Upgrading from V-belts to Serpentine

[rwthomas1]

Another project completed, hopefully permanently.....

Ever since upgrading the charging system on my E38 it was eating belts. The alternator is 125 amp cold and 107 amp hot rated. The progression went like this:
-Install upgraded alternator and use 3/8" belt. Not good, belt bottoms in new alternators 1/2" belt pulley. Kills belt pretty quickly, as expected.

-Install 1/2" belt, Gates "green stripe" variety. Sits quite high in the engine crankshaft and waterpump pulleys. It eats this too. Also likes to eat Dayco belts or anything else I can feed it.

-Regulator dies and new Balmar ARS5 can power limit the alternator so it is adjusted down to keep belts alive a bit longer but they still live on "death row"

-New waterpump pulley is fabricated by local shop and stock crankshaft pulley is modified with a wider, deeper 1/2" groove. It still eats belts.

The belts are turning to dust. Every hour of operation means the belt needs adjustment. Black dust tells the tale, everywhere. The alignment of all pulleys is checked and rechecked throughout this. They are always in perfect alignment. Checked with straightedge, etc. Once the alternator powers up the belt starts jumping and vibrating under load. I searched for a long time until I found a machinist in New Mexico, of all places that was capable of making custom 6 groove serpentine belt pulleys. Why a serpentine type belt? Well, by my estimates measuring the surface area of the serpentine belt has 100%-150% more surface area than a 1/2" belt. The other reason is that when perusing the engines at the boat shows, most if not ALL new engines have serpentine style belts. There has to be a reason for this. Be it increased surface area, reduced friction, reliability, etc. Maybe I shouldn't be refering to these belts as "serpentine" as they aren't always used in a serpentine configuration, they are really flat 6 groove belts, but thats semantics I suppose.

The new pulleys are installed and the engine has been test run at various RPM's. The serpentine belt is much more stable, doesn't jump around much at all at any RPM. I am optimistic that this will solve the belt wear issues, permanently. If not I do have one more option and that is to add an idler pulley that will cause a 270 degree belt engagement of the alternator pulley. Hopefully it doesn't come to that.

Once I get the approval of the machinist I will post his contact info. His work is extremely nice, bolted right on with no alignment issues. I would highly recommend him for custom pulleys, serpentine, V-belt or anything else.

The first shot is the pulleys, the second is the old 1/2" belt setup and the third the new serpentine.

Enjoy, RT

 

[newgringo]

Tensioner?

Rob,
The concept and the work look absolutely wonderful. A thing of beauty. What I am wondering is - why is there no spring loaded belt tensioner? Every application I have ever seen for this kind of belt there is one. Not sure where you could mount one but just wondering.

 

[rwthomas1]

Jerry,
There is no tensioner as I'm going to see how it goes first. Many of the new engines I see at the shows simply use these flat belts without the tensioners so I am hoping it works for me too.

There is little room for a spring loaded tensioner as the tensioner must be located on the "slack" side of the belt, not the loaded side. So it would have to be between the crank and waterpump or waterpump and alternator. There are quite a few designs that may work but I would have to fabricate a mounting plate that uses the timing cover mounting bolts to attach it. There are three of these bolts right where they need to be so at least its an option.

I would like to have a spring loaded setup as that assures correct tension at all times. I've got winter ahead of me, not much work right now and a pile of aluminum stock so there is a good chance that this thread will be updated in the future.....

RT

 

[newpbs]

Tensioner

As for adding a mechanism for tension, could you design one into your alternator bracket? What I'm thinking is you could remove the solid bracket at the alternator and create a spring mounted bracket that is adjusted with a bolt. The bolt would push against a spring. The tighter the bolt, the more tension the spring creates.

Just a thought to save room and from having to add another pulley and bearing assembly.

Paul

 

[rwthomas1]

Update:

I motored for two hours with the new pulley setup at 2000+rpm. No issues, belt still tight, no black dust. Apparently the new system works and has solved my problems.

If anyone is interested in custom pulleys, serpentine, V-belt, etc. the machinist authorized posting his contact info. Hes very good and great to work with:

Randall Allmand
4381 Hwy 15
Silver City, New Mexico 88061
rsallmand@signalpeak.net

RT

 

[Steve]

Excellent

Fantastic to see things like this come true.. I too have a seasonal belt eater that actually demanded I polish out the OEM pulleys in an attempt to minimize the consumption, it did, get about a season and a half out of belt.

My M30 or 5424 is likely the same pulley dimensions as yours, what is the ball park dollar range this fellow in NM is asking, and I suspect he needs the originals to mill from? The new ones look aluminum, the originals steel, so some weight reduction is gained.. true?

Steve
e35-3

 

[Loren Beach]

Rob started this belt adventure with a new alternator and the presumption that the bearings are turning properly.
For many of us with aging alternators I got to wondering if, as obviously great as the "serpentine belt" idea is, we might want to first have the alternator overhauled and new bearings installed. In other words, just be really sure that we have no drag on the rotation other than the magnetic drag of charging...


I certainly do like the idea of ending the Curse of the Black Dust in my engine compartment.

The cost per pulley would be nice to have published. I hope that the vendor does not feel hassled by a bunch of separate emails asking for essentially the same information.

Great thread. Thanks to everyone.

Loren

 

[rwthomas1]

Loren makes a good point. Checking the alternator bearings is pretty simple really. Remove the belt, grab the alternator pulley and pull from side to side. Any significant play means the bearings are cooked. Spin the alternator. It should spin freely, no grinding or loud rumbling noises. If it passes these tests 99% of the time its fine.

Yes the machinist needs your pulleys to work from. You could take careful measurements but you had better get it right. I purchased the serpentine alternator pulley from a local alternator rebuilder. Much cheaper that way however you then need to check to make sure that the new pulley aligns with the old, at least on the back side, so that there is some relative reference to fabricate the new pulleys from.

My pulleys were made from 7075 aircraft grade aluminum. Tough, corrosion resistant, easy to machine but cannot be welded.

So everyone wants to know how much? If you have to ask, well...... The pulleys cost $370.00 shipped. I sent Randall $400, he completed the work, shipped back with a refund of the excess. Is it expensive? You bet. I'm quite sure this is not the solution for everyone. I have a tendency to belt-n-suspenders everything. I want it bulletproof. IMHO, the charging system and the cooling pump drive should be. I hope that I have achieved this. Time will tell.

Understand that I can't justify the costs in any other way that to say I wanted it. I also have an old car I have dumped 5 times its value into. Its a hobby, it doesn't have to make sense.

RT

 

[Loren Beach]

Serpentine Belt idea

Too bad there is not a serpentine belt conversion "kit" for all of the thousands of M25 series Universal diesels.
The install and layout photos are interesting and thought-provoking, in any case.

http://shop.altmount.com/collections/frontpage

I noticed this in an ad in the last Lat. 38 magazine.

Cheers,
Loren
__________________
1988 Olson 34 #8
Sail # 28400
Fresh Air
Portland, OR USA

 

[rwthomas1]

Now that is some beautiful kit! Nicely done, looks bulletproof. That said, it ain't cheap either. I feel much better about what I spent after seeing that. My setup is still going strong however I do still get a slight amount of black dust. Maybe 10% of what is was previously. That said, I motored more this year than ever before and still on the first serpentine belt! I'm working on an idler setup that will "wrap" the belt around a much larger percentage of the alternator pulley circumference. That should permanently banish the black dust. RT

 

[Loren Beach]

"V" is for............

I have no plan, just yet, to upgrade to the flat belt and those spendy pulleys.
However I do have some questions about the stock V belt. Our alternator is the stock Moto 50 amp. Engine is a stock Universal M25XP.

My existing belt is showing wear and some cupping on the top edges. Basically it is setting too low in the pulley sides from several years of use.
I took that belt to a NAPA store today and they said that they did not carry a "green stripe" Gates, but did sell me a #7395.GAT XL V-Belt for a whole $13.99.

I shall give it a try, but this seems too inexpensive. (As if that could ever be a problem with anything destined for the boat!)

Attached is a picture of label and belt. I spoke with a marine electrician this morning about this and he confirmed the story that the Gates "green stripe" (and reportedly the equivalent Napa XL) should be the best choice. He also said to watch for the non-identical cog sizing, and this belt has that.

I have checked the pulley alignment and it appears to right on.

For several years we did shed regular carbon dust, but the present belt seems be a lot less of a shedder. It's just showing age and wear.

Anyone know anything more about the elusive Green Belt? There must be some cross-referenced way for ordinary "auto supply" store counter persons to find it, one might imagine...


As always, thanks!

Loren

 

[mherrcat]

I can see the "non-identical cog sizing" in your picture. Is this a good or bad thing? I have a new "green stripe" belt as a spare on my boat and if I recall correctly all its cogs are the same.

 

[Loren Beach]

I can see the "non-identical cog sizing" in your picture. Is this a good or bad thing? I have a new "green stripe" belt as a spare on my boat and if I recall correctly all its cogs are the same.

Supposed to be a good thing.

LB

 

[newgringo]

I use a NAPA 25-7390 on M25

I put a NAPA 25-7390 on our M25 in Jan 2006 for $11.39 and it works just fine. Does not shed. Keeps tension well. We have the new style alternator bracket and the stock alternator pulley. But, it does ride a little higher in the alternator pulley so I checked and adjusted the tachometer.

 

[Tom Metzger]

NAPA?Gates green belt

Loren - On my M-25XP I use a NAPA 4L410-FHP green belt. This is the same belt as the Gates 6841. It's a green power rated belt.
1/2 x 41".

Plug "6841" into the search block and you will get part #, click on the part # and you get the description.

http://www.gatespowerpro.com/Comerg...ngeSearchFrame&CFID=15892043&CFTOKEN=71322799

The length wouldn't work for you as I have changed alternators, but NAPA should have the length you need.

Opps! I just looked it up & it costs $14.49 @ NAPA. Sorry about that. I found the Gates 6841 on the net for $8.23, so it may be available locally for less than NAPA.

 

[Loren Beach]

Belt research

Thanks, Vikings.

When I put the # into the search box it did produce a result. Like you say, I would have to find the correct length. Interesting that the 1/2" size works for this application.
Regards,
Loren

ps: edit: I should mention that our just-completed boat show had a display of Betamarine diesels and all featured flat "serpentine" belts. Evidently a lot of these engines are ordered with 90-ish amp alternators.

 

[erobitaille]

Not to change the subject but how many of you use non "marine" parts on your boat i.e. belts batteries etc? About 10 -15 years ago my brother in law had a Piper Cherokee it need a new alternator so he shelled out $380 for a Delco aviation 70 amp alternator. My 57 Chevy had a Delco 70 amp alternator that was only a year old (I think I paid $40 for it) that looked identical. So we figure what the hell pulled them apart and they were absolutely the same, same Delco part # on the housing and right down to the part number on the Timken bearings

 

[Dan Callen]

V Belts

I am now retired but when I was working our plant used hundreds of v belts. I gave our supplier a Universal belt and he gave me several belts which supposedly matched. When I started using these belts they would last a few hours and turn to dust. I talked to Torrensen Marine and they said that diesels have a different angle belt than an automotive belt. I changed back to the Universal belt and have never had another problem. Just thought I would pass this on. Dan Callen Ericson 32-3 Andiamo

 

[Tom Metzger]

Dan- Torrensen is full of it. :0305_alar The V belt has no idea what fuel you use.

If you look up a Universal Diesel on the Gates Belt site you will find it uses an "XL" belt. I looked up the M-25 as an example (the M-25XP wasn't listed) and it took a 7410 belt. This same belt is on a '53 DeSoto (I learned to drive on one) and a '99 Dodge Neon, plus literally hundreds of other applications.

Loren - The 3/8" green Gates belt is #6741 where the length is the last two digits.

 

[rwthomas1]

Not to change the subject but how many of you use non "marine" parts on your boat i.e. belts batteries etc? About 10 -15 years ago my brother in law had a Piper Cherokee it need a new alternator so he shelled out $380 for a Delco aviation 70 amp alternator. My 57 Chevy had a Delco 70 amp alternator that was only a year old (I think I paid $40 for it) that looked identical. So we figure what the hell pulled them apart and they were absolutely the same, same Delco part # on the housing and right down to the part number on the Timken bearings

Marine is not always "marine" but just rebranded terrestrial stuff. Some things really matter like marine grade bronze seacocks. A V-belt will almost always have a land equivalent. Batteries are the same deal. Sure you can buy Rolls marine batteries but generic deep cycles, golf cart, truck batteries have all proven to work well. As always, research will usually prove if the "marine" name is worth it or not.

Regarding aircraft the reason the alternator was so expensive is it was for a "certificated" engine in a "certificated" aircraft. That alternator also needs to be installed by an licensed A&P mechanic, or supervised by one, so they can sign off in the logbook to the keep the FAA happy. The FAA essentially holds your aircraft hostage by not allowing anyone but a licensed mechanic work on it. Or you know a mechanic, have him check the work, pay him cash and he signs off, wink wink nudge nudge.

RT