over tightened belt or help diagnosing

Ramathorn · 09-10-2012, 03:35 PM

Precursor: Just installed new bosch cap, bosch rotor, ngk plugs, magnecore plug wires, and continental contitech fan/ alt belt

I just finished up install of the above since my order from pelican came a couple days earlier than expected

. Now that i have everything put on i go to fire the car up and there seems to be a knock/ tick. It sounds like it is coming from the belt associated area but im not 100% sure. The noise seems to increase with the rpm's, when warming up i noticed it and as the rpm's dropped so did the noise. Checked the oil and the level was good and the color was good for being less than 100 miles old.

I took the belt off per the way the book suggests. I replaced the shims in the same fashion as i took them off 1 inside and 5 outside as that is how i felt the belt deflection showed the 1/4" - 1/2" at the belts mid way point between the pulleys. The belt i removed was a continental contitech and replaced with the same size and brand.

Am i just being overly paranoid about these 3.0 making noise or do i have a bigger issue on hand?

Dave Colangelo · Dave Colangelo's Garage

I had a fan rattle issue and replacing the belt got rid of it. Try moving the shims around, 2 inside 4 outside maybe, remember the rattle can be on top or on the bottom depending on if the belt is to lose or to tight. If that does not take care of the issue and you are sure its the fan look at other belt options. luckily belts are cheap so experimenting will not break the bank. Even though you used the same belt from the same manufacturer the one that was on there was stretched so the washer placement may not be correct anymore.

Regards
Dave

Ramathorn · 09-10-2012, 03:53 PM

Would moving the shims around change the noise? I thought they were more to get the tension correct, which seems to be correct quarter to a half inch.

kwikt 911 · kwikt 911's Garage

Loosen the new belt slightly by adding one to the inside. If you noticed , the fan blades have a very close tolerance to the housing. So the slightest play in the alternator bearing can magnify to the fan housing. I personally keep mine slightly loose because of this. I'm sure you have noticed that it really doesn't take alot of force to spin the fan.

Ramathorn · 09-10-2012, 06:28 PM

never thought about that. Ill give it a shot tomorrow.

pete3799 · pete3799's Garage

Why not run it without the belt for a short time and see if it still makes the noise.

Juggino · Juggino's Garage

I just recently had a similar issue, its amazing how those spacers make a difference. If you originally had only one on the inside go to 3 or 4 on the inside better the belt a little loose that tight and you screw up the bearings. Normally there are up to 4 on the inside so don't worry about it, the worst would be your belt being a little loose and you will see that immediately then just take another out.

Targalid · 09-10-2012, 08:21 PM

Has anyone else noticed that the belt tightens as the motor gets warm? My belt is much looser when the engine is cold.

Ramathorn · 09-11-2012, 10:47 AM

Tried every possible combo (including running no belt to see if the noise is there) the noise is still there. Checked the gap in all the plugs and made sure they were torqued accordingly and they were. Made sure the plug wires were all seated properly and they seem to be.

Pretty much at a loss, right now.
180*F
Idles solid at 950 rpm's
Running battery voltage is 13.5 volts
AFR 14.0:1 at idle

Dave Colangelo · Dave Colangelo's Garage

If you ran with out a belt and the noise was still there I think its safe to rule out the fan and alternator as the source of this issue. Check the pulley at the crank and make sure nothing is hitting it. It could also be the valves rattling or a whole number of other things rattling around both in your engine as well as in the compartment. I know behind the fan there are 2 fins riveted to the fan housing one of my fins is lost and was rattling around causing a bit of a noise.

Regards
Dave

emac · emac's Garage

Ryan
Start her up at night and see if the ticking noise you see could be a plug wire jumping to ground.
Much easier to see in the dark.

Ramathorn · 09-11-2012, 01:01 PM

Where would i see it grounding out since all the connections are covered/ sealed with the thick silicone boots?

Oh on a side note. A little bit ago i found a pretty big vacuum leak.

dshepp806 · dshepp806's Garage

Arcing could occur anywhere along the electrical path,..from the connection points, as well as along the cables (insulation breakdown can induce this). Some have misted (via water bottle) the cables to induce the arcing should it be an issue. Aside from dynamic testing, you can get the resistance readings on the wires via VOM.

As to the vacuum leak: where? and what did you do about it?

BEST

Doyle

zensource · 09-11-2012, 01:40 PM

could be the fan or alternator bearing about to go

kwikt 911 · kwikt 911's Garage

Double check your cap and rotor. I made the mistake once by not seating the distributor cap in the notches. It made a clicking sound when the rotor was tapping the cap because of the misalignment.

tharbert · tharbert's Garage

I was gonna mention the cap until I got this last post... So, what he said above ^^^ +1. Look for a little damage at the cap contacts.