Pullies not quite aligned

Topic: Pullies not quite aligned (Read 1440 times) previous topic - next topic

Pullies not quite aligned

November 20, 2019, 04:56:36 pm

Several years ago we lost a hydraulic radiator fan. In the repair process the belt for the hydraulic pump was replaced - but with a six-ribbed one rather than the 8-ribbed one. (As I type this, I'm thinking the numbers may be off, but the result is the same.) The hydraulic pump isn't properly aligned with the engine pulley. With the wrong belt, that wasn't a problem. The belt simply adjusted itself so it was running properly. While in Nac I decided to put the right belt on. Checked the belt after the first day's drive and it seemed to be a little bit off. Checked it again after another day's drive and it was off just like before. The belt was riding on the outside (rear) edge of the pump pulley. I turned the belt around and made sure that it was properly in the grooves. You guessed it - the belt was back out. Today I put a straight edge on the pulleys. The pump is about 1/8" off from the engine pulley.

Is there an adjustment on that pump pulley? It looks like there are some bolts in the pulley, so I'm wondering if put some washers behind the pulley to move it rearward. Is there a better idea?

Re: Pullies not quite aligned

Reply #1 – November 20, 2019, 05:16:46 pm

Washers or make a shim to better support the pump over a larger area. Aluminum is available in most box stores in a range of thicknesses.

Re: Pullies not quite aligned

Reply #2 – November 20, 2019, 06:12:14 pm

The pump pulley is adjustable. Just loosen the bolts and tap the pulley in or out as needed. You will need to spray Liquid Wrench or a like lube on the area ahead of time. The angle of the tensioner is critical. Have you checked it yet? If it's off, you can shim the top or bottom with a small washer so the angle agrees with the crank and pump pulley.

Have you reviewed my old post with the photos?

Pierce

Re: Pullies not quite aligned

Reply #3 – November 20, 2019, 06:14:44 pm

Attachment of the correct 8 rib belt.

Re: Pullies not quite aligned

Reply #4 – November 20, 2019, 06:37:45 pm

I used to take an eight rib belt and cut off one rib. Self-aligned and no further problems.

Re: Pullies not quite aligned

Reply #5 – November 20, 2019, 07:03:24 pm

I just wanted to make it clear that while the crankshaft pulley and the pump pulley should be in the horizontal alignment, it's the idler pulley on the tensioner that is critical. While you may be able to get away with running the 6 rib belt and having it just jump one groove, the 8 rib belt must have perfect alignment in order not to wear on one edge and suffer an early failure. A hardware store/HD angle indicator can be placed on the face of all three pulleys to determine if there is a discrepancy. It does not matter if the coach is level when you check the angles. When done, the belt should ride entirely on the tensioner roller and not hang over an edge. The tensioner cannot be adjusted in or out but the entire mount on the block can be moved fore and aft. I just loosened the tensioner and placed a small washer under the top where it meets the mount to correct the 3 degree error. If you move the whole mount, you will then have to move the pulley on the pump to make sure the alignment is correct. Make sure to carry a spare belt or two with you as the 8 rib belts usually must be ordered. In the attached photos, you can see the four bolts that have to be loosened on the pump pulley to adjust it. In the last photo, you can see the small washer I installed at the 11:45 position. I can put an arrow on if if you can't see it.

While invistigating the belt problem, I called Gate directly and spoke to an engineer. He said that if the crank pulley has 8 ribs and the pump pulley has 8 ribs, the belt MUST also have eight ribs. Your 1993 U300 has two fans unlike the earlier models with one fan so the pump requires more HP to generate the pressure/volume needed for the larger pump and two hydraulic motors.

Foretravel just didn't take the time needed to get the three in alignment. Too bad as this is the most important belt on the engine and it's failure along with the fact that the warning lights are hidden by the steering wheel for many drivers, have contributed to damaged engines from overheating after losing a belt. Yes, the DDEC will go into 30 seconds of partial power before it shuts down the engine but several owners have used the override button on the dash several times and destroyed the engine.

Pierce

Re: Pullies not quite aligned

Reply #6 – November 20, 2019, 08:01:21 pm

Here is an arrow showing where the small washer is located.

Re: Pullies not quite aligned

Reply #7 – November 20, 2019, 08:44:00 pm

Thanks, Pierce. I'll poke at it again in the morning.

When I bought the belt I ordered two - just in case.

What brand is your angle indicator? Looks like something I need to get.

Re: Pullies not quite aligned

Reply #8 – November 20, 2019, 10:50:46 pm

Generic. Most hardware stores will have them. They should have a magnetic base. About $6. Here is an example: Dial Gauge Angle Finder Magnetic Protractor with Conversion Chart Polycast...

Ours was off 3 degrees. That's a lot!

Pierce

Re: Pullies not quite aligned

Reply #9 – November 20, 2019, 11:20:03 pm

David your a tradesman if i recall, whip out your level, run it across the flats of one pulley use a $2 feeler gauge to measure the distance, move to the other pulley and measure the gap backwards. Your a smart guy, metal is the same as wood. Shim as required

Re: Pullies not quite aligned

Reply #10 – November 22, 2019, 10:39:10 am

David,

I had the same situation with a 6 rib belt being used instead of an 8 rib. Pierce's solution with a 10 Cent washer aligned the pulley and tensioner up perfectly to allow the 8 rib belt being used.

It also cured most of the bounce and squeak in the tensioner. That was 6 years ago and I haven't had any problems since. I also carry an extra belt but haven't needed to change it yet.

Thanks Pierce!

Jerry

Re: Pullies not quite aligned

Reply #11 – November 22, 2019, 10:41:34 am

When you find either an accessory pulley or tensioner mis-aligned, be sure to check the bracket to which they are secured.

I have run into brackets that were cracked, those that had one or more bolts loose.

Said another way, look for the ROOT CAUSE before shimming.

Re: Pullies not quite aligned

Reply #12 – November 22, 2019, 12:16:09 pm

Quote from: wolfe10 – November 22, 2019, 10:41:34 am

When you find either an accessory pulley or tensioner mis-aligned, be sure to check the bracket to which they are secured.
I have run into brackets that were cracked, those that had one or more bolts loose.
Said another way, look for the ROOT CAUSE before shimming.

The bracket on our Detroit U300 is massive with the tensioner and the hydraulic pump bolted to it. It is secured to the engine block and may, with a little work, be moved fore and aft to center the backside of the belt on the tensioner roller. Agree that on some engines, the mount may be marginal and could be out of alignment so must be checked.

The mount/bracket was the first thing I checked. The hydraulic pump matched the crankshaft pulley exactly and gave the same reading as the bracket.

The process of checking vertical alignment with the angle indicator only takes a minute or so. You just place the magnetic base on the crank pulley, tensioner roller the pump pulley, the mount and write down the readings. I pulled the tensioner off and examined it but could not determine the reason for the three degree difference. It was dry when I spun it so I used some oil to lube it. It felt perfect after that and has worked perfectly for 50,000 miles since then.

I used a straight edge to check the horizontal alignment but had to take into consideration the difference in thickness of the edge of the two pulleys to the belt. That's pretty easy and fast also.

The coach can be at any angle so you just have to open the engine door to do it. Ultra quick job.

If the tensioner bounces at idle, it's probably the alignment as the apparent path of the belt will change in length several times a second as the belt moves sideways and returns. Any fraying on either side of the belt indicates the alignment is off and will cause premature belt failure.

Pierce

Re: Pullies not quite aligned

Reply #13 – November 28, 2019, 06:44:04 pm

I bought an angle indicator the other day, so it promptly got cold and nasty outside. Today was much better, so I decided to check the pulley alignment with the new toy. "Toy" is the correct word. The angle didn't change - even as I moved the indicator from one pulley to another! What does this mean? Took the angle indicator out of the engine area and checked various items out where I could easily see what's what. I had to move the indicator quite a bit before the needle would move. This one will go back to the store for an exchange. I'll check the next one before it even leaves the store.

Yes, made in China.

More later when I get a new angle indicator that actually works.

Re: Pullies not quite aligned

Reply #14 – December 14, 2019, 11:56:08 am

Finally got some pictures of what I'm dealing with. The first one shows the difference in alignment. The other three show the angle of each pulley. There is some glare on those, so it is difficult to read the angles, but it looks like the tensioner and pump are pretty much aligned with each other. I'm thinking that if I can move the whole bracket rearward about 1/4" that will help a great deal. If I can get the angles matched up while I'm at it that would be a plus.

Re: Pullies not quite aligned

Reply #15 – December 14, 2019, 12:09:30 pm

David, your first picture must be deceiving, it looks like they are more than an inch out of alignment. You have the stick on the end of one pulley and on the bracket of the other.

Re: Pullies not quite aligned

Reply #16 – December 14, 2019, 12:13:00 pm

No, it is actually only about 1/4" off. The ruler is flat against the pump pulley and the left edge is up against the engine pulley. The ruler is about an inch wide.

Re: Pullies not quite aligned

Reply #17 – December 14, 2019, 12:33:31 pm

David,

I can't see exactly what you are checking in the bottom foto-0076.

How is the vertical angle between the tensioner roller and the other two? If it's off, you may have to remove the tensioner and place a shim on one side until the angle is exactly the same as the other two. I used a small washer abut 0.025" thick on one corner of the tensioner where it bolts to the main mount. That was the big 3 degree difference on ours and made a huge difference when corrected. I oiled my tensioner bearings when I had the tensioner off as they were dry (2 bearings so each side). It's much smoother now and is 40K miles later.

in 0073, you have to take in account for the different thickness of the edge of the crank pulley and the pump pulley. So, I measured with a straight edge from the crankshaft pulley to the hyd. pump pulley and then figured the thickness of the edges before it came to the first groove. It's the groove alignment that must be the same on both pulleys, not the pulley face itself.

There should be no need to move the whole mount unless the belt is starting to go over the edge on the tensioner roller. If that is OK but your alignment is off on the crank pulley to pump pulley, then just loosen the bolts on the pump pulley and slide it in or out. You may have to spray it a day before so it will move.

The crankshaft pulley won't move in and out. The hydraulic pump motor's pulley will.

Pierce

Re: Pullies not quite aligned

Reply #18 – December 14, 2019, 01:52:19 pm

Note our old posting:

Removing Hydraulic belt tensioner and Alternator

showing a spacer plate installed by Foretravel when coach was built.

Re: Pullies not quite aligned

Reply #19 – December 14, 2019, 03:00:16 pm

I went out again just now and looked at the BOTTOM part of the belt. I put my straight edge on the pump pulley, running along the bottom part of the belt. Long story short, the outside edge of the pump pulley lines up with the first ridge (measuring from the rear) of the engine pulley, so it looks like my 1/4" is about right. The edge on the engine pulley is quite a bit thicker than the edge on the pump pulley.

Fortunately, I'm landed for a couple of months, so I can work on it without having to worry about cooking my fingers on hot engine parts. I've got some PB Blaster that I'm going to spray on whatever parts of the bolts I can get to, taking the wind into account. Tomorrow I'll see what, if anything, is willing to turn.

Re: Pullies not quite aligned

Reply #20 – December 14, 2019, 03:06:35 pm

I hope the stars in the heavens are aligned for you David.

Re: Pullies not quite aligned

Reply #21 – December 14, 2019, 07:07:31 pm

OK, the U300 tensioner and hydraulic pump installation is nothing like on a Cummins. There is a massive mount that is bolted to the engine that both the tensioner and hyd. pump are mounted on. If the vertical alignment is the same on the face of the mount is the same as the crank pulley, the hydraulic pump pulley will probably be in vertical alignment but not necessarily in horizontal alignment. If the pump shaft is sprayed with Liquid Wrench ahead of time, it will move easily as soon as the bolts next to the shaft are loosened. Once the crank pulley and hyd pulley are in alignment, the tensioner roller can be checked for alignment in both horizontal as well vertical. One bolt pulls it off and it can be cleaned, lubed if necessary and then replaced with any washers added to bring all angles to the same. After they are all in agreement, the belt can be replaced and the engine started observing to see where on the roller it rides and whether it bounces. If it is nice and smooth but rides toward or sticks over an edge, the tensioner may need a flat full sized washer to fit between it and the mount. Plus any small alignment washer that may be necessary. I've seen a member install a new tensioner but have the same exact problem. Foretravel just didn't spend enough time aligning the three.

The video described above is more to sell tensioners than anything else. Ours bounced like a pogo stick until I aligned the tensioner. It now is as smooth as glass. The other reason it may bounce is that the belt is the wrong length. Again, if the pulleys have 8 grooves, the belt MUST have 8 grooves. This is not a truck stop/parts store belt so order a spare or two. Much cheaper that way.

The earlier U300s 350hp with the side radiator will have it in a vertical installation and only one fan compared to the horizontal radiator and two fan installation. The pump is also different. The belt may or may not be the same on the single fan motor variety. Foretravel does not include belt numbers for the Detroit and if you find them, they will probably be wrong.

This should not require moving the big mount and if you have a few washers to use as spacers, this should only take 15 minutes at most.

Pierce

Re: Pullies not quite aligned

Reply #22 – December 14, 2019, 10:09:12 pm

Safety question before I start taking things apart:
When the belt is ON, the tensioner presses on the belt. When the belt is OFF, the tensioner presses on the hydraulic pump pulley. Is there a stop so that the spring in the tensioner isn't going to send things flying around if the tensioner isn't pushing on something?

Alignment question:
Pierce, you reference horizontal and vertical alignment above. I'm assuming that horizontal alignment is the main issue that I'm trying to solve, in that the big pulley on the engine doesn't quite line up with the smaller pulley on the hydraulic pump and that's why my new 8-rib belt doesn't want to stay put. By vertical alignment you mean that when I put the angle indicator on the big pulley and saw a tilt of 3* and then put it on the small pulley and saw a tilt of 1* I need to adjust the small pulley to have the same 3* angle as the big pulley.

Sounds like I need a shim that moves the whole pump assembly rearward by ~1/4" AND one or more smaller shims to move the pump assembly to match the engine. As I write that, it sounds pretty simple. I'm guessing that Mr. Murphy is hanging around here somewhere, though.

Re: Pullies not quite aligned

Reply #23 – December 14, 2019, 11:05:22 pm

No, you don't have to move the pump assembly. You leave the pump bolted to the big mount and slide the pump pulley until it is alignment with the crank pulley.

You can just put a breaker bar or ratchet in the square recess in the tensioner arm and the pull it with one hand while you take the belt off with the other. Once the belt is off, you can relax the breaker bar and remove it. The square recess will be either 3/8" or 1/2".

I practiced and I can put the belt in one hand, the breaker bar in the other, install the breaker bar AND the belt and start the engine in 7 seconds. So, it's not very difficult.

When I say vertical alignment, the tensioner roller can't lean over at any angle or the belt with move over while the engine is running and since it's pulling the tensioner roller down, it will suddenly move back to the original position. This happens SEVERAL TIMES A SECOND. This movement causes the roller to move rapidly up and down and is easily visible to the eye. This is what the tiny washer does between the mount and the tensioner but it must be put in the right spot so it corrects the "lean." When the belt is deflected sideways, it's only moving perhaps 1/16" or so before jumping back.

Once the three items, crank pulley, tensioner roller, pump pulley are all in alignment, the belt will ride nicely in the grooves and won't rub against the side of the pulleys causing chaffing and a short life. I've seen some so bad that the owner installed a 6 rib belt as it would jump grooves and that was the only way to keep it off the side of the pulley.

Yes, if the crank pulley shows 3 degrees in the vertical plane, both the tensioner roller and the pump pulley also have to indicate 3 degrees. The angle of the coach itself has nothing to do with the measurement. All three could indicate 7 degrees as long as they all agree.

You may have to adjust the washer thickness and placement several times before you get it just right. Once you try it, you will feel much better about it.

The hydraulic belt is the most important belt on the coach as there is no cooling if it fails. You may not notice the failure and not see the warning light. The DDEC will go to half power for about 30 seconds and then shut down to protect the engine. Never use the override on the dash. If the belt breaks, it will be long gone by the time you stop. That the reason you need a couple of spares as otherwise you would have no idea of the belt part number and would be up poo creek. I keep the spare and breaker bar in the little drawer by the fuel/propane tank. Nice to have a flashlight too. Properly aligned, the belt should last almost forever. You get one crack per inch per rib so and 8 rib belt can have 8 cracks per inch. Best to replace well before it gets this far. Ours has 40K on it now with zero cracks.

Just find yourself a breaker bar to match the square recess and make sure it's long enough (probably about 24 inches) so it's an easy pull with one hand while you have the belt in the other hand. Do it once and you will be the expert answering all the posts!!! Like I said, with practice you can insert the breaker bar, install the belt and hit the engine room starter button in 7 seconds so it can't be too hard.

Don't work around a running engine with a tie or loose long sleeve shirt or you could be like Isadora Duncan.

Call with questions or PM.

Pierce

Re: Pullies not quite aligned

Reply #24 – December 15, 2019, 10:27:42 am

Thanks. Yes, I have a 1/2" bar, and with the rear end of the coach down low and me standing on the same level it is very easy to remove or install the belt. When the rear end of the coach is up on two levels of 2x8 boards and the air bags are fully extended it is rather difficult to easily reach things there. That's why I waited until we got back to our lot at The Ranch. I'll see if I can play around a bit this afternoon.

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