2018.5 Seneca – S2RV Chassis Wind Noise Fix
Wind noise in a 2018.5 Seneca – S2RV chassis.
Our new Seneca had a lot of cabin noise mostly linked to wind whistling at levels so loud that it inhibited conversations. When we purchase our Seneca, I had read that there were a few things that could help like plug the mirror bracket holes. I felt a door adjustment would, and it did help a bit.
Here are my steps to resolve the issues:
1. Had the dealer plug the mirror bracket holes prior to picking the Seneca up. I later added plugs to all the mirror bracket holes.
2. Went to the local Freightliner dealer in Bryan, Tx and they adjusted the doors – they did a great job and were wonderful to work with. - Minor Improvement.
3. Went a on a trip and used tape on the outside doors to try and reduce the noise. No improvement. This is when I discovered that the source of the noise was not the doors, and since I have already covered all the door related problems, I knew there was another source that HAD to be found.
Went nuclear and did the following:
• It appeared the noise was around the dash level of the front.
• The side cowling in front of the door is fiberglass and is not a great fit – Blue arrow (Photo -Seneca 1).
• Both sides have a gap on the top as well. I ran a bead of RTV just in case – Green Arrow (Photo - Seneca 2).
• I opened the door and opened the hood and looked to see if there was light coming from the front (engine compartment) – on yes, plenty of light.
• Plenty of small air leaks and potential whistles.
o Using black RTV, I sealed all openings until there was no light seen through the door opening looking forward to the engine. One large opening at the top required a piece of insulation prior to applying the RTV – a big opening.
• The yellow arrow (Photo - Seneca 3) shows that the bottom flap of the fiberglass cowling does not have a screw to hold it, and the cowling can move in the wind. I bolted it to the bottom piece. The lower piece has an indenture formed in the fiberglass where a nut should be (this can be seen by looking in the wheel well, but no bolt or nut was in place. Secured these pieces with a small bolt and nut - you can look in the wheel well to see where to drill your hole (NO more flapping in the wind). I had noticed that the wind noise varied with wind direction and could have been the result of this piece fluttering a bit due to wind. I also put an RTV seal on the bottom of the cowling - outside. It is not possible to put it on the inside due to space.
• Used RTV around loose rubber fitting on the windshield – lower drivers and passenger’s sides.
• Used RTV around the top of the doors to cover the gaps of the original door rubber strip covering the window.
• I used RTV for the gap between the mirror top mount long gap – bracket and the actual mirror arm (Red Circle in Photo - Seneca 4). I had previously plugged and RTVed the holes – some improvement.
• Removed the antenna – capped the stud with a plastic cap. Installed a whip antenna on the mirror bracket – I hope this provides better reception.
The cab is now quiet! A BIG difference.
The issue related to my fix is that I made all the modification at one time and cannot validate which specific modification cured the problem. I feel that sealing the gaps on the front cowling (in front of the doors) was the primary fix, with each of the other gaps contributing a little to the wind noise. We just finished a 4-hour trip with an exceptionally quiet cab that allowed us to have good conversations.