Reocurring problem, alternator belt on rb25 squeals. Frustrated, super long post

[240z4u]

Alright guys, I am getting to my wits end with this issue. Its very frustrating and is the reason that I leave my 240 home some days.

My RB25 likes to tear up alternator belts and I am NOT sure why. It has been doing this since day 1 of my swap.

When Idling in traffic, if the RPMS drop too low (with any sort of electrical load at all) the belt starts to squeak. I have to feather the gas to get it to start charging again. It also squeals for a second immediately after starting the car. If I hold the RPMS at 1k or so it generally will not squeal. I have also noticed the belt squealing when downshifting as well.

My setup is as follows;

Optima redtop in trunk with 0ga wire feeding it. Chassis grounded in trunk, and dual 8ga jumpers that are bolted to the floor every 3' and terminate in the engine compartment fenderwell for ground as well. The alternator is grounded to the chassis with two 8Ga wires. I also have a fuse in the engine compartment (200amp) to protect the power wire. Its a monster cable blade unit. Good connection there and no corrosion.

This battery is NEW and I also had an SVR in the car for a year or so with the same issues.

I did this relocation when I had the KA in my car. No problems there.

My motor has the following pullies and I do have a pulley alignment issue. I have an RB20 crank pulley, and water pump pulley, and I have tried using an RB20 and an RB25det alternator. They don't seem to line up correctly. I took out the factory thick spacer and used washers to get everything to line up. I also had to shim out the water pump pulley. I am not sure if this has to do with me having the crank snout elongated for the oil pump drive. I cannot remember how much I had him add for material. Right now I have a nissan quest alternator and everything seems to line up well. I just put a second quest alternator on last night to eliminate my crappy hole enlarging in the bottom mount as a possibility. Seems to bolt up nice and straight.

I have heard it is possible to glaze a crank pulley from so much belt misalignment and slippage (which was the case in the past for sure). I have shredded at least 10 or so belts in a year and a half. Some fall apart (the inside two rows get chewed up and the outside looks fine). I have had a couple straight up snap (prob. from overtightening the belt).

I read its possible to check if its misalignment or slippage by spraying water on the belt. Misalignment, water should quiet it. Slippage, water should make it louder. I have not done this yet after the new alternator last night.

If you have ANY suggestions whatsoever I am all ears. This is really freaking frustrating. Also does anyone know of a dead on way to align pullies? I was using a 6" piece of flat/straight belt that I cut up. I would press it into the pulley and rotate the pulley so the belt would drop flat down into the next pulley.

Thanks for the read guys. I know its long winded.

Evan

[Booztd 3]

Alright guys, I am getting to my wits end with this issue. Its very frustrating and is the reason that I leave my 240 home some days.

My RB25 likes to tear up alternator belts and I am NOT sure why. It has been doing this since day 1 of my swap.

When Idling in traffic, if the RPMS drop too low (with any sort of electrical load at all) the belt starts to squeak. I have to feather the gas to get it to start charging again. It also squeals for a second immediately after starting the car. If I hold the RPMS at 1k or so it generally will not squeal. I have also noticed the belt squealing when downshifting as well.

My setup is as follows;

Optima redtop in trunk with 0ga wire feeding it. Chassis grounded in trunk, and dual 8ga jumpers that are bolted to the floor every 3' and terminate in the engine compartment fenderwell for ground as well. The alternator is grounded to the chassis with two 8Ga wires. I also have a fuse in the engine compartment (200amp) to protect the power wire. Its a monster cable blade unit. Good connection there and no corrosion.

This battery is NEW and I also had an SVR in the car for a year or so with the same issues.

I did this relocation when I had the KA in my car. No problems there.

My motor has the following pullies and I do have a pulley alignment issue. I have an RB20 crank pulley, and water pump pulley, and I have tried using an RB20 and an RB25det alternator. They don't seem to line up correctly. I took out the factory thick spacer and used washers to get everything to line up. I also had to shim out the water pump pulley. I am not sure if this has to do with me having the crank snout elongated for the oil pump drive. I cannot remember how much I had him add for material. Right now I have a nissan quest alternator and everything seems to line up well. I just put a second quest alternator on last night to eliminate my crappy hole enlarging in the bottom mount as a possibility. Seems to bolt up nice and straight.

I have heard it is possible to glaze a crank pulley from so much belt misalignment and slippage (which was the case in the past for sure). I have shredded at least 10 or so belts in a year and a half. Some fall apart (the inside two rows get chewed up and the outside looks fine). I have had a couple straight up snap (prob. from overtightening the belt).

I read its possible to check if its misalignment or slippage by spraying water on the belt. Misalignment, water should quiet it. Slippage, water should make it louder. I have not done this yet after the new alternator last night.

If you have ANY suggestions whatsoever I am all ears. This is really freaking frustrating. Also does anyone know of a dead on way to align pullies? I was using a 6" piece of flat/straight belt that I cut up. I would press it into the pulley and rotate the pulley so the belt would drop flat down into the next pulley.

Thanks for the read guys. I know its long winded.

Evan

Get the belt tighter

Nissans are pretty notorious for squeeky alt belts if you dont get them super tight. I had the exact same issue on my Z a few years ago....I would start the car and it would squeel for a few seconds and then just stop. From now on I always crank the belt tension down a little extra and have yet to have that problem

[240z4u]

How tight do you suppose I should go? It wasn't guitar string tight but seemed just as tight as my PS belt.

I am afraid to overtighten and break the damn belt.

It almost seems like its slipping on the crankshaft pulley due to the squeal during downshift.

I did notice the crankshaft pulley grooves are brightlly polished with no texture. I am going to rough them up a bit and see if that helps any.

Evan

[240z4u]

Well I put some stank on it, and its really tight now. Almost too tight (sounds about right from what your saying).

Squealing is mostly gone except its still there on startup for a second and it did it on a downshift.

I think my crank pulley is glazed too. Ill have to sand it down.

Evan

[Shocker]

just upgrade to Quest alt, and problems will be solved.

[240z4u]

Yeah thats definitely not the problem. I have a quest alternator LOL. I actually wrote the post on racebread about it.

Ill let you guys know what I figure out.

Evan

Noticed something wierd tonight. When turning on my headlights no alternator squeek. When rolling down my windows, and hitting the bottom the belt squeaks if you hold the switches down. Must be high load? I am going to put an ammeter clamp on it and see wtf is going on.

[sky20sx]

of course it is hard to say without looking at the car, but I think it is your crank pulley that is messed up not your alt., is your crank pulley setted all the way that the belts are lined up completly straight, and if it is glazed that is the cause of slipping/ squealing I would try sanding like you said or trying to find a different pulley which probably would be expensive or hard to come by unfortunatly

[240z4u]

Yeah its seated totally. There was a time when my alternator was way out of alignment and I think it glazed the pulley. Ill try sanding and see if it helps out any. Should be a real treat!

Ill keep everyone updated.