6BTA 370 Vibration in Tensioner

[Zac Schramm]

Hi,

I just completed a complete cleaning of a rusty coolant system, rebuilt the turbos while at it, and a lot of other stuff.  I noticed when running again near idle one of the tensioners is vibrating visibly (maybe 1/4″).  This engine also has more vibration visible on it from the coolant reservoir for example.  

I replaced the tensioner and idler (not upgraded idler, next time) last year (50 hrs since) with OEM parts and so not sure what to do next.  I suppose first step is to change the belt.  Also the valves haven’t been serviced ever as far as I can gather (730 hrs now) and so I am planning to do that.   There is also some mention of injectors needing cleaning.

Maybe the tensioner I got had a weak spring and should be replaced with better one, there are so many varying part numbers it seems.  

So I’m inclinded to change the tensioner and belt, then do the valves, and then see how operation is.

I installed EGT and boost sensors and I ran WOT (for the 1st time) and was running about 2950 – 3000 RPM, boost pressure 34 psi, EGT 875-920 degrees.  Didn’t take good enough notes as to which engine was which readings unfortunately as I was still trying to get the instrumentation dialed in.

Appreciate any thoughts.

Topic

[Rob Schepis]

Could of been load on alternator. 

[Zac Schramm]

I agree looks okay now, thanks for your opinion.  There was more vibration previously but that was after completing all the work and before we went out for a sea trial, so maybe the belt equalized a bit after that.

2-3 years sounds like a good range for belt replacement.

[Rob Schepis]

All looks a-okay to me.  As to the serp belts that’s your call based on how they look and how long in service.  I do mine every 2-3 years but I know they could go more.

[Zac Schramm]

See video here at idle.  The movement on starboard looks to be less than a few days prior when I made this post, but still wondering if I should replace belt and tensioner first.

[Rob Schepis]

Some vibrations and movement of the tensioner are normal.  Can you take some videos of the vibrations you are seeing and upload to YouTube and post the links here?  If you don’t mind the extra work you can switch the belt and tensioners between the two engines and see what that tells you as to what follows and what stays.

[Zac Schramm]

Also, wanted to mention that I have some white smoke when cold and then when back at idle later on.  When moving faster hard to say since it’s not so much smoke.  Also vibrating engine seems to run smoother at higher RPM.

[Author]

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