Perkins 4-108 belts

Wahoo Sails · 12-04-2007, 15:33

I have several friends with 4-108 engines in their boats, and all complain about short belt life. Some of them have done the "straightedge" technique to insure pulley alignment ... but none of them have found the belt life to be acceptable. OK forum members ... what's the secret?

Bob

btrayfors · 12-04-2007, 16:07

The 4-108 belt setup isn't ideal to begin with. The belt turns both the water pump and the alternator and, if you've got a big alternator, that introduces considerable load.

Nevertheless, with proper alignment and tensioning and the choice of a QUALITY belt, you should be able to get reasonable life from the belt.

Mine turns a 110 Amp Balmar alternator, as well as the water pump. For some years I was going thru belts pretty fast. Turned out to be an alignment problem and an alternator mounting problem: the bracket holding the alternator to the engine had a stripped bolt in the engine, and the damned thing wasn't tight.

After fixing these problems, I get several seasons on the belt with no problems.

Gates Green Stripe belts are good.

Bill

GordMay · 13-04-2007, 03:52

I’ve always recommended high quality drive belts such as: Gates “Green Stripe”, or Dayco “HPX - Top Cog” belts.

See the excellent article:

Simple Techniques for Preventing Drive Belt Alignment Problems
by Dan Parsons
SIMPLE TECHNIQUES FOR PREVENTING DRIVE BELT

and

Proper Installation and Maintenance Can Prolong the Life of V-Belts
By John C. Robertson
Proper Installation and Maintenance Can Prolong the Life of V-Belts

CSY Man · 13-04-2007, 09:12

Belt life has not been a problem since I alligned the pulleys and installed a better pulley on the crankshaft that does not "bottom out" the belt.

Also using "ribbed" belts from the NAPA auto stores.

Before I did the above, there was black dust flying around, now everything is perfect....

Turning a 150 amp alternator, and yeah, probably should have dual belts, but the present system works fine.
(The highest output I have seen from the alternator is 95 amps with the battery bank 50% down)

Wahoo Sails · 13-04-2007, 12:26

Hey Dag,
Where on Earth did you find a replacement crank pulley? Have heard from another 4-108 owner who blames "cheap stamped pulleys" on Water pump & alternator, as well.
By the by... anticipate being in Lake Sylvia around the 25th ... maybe you could stop by for a cold beer? Tell me all about cruising in Tajikastan

Bob

Alan Wheeler · 12-04-2007, 23:48

I agree. Belt quality is No.1 priority. Second is section size. Ensure you have the right section for the pulley.
If you are turning heavey loads like a big alternator, you should also fit a double belt system. For instance, btrayfors 110A alternator is ruffly a 2hp load. I have an 80A unit and I use twin belts.

Alan Wheeler · 13-04-2007, 14:31

The cheap stamped pulleys can commonly be "A" section. Many Asian equipment are commonly coming out with "M" section now. You need a "B" section pulley and belt at minimum for these loads. An "A" section belt in a "B" section pulley would hit the bottom of the V and cause it to wear like you said CSY. Certainly a proper machind pulley is far supperior to the stamped one.
Wahoo, I have often had to take a machined pulley and mate it to the crank boss or even machine the Crank pulley if it is cast.

CSY Man · 13-04-2007, 15:07

Quote:

Where on Earth did you find a replacement crank pulley?

Uh, wrong info, I must have been smoking crack..

The belt was indeed bottoming it out before, but I got wider belts, not a new crank pulley..Did not think before I typed.

I got a new pulley for the alternator, a machined one, also aligned better with spacers.

Quote:

By the by... anticipate being in Lake Sylvia around the 25th ... maybe you could stop by for a cold beer? Tell me all about cruising in Tajikastan

Well, I cruised in Kazakstan and Kyrgystan for a while.
Not much water there, but beatiful prostitutes..

Then went to Italy for a few days and broke my ankle there..

Not sure I can come down to Lake Sylvia and sip cold ones, but can try...
(Have not tried to drive my stick-shift truck yet...Nor climb into dinghies..Keep me posted however, it could work despite the cast and crutches)

Wahoo Sails · 13-04-2007, 18:09

Dag,
the plan is to stay at Lake Sylvia for as short of time as weather allows, and then head for West End ... planning to leave around 9:00PM. IF weather is gonna hold us ther for any length of time ... I'll try to dinghy over & see you ... PM me or E-mail me with your phone #.
Bob

12-04-2007, 15:33	#1
Wahoo Sails Registered User Join Date: Jul 2004 Location: Marathon, Florida Boat: Cape Dory 28, "Night Wind" Posts: 353	Perkins 4-108 belts I have several friends with 4-108 engines in their boats, and all complain about short belt life. Some of them have done the "straightedge" technique to insure pulley alignment ... but none of them have found the belt life to be acceptable. OK forum members ... what's the secret? Bob

13-04-2007, 03:52	#3
GordMay Registered User Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 12,582	I’ve always recommended high quality drive belts such as: Gates “Green Stripe”, or Dayco “HPX - Top Cog” belts. See the excellent article: Simple Techniques for Preventing Drive Belt Alignment Problems by Dan Parsons SIMPLE TECHNIQUES FOR PREVENTING DRIVE BELT and Proper Installation and Maintenance Can Prolong the Life of V-Belts By John C. Robertson Proper Installation and Maintenance Can Prolong the Life of V-Belts __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?"

13-04-2007, 09:12	#4
CSY Man Registered User Join Date: Aug 2003 Location: Ft. Lauderdale Boat: CSY 33 Cutter, "Rhapsody" Posts: 1,902	Belt life has not been a problem since I alligned the pulleys and installed a better pulley on the crankshaft that does not "bottom out" the belt. Also using "ribbed" belts from the NAPA auto stores. Before I did the above, there was black dust flying around, now everything is perfect.... Turning a 150 amp alternator, and yeah, probably should have dual belts, but the present system works fine. (The highest output I have seen from the alternator is 95 amps with the battery bank 50% down) __________________ If you can read this, I have too much time on my hands..

12-04-2007, 23:48	#6
Alan Wheeler Registered User Join Date: Dec 2003 Location: Marlborough Sounds. New Zealand Boat: Hartley Tahitian 45ft. Leisure Lady Posts: 8,042	I agree. Belt quality is No.1 priority. Second is section size. Ensure you have the right section for the pulley. If you are turning heavey loads like a big alternator, you should also fit a double belt system. For instance, btrayfors 110A alternator is ruffly a 2hp load. I have an 80A unit and I use twin belts. __________________ Wheels For God so loved the world..........He didn't send a committee.

13-04-2007, 14:31	#7
Alan Wheeler Registered User Join Date: Dec 2003 Location: Marlborough Sounds. New Zealand Boat: Hartley Tahitian 45ft. Leisure Lady Posts: 8,042	The cheap stamped pulleys can commonly be "A" section. Many Asian equipment are commonly coming out with "M" section now. You need a "B" section pulley and belt at minimum for these loads. An "A" section belt in a "B" section pulley would hit the bottom of the V and cause it to wear like you said CSY. Certainly a proper machind pulley is far supperior to the stamped one. Wahoo, I have often had to take a machined pulley and mate it to the crank boss or even machine the Crank pulley if it is cast. __________________ Wheels For God so loved the world..........He didn't send a committee.

12-04-2007, 16:07	#2
btrayfors Senior Cruiser Join Date: Jul 2006 Location: Chesapeake Region Boat: 42' Bob Perry sloop, "Born Free" Posts: 1,242	The 4-108 belt setup isn't ideal to begin with. The belt turns both the water pump and the alternator and, if you've got a big alternator, that introduces considerable load. Nevertheless, with proper alignment and tensioning and the choice of a QUALITY belt, you should be able to get reasonable life from the belt. Mine turns a 110 Amp Balmar alternator, as well as the water pump. For some years I was going thru belts pretty fast. Turned out to be an alignment problem and an alternator mounting problem: the bracket holding the alternator to the engine had a stripped bolt in the engine, and the damned thing wasn't tight. After fixing these problems, I get several seasons on the belt with no problems. Gates Green Stripe belts are good. Bill

13-04-2007, 12:26	#5
Wahoo Sails Registered User Join Date: Jul 2004 Location: Marathon, Florida Boat: Cape Dory 28, "Night Wind" Posts: 353	Hey Dag, Where on Earth did you find a replacement crank pulley? Have heard from another 4-108 owner who blames "cheap stamped pulleys" on Water pump & alternator, as well. By the by... anticipate being in Lake Sylvia around the 25th ... maybe you could stop by for a cold beer? Tell me all about cruising in Tajikastan Bob

13-04-2007, 18:09	#9
Wahoo Sails Registered User Join Date: Jul 2004 Location: Marathon, Florida Boat: Cape Dory 28, "Night Wind" Posts: 353	Dag, the plan is to stay at Lake Sylvia for as short of time as weather allows, and then head for West End ... planning to leave around 9:00PM. IF weather is gonna hold us ther for any length of time ... I'll try to dinghy over & see you ... PM me or E-mail me with your phone #. Bob

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