Jayco Seneca─ Engine knocking noise

Pookieandsparky · 02-15-2019, 05:48 AM

2018 Jayco Seneca 37TS─ While the engine is accelerating to a shift point there is a loud knocking/ tapping noise until the transmission shifts this repeats anytime you accelerate . It is still at Freightliner and they can't figure it out, even the Cummins engineers can't figure it out. Any ideas what is causing this?

Sundancer330 · 02-15-2019, 12:06 PM

Sounds like you have it at the best place to figure it out, anything from here would be a guess since we can't hear it.

Pookieandsparky · 02-15-2019, 01:23 PM

It has been a couple weeks now and still can't figure it out.

Robbbyr · 02-15-2019, 02:03 PM

Has it gone on a while, or just start? If new problem, have you refueled since it began? Has the dealer checked the fuel quality in your tanks? Have they checked/changed your fuel filters (primary and secondary) to ensure you don't have a fuel restriction? No MIL illuminated? If you have a ScanGauge installed, have you noticed any changes?

Our engines are electronically controlled, I would hope they ran it while connected to a laptop so they could live monitor the engine. They should be able to assess whether the injector timing is correct and that the turbo boost and other parameters are within specs.

Grumpy · 02-15-2019, 02:12 PM

Drive shaft slap? Sounds resonate to strange places.

Pookieandsparky · 02-15-2019, 02:39 PM

They think they have narrowed down the problem to the Harmonic Balancer. This is a brand new unit. How would the harmonic balancer go bad?

Robbbyr · 02-15-2019, 02:53 PM

Quote:

Originally Posted by Pookieandsparky

They think they have narrowed down the problem to the Harmonic Balancer. This is a brand new unit. How would the harmonic balancer go bad?

Probably not "Made in America"!

Grumpy · 02-15-2019, 02:54 PM

Quote:

Originally Posted by Pookieandsparky

This is a brand new unit. How would the harmonic balancer go bad?

It's rubber bonded to metal so something came loose, or was bad from the beginning.

jtad · 02-15-2019, 09:39 PM

Someone taught me a long time ago N-E-W does not spell GOOD..

SloPoke · 02-16-2019, 12:29 PM

Quote:

Originally Posted by Grumpy

It's rubber bonded to metal so something came loose, or was bad from the beginning.

They can be damaged when installed improperly too...

Pookieandsparky · 02-18-2019, 06:43 PM

Blows my mind! We shall find out more tomorrow afternoon. I will post an update.

MixTracks · 05-09-2019, 10:38 AM

Did you ever find what the noise was from? I have the same problem on my 2018 Grayhawk. Thanks.

Pookieandsparky · 05-09-2019, 02:11 PM

Yes, it was the harmonic balancer on the engine. Took a lot of man hours and Cummins Engineers to figure it out.

Pookieandsparky · 05-09-2019, 02:14 PM

It fixed the problem! I give the Ocala Freightliner Service Manager Scott Pauley a lot of props! They did an amazing job!

You may also like: