Engine Cant figure out drive pulley's???

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
I have an 04 Mach 1 with just barely 100k miles.
My issue has me puzzled.
If the car sits overnight and it rains during the night then the 1st start of the day the volt gauge will drop instantly from 14v to 12.1v for about 5-10 secs and just before the gauge jumps back to 14.3ish volts the belt will squeal for a couple seconds. Then the rest of the day its fine even if its been raining.

In the last 2 yrs or less I have replaced the water pump, all idler pulleys, rebuilt alt,new power steering pump,belt tensioner,new AC comp and the belt. Nothing fixes the issue. I did not replace all of those items because of this issue.

When I got new belt I replaced all idlers and tensioner.
Had alt rebuilt do to not properly charging.
AC comp was leaking and so was PS pump.
Water pump and alt were about the same time 2 yrs ago.

Everything works, runs great and did a full repaint this past summer.

Today I removed the belt and replaced the tensioner again, then checked to make sure all pulley's spun freely and they did. For a second I thought I might have a heard a very small and quick squeak on the alt pulley but not sure.

So Im at a loss, any ideas?

Pic just to show...lol

Mach1.jpg
 
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STEVE PATTON

I smell a conspiracy
Jan 6, 2019
201
100
53
71
ohio
I have an 04 Mach 1 with just barely 100k miles.
My issue has me puzzled.
If the car sits overnight and it rains during the night then the 1st start of the day the volt gauge will drop instantly from 14v to 12.1v for about 5-10 secs and just before the gauge jumps back to 14.3ish volts the belt will squeal for a couple seconds. Then the rest of the day its fine even if its been raining.

In the last 2 yrs or less I have replaced the water pump, all idler pulleys, rebuilt alt,new power steering pump,belt tensioner,new AC comp and the belt. Nothing fixes the issue. I did not replace all of those items because of this issue.

When I got new belt I replaced all idlers and tensioner.
Had alt rebuilt do to not properly charging.
AC comp was leaking and so was PS pump.
Water pump and alt were about the same time 2 yrs ago.

Everything works, runs great and did a full repaint this past summer.

Today I removed the belt and replaced the tensioner again, then checked to make sure all pulley's spun freely and they did. For a second I thought I might have a heard a very small and quick squeak on the alt pulley but not sure.

So Im at a loss, any ideas?

Pic just to show...lol

Mach1.jpg
Check to see if your tensioner is "bottoming out " limiting proper tension.
 

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
I even replaced it today to be sure.
There is enough movement in both directions, tensioner really does not move at all when I give it that first start and the volts drop. But the short couple second squeal sounds as if its coming from the driver side but Im not sure on that, doesnt last long enough to really locate.

EDIT:
Only original pulley left now is the crank pulley.
 

STEVE PATTON

I smell a conspiracy
Jan 6, 2019
201
100
53
71
ohio
This is a good one, my 98 gt with aluminum underdrive pullies wore out cup in the waterpump pulley and gave me a constant squeal.do with that what you will.I hate throwing parts at a problem but you might try a 1/2 inch shorter belt to make the tensioner work harder preventing this obvious slipping.Of course I'm now grasping at straws.
 

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
I was thinking about the shorter belt to try. It just started doing it a few months back out of nowhere. I hate annoying little problems like this that are a PITA to locate.
The slippage I think is apparent since the black is wearing off the idler pulley's. My old pulley's still had the black finish on them.
I hope its not alt issues because it was impossible to find a new/rebuilt alt for the mach when mine went bad.
I tried everywhere and none would fit, even from Ford. The mounting holes are different from GT or Cobra and the ones everyone claimed were for the Mach werent even close.

The shop that rebuilt mine seemed to do great work. The claim to replace all wearable parts,media blasted the outside parts and new pulley all for $100 and had it done in about 4 hrs.
 

Eilermoon

Member
Dec 18, 2019
19
1
13
25
Chicago, IL
Sounds like a similar problem to what I'm dealing with. I just threw a new belt on mine and almost immediately started getting squeaking out of it, I replaced the tensioner because of squeak back in the fall.
 

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
Sounds like a similar problem to what I'm dealing with. I just threw a new belt on mine and almost immediately started getting squeaking out of it, I replaced the tensioner because of squeak back in the fall.

I still havent figured mine out.
Took belt off, all pulleys move freely, no issues. Replaced to tensioner again just to be sure mine hadnt failed and still no go.
I may pull the alt and have it checked out at the shop that rebuilt mine since I thought I kinda heard a squeak for a second, other than that no clue.

But its gonna be a few days before I mess with it, spent all day hunched over under the hood and under the car trying to find out why it would stumble at 4k rpms.checking,fuel,cops,plugs all the usual stuff. The old back cant handle that these days.
Come to find out it was the damn crank sensor plug came loose...lol.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,871
512
204
Houston Texas
Can you post a picture of the belt routing. I'm especially interested to see the idler pulley near the alternator on the right side of the motor.

Have you done a through inspection of the crank damper to see if the outer ring is either our of round from the inner ring or has slipped out of position?
 

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
Can you post a picture of the belt routing. I'm especially interested to see the idler pulley near the alternator on the right side of the motor.

Have you done a through inspection of the crank damper to see if the outer ring is either our of round from the inner ring or has slipped out of position?

This is the best I can do tonight without removing the shaker, can get better pics tomorrow if needed. The pulleys have the rust color on them since it hasnt been driven much last couple days and been raining.

I went ahead and replaced the idlers and tensioner just to be sure and they werent too much.
The crank damper looks ok to me,didnt see any cracks in the rubber or anything, doesnt seem out of round.
What do you recommend the best way to judge and check for that?

20200407_203451.jpg 20200407_203506.jpg 20200407_203708.jpg

This the routing diagram I keep and follow.
pulley 3.gif
 

rabidscoobie

10 Year Member
Jun 21, 2007
612
12
48
College Station,TX
Got some daytime with the shaker off. I cleaned that entire area since 1 pulley looked as if it might have had some oily residue on it. And me tell you that aluminum covers and such pits so bad and hard to get cleaned up.

The belt didnt squeak after getting wet today but the volts started out around 12v at start then after about 3-5 seconds jumped back to 14v+. It will only do that if it has sat,cooled down and started only after a few hours of sitting. Went to a couple auto stores to have the charging system checked to be sure, all came back good. All pullies spin freely with belt off.

20200408_162637.jpg 20200408_162643.jpg