Engine noise help (1 Viewer)

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Joined
Aug 5, 2013
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Location
Nashville, TN
Hey gang.

My 18 year old son was driving my 2000 100-series (his Isuzu VehiCROSS is temporarily down for issues of its own) when he said it stalled in traffic. He restarted it and moved to a parking lot but didn’t feel comfortable driving it home. (He’s only been driving for about a year and it’s really mechanically inclined and he didn’t want to risk further problems on the way home.)

So I drove over to where he was and had him start the engine. I noticed a noise coming from the serpentine belt area that I’ve never experienced before and I can’t quite identify. Although the sound was unusual it didn’t seem calamitous, so I drove the Cruiser home about 5 miles from where it first stalled out. There was nothing off about how the truck drove—power seemed normal and there were no drivetrain vibrations—but if I turned the radio down I could still faintly make out the rattling from the engine area. Gauges read fine and my onboard OBD2 reader didn’t pick up any codes or abnormal sensor readings. However, when I got home after this 5 mile drive and popped the hood again to listen for the sound, the truck did stall again the moment that I closed the hood. This all has me kind of stumped.

For background, I did have the timing belt, the serpentine belt and the idler pulley replaced (at a Firestone Complete Care, I was out of town and desperate) about 6 months ago after the serpentine belt grenaded itself and locked up around the pulley (or vice versa). I haven’t had any problems with any of the belt-driven accessories since that time but if there’s any one thing that I can tell might be a little visually off it would have to be that the fan pulley/fan clutch assembly seems to maybe be a little off balance. But would that make this kind of noise?

Any ideas or suggestions would be greatly appreciated. I’m out of work at the moment and don’t have a lot of extra money for a mechanic to do exploratory surgery, but if someone had an idea of what I should check I’m handy enough to fix it myself. I’m just not great with the diagnostic part.

(Edited to add the YouTube videos as recommended by 2001LC.)





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I post videos in Youtube, than link in here.

Check for DTC (codes) when stall happens, without turning OFF IG SW (key).

Check you battery post & clamps connections. They need to be clean and sung (do not over tighten, which damages clamp)

Check to see that no wires are rubbing on serp belt or pulleys. Very often during T-belt service. Shops rout the wire harness of cam sensor & oil sending unit wrong, in front of fan bracket.
Crank wire routed wrong.JPEG

Engine wire harness main (1)a.JPG


Check your Serp belt and it's tensioner & idler pulleys. Indy shop very often use after-market junk and or install idler pulley backward.
 
I post videos in Youtube, than link in here.

Ooh, good thinking. I was tired last night and I haven’t been on this forum for awhile so I had forgotten about the option to link YouTube videos. Here are a couple of videos that illustrate the noise I’m hearing. It’s sort of a loping, muffled clunking like something connected to the belt is skipping or engaging/disengaging. The first video also shows how the fan assembly seems to be wobbling a little bit but I can’t tell for sure if this where the noise is specifically coming from.





I’ll take another look in the engine bay to check the battery terminals and look for any loose or frayed wires. I’m sure the battery terminals could use a little cleaning if nothing else.
 
You may have a bad fan bracket. I say that because I "thought" (difficult call), I saw a slight wobble or hop at it's pulley. Which usually means bad fan clutch also.

I use $5 mechanics stethoscope on fan bracket. Just behind it's pulley on the FB housing. Which can also be used on tensioner and idler bearings.

Many videos around on how to inspect fan clutch. Sometimes they freeze. Which just trying to spin engine off, they wont or will be difficult to spin.

I'd then take off the belt, start engine and see if sounds gone.
 
You may have a bad fan bracket. I say that because I "thought" (difficult call), I saw a slight wobble or hop at it's pulley. Which usually means bad fan clutch also.

I think you may be right about the fan bracket and clutch. I just shot another video focused on the fan bracket pulley and it does seem to wobble. I also found a video about how to diagnose (and replace) a 100-series fan clutch and it said that the fan shouldn’t normally keep spinning when the engine is cold and mine definitely is. So I’ve got the correct Aisin parts on order from Amazon, hopefully they’ll arrive tomorrow according to the estimate. I’ll start the fan shroud tear down this afternoon and maybe then I can get a read on if the noise is still happening with the belt off.



Here’s the video I watched about the fan clutch replacement. Just want to give credit where it’s due. I’m sure this guy is a fellow Mudder.
 
Not to derail your tech thread, but do you have some pics or videos elsewhere online about that vehicross? Those things are amazing.
 
I think you may be right about the fan bracket and clutch. I just shot another video focused on the fan bracket pulley and it does seem to wobble. I also found a video about how to diagnose (and replace) a 100-series fan clutch and it said that the fan shouldn’t normally keep spinning when the engine is cold and mine definitely is. So I’ve got the correct Aisin parts on order from Amazon, hopefully they’ll arrive tomorrow according to the estimate. I’ll start the fan shroud tear down this afternoon and maybe then I can get a read on if the noise is still happening with the belt off.



Here’s the video I watched about the fan clutch replacement. Just want to give credit where it’s due. I’m sure this guy is a fellow Mudder.


Fan bracket looks visually wobbly in that video but shoot I wouldn't think anything could be seized up enough to cause the engine to stall. That would be more along the line of the wires that 2001lc mentioned above. Careful with ordering parts on Amazon.

But as with all engine belt / pulley noise diagnosis, you must follow the steps.

  • Remove serpentine belt by taking tension off of the belt tensioner
  • Start the engine, if the noise goes away then it's related to your accessories / belt
  • If the noise doesn't go away you can start cursing firestone for whatever they screwed up in the timing belt job

  • Assuming the noise went away and now the belt is off, you can spin each pulley. Start with that fan and see if it has any wobble. Work your way around and report back with your findings.
  • The fan bracket is buried deeper within. The clutch is an easier repair.
 
I agree this is not engine stall issue. Low battery or bad connecting may cause a stall. So will many thing, like fuel pump (lean condition), coils, etc.

Tough call on fan bracket, based on video. I'd use stethoscope or at minimum pull belt off. Spinning by hand, it should be silent. Grab pulley, there should be no side to side or up and down play.

Tim does good work, seee his vidoeo on fan clutch.
 
Hi all. Sorry I was away for a few days, family stuff. So I now have the parts to replace the fan clutch and fan bracket, which I believe is the culprit of the sound I posted in the videos. I’ve started the disassembly of the fan shroud, fan assembly, serpentine belt and LH and RH timing belt covers, all according to the FSM. I now have all of the nuts/bolts removed from the fan bracket assembly but this thing will just NOT come out. I’ve been rapping on this thing at different angles with a hammer, to the point that bracket casting has chipped in a couple places, but still no movement of the bracket itself. Very frustrating.

For those of you who have replaced a fan brackets, or done a full timing belt change on your own, is there some magic to removing the fan bracket cover? I’m stumped.

Thanks
 
I think I've figured out my issue with the fan bracket not coming loose. After watching a video of someone doing this same repair on a Tundra, it's apparent that I need to loosen two bolts that hold the A/C compressor to the fan bracket, and these can only be accessed by removing the front skid plate and going at them front underneath. For some reason this step is not mentioned AT ALL in the FSM procedure for the timing belt change, even through the fan bracket has to be removed completely to do that repair. Hopefully this is what I needed to know.
 
I think I've figured out my issue with the fan bracket not coming loose. After watching a video of someone doing this same repair on a Tundra, it's apparent that I need to loosen two bolts that hold the A/C compressor to the fan bracket, and these can only be accessed by removing the front skid plate and going at them front underneath. For some reason this step is not mentioned AT ALL in the FSM procedure for the timing belt change, even through the fan bracket has to be removed completely to do that repair. Hopefully this is what I needed to know.
My mistake, thought you said clutch. The bracket is a doozie to get to , I tapped out and brought mine to Toyota =] Good luck
 
Just to give an update, the sound referenced in the first post was definitely due a bad fan bracket. That bracket is a real SOB to get out, mainly due to the two hidden bolts that attach to the A/C compressor, one of which is completely hidden and requires a Rube Goldberg-like combination of socket extensions and wobble bits to reach. It's even more fun putting that bolt back in completely blind.

Still not sure what caused the truck to stall in the first place but I'm just going to guess that it might have had something to do with the belt slipping on the alternator. The belt did have a pretty good nick in it despite only being a few months old after the Firestone timing belt change. So new belt and no problems so far. (Knocks wood.)

Thanks to all who chimed in with advice.
 
Not to derail your tech thread, but do you have some pics or videos elsewhere online about that vehicross? Those things are amazing.
Hey Oakback, sorry to leave you hanging. The VehiCROSS is in a nutshell just OK in my opinion, but my son loves it. He wanted something weird and cool, and cheap, for his first car and we lucked out and found one locally for just $4000 even though it needed some work. Driving experience is pretty different than anything else I've driven so far. It's definitely a truck (ladder frame) but the cabin is pretty low-slung so it's like you're driving in a lifted Miata or something like that. Mechanical parts are pretty easy to come by because most of the drivetrain came out of either a Trooper or Rodeo (actually the whole VX chassis is based on a 2-door Trooper, which itself is kind of a rare truck) but any of the body components or trim pieces are rarer than hens' teeth. They only imported about 4000 VXs in their three year run (only about 5000 made globally) so they are rarer than most exotic supercars. We're lucky that his VX is really good shape body-wise. It does have some nagging mechanical issues but nothing that's uncommon for a 22 year old truck that had been sitting for several years prior to him buying it.

I don't have any good beauty shots of his VX but here's a video we shot after rare snowstorm in Nashville last year...
 

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