Serpentine belt 2017 R29

[Mastercraft]

I am looking for advice on how to change D4 300, 2017 R29 serpentine belt. I am ready for the challenge!!! I have a great photo of the front of a D4/300. It looks like there is no automatic tensioner like most serpentine belts. I was hoping there was an automatic tensioner. That is what makes serpentine belts highly desirable.
Do I loosened two bolts on idler pulley to remove belt. To tighten, use 1/2” breaker bar clockwise to hold tight and then tighten bolts? FUN !!!!

 

[Mastercraft]

I meant to say tighten counterclockwise, as you face the front of engine.

 

[Mastercraft]

How tight should belt be?

 

[BB marine]

There should be a square knock out on the tensioner bracket. It is 1/2" or 3/8" this is for a torque wrench. The tension is set by using the torque wrench in the square.The belt is properly tightened when there is 70 NM of torque applied. Tighten one of the bolts to hold the tensioner in this position. Once you have the tensioner set properly tighten the other bolt and confirm the bolts are tight. The torque spec for them is 50NM. It is a PIA to do this because of the tight quarters. Take your time when doing it the first time. Once you install the new belt you should check the tension after a good run. Let the engine reach full operating temperature. After that, inspect tension every 100 hours. It does not self adjust so you must manually tighten like old style V belts.

 

[Mastercraft]

Thanks Brian - you are helping many boat owners, over and over
The torque values help a lot!!! I wish it was self tightening, yet no such luck.
I am ready for the challenge.

 

[tranmkp]

Wait ~ I thought the D4 had a timing chain?

 

[Mastercraft]

Serpentine belt is visible on the very front of outside engine, timing belt or chain is inside engine. We are talking about the serpentine belt outside of engine

 

[JeffreyAC77]

How ofter should the belt be changed? Thanks in advance.

 

[BB marine]

How ofter should the belt be changed? Thanks in advance.

Belt inspection and adjustment should be done once a year or every 200 hours which ever comes first. If this is done and the belt is adjusted properly. It is recommended that it be replaced every 800 hours or 5 years which ever comes first. Marine age usually takes over engine hours. As long as the belt tension is set properly you will get plenty of hours of usage. I'm not sure why Volvo did not uses a self adjusting tensioner on the D4. They used it on the D3. Unfortunately the tensioner used on the D3 has a shorter life expectancy than the belt it self. Could be the reason why!

 

[Mastercraft]

Thanks for all your help. I was successful in less than an hour! It helped to be 180lbs and no older than 65.
I am surprised somebody didn’t say that if I buy an outboard, that would fix the serpentine belt.
Outboards are great, yet I will stick to a diesel for a tug, it just a matter of personal preference.

 

[Bobby P.]

Nice work! Just a suggestion to anyone reading this thread. Always carry and extra serpentine belt.

We changed the serpentine belt as part of our 1000 hour service. If you don't carry a new one, consider keeping the old one as a spare. If your serpentine belt fails, you are dead in the water. No more alternator to charge battery or water pump to cool engine. It's a critical spare.

Hope everyone has a happy new year and plans for lots of boating!

Bobby

 

[Mastercraft]

Also carry a torque wrench unless you want to guess at the critical torque.
I will carry a 3/8 torque wrench with a 1/2” male adapter. Make sure the wrench has a high enough rating. Also, i can’t gain weight or I won’t fit.