I installed air conditioning from a donor truck two months ago, replaced the belt and tensioner at the time too. Now the belt has started popping off repeatedly. All pulleys appear to be in good shape and spin ok. I think it is the aftermarket tensioner but I am not sure. Anybody have a good tensioner brand they can suggest? Thanks.

 

Are you sure your water pump bearing is not bad? On my '88 F-150 with the 4.9 I had that problem of the belt being thrown off. The water pump bearing went bad on me twice, several years apart, and the water pump never leaked either time. The next time your belt is off grab the fan blades and wiggle them to make sure the water pump bearing is good. Where are you in SD? I am east of Winner.

 

I wiggled the fan blades and everything felt tight, and it's not leaking. The power steering pump is leaking a little oil on the pulley and throwing it everywhere so I'm thinking it's either that or the tensioner. Up by Aberdeen. Picture is when running, the belt is lipping up the side of the pump pulley

 

Turn that belt over and see if it still wants to walk forward
Is the tensioner putting enough tension on the belt? (are the marks on the tensioner and the lines lined up)?
I have had good luck with run of the mill Autozone Duralast tensioners and pulleys

 

Your tensioner appears to be original AND missing a part of it. It also appears to be physically deformed but it could be the photo deception. Frankly, you have 0 to gain belt wise when you dont even have the tensioner doing its job.

Replace the tensioner and ensure youre using the right size belt. The ac compressor pulley is different depending on the year, application, and TSB sometimes. The proper Tensioner has marks to show you if its properly adjusted, they are small arrow like things

 

THe tensioner was aftermarket, AC Delco I think, I put it on two months ago. I'm suspecting that is the problem, I will double check the belt size though

 

So did you wiggle the fan blades while the belt was off? That sure threw me for a loop on my'88. I couldn't notice the water pump bearing being loose with the belt on.

I got another one for you. My power steering pump was leaking on my '88, throwing a nice film of fluid on the bottom side of my hood. So I added a container of Bars leaks power steering stop leak. This was around the year 2000. The leak stopped in fairly short order and still doesn't leak a drop of fluid to this day. Honest to god. Your results may vary.

 

Yes, I checked everything with the belt off. I'm gonna dig through my box and find the old tensioner I took off to see if it makes and immediate difference, I'll flip the belt around too. I'll have to try some stop leak as well. I post what I find when I get time to work on it tomorrow.
​​​​​

 

I put the old tensioner back on and flipped the belt around, belt never fell off but now it squeaked on acceleration and it whined and vibrated when turning. Belt has too much memory as it was curling still, starting to think my power steering pump may be causing my grief. Any thoughts?

 

No opinion on whether or not your power steering pump may be causing your grief. What do you use for fluid in your power steering system?

 

I've never changed it so there's a good chance its original

 

Burnt and contaminated type F thats about 5x its service life time wise

I dont think it neeeds to be stated what you should do about that

Your squealing is likely AC Compressor if you have AC on or the water pump pulleyu. you dont seem to really be into listening... but the belt flipping was not necessary and the tensioner NEEDS to be replaced. When you get an OEM one or a dayco one or etc, you NEED to see where on the adjustment/swing of the tensioner the belt you have is at. If its at one of the edges, you need a new belt. this is all based on having the original tensioner and idlers and pulleys, the 4.9 had a revised tensioner pulley in a year or 2 in that era

 

also it would help a lot if you told us what your truck year is.. my guess is 88-93?
========================

Article No.
97-4-8

02/17/97

ACCESSORY DRIVE BELTS - FEAD BELT COMES OFF - VEHICLES WITH 4.9L ENGINE

LIGHT TRUCK:
1987-96 ECONOLINE, F-150-350 SERIES

ISSUE:
The Front End Accessory Drive (FEAD) belt may come off on some vehicles equipped with a 4.9L engine. This may be caused by minor pulley misalignment and FEAD belt vibrations.

ACTION:
Replace the idler pulley with a revised idler pulley which should reduce belt vibration and misalignment by shortening the span between the belt and pulley. Refer to the following text for details.

Install the Idler Service Kit (F6PZ-6K007-AA) per Instruction Sheet 7172, included in the kit.

PART NUMBERPART NAME

F6PZ-6K007-AA Idler Service Kit

 

Article No.
94-10-19

05/18/94

^ACCESSORY DRIVE BELT - FEAD BELT "CHIRP"/"SQUEAL" NOISE AND BELT EDGE WEAR OR LOSS - VEHICLES WITH 4.9L ENGINE
^ENGINE - 4.9L - FEAD BELT "CHIRP"/"SQUEAL" NOISE AND BELT EDGE WEAR OR LOSS
^NOISE - "CHIRP"/"SQUEAL" SOUND FROM FEAD BELT - VEHICLES WITH 4.9L ENGINE
LIGHT TRUCK:
1987-94 ECONOLINE, F-150-350 SERIES
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This TSB article is being republished in its entirety to provide specific bolt number references in Figures 3 and 4.
ISSUE:
Front-end accessory drive belt (FEAD) belt noise may be heard and excessive belt edge wear or loss may occur.
^The "chirp" noise may occur at constant engine speeds and all engine loads. It is caused by belt/pulley misalignment.
^The belt "squeal" noise is intermittent and is heard during engine speed variations, usually at engine start up. The noise is caused by belt slippage.
^Belt edge wear and/or belt loss is caused by belt mistracking across the automatic belt tensioner. If the automatic belt tensioner is out of parallel, the belt can be "driven" to either flange of the pulley, causing belt edge wear and in some cases, the loss of the belt.
ACTION:
Use the following service procedure to correct these conditions.
BELT CHIRP
1.Start the engine and while idling, wet the ribbed side of belt by spraying water on the belt where it enters the A/C compressor pulley.
2.Listen for belt "chirp" as the belt dries at the entrance point of each grooved pulley to identify the noisy pulley.
3.If the "chirp" is at the power steering pulley entry, check for belt mistracking on the tensioner pulley, otherwise go to Step 13.
4.Check press of the power steering pulley. The pulley hub should be flush with the end of the pump shaft.


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5.If the pulley is flush, start engine and while idling, visually compare the size of the gaps between the belt and front and rear flange of the tensioner pulley. If the larger gap is twice as wide as the smaller gap, Figure 2, proceed with Step 6, otherwise, go to Step 13.
6.Mark the accessory drive belt with an arrow to denote rotation of belt. Remove belt.
7.Loosen all fasteners attaching A/C bracket to cylinder block and cylinder head. See Figures 3 and 4.
8.Tighten nuts # 3 (and, on 1987-93 model only, bolts # 4) on side of cylinder block to 62 N-m (46 lb.ft).
9.Tighten bolt # 2 on side of cylinder head to 47 N-m (35 lb.ft).
10.Tighten bolt # 1 on front of cylinder head to 47 N-m (35 lb.ft).
11.Install the accessory drive belt. Be sure belt is installed with arrow mark denoting original rotation of belt.
12.Start engine and check for belt "chirp" noise.
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13.Remove the accessory drive belt and replace it with a new service replacement belt. See Figure 1 for correct belt usage.


BELT SQUEAL - F-SERIES
1.Remove the accessory drive belt automatic tensioner assembly. Refer to the appropriate Truck service Manual, Section 03-05, for the removal procedure.
2.Replace it with automatic tensioner assembly (E7TZ-6B209-G). Refer to the appropriate Truck service Manual, Section 03-05, for the installation procedure.
3.Replace the accessory drive belt.
BELT SQUEAL - ECONOLINE (A/C EQUIPPED MODELS ONLY)
1.Remove and discard the accessory drive belt.
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2.Remove 90 mm diameter pulley from automatic tensioner assembly. Discard bolt, pulley and bearing dust shield. Refer to Figure 5.
3.Install new 76 mm pulley, bearing, dust shield and bolt assembly (E7UZ-8678-A) to automatic tensioner assembly. See Figure 5.
4.Install new accessory drive belt. (1987-93 models - E7UZ-8620-J, 1994 models - E8TZ-8620-S).
BELT EDGE WEAR AND LOSS
1.Remove and replace accessory drive belt with new service replacement belt. See Figure 1 for correct parts usage.
2.Start engine and while idling, observe location of belt on automatic tensioner pulley. If belt tracks near the pulley flange, Figure 2, replace with automatic tensioner (E7TZ-6B209-G).
3.Start engine and observe belt movement. If belt moves too far rearward on tensioner pulley, proceed as follows:
a.With belt installed, loosen all A/C bracket fasteners. Belt tension will pull A/C bracket inboard towards the engine. (Refer to Figures 3 and 4 for bolt and nut position identification.)
b.Tighten bolt # 1 on front of cylinder head to 47 N-m (35 lb.ft).
c.Tighten bolt # 2 on side of cylinder head to 47 N-m (35 lb.ft).
d.Tighten nuts # 3 (and for 1993 and prior model years, bolts # 4) on side of cylinder block to 62 N-m (46 lb.ft).
4.Start engine and observe belt movement. If belt moves too far forward on tensioner pulley, proceed as follows:
a.Remove accessory drive belt and loosen all A/C bracket fasteners.
b.Pull A/C bracket toward drivers side of vehicle.
c.Tighten bolt # 1 on front of cylinder head to 47 N-m (35 lb.ft).
d.Tighten bolt # 2 on side of cylinder head to 47 N-m (35 lb.ft).
e.Tighten nuts # 3 (and for 1993 and prior model years, bolts # 4) on side of cylinder block to 62 N-m (46 lb.ft).

 

Thanks for the advice, I put a new belt (Duralast 6PK2565) with the original tensioner on, I'll check alignment again and power steering fluid and a new tensioner is on the list. Didn't know adjusting the bracket was a thing, could be off as it was never adjusted after adding AC, and it is a 93. Listening good as I can, just learning as I go.