the fan into a frenzy.

Anyone ever seen the stress cracks between fan blades on the plastic base? When I initially thought the vibration was the fan itself, I looked at another fan at a local salvage yard but it had more/deeper cracks than mine did! Just curious.

[Towncivilian]

Yes, I've replaced my fan blade due to cracks.

[barnum]

So I crawled under the truck, pulled the belt, and its definitely the fan clutch or blade, there's no vibration without the serpentine belt. Saw a drop or two from what looked like the water pump but since I've never seen any leaks, poor temp control, or low coolant I'm just gonna let it ride.

As for the fan clutch and maybe fan blade replacement, I'm going to take your advice Towncivilian and go with Beck/Arnley. Where did you get your fan blade? It seems to be an elusive aftermarket part. OEM is $130 which seems steep for a piece of plastic. RockAuto doesn't have it for 01-04 but they do for the 2000. Are the 3.3L fan blades compatible with the 3.5L? If so then I can get it for only $30 from a variety of retailers.

[Towncivilian]

There is no aftermarket option for fan blades. 3.3L ones won't fit. I found mine at a junkyard, it has cracks but they are less severe than my original fan which had a large deep crack on the inner portion.

Did you check Courtesy Parts' website? They generally have the best online prices for OEM parts. Rob usually beats them though, so give him a call when the week starts too.

You may want to inspect the radiator cap, too; there is a TSB with the inspection procedure which you can find in the general information thread linked in my signature.

[barnum]

Well... I replaced the fan clutch with a Beck/Arnley clutch and the vibration was even worse than the stock clutch. There was noticeably loose play with minimal force applied on the Beck clutch whereas the OEM would deflect slightly with moderate force applied.

I'm now suspecting the fan blade may actually be the real problem. It's very hard to tell which enters the second vibration mode first, but theoretically even if the clutch has some loose play, at high RPMs it should even out so I wonder if the fan is throwing it out of equilibrium.

On to purchasing a new fan blade. Hopefully Amazon pays shipping on returned items...

[barnum]

Here we are again.

Ordered an OEM fan blade, installed it, same vibration! This has begun to be very frustrating as it is a pain to remove/reinstall these components. In the process, the crappy aluminum housing on the fan clutch now has two stripped threads. I admit defeat in all of my previous hypotheses. I am still weary of going back to the original setup since the vibrational loading on the fan pulley, bracket, and water pump is fairly significant - I don't want to further damage anything over time. I intend on keeping the vehicle alive as long as possible (obviously).

So... now what.

Well the vibration I now assume is engine side rather than fan clutch or blade since it is significantly reduced without either the fan components. There's pretty much two options I see now: 1) direct drive fan using a Flex fan setup 2) electrical fan conversion. Since I don't want the fan on all the time especially in cold temps, I'm considering going electrical. Town, the write ups you gave me were definitely helpful. Since RockAuto has the alternators at 110A, I assume that's the stock spec so I'm going to go to Autozone tomorrow and get them to check the load on the alternator with every possible accessory on to see how much spare amperage I have. The fans I've been looking at will draw about 20A for a dual fan option. Tungsten from http://www.nissanpathfinders.net/forum/ ... us-38-fan/ used a 90A alternator instead of the old 70A so I'm hoping the 110A stocker will be sufficient.

Since there are two options out there I'd like to see any here has anything to say on the matter:
1) Do the dual 12" fans with no shroud (diagonally in accordance to coolant inlet/outlet corners)
2) Do a single large (16"-18") fan w/ a shroud

If CFM's are the biggest player, then is there a big enough concern with flow distribution?

[Slumpert]

You mentioned that you saw weepage from your waterpump. No good will come from ignoring that as it is a sign the seals inside the pump have failed and it can go from not being a problem to complete failure in just a short trip.

What does your fan clutch attach too? On my 3.3 it is attached to the warerpump and it "wobbled" like your video as it was failing due to the bearings loosening up on the waterpump shaft.

[barnum]

Yes the fan clutch attaches to the pulley and behind the pulley and fan bracket is the water pump (I believe). I ran the engine without the fan clutch/fan blade and kept an eye on the pulley to see if it was the reason I was getting the vibration but visually there was no sign of vibration. Also a stethoscope to a water pump bolt didn't reveal any unnatural sounds. With the fan assembly on the engine, it shakes the whole front end in that RPM range. Without the assembly it ran as smooth as butter. I should also re-mention that even at idle, I can see that the fan blade is out of whack. At least one blade is misaligned and that is without any vibration or wobble at the fan clutch - that's why I haven't suspected the water pump to be the cause.

I do however see what you are saying as far as the water pump leak. It would emit a very small drop every 3ish seconds running at 3000-4000rpm. My uneasiness about having to deal with the timing chain to get the water pump out has kept me from considering the replacement if there seems to be an immediately available solution - even if it is a limp-a-long fix. Also, without the fan assembly, the life of the pump is extended with the lack of the significant vibrational loading.

Slumpert, did you do the water pump replacement yourself? How bad was your fan vibration due to the shaft bearings?

[barnum]

I retract my initial statement that the water pump is behind the fan bracket. On the 3.5L it is in a different area with it's own access cover as seen below.



Since it is in a different area and is chain driven then I shouldn't have to worry about the water pump being the source. But, now I'm not sure of the source of the drops I saw before. I must have been referencing a 3.3L diagram previously.

Still awaiting a response from Procomp on their fans. I'm looking forward to being able to use the full RPM band now rather than being restricted to less than 3500rpm. Any fuel mileage gains from the fan conversion will be quickly lost in now being able to use the full RPMs with an improved throttle response!

[Slumpert]

That part 21052 would be what I would check next. Since that is the foundation everything is spinning on. That much vibration might be causing the slight seepage.

[barnum]

Ended up ordering two 14" Procomp electric fans w/ the Derale 16738 fan controller/thermostat kit. Turns out it fits perfectly. I new it was going to be a tight fit but without having considered an AC line and the steering linkage, even 1/8" wider fan setup would have been too wide. It wired up easy, used some wire cover for a clean look, but the thermostat switch doesn't work. I'm going to request a replacement and in the meantime have wired in a manual switch using the AC override wire. I need to determine if I want to stay with the 180F on 165F off Tstat switch or go with like a 195F on 175 off switch to keep engine tstat open. Or I could keep with the manual switch but I don't trust myself to monitor coolant temp every single time I idle or am parked.

Once I had the fan/fan clutch off, I checked the fan bracket (#21052M) for vibration and it was fine. Now that this thread has gone from vibration diagnosis to electric fan conversion, I should probably revert back and state that my initial vibration issues was indeed from the mechanical fan blade and fan clutch. I've alleviated the issues with the dual electric fans, have recovered my RPM band, and noticeably tell improvement in throttle response and overall feel of engine performance. Just runs a heck of a lot smoother. Time will tell if I reach any benefits of fuel economy. I'll make sure to come back with an update on mileage after I go through a tank of gas and back-calculate my MPG.

If anyone wants to see pics let me know and I'll post some.

[Towncivilian]

I'm glad to hear you were able to do a successful electric fan conversion and that it fixed your problems. Some pictures would be cool to see.

[barnum]

Here's a couple pics:





And a quick walkaround:

[youtube]O91qyGCFWpE[/youtube]
http://www.youtube.com/watch?v=O91qyGCF ... e=youtu.be (in case I still can't figure out how embed videos properly)

Called the company I ordered the kit from (Northcoast Performance out of NY) about the defective thermostat. No questions asked they said they'd send me another one right away. I'd highly recommend them. Also the kit ran around $75 shipped including two 14" fans, fan mount kits, and fan controller kit. Got here in two days. All in all I'm very pleased.

[barnum]

I'm trying to determine when I should activate the fans and have done some research with no definite answer. I know that I want them on only when the thermostat is open and to turn off prior to thermostat closing (opens at 170F/77C). But I don't know if I should wait to turn it on after the water control valve opens or not (opens at 203F/95C). So is it beneficial to have the coolant flowing through the block as well as the head or is that more of a failsafe valve and you actually want to run in the 170F-203F range with only the thermostat open?

Reference:


The truck has been running between 89C-92C on the highway and obviously fluctuates in town depending on traffic, idling, and terrain. Does anyone happen to know what theirs sits at when at a stoplight on a given day with the mechanical fan? Since I can now have better temp control, I want to use it efficiently and consider the various tradeoffs.

The temp gauge on the dash is not very useful as it does not have a linear response to coolant temp so any actual numbers or other information would be helpful.

[Towncivilian]

Mine sits anywhere between 176 - 192F at a stop light. I've never seen it over 200F.

[barnum]

Hmm that's lower than I expected. Since I run up to 92C (198F) on the highway maybe I ought to have it cut on around 94C and turn off at 90C or something.

Any info as far as the water control valve goes?

[Towncivilian]

I have no idea, sorry. I just know as per the FSM it's supposed to open at the temperature you quoted.

Ensure your A/C condenser and radiator are free of any bugs, leaves etc that can impede airflow. What is your coolant service history?

[barnum]

Alright, no worries. Condenser and radiator are pretty clear of any obstructions or damaged fins. As far as the coolant service history, there's been essentially none on my part (owned for only like 5 months). A radiator flush could be in order.