[Vwdiesel] Diesel noise levels

[Bob Soukup]

The "quieting a vanagon" post prompted me to pull out my notes on some
noise level tests I ran on my '81 RabbitTruck.  Thought it might be of
interest to the list members.

I borrowed a recently calibrated sound level meter (Simpson model 886) from
the safety and risk management office at work after spending a lot of time
tracing down and fixing a number of rattles & other noises in my truck.
(It still has one horrific body rattle at 34 mph that only occurs when the
truck is in motion, can't get it occur standing still, really hard to find
those kind).  I then made the following measurements:

Measured a static background noise level of 50db to 60db.  This is the
combined general noise in my neighborhood (kids playing, dogs barking,
traffic on nearby streets, etc).

Measured a noise level of 55db inside the cab of the truck from the seat
belt warning buzzer with the windows up and engine off.

Started engine & made measurements, windows up, in the cab.
   Cold idle = 72db
   After one minute warmup, at idle = 69db
   Put "foot to floor", vehicle stationary (high engine rpm) = 75db to 80db

Made outside measurements, engine at normal idle.
   Drivers side door, near handle = 72db
   Left front tire area = 80db
   Front grill area = 87db
   Right front tire area = 81db
   Passenger side door, near handle = 72db

Opened hood, took readings at idle and high, but unknown rpm.
  Over injection pump:
     93db at idle
     106db at high rpm
  Over valve cover:
     97db at idle
     111db at high rpm

On the road (average readings)....

 0 to  5 mph (gear 1) = 73db
 5 to 10 mph (gear 2) = 69db
10 to 15 mph (gear 3) = 68db
15 to 20 mph (gear 3) = 73db
25 mph (gear 4) = 68db
30 mph (gear 4) = 68db
34 mph (with body rattle) = 80db
35 mph (gear 4) = 75db
40 mph (gear 4) = 73db
45 mph (gear 4) = 73db
50 mph (gear 5) = 75db
55 mph (gear 5) = 77db
60 mph (gear 5) = 75db
65 mph (gear 5) = 74db
70 mph (gear 5) = 82db

Couldn't find a place here in the Los Angeles metro area the day I did the
tests to go any faster than 70 mph.  By the time I finished the study
traffic got so bad the best I could do was 50 mph.

As I recall, OSHA sets limits on occupational noise exposure of no more
than 80 db over an eight hour day.  (Since I'm not employed to drive my
truck, if I loose my hearing I guess I have no recourse.)


Bob Soukup
'81 diesel RabbitTruck