My generator belt is a Gates XL 7305. At least 12 years old probably 20. Barely slips by hand, no operation issues. Ordered a Napa xl7305, too loose slips, ordered Gates 7305 XL exactly what was removed, too long, yes it's longer than the old belt. I think it should have a 7300 belt which is 6/10 inch shorter. What is the preferred belt to use. Brand and size? Shouldn't be this difficult to figure out, PT part number is 03BF7305. There is no belt idler, how tight should the belt be? I will take old belt and measure.
Scott
You should be able to just turn the belt 90 degrees half way between pulleys with your fingers.
Pierce
Old belt you can just barely cause it to slip by hand, it's old too. New belt can be rolled on pulley by hand. Loose. X2 Same numbers but bigger? Putting a third same part number belt and expecting different results is a technical sign of insanity.
Scott
Yes I've been in the heat working since July on this fine piece of equipment, It is taking its toll, there has to be a correct answer.
Take the old belt to a store that has the belt sizing apparatus,get the same size belt regardless of part number,they may let you take
3 different size belts and see which one fits the best,us telling you a part number is not helping.
I have been wondering myself about this very subject? I was considering replacing my belt for it is also a tad too loose but it appears not to have any adjustment capabilities? Is it my understanding removal of old belt ( could be cut off) and replacement belt are stretched and rolled on or off the pulleys? It appears there is no way to adjust tension???? Is this correct?
Not sure on yours but the 8K models adjust like a car belt.
If you slide the generator out, then look under the bottom of the of the coach you will see a cover under the generator bay. It will have 4 bolts 1/2 or 9/16 wrench IIRC. Remove that you can get to the back of the generator. There is an adjustment idler for the belt and installation is much easier.
Ok, appreciate that. Thank u!
So on mine there is no adjustment idler or alternator. Belt runs direct from crank pulley to water pump pulley. Both pulleys are fixed in location and size. No adjustment. No lower panel to open. Belt has to fit out of the package.
Scott
Generator info
The engine is a Kubota. Was the generator made by Power Tech?
The engine setup must have planned to have an alternator and rather than design an idler pulley found a belt you could pry on or remove water pump pulley to put the belt on. Whoever approved it should be put in the corner.
Rather than prying the belt over the edge of a pulley, I've taken the water pump pulley off, put the belt on, taken a longer bolt and threaded it into to one of the water pump pulley threaded holes, turned the pulley until the other holes lined up and then pulled the pulley in flush, then removed the long bolt, replacing it with the bolt that matches the other three.
Pierce
It would seem to me that if you loosen the bolts for the water pump pulley, it would wobble down enough for the belt to be slid into the groove. Then it would be tight when the bolts are tightened. I've done this on other applications.
Glen
Pierce yes that is how it should be done except new belts are so loose they slip over by hand
The old belt is visually smaller than the new belts x2
Scott, if you don't own one of these, go to an old school parts house and get the size off the belt that came off and buy one smaller.
On pulleys that close together a 1/0th of an inch would make a difference. When the belts are manufactured there is a variance in sizes on the run. I had to get matched belts for my crane as 3 of the same part number would leave 2 of them loose when I tightened them up.
Yes, I understand that. Auto-correct changed it. I was wondering if Power Tech built the generator. They offer good support and should be able to provide the right belt.
Can you read the number on the back of the old belt? Or, you could take the old belt to the part counter and compare.
For U300 Detroit owners, the twin alternator belts are the same size as the Kubota 10K generator belt and do have an adjustment. You may have a choice of no cog, bottom cog or top cog belts. Don't know of an advantage one over the other. I do know generic O'Reilly belts are $6, Dayco $16, Gates $20 at the same store.
Pierce
Sorry for the wrong info mine is an Isuzu.
Here is what I have on mine but Napa couldn't match it, no longer made and they could not cross reference??I Ordered a gates xl7312 hoping it will fit but haven't tried it yet.
Hope you don't have the same luck as Scott, matching his original number the belt is too long.
So Auto zone 15305 11AV0775 is the same length as my origanal belt Gates XL 7305. It is still looser than I would mechanically adjust if I could, but should work. Hecho En India. Not my first choice but I'll hold on to my 20 year old belt and work this problem another day.
It doesn't take a lot of torque to spin the water pump so slippage might not be an issue.
Yes, Chuck has it correct in that it does not take too much to spin the pump. Is it possible you have a two piece crank pulley with shims between the two parts? Like a VW Bug.
Pierce
Looking at reply #8 it is a one piece cast iron pulley.
Not sure if this helps, but I have the same year, and mine takes the NAPA 7300 belt. Based on your 7305, would that be a little longer belt and maybe causing the issue ?
I actually thought about striping the outer half of the pulley off in the lathe and cutting a aluminum cup with half the pulley on it and separate with shims like a vw aircooled generator. Lol. Less is always better. Too easy to add a idler pulley on the back side if I couldn't get a belt to work. May consider when I have the generator out of the coach in the future to sound deaden and replace all the cooling hoses. It's stripped clean currently. Zero decomposing foam inside. Always liked the adjustable pulley idea. I can twist the belt 180 deg with fingers, but it currently slips very little. Have to keep an eye on it.
Scott
Mark the 7300 is 30.0 inches. The 7305 is 30.6 inches. It would be really tight with 7300. Still I'll pick up a Napa 7300 and give it a try
Scott
I just checked my Powertech manual. It also calls for the NAPA 7300 as the correct belt. Maybe that .6 inch shorter belt will solve your issue ?
I replaced my generator water pump belt a couple of years ago. Power Tech web site calls out a 7305, I replaced mine with what was on there a 7304. I loosened the water pump pulley to give the necessary slack for install. Old belt was definitely slipping, new belt no slip.
Just another data point.
Bob
Not sure about today but in the past, belts like Dayco, Gates, Continental didn't stretch like the cheap ones. When they stretch, they get loose and slip. Slipping makes them hot and then they stretch out further. Old Firestone belts on VW Bugs stretched like rubber bands.
Pierce
Couldn't agree more. My 19 year old belt was barely slipping. Worked great. No issues. Too old for me. Gates XL 7305 purchased a Napa 7305. Too long. Major slipping, unacceptable. Ordered a Gates XL 7305. (Same belt as original) Too long Major slipping unacceptable. Auto zone 15305 11AV0775 is the same length as my origanal belt Gates XL 7305 Which worked fine with slight slipping. In my experience I agree 100% with Pierce. Point being don't buy a belt that is the correct number and expect it to actually work like it SHOULD! Changing quality control and standards? There is no adjustment. It must fit. Crainman is correct in saying someone should be sent to the corner. This particular application belt must be physically verified before being added as a spare part. If I was boondocking and had to use my spare belt and it was unusably too long I'd have fit. PT shows mine as a 7305 and a 7300 in today's standards is probably correct (unverified by me) i got a 100hrs to get a new belt and a verified spare. This is all good, just a bid pathetic quality control. Here is my personal zany belt issues
Scott
Duel alternator chev 6.0 or 8.1 ?
Currently 5.3 LS conversion in Bronco. Hope to end up with LS3 when I'm done with mock up. No time too play with it. U320 has consumed all my free time. Have to get it ready for October trip to North Carolina
Yes I couldn't help myself. I swapped out the 7305 for a 7300. No possible way to install. Way too short. Was unaware they made a 7304 and will look for it now. The autozone belt after 10 minutes of running is looser than the 20 year old belt. I knew better.
Scott
If it works you have some cars that take that belt. Might make it easier to find. I like where it says it tightens as it gets hot wonder how?
Gates 7304 Accessory Drive/Serpentine Belt | CarPartsDiscount.com (https://www.carpartsdiscount.com/auto/drive-serpentine-belt-accessory.html?3593=139369)
Top Width: 0.375 in. On the 7304 belt
Top Width: 0.41in. On the 7305 belt
I'll pick one up and try it tomorrow. Who knows Old belt is looking more serviceable every day
Scott
The .375 width will fall in the pulley more as you know and may give you the slack you need.
Poly-alternator Syndrome:
7304 is so narrow that it allows 2 inches freeplay when installed. Will not work.
I will contact PT and order one of the belts. Next year there will be a adjustable pulley installed on the water pump. I'll make it when the sound deadening is reinstalled.
Scott
When I called PT on 9/8/20 they told me a 7305?
My original was a Gates XL 7305 (best fitting) replaced with Napa 7305 too loose, ordered Gates XL 7305 too loose. I'm at a loss. Generator hours 930hrs. I'm not going to worry about the water pump slipping for now. When I pull generator out to replace sound deadening I'll either add a idler or make a adjustable pump pulley. Thought I was competent to proactively change a belt. Should probably rethink that.
Scott
The belt manufacturing is not very precision. On my crane that requires 3 belts on the same pulleys I would go to the parts store with my belt measuring tool and try to get 3 belts close enough to not have slack in 2 of them. Didn't ever work I would put on the closest 3 and keep retightening daily until the tight ones stretched and all were equal tension. When I wasn't in a rush I could special order a matched set of 3 belts for quite a bit more money. There are batch numbers on the belts and when I ordered a matched set the numbers were sequential. Eventually you might get a xl 7305 that is tight enough. Hard to believe that the crank pulley and water pump pulley could be that far off on different generators.
Cat 3208 needed matched belts from gates to last
Since a couple of years have passed I'm wondering if Scott ever solved the water pump belt issue on his generator?
As i recall the Napa belt was tighter fitting. A permanent adjuster is still going to happen eventually, but hasnt happened yet. Generator is running as we speak. Lol too many other projects but its on the fix list along with soundproofing
Scott
On my generator the belt has an adjustment. Did the enclosed sets do away with it?
Two fixed pulleys and no adjustment. Guess it would be okay with perfect fitted belts but I tried a bunch of belts till I found one that would work. Little spring tensioner would easily resolve. A adjustable pulley would also work
Don't know why they eliminated the adjustment, agree having just the right size belt for a spare would be problematic.
Fighting this now. Removed broken broken napa 25-7300 from the housing and cannot figure put how it is possible to install new belt. Have a 10k powertec with the kubota engine. Crank pulley and water pump pulley, no tensioner or other belt adjustments available just like Scott reported. Have scoured the internet for a how to on re-installing this belt with no solutions. Have removed the water pump pulley and there is just no way to get it back in place with the tension required to stretch the belt. Pierce's suggestion of a longer stud to reinstall the WP pulley is a great idea, sounds like i need to find a slightly longer belt....
How were you able to get the Napa 25-7300 belt onto the pulleys Scott? Did you take the side panel off? Ive seen videos of reinstalling v-belts with a screw driver while the engine is running.....im not brave enough to try that.
So I've had good service with the last belt I installed. No tensioner. I'm planning when I reinsulate the box build a tensioner that can be installed to resolve problem. I'll make several at that time. Tensioner or adjustable pulley would resolve this issue. Too many other issues to resolve now. My concern is if it's too tight it will damage water pump bearings. Just rolled up on pulley and rotated engine drive pulley with tool till installed with front screwed on panel removed. The side is a pain to remove
Scott
Sometime in the past I worked on something that had a split pulley and shims between the sides to remove to make the belt tighter. Might have even been a go cart. My memory doesn't hold everything I have done.
Air cooled VW air cooled engine generators!
That system worked very well.
And, recently saw a "20 something" replace the belt and threw away the shims.
Can't imagine the belt breaking unless it was too tight. Also can't believe it's been three years. The loose belt will allow a little slippage and on a water pump it will probably be fine. It really doesn't need much HP to turn it compared to a alternator
Thanks Brett, I had forgot the Beetles I worked on as an auto mechanic.
So it looks like you ended up with the Autozone 15305 and that is what has served you well since this thread originated?
My belt didnt fully "break", but the rubber deteriorated so badly it is breaking off in chunks. Rubber is rock hard and cracking. Unsure how long it has been installed.
I dont see how it is possible to install the current version of the napa 25-7300.
I will pickup one of the autozone belts and give it a try.
Reply #38 showed the autozone relaxed too much. I'll look at it on Tuesday to see what is currently installed. All I remember is it pissed me off being so simple yet unresolveable.
You can loosen the bolts on the water pump pulley so that it will relax enough to get the belt on and then tighten them up.
.....if you have the correct length belt to do so, I suspect this is the case. The current version available of Napa's 25-7300 belt is nowhere near long enough for this to be possible. The pulley is still 1/4" or so too short on each leg of the belt from being able to go back over the water pump hub after fully removing the pulley from the hub and installing the belt over the crank pulley and the loose water pump pulley.
Gates 7305 fit perfect for me. Bought one from Oreilly for $22, same NAPA branded belt cost $33, but I have a backup now. Installation required removal of 3 bolts from the water pump pulley, and some loosening of the 4th bolt about 3/4 of the way to full removal. This allowed me to wrap the belt on the crank pulley, and start it on the water pump pulley. I was able to grab the belt & water pump pulley together and rotate them slowly, which also rotated the crank pulley. This walked the belt onto the water pump pulley. Once the belt was on the water pump pulley, I slowly tightened up the single bolt still installed and re-centered the pulley on the water pump hub. I reinstalled the other 3 bolts and then snugged everything up. In my opinion the belt is more than tight enough, I have zero concerns of slippage or need for a tensioner. Hope this all helps someone in the future.
I should add - Powertech 10kW generator with Kubota engine. 2000 U320 coach.
Just to add to the water pump pulley belt issue. On the 4cyl Kubota in my 2001 U320..... I just finished rebuilding my generator pan, replacing the vibration mounts(all 8) new H2O pump/&hoses and the burnt up switch in the GCU. The head scratcher was the damn belt! Bought two Gates 7305XL (which was the old one I'm replacing) BOTH new ones were too loose! After MUCH time scouring the forms and the Internet, I came up with a Dayco 15305 belt. It was tight, and with the aide of a pry bar ... viola! Hope this helps those with the same issue.
James,
Can you verify that the "shorter" belt is not over-tensioning?
Easy to pull bearing out of driven accessories with too much belt tension.
Bar-tight "ain't rite".
Brett.. though the belt is tight... I can still give a squeeze with my two fingers on each side pinching inward and the belt moves. It's definitely not banjo tight or even close.
I needed the bar to help install, as I was putting it on with only the top of the cowling removed. Would have been a bit easier if all of cowling (box) was not installed.
2003 U320, Power Tech (Kubota):
Napa or Gates 7300, Kubota 14911-97010
James,
Glad you finally got it done and back together. I know we've spoke on it a few times. Cannot explain at all why a 7305 worked perfect for my application and wouldn't work for yours....mine was not very tight at all, but also not sloppy loose, and it really does not take much tension at all to keep that water pump turning...I have two kubota tractors, one 12 years old, another under a year, bit have quite loose belts, and other than they do have an alternator, same identical setups that these gens have.
I might add, the belt had to be installed to the Wp pulley first, then bolt the pulley to the pump. Was too tight to force on.
.As you followed my lead on my rebuild, curious to see pics on how yours turned out.
Mike.
Here's a pic of the New gates 7305xl, which was an exact replacement of what came off..... loose as a goose
Mike, this weekend the genny goes back into the nose, then put the rest back together...... fingers crossed, everything goes smoothly.
Wow-- that one isn't even close.
Wonder if that "too long" belt was mislabeled.
Gates belts are usually a top choice.
Where is the idler???
Chris
Those with the Isuzu engine- I removed the 4bolts on the pump pulley. Installed the new belt and replaced the pulley. No idler on this engine.
Correct-- no idler.
And, yes, removing or at least loosening the bolts on the water pump pulley is easier on the belt than "popping it" over the pulley.
A little like the old VW air cooled engines, except they used shims between the pulley halves to allow for proper tension (more shims and the belt rode a little lower on the pulley). A very simple and very time tested means of adjusting belt tension.
Any chance there ARE shims/spacers between the water pump pulley halves???
I have the isuzu engine and it has a idler in the empty hole on right side of picture
Chris
Brett, I bought two of the exact same Gates brand and both were the exact same. Too long.
Yes no pulley tensioner on this Kubota V1505 4cyl. I thought about designing and making my own where an alternator would go, but the time involved wasn't worth it.
Nothing wrong with a "no idler" arrangement with just the two pulleys.
Again, that arrangement worked just fine for many millions of miles on the air cooled VW's.
The shims that allow the belt to ride higher/lower in the upper pulley was very simple and effective.
James,
think that might be the same pic you sent me to my phone few weeks back....yep serious loose, mine was not that way. Odd. Good to hear its about finished I know your glad as well.