New Belts and Idler Pulleys(Grinding Noise)

[FzeeJ]

Hey Guys, long time lurker and first time thread starter. I’ve searched thru what feels like thousands of pages of info to try to find an answer and haven’t found it yet. Was wondering if anyone could help.

First off my 96 FZJ80 started making a random noise coming from belts(scraping noise) about a month after buying. I decided to change belts and both idler pulleys all in one swoop to see if that took care of it, thinking it was a bearing. Right before changing belts I noticed what appeared to be the power steering hose coming from the power steering reservoir hitting the alternator belt closest to fan(causing the scraping noise I had heard). Long story short I decided to change belts and pulleys anyway as I don’t know last time they were changed and already had the parts(all OEM).

I will post a pic of what I believe to be the power steering hose sitting against the alternator belt which I have since pulled away from it.

After installing new belts and idler pulleys the 80 started up and idled perfect and ran perfect… Took it for a test drive and before making it back home I heard like a grinding noise coming what sounds like the engine when the vehicle is under load or revved really hard. No loss of power. The vehicle also makes the noise in park if it’s revved high enough.

Anyone had anything similar that can point me in the right direction? Thanks!

I will try to post a video tomorrow of the new noise as I don’t have access to the vehicle today.

 

[george_tlc]

What belts did you install? Some pics of your handy work will help us point out any issues. I'd be checking all the rotating bits at the front given what looks like minimal maintenance by the previous owner.

Cogged belts (like in your picture) are well known to make noise - use toyota oem belts and you buy them as a 'matched' pair.

cheers,
george.

 

[BILT4ME]

 

[FzeeJ]

What belts did you install? Some pics of your handy work will help us point out any issues. I'd be checking all the rotating bits at the front given what looks like minimal maintenance by the previous owner.

Cogged belts (like in your picture) are well known to make noise - use toyota oem belts and you buy them as a 'matched' pair.

cheers,
george.

George,

I installed all 3 factory OEM(mitsubishi) belts. 2 OEM idler pulleys. I didn’t get a chance to take a finished pic last night of the work as it was late. Every other pulley I tested rotated freely but was not thinking making sure they did, just remember them all feeling good(I could have missed one though).

The sound it’s making after the belt and pulley change sounds like grinding from front of engine which only happens when accelerating in forward or reverse or when revving engine hard.

Thanks

 

[BILT4ME]

George,

I installed all 3 factory OEM(mitsubishi) belts. 2 OEM idler pulleys. I didn’t get a chance to take a finished pic last night of the work as it was late. Every other pulley I tested rotated freely but was not thinking making sure they did, just remember them all feeling good(I could have missed one though).

The sound it’s making after the belt and pulley change sounds like grinding from front of engine which only happens when accelerating in forward or reverse or when revving engine hard.

Thanks

You may have unrelated issues here and you can hear it now because you've eliminated other noise.

When you say accelerating, do you mean in gear or in neutral or park while sitting still?

It looks like there's a serious buildup of crud under that hood. Did you disturb a chunk and one of the new idlers is grinding on it now?

 

[robnicko]

welcome to the forum !

you havent overtightened them by any chance? doing so can result in grinding type sounds

 

[FzeeJ]

You may have unrelated issues here and you can hear it now because you've eliminated other noise.

When you say accelerating, do you mean in gear or in neutral or park while sitting still?

It looks like there's a serious buildup of crud under that hood. Did you disturb a chunk and one of the new idlers is grinding on it now?

BILT4ME,

Don’t think I could have missed this noise as this grinding is way louder than original scrapping from the belt rubbing the hose.

It makes the noise when in drive or reverse and I accelerate(also when driving at road speed accelerating I can hear it s as l though it’s off and on but very consistent). It makes the noise too when I’m in park and revving the engine to about 3000rpm.

There was a lot of crude on that part of engine and it was getting disturbed with me working on it. That sounds like a possibility I just didn’t know that could cause issues like that. I could take the belts back off and start over making sure to clean the areas around all pulleys. I do remember the alternator looking very bad with crude and possible corrosion inside.

Thanks

 

[FzeeJ]

welcome to the forum !

you havent overtightened them by any chance? doing so can result in grinding type sounds

Robnicko,

Thanks and glad to be here!

I could have overtightened them as I read a few posts saying a tad bit tighter is better as the belts will stretch. I tightened them to the point you could push the belt in about 1/4 inch with your finger. I would say they were tighter than any other vehicle I have put belts on though. That very well could be it. I think I’ll loosen them a tad tomorrow and see if that fixes issue.

Thanks

 

[John McVicker]

Maybe check to see if you have a broken driver side engine mount. This would allow your engine to move upwards as you rev the engine, possibly causing moving parts to hit & make noise.

 

[FzeeJ]

Maybe check to see if you have a broken driver side engone mount. This would allow your engine to move upwards as you rev the engine, possibly causing moving parts to hit & make noise.

Thanks John,

I’ll check that tomorrow.

 

[BILT4ME]

Robnicko,

Thanks and glad to be here!

I could have overtightened them as I read a few posts saying a tad bit tighter is better as the belts will stretch. I tightened them to the point you could push the belt in about 1/4 inch with your finger. I would say they were tighter than any other vehicle I have put belts on though. That very well could be it. I think I’ll loosen them a tad tomorrow and see if that fixes issue.

Thanks

Check the alternator bearings with a mechanics stethoscope ($15 at harbor freight), as the new belts and being tighter may have disturbed the bearings in there enough to make them rough.

Otherwise, I'm thinking U-Joints and or birfields. and wheel bearings.

 

[flintknapper]

Look at your fan and fan shroud also. Broken/Split drivers side motor mount (VERY COMMON) will allow the engine to torque upward.

Could be a number of things.....but check that too.

 

[Kernal]

One quick way to eliminate the belts as the cause of the noise (or confirm they are the cause) is to spray water on the belts while the engine is idling. If the noise goes away for a couple of seconds and comes back, it's the belts.

But then again the OP said the noise only occurs at a higher RPM??

Are the belts snug, not too loose and flopping around, and how are the belts routed? Can you post up photos of that showing the belts on the pulleys?

Assume all nuts (fan clutch/water pump pulley), the mounting bolts, and adjuster bolts are all in place and tightened correctly?

 

[FzeeJ]

One quick way to eliminate the belts as the cause of the noise (or confirm they are the cause) is to spray water on the belts while the engine is idling. If the noise goes away for a couple of seconds and comes back, it's the belts.

But then again the OP said the noise only occurs at a higher RPM??

Are the belts snug, not too loose and flopping around, and how are the belts routed? Can you post up photos of that showing the belts on the pulleys?

Assume all nuts (fan clutch/water pump pulley), the mounting bolts, and adjuster bolts are all in place and tightened correctly?

Kernal,

Yeah it idles perfect so that’s what’s really throwing me off. I’ve had the 80 for maybe 2 month and it’s drove perfect. I’ve been doing all the basic maintenance getting all the fluids/grease/oil/coolant baseline so I know it’s all been done and when. Next on the list were belts. Well about a week ago I kept hearing a scraping sound come from belts… Come to find out it was the power steering hose rubbing against the outer alternator belt(how it worked it’s way over there I don’t know because that hose in not very movable). Anyway I got it moved out of the way and went ahead and replaced all 3 belts(OEM) and 2 idler pulleys(OEM). Once I got done I figured everything would be fine again. Now under load or in park revving engine to around 3000rpm there is an awful grinding noise coming from engine(can’t tell where it’s coming from). It’s bad enough to not want to drive it til diagnosed.

I did torque all pulley bolts to factory spec and routed them correctly although I will post pics tomorrow so you guys can double check. I’m pretty confident the belts aren’t too loose but could be too tight. I don’t have a belt gauge so I pretty much eyeballed it. Also I didn’t change any other pulleys so I didn’t check them other than spin them around to see if they turned freely.

I’ve got a few good leads I will check tomorrow from all the comments on here so I’ll start from there. I will also post a video of noise and pics tomorrow.

Thanks

 

[Broski]

Like @flintknapper said check the fan shroud, run your fingers along the inside at around 10 o’clock if the fan is hitting it it will be rough there.

 

[John McVicker]

Again, recheck posts #9 & #12 & #15. You have classic symptoms of this issue. Easy to verify, do a search.

 

[FzeeJ]

Just getting back under the hood today, here’s some pics of the belts in case anyone can see anything out of place. Also the noise is happening just barely revving it up now.

 

[John McVicker]

🙈🙈🙈
🙉🙉🙉

 

[FzeeJ]

More pics

 

[flintknapper]

Did you replace the tensioner pulley for the A/C belt also?

IF so....the dust cover on the front of it needs to be oriented a certain direction or it can rub on the pulley.