Does anyone know of an upgraded alternator belt for a Perkins 4.154?

[Near2KR]

Hi all,

We just had a friends Perkins 4.154 rebuilt and it’s running great. It is still eating alternator belts. It generally needs tightening every 25 hrs and replacement at 100 or so. It is a Delco 70amp alternator. We have not been able to source a serpentine or dual belt setup for this engine. Currently using Napa 7490. Is anyone aware of a belt like the Gates green poly or equivalent that might hold up better for this application?? Thanks in advance.

[tkeithlu]

I suspect that the belt is not the problem. No professionally designed and built belt/pulley system eats belts. Let's think about other causes.

Are the alternator and the engine pulleys aligned? This is the obvious one. Take a string, run it around the route of the belt, and sight down it to see that everything is in one plane. Often alternators need shims (washers) to shift into line, partcularly if the alternator has been changed.

Is the alternator wobbly? Can you rock it back and forth on its axle (without the belt)? A second and related test is whether when running the belt appears stationary while spinning. If there is any run-out (belt jumps up and down, seems to vibrate) go looking for looseness/alignment in the system.

Is the alternator bearing OK? With all this tightening, have the shaft bearings in the alternator failed?

Are you tightening it too much? You should be able to deflect the belt slightly, but not so loose that it squeals.

Are you producing rubber dust? If so, the belt is binding against something.

Type of belt could still be an issue, but I would think that if so, it would be your needing an "X" series belt (the ones with a knobby underside) designed to go around a small pulley, when regular A belts can't make the turn.

[flightlead404]

I second everything tkeithlu says. The belt dust would be a dead giveaway. Checking alignment is easy, either with a piece of string as recommended or a metal straightedge.

If the alternator pulley moves around under load, either because of weak mounting or bad bearings/bushings that will cause wear, which will accelerate the mounting/bearing failure, which will cause more wear, which will...you get the picture.

Pull the belt, check for wobble on the alternator mounting and pulley bearing as well as alignment.

I've found that some of these mounting systems need adjustment to the bushing in the pivoting mount point. Also the system often used for tensioning the belt, ie a slotted arm that you lean on with a persuader of some kind to get that 1/4 turn of the belt and then bolt down, can be a weak point. Sometimes there's a lot of flex in the arm, sometimes the thing moves under load. There are better tensioning systems that you can buy, or build yourself, that use a threaded rod, a block, and a couple of nuts so you can turn the block on the threaded rod to adjust tension.

[Near2KR]

Thanks for all the suggestions. I’ve watched the belt while running under load and it does not seem to jump around. Any dust created is very fine not like would be from rubbing on anything. We tried a balmar threaded adjusting bar but it will not fit with the configuration of the heat exchanger on this one.

I’ll be changing it soon so I’ll try to get a good look with a string and see what I can. This thing is deep inside a center cockpit ketch so access is horrible of course. Appreciate the help all

[Disailor]

On a delivery from Beaufor to NYC, the Perkins ate 4 belts. Turns out when the engine was reinstalled (PO) the waterpump pulley was bumped & ever so slightly wacked out of true.

[Cheechako]

You have an alignment issue I think. Also, Do all pulley's match in width? A 70 amp should not be doing that, even if you had a high output regulator. (do you?) I used Gates Green Stripe single belt with 100 amp alternators and high output regulators on Perkins engines without issues. But I had a Yanmar which ate belts fast with the same alternator setup. I never did get it figured out fully. I think the Yanmar didn't allow the belt to go around the V pulley for enough contact area.

[Scubaseas]

Assume you are using an XL Napa belt. You might try an industrial "A" belt (Dayton A47) unless you know for sure the pulley angles are all 37* which is what an auto belt uses.

70Amp on a single 1/2" belt is right at the edge of it's capability. You should have a 5/8 belt (requires new pulleys) or double 1/2 belts (also requires new pulleys). Going to a 4 or 5 groove multi vee might be your best bet. If you can't find them a good machine shop could make them or adapt off the shelf ones to fit. Summit Racing would be one source.

There are laser alignment tools you can buy or rent to check the pulleys for true. Or get a good straight edge tool.

[Q Xopa]

Originally Posted by Near2KR

Hi all,

We just had a friends Perkins 4.154 rebuilt and it’s running great. It is still eating alternator belts. It generally needs tightening every 25 hrs and replacement at 100 or so. It is a Delco 70amp alternator. We have not been able to source a serpentine or dual belt setup for this engine. Currently using Napa 7490. Is anyone aware of a belt like the Gates green poly or equivalent that might hold up better for this application?? Thanks in advance.

Yes agree with the previous posts.

I use a straight edge piece of whatever you can find. Something like a nice piece of aluminum angle. A couple of feet / 60cm is a good size.

Digital calipers are great to get a measurement frim pulley rim to straight edge, for what size shims you want.
You can measure the pulley rims between the pulley edge to the edge of the belt to allow for different thickness pullies.

Any reasonable machine shop can whip you up pullies or spacers etc, to get everything nice and aligned and solid. You can get multi rib belt pullies done, but for 70A I wouldnt think it was needed.

[Cpt Mark]

I have one Yanmar engine that ate belts too. Problem was rust where the belt made contact. Starting the engine without the belt and running (carefully) sandpaper down there solved the issue.

[skipgundlach]

I have the same engine; likely I have the same setup as you.

I went to some effort to twist/pry/whatever to get the mild steel mounting ears such that the alternator pulley was in alignment with the crank and FW pulleys. Yours may need some attention to that end.

An alternator shop sold me an alternator with a 1/2 inch pulley. Not thinking, I bought half inch, flat (no notches) belts. I was lucky to get 10 hours from them, despite my buying the highest grade, strongest belts I could find.

Then I looked closer and saw that the water pump pulley was appropriate to 3/8" belts. Further research revealed that if you don't have a notched belt (I think what you're using is one such), heat won't dissipate over the hard turn needed on the alternator pulley. Moving to a notched belt led to my now exceeding 200 hours per change, and those always being a matter of running out of expansion room on the adjusting bar. The solution to that would be to get a new one fabricated, with more length.

However, I also found that my hot water heater hose contacted that arm's end; I took a small chunk of relatively hard, plastic-wire-reinforced hose, slit it, and slid it over that point; no further wear occurred (in case you have the same issue) on that soft rubber hose.

Back to the belt itself, my solution to the length-of-belt issue was to use the next shorter one, the 7480. However, that is short enough that even with the alternator hard against the engine (which has perhaps an inch of space left in the adjustment arm) the belt must be manipulated to get on. My solution, which may not be available to you because of access issues, is to use a long #3 flat screwdriver, against the shaft pulley bolt head and crankshaft/PTO extension to turn it, while using a very small screwdriver to pry it over the alternator pulley.

My case of wear is exacerbated by age; the water pump pulley is pitted from past rust during extensive layups, and the PTO/crank pulley is similar, though not in danger of failure. My not-very-good solution, again perhaps unavailable to you due to access issues, was to remove both water pump belts and, with the engine cold and idling, use a file held against the angled faces of the crank/PTO pulley. During cooling periods between such exercises, I manually rotated the water pump (pulley attached) to do the same thing. Finally, I swapped alternators for one I had with a brass pulley. All of those efforts cut my belt dust generation enormously, while not fully. I need to find a replacement water pump pulley as I don't trust the age of the one I have to take it to someplace to have it turned down to smooth. Ideally it would be like the aluminum RW pump top-hat-style pulley I bought from Trans-Atlantic Diesel in that it would no longer be subject to rust, or like my alternator pulley, in brass.

As to the string trick, given the flat nature of the pulley bottoms, you'll have to push it to the front or back, all around the respective pulleys, to be certain of the alignment; due to the relatively flexible nature of the mounting brackets (which I manipulated during my alignment excersizes by using an extremely long crescent/adjustable wrench), unless you have a special cast or otherwise stable mounting bracket, it's not going to stay perfect, I'm afraid...

And, for what it's worth, despite all my efforts, and an apparently still belt when running once tightened, I still have some dust. and, based on the belting (like tire belts) which becomes more evident, and the top width, which becomes narrower as the belt slowly deteriorates, I do have wear despite all my efforts. However, I am getting more than double your life experience with what I expect is the same alternator....

Hope that's of use; on a fresh rebuild, about the only problem points I'd expect would be either the pulleys or alignment; unless they were turned to absolutely flat and true, the pulleys likely are the cause of wear...

Edit: BTW, pix of my pulley and the replacement of my water pump can be seen here:
http://skip.justpickone.org/gallery/...+Pump&start=81

[Scubaseas]

For 70 Amp you need either double 1/2 " or a single 5/8" but if you go to multi vee you can go up to 150amp or more at anytime. Costs about the same if having them made up. Most kits these days will be multi vee. I agree a multi vee is overkill for 70amp.

[jacktheflyer]

Originally Posted by Near2KR

Hi all,

of a belt like the Gates green poly or equivalent that might hold up better for this application?? Thanks in advance.

I would buy the Gates Green Stripe anyway. Doesn't cost that much more. Solved my belt eating problems.

[billgewater]

You will have seen a few respondents refer to using a straight edge against the pulley edges. This really is simple and will show up any misalignment ..... it works well. Pinch the kids ruler ... anything ..

Generally the belt passes around the harmonic balance pulley and the engine water circulating pump. These two should be perfectly aligned unless someone has damaged the water pump or replaced it with a misfit (highly unlikely). This means that mis-alignment between the water pump pulley and the alternator pulley is the likely culprit. Often there is a spacing washer that positions the alternator correctly and it is easy to either forget or misplace it - i.e. position it incorrectly. Don't ask me how I know this.

Putting in a grooved or dual belts etc. seems inappropriate as a 70 Amp alternator should really get by with a standard single pulley arrangement ...... unless you are using the system to push 50 to 60 amps continuously.

Edited bit. I noticed that from your gallery of pictures that the water pump pulley has been painted. Including the belt groove. This is a possible source of problems according to my old engine mechanic. This metal groove should be unpainted because that is the surface material the belts are designed to run on.

[dfelsent]

I’m running a Yanmar 4jh4-te with an alternator and regulator that puts out 80-90 measured amps when the batteries are low. Higher when really low. It’s a 150 amp alternator. I’d guess averaging 30 amps mostly. 1/2” Gates Green Stripe. I made up a tensioner from an old turnbuckle. About 400 hours so far. No dust issues. Retension every 200 hours maybe. Checked far more often.
I paid close attention to good alignment, both angle and fore and aft. Made really really sure the alternator shaft and crankshaft were parallel. And the pulley groove centers coplanar. Rulers etc.
The alignment is very important. The belt quality is important.
I’ve had misaligned shafts and eaten belts with smaller alternators.
I am pleasantly surprised at the longevity and lack of slip I have right now.
Gates has a wonderful power transmission handbook. It has a wealth of information about alignment, grooves, belts, dust, and life. I’ve designed a few belt drives and this is a fantastic resource.

https://assets.gates.com/content/dam...ign_manual.pdf

Take a look at page D31. Straight edge and string!

[RexSnr]

You have been given a huge list of possible causes of rapid belt wear - all very real. However, I will vote with rusted pulleys as well. I have had this problem three different times now and now know only too well how quickly belts are worn by corroded pulleys. We are talking about boats and particularly one which has had a rebuild - potentially old in time. She'll be right mate, let the first belt chew up the rust -nope. Sand the rust off - nope. Paint over it - nope. Chuck the pulleys out if there is any rust on them and your problem will be over - presuming of course alignment is ok. This has to be good, but it doesn't have to be perfect. You get some lee way. You don't with rust. The pitting in a perfectly sanded or belt "shinied" pulley will still eat belts. I actually have this (now known to me) problem on a Toyota HiLux currently. The previous owner had no belt on the AC when I purchased it. The pulleys had rusted. Any belt - all the good brands tried, require readjusting after about 5 hours of engine use and hit the bottom of the groove after a few adjustments. If you do a country drive, the 5 hours comes up fast. The rust does not look that bad but it annihilates belts. Just another one to fix for me.

I also used to deal in belt driven machinery. Poly vees (multiribs) are great load carriers, but I'll warn all now, they will cause you nightmares when the little (always the little) pulley wears. You cannot see pulley wear on these and it becomes near impossible to diagnose belt slip initially. Replace the little pulley and it will be fixed. To diagnose a worn one of these, get a new belt and put a light behind the pulley. Loop the belt away from the pulley then put it into the grooves. If you see any light coming through the belt, get rid of the pulley. When they wear, the belt drops down into the pulley until the outer tips of the pulley vees actually comes to touch on the bottom of the belt grooves. You effectively are trying to drive on the points only - impossible to stop it spinning. A lot of people do not know that any vee type belt requires perfectly flat pulley sides and that the bottom of the belt never touches anything. All Vee belts rely on the belt sides to sit against the pulley sides, but NEVER should touch the bottom. ALL drive is done on the sides, always. M, A, B and C sections are pretty easy to see the wear. The belt should sit flush with or just above the sides of the pulley. If it sits correctly on the big pulley but down in the groove on the little, then the little pulley is badly worn and the belt will soon hit the bottom and slippage becomes uncontrollable. If the belt sits evenly low in both pulleys, you just need a new belt or you have the wrong section belt. Poly vees are near impossible to see wear as the grooves are so small.