84 M20 Timing Belt Howl

[nebulous123]

So I have been reading through my Bentley, researching on r3v and on any website that could potentially have the cure to my problem, and nothing as solved the problem.

Its an 84 eta with just over 200k on the odo. I decided to do a little freshening up of motor and replaced anything I thought could use some changing.

Intake Manifold Gaskets
Exhaust Manifold Gaskets
Rebuilt and flow matched Injectors
Fuel Pressure Regulator
TPS
CPS
Reference Sensor
TB Gasket
7th Injector Gasket
Plug Wires
Distributor Cap
Rotor
Valve Cover Gasket
Rocker Shaft Plugs
Crankcase Seal
Timing Belt
Timing Belt Tensioner
Accessory Belts
All Vacuum Hoses
All Fuel Hoses
Fuel Filter
Motor Mounts
Trans Mounts
Bitch Tube gaskets
All Radiator Hoses
All Coolant Hoses for Heater Core
Oil Pressure Sensor
Thermostat Housing
Thermostat Cover
Thermostat
Bleeder Screw
Water Pump

So I get it all together, start the car up and there is this terrible howl coming from the belt tensioner/waterpump area. Also the water pump is leaking something fierce. So after listening, removing the accessory belt, etc. I figured out with the accessory belt removed the car didn't howl....must be a bad water pump.

Sent the water pump back, a week later got the replacement. Installed it. Put everything back together, boom howling again. Took the accessory belt off again to check, no howl. I remembered I had painted the pulley, maybe some of the overspray is causing the howling. Removed the paint. Still howling.

Decided to release the tension on the alternator so see if that would help. The car would start without the howl, the belt would squeal a little, but as soon as I revved it, the howl would come back and not stop.

Did some more listening and the sound is not originating at the water pump its coming from the belt tensioner or the cam gear. Since they are so close, its hard to tell exactly where its coming from but my guess is the belt tensioner.

So for the sake of my own sanity, I loosened the timing belt tensioner, cranked the motor per Bentley specs (720 degrees) then tightened everything back up. Still howling.

So here is my question, I have ran into issues before with Early Model and Early Early Model stuff. The 84 and 85 just have some random stuff different and I was wondering if this was one of them? Currently have the Conitech belt and tensioner with the Z127 on it. Is that the one I should have on it?

Any other thoughts? I am posting a video too for you guys to hear the howl. Thanks for your help guys.

[Cabriolet]

your tensioner is way too tight. let the spring adjust it.

loosen the 2 bolts that hold the tensioner. till they are barely tight.
then by hand turn the crank 4 times around.
then tighten the bolts.

should solve it.

[FLG]

Leave it, sounds cool..because race car..jk

You say if you remove the accessory belts it goes away?? Wouldnt make sense in that case for it to be the timing belt.

With the accessory belts removed, does it make the noise?

I remember my t-belt had a similar howl after replacement (though not as loud), it went away after some driving.

How much tension did you put on the belt? seems it might just be a bit to tight.

[nebulous123]

your tensioner is way too tight. let the spring adjust it.

loosen the 2 bolts that hold the tensioner. till they are barely tight.
then by hand turn the crank 4 times around.
then tighten the bolts.

should solve it.

I did. From what I have been told the tensioner should rest in the middle somewhere. It does bounce around when I am cranking it its usually half way or all the way to the right (spring compressed the most, with least amount of tension on the belt). So should I crank it till its gets to that loose area and tighten it up and see how it sounds?

Leave it, sounds cool..because race car..jk

You say if you remove the accessory belts it goes away?? Wouldnt make sense in that case for it to be the timing belt.

With the accessory belts removed, does it make the noise?

I remember my t-belt had a similar howl after replacement (though not as loud), it went away after some driving.

How much tension did you put on the belt? seems it might just be a bit to tight.

Let me rephrase. With just the water pump / alternator accessory belt removed the howling stops. But I think it might have to do with the extra load on the engine to turn the water pump and alternator.

I will try to readjust tonight and give it another go.

[Cabriolet]

Let me rephrase. With just the water pump / alternator accessory belt removed the howling stops. But I think it might have to do with the extra load on the engine to turn the water pump and alternator.

I will try to readjust tonight and give it another go.

this. your belts are too tight. they should deflect 1/2" in the middle.

i can tell you have too tight of a belt from the video. your engine has too much load and drops in revs too fast. run your V-belts slightly looser

[nebulous123]

this. your belts are too tight. they should deflect 1/2" in the middle.

i can tell you have too tight of a belt from the video. your engine has too much load and drops in revs too fast. run your V-belts slightly looser

Thank you sir. I will adjust tonight and repost if everything is okay. I have since adjusted the belts after this video. That was just the one I took right after I noticed it.

[jlevie]

A howl from the engine that goes away when you loosen or remove the alternator/water pump belt will be; a) a bad alternator, b) a bad water pump, c) a frozen fan clutch.

[nebulous123]

A howl from the engine that goes away when you loosen or remove the alternator/water pump belt will be; a) a bad alternator, b) a bad water pump, c) a frozen fan clutch.

a) a bad alternator - the noise is no where near the alternator

EDIT: well it was a bad alternator. the noise was echoing in the timing cover and being transferred through the adjusting bracket. but even on the alternator you couldn't hear the noise. swapped out the alternator with a spare laying around and she purred like a kitten.

thanks for your help guys.

[iwantspeed]

a) a bad alternator - the noise is no where near the alternator

EDIT: well it was a bad alternator. the noise was echoing in the timing cover and being transferred through the adjusting bracket. but even on the alternator you couldn't hear the noise. swapped out the alternator with a spare laying around and she purred like a kitten.

thanks for your help guys.

awesome!
junkyard trips becoming useful!