Double belts?
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Tuned
Joined: Dec 2017
Posts: 308
Likes: 8
Double belts?
Hey all,
I have a 1983 300-six. Been having a number of engine noises thrown together that I've been slowly eliminating over the past months.
One noise I've noticed is a rubbing or swooshing noise coming from the belt drive and fan area, which happens every crank rotation and it loud enough to seriously disturb what could be a smooth engine note.
I pulled off the power steering belt last night, which improved it slightly but still left a very loud and distinctive periodic noise that went with engine RPM.
My only other belts are two parallel belts going from the crank pulley to the water pump and the alternator. It seems these would be prone to make noise if one wears quicker than the other.
Dunno why they'd put double belts on there, except for redundancy in case one breaks. I'm thinking someone messed with it once and put the belts on in the wrong places.
Anyone else with a 300-six or any other engine have dual belts like I do? I can't find much info about the v-belt routing on these trucks.
When I had an air injection pump, I had a large belt on it, but I've seen trucks with the same engine and a tiny belt on the air pump. Is there anywhere that these belt drive differences are archived?
I have a 1983 300-six. Been having a number of engine noises thrown together that I've been slowly eliminating over the past months.
One noise I've noticed is a rubbing or swooshing noise coming from the belt drive and fan area, which happens every crank rotation and it loud enough to seriously disturb what could be a smooth engine note.
I pulled off the power steering belt last night, which improved it slightly but still left a very loud and distinctive periodic noise that went with engine RPM.
My only other belts are two parallel belts going from the crank pulley to the water pump and the alternator. It seems these would be prone to make noise if one wears quicker than the other.
Dunno why they'd put double belts on there, except for redundancy in case one breaks. I'm thinking someone messed with it once and put the belts on in the wrong places.
Anyone else with a 300-six or any other engine have dual belts like I do? I can't find much info about the v-belt routing on these trucks.
When I had an air injection pump, I had a large belt on it, but I've seen trucks with the same engine and a tiny belt on the air pump. Is there anywhere that these belt drive differences are archived?
FTE Legend
Joined: Nov 2015
Posts: 30,828
Likes: 4,094
From: Angier, NC
And I am sure it does.
IIRC the non-AC trucks have 2 belts for the ALT where the AC trucks only have 1. Why I don't know as you would be working the ALT harder with AC.
As a test you can try and remove 1 belt at a time to see if it is 1 of the belts.
Are you sure it is not a bad bearing in the water pump or ALT making the noise?
You can remove both belts and run the motor for a few min. to check for noises.
Also if anything is using duel belts the belts should be changed out in pairs and a matched set.
Dave ----
IIRC the non-AC trucks have 2 belts for the ALT where the AC trucks only have 1. Why I don't know as you would be working the ALT harder with AC.
As a test you can try and remove 1 belt at a time to see if it is 1 of the belts.
Are you sure it is not a bad bearing in the water pump or ALT making the noise?
You can remove both belts and run the motor for a few min. to check for noises.
Also if anything is using duel belts the belts should be changed out in pairs and a matched set.
Dave ----
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 308
Likes: 8
Well I have some good news!
I took off the looser of the two belts just now and ran the engine with 1 on it. The harsh vinyl-like sound from the fan area stopped completely; now all I can hear from the front is the timing gears and that's a very good thing!
it still ticks kind of a lot, though, from somewhere. I can't tell if the tick is internal (top end) or an exhaust leak on one cylinder or a bad pulley bearing.
i can hear it loud and clear if I take the spare tire key off the rad support and use it as a stethoscope anywhere on the engine block.
i got too excited today and let it warm up completely with one belt on it, so I'll have to come back tomorrow if I'm gonna try it with no belts for a bit so it won't overheat.
I took off the looser of the two belts just now and ran the engine with 1 on it. The harsh vinyl-like sound from the fan area stopped completely; now all I can hear from the front is the timing gears and that's a very good thing!
it still ticks kind of a lot, though, from somewhere. I can't tell if the tick is internal (top end) or an exhaust leak on one cylinder or a bad pulley bearing.
i can hear it loud and clear if I take the spare tire key off the rad support and use it as a stethoscope anywhere on the engine block.
i got too excited today and let it warm up completely with one belt on it, so I'll have to come back tomorrow if I'm gonna try it with no belts for a bit so it won't overheat.
Moderator
Joined: Jan 2001
Posts: 56,949
Likes: 2,718
From: Virginia
I bet it's supposed to have only one belt, if you look closely I am thinking one of those grooves in the crank pulley is just slightly larger diameter than the other, probably why it was making so much noise. One belt was trying to turn everything faster than the other belt was.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 783
From: Simi Valley, CA
I bet it's supposed to have only one belt, 
if you look closely I am thinking one of those grooves in the crank pulley is just slightly larger diameter than the other, probably why it was making so much noise. One belt was trying to turn everything faster than the other belt was.
if you look closely I am thinking one of those grooves in the crank pulley is just slightly larger diameter than the other, probably why it was making so much noise. One belt was trying to turn everything faster than the other belt was.2) C9PZ-8620-GM .. Alternator Belt - 42.00" x 15/32" wide - Use with dual belt 40 & 60 amp alternators without A/C (Motorcraft JB-420).
2) C9PZ-8620-GK .. Alternator Belt - 43.00" x 15/32" wide - Use with dual belt 70 & 100 amp alternators without A/C (Motorcraft JB-430).
With A/C, these trucks have single belt alternators.
Pic: What is says:
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Cargo Master
Joined: Mar 2002
Posts: 3,132
Likes: 217
From: W (BY GOD) V
Matched Dual Belt Sets are cut off a drum roll at the same sequence so as not to have much variance in the dia. What happens is one buys CHINESEIUM belts or change just one belt at a time or two belts from different manufacturers.
A trick if suspecting a belt noise is to spritz the belts with a water spritzer while running. If the noise goes away, it is either the belt or pulley.
Dueling belts ...
... give better drive to something as an ALT that may increase turning resistance while driving as compared to a single belt.
A trick if suspecting a belt noise is to spritz the belts with a water spritzer while running. If the noise goes away, it is either the belt or pulley.
Dueling belts ...
... give better drive to something as an ALT that may increase turning resistance while driving as compared to a single belt.
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Thread Starter
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Tuned
Joined: Dec 2017
Posts: 308
Likes: 8
Makes sense. I think belt #2 was probably changed and either was the wrong size or simply was stretched less than belt #1.
Taking off one belt has significantly decreased under-hood noise and so far my alternator seems to be running just fine, although the charge warning light doesn't work so I'm not 100% sure about every situation.
On the topic of under-hood noise, I also found several loose bolts in my intake and exhaust manifolds. I tightened every bolt I could find on the manifolds and it seemed to get rid of the "ticking" for a bit, until the engine got nice and warmed up, then it came back!
I can hear the tick thru the shifter if I get my ear close to it.
On the bright side, tightening the manifolds seemed to help a little. I've got a pretty steady 16 to 16.5 inches of vacuum now at my fully warmed up idle, where it used to be 15.0 to 16.0.
Taking off one belt has significantly decreased under-hood noise and so far my alternator seems to be running just fine, although the charge warning light doesn't work so I'm not 100% sure about every situation.
On the topic of under-hood noise, I also found several loose bolts in my intake and exhaust manifolds. I tightened every bolt I could find on the manifolds and it seemed to get rid of the "ticking" for a bit, until the engine got nice and warmed up, then it came back!
I can hear the tick thru the shifter if I get my ear close to it.
On the bright side, tightening the manifolds seemed to help a little. I've got a pretty steady 16 to 16.5 inches of vacuum now at my fully warmed up idle, where it used to be 15.0 to 16.0.
FTE Legend
Joined: Nov 2015
Posts: 30,828
Likes: 4,094
From: Angier, NC
This is a 300 six right?
The tick is an exh leak between the head & manifold. When I installed the EFI manifolds I used a new combo gasket (intake & exh) and when I got it running I also had a tick, sounds like a lifter, but I could see the leak as it is on the front port.
Get it hot again and try to take out on the bolts again just be careful not to break them. I took up on mine and it helped a little but still leaks a little when you give it gas.
Dave ----
The tick is an exh leak between the head & manifold. When I installed the EFI manifolds I used a new combo gasket (intake & exh) and when I got it running I also had a tick, sounds like a lifter, but I could see the leak as it is on the front port.
Get it hot again and try to take out on the bolts again just be careful not to break them. I took up on mine and it helped a little but still leaks a little when you give it gas.
Dave ----
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 308
Likes: 8
This is a 300 six right?
The tick is an exh leak between the head & manifold. When I installed the EFI manifolds I used a new combo gasket (intake & exh) and when I got it running I also had a tick, sounds like a lifter, but I could see the leak as it is on the front port.
Get it hot again and try to take out on the bolts again just be careful not to break them. I took up on mine and it helped a little but still leaks a little when you give it gas.
Dave ----
The tick is an exh leak between the head & manifold. When I installed the EFI manifolds I used a new combo gasket (intake & exh) and when I got it running I also had a tick, sounds like a lifter, but I could see the leak as it is on the front port.
Get it hot again and try to take out on the bolts again just be careful not to break them. I took up on mine and it helped a little but still leaks a little when you give it gas.
Dave ----
What are you saying to do with the manifold bolts? Should I try to tighten them or loosen them? If I can fix the tick without taking the engine apart that would be great.
FTE Legend
Joined: Nov 2015
Posts: 30,828
Likes: 4,094
From: Angier, NC
My truck is apart, no glass, hood, dash not all together and no shifter boot.
I only hear the tick when I am moving the throttle fast from outside the truck.
Also because I know of this I don't pay much to any of the noises the truck is making at this time.
On yours I would try and get the motor up to temp then try and tighten them a little more.
If that fails to make the tick go away you will need to replace the gaskets between the manifolds and head as it burnt a hole thru it.
Being the vacuum went up when you tighten the bolts I would say the exh gasket burnt thru and most likely needs to be replaced but try to tighten first.
Dave ----
I only hear the tick when I am moving the throttle fast from outside the truck.
Also because I know of this I don't pay much to any of the noises the truck is making at this time.
On yours I would try and get the motor up to temp then try and tighten them a little more.
If that fails to make the tick go away you will need to replace the gaskets between the manifolds and head as it burnt a hole thru it.
Being the vacuum went up when you tighten the bolts I would say the exh gasket burnt thru and most likely needs to be replaced but try to tighten first.
Dave ----
Thread Starter
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Tuned
Joined: Dec 2017
Posts: 308
Likes: 8
My truck is apart, no glass, hood, dash not all together and no shifter boot.
I only hear the tick when I am moving the throttle fast from outside the truck.
Also because I know of this I don't pay much to any of the noises the truck is making at this time.
On yours I would try and get the motor up to temp then try and tighten them a little more.
If that fails to make the tick go away you will need to replace the gaskets between the manifolds and head as it burnt a hole thru it.
Being the vacuum went up when you tighten the bolts I would say the exh gasket burnt thru and most likely needs to be replaced but try to tighten first.
Dave ----
I only hear the tick when I am moving the throttle fast from outside the truck.
Also because I know of this I don't pay much to any of the noises the truck is making at this time.
On yours I would try and get the motor up to temp then try and tighten them a little more.
If that fails to make the tick go away you will need to replace the gaskets between the manifolds and head as it burnt a hole thru it.
Being the vacuum went up when you tighten the bolts I would say the exh gasket burnt thru and most likely needs to be replaced but try to tighten first.
Dave ----
I warmed the motor up completely, and I tightened up 11 out of 12 bolts with a socket wrench, as much as seemed reasonable.
When I ran it, it sounded really good at idle. I didn't hear any ticking under the hood until I rev'd it up a little and let it fall. I shut it down and tightened them up again.
I drove for about 20 mins, and it seemed to come back somewhat. I think it's slightly better sounding than it was, but now I can hear it at idle again. With the rear glass open, I can hear a lot more exhaust noise than tick, which is good.
FTE Legend
Joined: Nov 2015
Posts: 30,828
Likes: 4,094
From: Angier, NC
Sometimes you just have to bite the bullet and replace the gaskets.
You don't have to remove the manifolds just pull them, as a whole unit, away from the head so you can scrape the old gasket from head & manifolds.
Slip new gasket in and bolts and you are done.
Dave - - - -
You don't have to remove the manifolds just pull them, as a whole unit, away from the head so you can scrape the old gasket from head & manifolds.
Slip new gasket in and bolts and you are done.
Dave - - - -
More Turbo
Joined: Jan 2007
Posts: 614
Likes: 51
I have never seen parallel/dual V-belts cause anything but problems, even on big trucks.
No matter how precision the belts are made, one of them will end up doing all of the work while the other one wears quickly from the slipping caused by being just a wee bit looser; the more it slips, the more it wears; the more it wears, the looser it becomes; and so forth and so on.
On big trucks, on more than a few occasions, I have had one belt of the pair to turn itself over in the grooves; once this happens, the upside-down belt will eventually start squealing and smoking and the only realistic remedy thousands of miles from home is to cut it off.
I would far rather have that second belt stashed in the truck somewhere as a spare, than to have two side-by-side V-belts and the problems they will create.
There is nothing on any engine that one belt won't pull as good as two.
This is just my own personal experiences; I am sure others will differ.
No matter how precision the belts are made, one of them will end up doing all of the work while the other one wears quickly from the slipping caused by being just a wee bit looser; the more it slips, the more it wears; the more it wears, the looser it becomes; and so forth and so on.
On big trucks, on more than a few occasions, I have had one belt of the pair to turn itself over in the grooves; once this happens, the upside-down belt will eventually start squealing and smoking and the only realistic remedy thousands of miles from home is to cut it off.
I would far rather have that second belt stashed in the truck somewhere as a spare, than to have two side-by-side V-belts and the problems they will create.
There is nothing on any engine that one belt won't pull as good as two.
This is just my own personal experiences; I am sure others will differ.