I just got home(Lufkin, TX) from the Davis Mountain State Park. Its was a great, awesome, fun, cool, 8 day round trip(1300miles). I was checking on things(U-240 Cat 3116, Allision MD3060R, 180K miles on this trip) and a tweety bird sound(belt tensioner). I found it. The Hydraulic Pump Tensioner has contacted/touched the pump pulley. In the pics, you can see the back side of the pulley is flatten and shiney. You can also see that at rest the tensioner does not touch. I did notice that at idle there was no noise, but off idle there is a tweety bird/squeeking sound. I think that it must be bouncing hitting the pulley. So far the pulley is working and the belt is staying on. I will replace the tensioner. I did check the bearing on the roller and it is used, seams ok. My question is why did the tension roller touch the pulley?
Pat,
Before just replacing belt and tensioner (which you need to do, pull HARD on the upper part of the belt.
Look carefully for any movement of the pump bracket. I have seen them cracked which allows the pump to move closer to the crank pulley and also at an angle.
Let us know what you find.
Brett,
Thanks for your response. I did pull on the belt and the tensioner moves. I did not see any thing else move. The bracket seams to be good. I did start the engine and noticed that the tensioner moves and does come close to the pulley. No noise at idle.
Replace the belt and tensioner. Make sure they are in absolute alignment, as that short a belt off even a couple of degrees will wear quickly/make noise.
You may or may not have to add/subtract tension from the tensioner to get it "right". Easy to do, as the bracket the tensioner is mounted to is mild steel. Drilling a new hole for the detent pin on the tensioner allows you to fine-tune tension.
As I recall, no that installation, the belt is so short that I had to loosen the tensioner bolt, slip in the belt, then use water pump pliers to twist the tensioner so the detent went into the hole. Sounds more difficult than it is if you have large pliers.
Brett,
How do I know that I have the right tensioner? Do we have a part number for that?
Pat,
Need to check with MOT or Foretravel. The 1995 may be different than the 1993.
Here is what I have for the 1993 U240:
Replace engine belts: 11/07 127k: Goodyear Gaterback. Serpentine: 4070735 7PK1865. Hyd: 4060445 6PK1130 replaced 9/09 145k mi. Water pump belt Cat 7E0744 (½" X 34.5"/13mm X 876 mm). Replace belt tensioners 5/20/10 149,090 mi. Serpentine Tensioner Caterpillar 7E3999= Gates 38509. Hydraulic Tensioner Cummins 3937553= Gates 38504. Gates belts: water pump 9345HD, serpentine K070735HD, hydraulic: K060445. Belt idler bearings (2 each) for Cat 7E3999: NTN 6203LU. Fed Mogul BCA203-FF. 5/1/11 154,661 miles, replace water pump idler bearings (2- 202FF).
It's really hard to see the polishing on the rear side/engine side of the pump pulley as most of the pictures are either out of focus or have bad lighting. If the smooth side of the tensioner roller is touching the pump pulley, it's because the belt has stretched and is too loose allowing the tensioner to jump up and down. Gates Fleet Green Stripe don't stretch and last longer than any others. In other words, your belt is too long.
Do you know how to stick either a 3/8" or 1/2" breaker bar in the square hole on the tensioner to remove the belt?
Jumping at any speed is either because of the tensioner being a different angle compared to the crank pulley and the pump pulley or because the belt is too long. $5 buys an angle finder with magnetic base at any hardware store. The coach can be at any angle. See my old posts on how to do it. Use a straight edge to make sure the pump pulley is in line with the crank pulley. The pulley on the pump can be adjusted in or out on the shaft. You can see the bolt heads in one of your photos. I had to shim one side of the tensioner where it mounted to get all angles the same.
Your belt is riding just about right on the tensioner roller.
Only takes a few seconds to remove the belt with the breaker bar. Tensioner is also easy to remove. You should spin the roller to make sure it does not have rough spots or make a dry whirring sound. I injected some oil in both the back side and front side of the roller's bearings. Well over 100K and original.
If the roller on the tensioner is out of line, the belt will move sideways on the roller face and then snap back several times a second creating the noise and the jumping you see. Essentially, the belt's path is getting shorter and then longer several times a second. This was our problem.
Again, if the belt has stretched, the tensioner will not have enough spring strength to push hard enough on the belt and the flat roller surface may contact the pump pulley flange as well as the tensioner jumping up and down.
The belt should ride on the groves and not rub much on the flanges of either one of the pulleys. A tale tale is seeing any fraying of the white cords on the side of the belt.
Always have a spare belt available as in case of one breaking, the belt may be a mile behind the coach and you will have no idea what length you need. Do NOT depend on listed specs for the belt.
Pierce
Thanks Brett & Pierce,
I have discovered that the pulley is damaged. The tensioner flatten and rolled the inside edge of the pulley and cut into the outside edge. This makes the new belt run funny and causes the tensioner to jump a lot. I guess that the belt stretched to let this happen.
Does the pump shaft turn smoothly and with even resistance over the complete 360 deg. ?? Mine seams to be a little like a compression engine with low compression.??
Here is more pics.
One pic is of the new tensioner stressed to be able to install. I just put it in a vice and use a ratchet to stress and then anything that will stay in the slot where the rusty wrench is.
Thanks for the help
Well today I was looking at the hydraulic fan motors and noticed the one on the rear of the MH is leaking(pretty good}. Looks like the leak is on the top, not the shaft seal. Maybe/i am hoping the leak is a connection(o-ring) problem. I had a o-ring start to leak at the high/low speed value. I got that fixed. While looking I also noticed that the hydraulic pump belt is starting to fray on the outside. I also noticed that the tensioner has started to touch the pump pulley intermittently again. As in the first of this thread, I replaced belt, tensioner, and pump pulley less than 10k miles ago. I did not know what caused the problem to start with and still do not now. The only thing I remember from the first fix was that I thought that the pump pulley kinda had a hard spot when turning by hand. Not every turn, but sometimes. Wonder what is going on???
Pat,
Pat,
Make sure the bracket that holds the hydraulic pump is not cracked. With belt installed, engine off, pull hard on the belt and see if the pump moves. That will cause all kinds of alignment issues.
Been there, done that.
OK, here are all the photos for how to align the crank pulley, tensioner and hyd. pump. This is for a U300 but the idea is the same. Did you use a Gates Green Stripe belt when you changed it?
Pierce
Thanks Brett and Pierce for the response. I will test those items today. I am concerned how the pulley should turn without the belt on. Should it be smooth, even and light pressure, or smooth, even and hard pressure, or smooth, uneven pressure within 1 or more turns, or something else??? I will test this also today.
Pat,
I checked the pump bracket for cracks, no to see and pulling on the belt shows no movement. I did check the pulley for alignment and found that the pump pulley was to far on the shaft by +/- 1/16". No problem I can correct that, but I still don't understand why the tensioner roller is touching the pulley. I do believe that I have the right belt. In the video, the contact point is at the bottom edge of the pulley. The light shines on the top edge, but that is just light.
The following is Google Drive Shareable link to a video of the pulley.
Video Link (https://drive.google.com/open?id=1KSnE9F13jngTH5p1zgXSzIRQ6v1dN_bs)
Pat,
If the belt is too long, the tensioner will hit the pulley. That's why I asked about the Gates Green Stripe as they don't stretch. Now, picture the belt being about an inch shorter. Would that keep the tensioner away from the pulley?
You can see in photo 2 above that If the belt were longer, it would allow the flat idler pulley to hit the pulley on mine. Don't pay that much attention to what the part number is supposed to be. It's what works. I had to try several different belt lengths until I found the right length that show in photo 2.
Do you have a photo of the whole assemble like my photo 2? Perhaps we can figure out your problem then. The parts store was nice enough to loan me belts of different lengths until I was happy with one.
Pierce
I just changed both my tensioners on my 1996 8.3 Cummins. Got OEM Cummins off Ebay for $75 each and replaced all 3 belts with Gates HD. I bought a long 3/8 drive socket arm from Harbor Freight for $10 bucks and made the job way easier. You need to really move the new tensioner to put the belts on but didn't modify anything
On my coach (older and different pump than yours but should be similar) I was able to turn the hydraulic pump by hand. As I turned it a few revolutions the fan (I have a single fan) would turn showing it was working properly.
Pierce's response is correct. You want the belt to be aligned. If you don't have a gauge a long straight edge will get you close.
see ya
ken
Pat,
I annotated one of my photos showing the tiny washer I had to use to get the tensioner angle to match the other angles on the crankshaft pulley and the hydraulic motor pulley. It is a single washer and placed just in the right spot to correct the 3 degree difference. I experimented in the washer thickness and placement until all angles matched. Then I tightened the tensioner back down. And yes, the back of the tensioner is no longer is flush with the mount. The mount face was the correct angle but the 3 degree difference was somehow in the tensioner itself. I've seen other coaches where the back of the tensioner and the roller angle were off a little. Again, this was a three degree difference. The correction made all the difference in the world. The belt you see in the photo is the same one that is on today with 50K more miles. I have two more I carry with me.
I also used a long straight edge like Ken suggested so everything aligned in the horizontal plane. The four bolts visible inside the hydraulic pump pulley may be loosened and the pulley moved in or out on the shaft. (after using a Liquid Wrench type product)
Pierce
Good Morning Pierce,
I do have the same set up as yours. I have owned my U-240 for 13 yrs and 120k miles. I have never had any problems with this system. I have replaced the belts several times and the tensioner 2 times. I am thinking that all the alignment is fine. For some reason the tensioner must be bouncing and hitting the pulley sometimes. I can hear a noise while driving past walls, it is not continuously, it does sound like a rattle, very tinney(light metal sound).
Pat,
Make sure it's not your AC compressor clutch pulley. Ours rattled, stopped when I removed the belt.
Tensioner roller should clear the pump pulley by at least 3/4". Distance should increase if tensioner roller bounces. Check belt length.
My photo is off slightly with the arrow pointing about 1/2 inch from the back of the tensioner.
If you don't show any belt wear, you are in good shape. The PO of ours was stuck by the side of the road a couple of times with the belt problem before we bought it. Not all coaches have this problem but in case of belt wear, it's the first thing to check.
Pierce
Hi Pierce,
I have been working on belt length on my hydraulic pump. I have found that a Gates K060445 (13/16" x 45 1/8") will fit with very little slack to install. I also know that Gates K060448 (13/16" x 45 3/8") will fit, because that belt I have been running is a Gates K060450 (13/16" x 45 3/4"). I will see what the new K060445 belt does and go from there. Thanks for all the input.
Pat,
Pat,
Do not go any shorter than OE/absolutely necessary, as it can over-tension the belt, tensioner bearings and pump bearings.
I would shorten the belt a little at a time untll happy with the idler pulley to pump pulley clearance. Check my photos for the approx deflection. I just checked the distance on ours and metal to metal, it's between 1/4" and 3/8" idler roller to pump pulley. It's been working great at this distance for many thousands of miles. As Brett says, don't shorten it too much.
Pierce
Good Morning Brett & Pierce,
I started with K060445 (45 1/8") to see if it would fit on and since it did I have not changed to the K060448(45 3/8") belt. I also noted when reading this post again that in reply #5 you said you(Brett) used a K060445 belt. I am not sure if I have ever known what the OE belt is/was. I have replaced this only a few times in 13 yrs and 100k miles. I only did that due to age. I have never had this problem before a few months ago. This may not help if the pump is having problems???!!!!
Pat,
You think that there is a possibility that the pump is starting to seize up and overheating the belt until it stretches and allows contact between the roller and the pump pulley? I think the pump would probably quickly fail and you would lose the cooling fans. Other possibilities for more pump drag would be if the hydraulic lines are having an internal problem and creating a restriction. How is the filter?
The belt wraps around over 75% of the pump pulley and at least 60% on the crank pulley on our coach. This is considered high in the belt business and slippage is not that likely. Serpentine belts also have a lot more contact area so are less likely to slip compared to one or two V belts.
Pierce
Pierce,
I really don't know what is going on. I know that over 13 yrs and 100k miles I have changed the belt a few times due to just age. The tensioner has never touched the pump pulley and now all the sudden it has and damaged the pulley. I have measured the old belt and it is still 45 3/4" long. I believe that the belt does no stretch, but flexes to the extent that the roller contacted the pulley, but why?
Pat,
FWIW, Ours has a K060445 belt and there is appx 9/16" between the idler roller and pump pulley.
Hi Dave,
Good to hear from a '95 U-240 owner, THANK YOU for the measurement and comment. I measured mine just now and I have a good 1" with new K060445 Gates. I wounder how much the tensioner oscillates normanly? I will post a video link in little while.
Pat,
How old is the tensioner? The DO wear out.
http://www.youtube.com/watch?v=Hza9Ulhe4DQ
Hi Brett
the tensioner is new less 3k miles today. I am going to post 3 videos of the tensioner. I don't believe that I have ever seen either of mine stand still. The alternator belt tensioner is more stable, but still have some movement. The videos will be at 550 engine RPM. A john deere man told me today that they all move some.
Video 1 (https://drive.google.com/open?id=1kpv8XpQ_H4Zj202jemb7ivccuOgiuouR)
Video 2 (https://drive.google.com/open?id=1a2U7rdl0uikE0-ImClHvBosYM3ePOFjb)
Video 3 (https://drive.google.com/open?id=1CjcNgn6F_vtJIPnH1Uxr2nAwMNl1yG08)
Check the runout you have in your crank pulley in video #2. With the engine stopped, turn it over with a socket and long breaker bar with a dial indicator on the pulley. A piece of chalk would also do with the engine running if you promise not to lose an arm. Your pump pulley looks fine.
Yes, they all move some. Your does not seem excessive especially considering what the crank pulley is doing.
Our RAV4 tensioner is going strong at 240K and our MBZ ML320 has 210K and also working fine. 120K on the Detroit tensioner.
Pierce
Looks like what may be a harmonic balancer behind the crank pulley. It seems to be spinning without any movement.
Pierce
Yup, either harmonic balancer or the crank pulley is not centered (lots of run-out). Can certainly see run-out in the pulley.
As I recall, the mounting holes for that pulley allow some realignment.
Brett,
I went to full big screen and played it a dozen times trying to keep other parts in view as the balancer and pulley were spinning. Like to see a close up photo of the pulley showing the mounting fasteners. It almost looks like it has been damaged some how as the runout does not seem even on the pulley. Perhaps as the engine was installed or removed the pulley was hit. Seems tough to recenter the existing pulley but wish I were closer to see it better.
Pat, nice job posting the short videos!
Good Morning All.
Spring is coming to East Texas!
I agree with Pierce, I think the crank pulley looks like it is not round or something. I have never messed with it. He are some new pics with shorter belt(k060445). If the roller hits the pulley with this much clearance then I will ../././.>?>?
Thanks for all the help.
Pat,
Pat,
Remove the belt.
Loosen the 4 bolts holding that pulley.
See if there is enough play to re-center the pulley. I believe you will find you DO have a small amount of play.
If so, mostly tighten the bolts-- loose enough that you can tap the pulley to re-center it.
Start the engine and move a piece of chalk (yes carefully) closer and closer to the pulley until it marks the spot with the most run-out. Shut down the engine and with something soft like a 2X4" tap the pulley in the direction needed. Repeat until no run-out.
As Brett says, "carefully." No need to have an "Isadora Duncan" incident :)
Pierce
Hi Pierce,
do you know that your mail box is full? I have tried to send you messages and it will not do it due to mail box full. I want to talk with you about Antonio Geraldo.
Pat,
936-824-2714
Pat,
Did you ever resolve this/were you able to lessen the crank pulley run-out?
Hi Brett,
I have not worked on that. It has been real busy around here. I will look at that soon. Thanks for checking on me.
Pat,