New pulleys

Stodge

During our long trip last season we lost an idler pulley.  It was the smooth one down by the alternator.  I replaced that pulley on both engines.  I noticed that the tension pulley, which is grooved is the same design.  I just replaced both of them because they are the same design as the idlers.  

Basically these pulleys are bearing inside a plastic wheel.  The bearing appears to be sealed, so no maintenance option.  Not sure how long they are expected to last, but mine failed around 750 hours/15 years.  So with luck I'm good for another 750 hours and or 15 years. 

reneechris14

If the sea water pump seal leaks the pulley above is sure to go.just an fyi

LaRea

OEM pulleys?  No shiny candy-like Hardin Marine pulleys for you?

Black_Diamond

Those idlers have a life span based on the bearing. L-10 is the term and predicts hours of life based on loads and rpm. The bugger on a boat is the bearing is static so much you can get fretting/false brinneling internally that leads to ‘premature’ failure.  

Engineering theory seminar #2.  lol

Stodge

@LaRea I put in Merc pulleys.  Not a fan of Sierra parts.  

Dream_Inn

I've got a squeal coming from my port engine.  I need to figure out if it's a pulley.  It was there last year and I replaced the belt, but was still there.  My mechanic said it was still from belt (showed me by touching it with a bar of soap and it went away).  It's not there past idle speed.

Black_Diamond

Belt squeal is from the belt slipping. The soap just added lubrication. Causes can be low belt tension, worn belt, damaged pulley(s), rust or contamination on the pulley(s) this can include an idler. 

Wildboating

Stodge,   Where did you procure them from?  I need to replace mine, i have a bearing chirp.

Willhound

I remember your post from last year @Stodge and consequently picked up 2 new pulleys and a belt before my trip to Georgian Bay last fall. Had them as spares but plan on installing soon and keep the old as emergency spares after.

Stodge

I used the Mercury Parts Catalog:  https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog  To get the part numbers.  Then your vendor of choice.  I've gotten parts from iBoats recently.  Amazon may have them as well.

Dream_Inn

Black_Diamond said:

Belt squeal is from the belt slipping. The soap just added lubrication. Causes can be low belt tension, worn belt, damaged pulley(s), rust or contamination on the pulley(s) this can include an idler. 

Yeah, the mechanic kind of said the same thing and while looking over it with it running we both thought the pulleys look new (no rust or damage), he just replaced belt, and I did play with tension a couple times.  It is one of those things that has come and gone since I've had the boat, and nothing seems to be a culprit.  I had even swapped the idler between motors years ago and it didn't seem to matter.  It goes away the minute there is any throttle given.  I always keep a spare belt as well.  I need to look closer at the pulleys to see if one is misaligned somehow.

craigswardmtb

reneechris14 said:

If the sea water pump seal leaks the pulley above is sure to go.just an fyi

Thats what happened to me.  Leaky water pump during one trip and then a couple months later the idler pulley went on that engine.  I replaced all the idlers and water pump pulleys while in there.  I hate alarms while underway.  So whatever i can do to prevent something from happening again, i'm all about it....

Stodge

There's actually 2 idlers, at least on the 350.  The smooth one near the bottom and the tension adjust.