“Howling” noise in 1990 740GLE Wagon

[Perk]

Hi all,

Situation – 1990 740 GLE Wagon with a B234F engine. It has about 116,000
miles on it and, according to the records of the previous owner, the
timing belt was changed about 10,000 mi ago. We’ve had it almost a year
and it runs like a champ.

One curious noise, though not too bothersom, and it’s always been there.

When at highway speeds there is a sort of low howling noise that is
present when you either press on the accelerator or let off on it. By
that I mean, that it disappears if you hold the accelerator in a
neutral, “no load”, condition.
Could it be coming from the differential ? The fluid levels have all
been checked recently.

Thanks much,

Perk >)

 

[mjc13]

Hi all,

Situation – 1990 740 GLE Wagon with a B234F engine. It has about 116,000
miles on it and, according to the records of the previous owner, the
timing belt was changed about 10,000 mi ago. We’ve had it almost a year
and it runs like a champ.

One curious noise, though not too bothersom, and it’s always been there.

When at highway speeds there is a sort of low howling noise that is
present when you either press on the accelerator or let off on it. By
that I mean, that it disappears if you hold the accelerator in a
neutral, “no load”, condition.
Could it be coming from the differential ? The fluid levels have all
been checked recently.

Thanks much,

Perk >)

Have the trailing arm bushings checked. They can get worn out,
allowing the rear end to 'wander' forward and back, and make the
driveline - especially the driveshaft carrier bearing - complain. This
produces exactly the symptoms you describe.

 

[James Sweet]

how difficult is it to replace those bushings? I have much the same symptoms
in my '89 240 wagon, and with the age and milage, wouldn't be surprised if I
need to do the same... easy enough for a shade tree mechanic? or do I need
special tools, expertise?...

probably due to replace ALL the rubber components in the suspension, front
and back...

On a 240 you need a special tool. I built mine from plans I found online
but then having access to a machine shop helped tremendously, still a
handy person with a bench grinder and power drill could duplicate it
with patience. The other option is to buy the $180 tool or have a shop
do those bushings.

 

[Perry Noid]

how difficult is it to replace those bushings? I have much the same symptoms
in my '89 240 wagon, and with the age and milage, wouldn't be surprised if I
need to do the same... easy enough for a shade tree mechanic? or do I need
special tools, expertise?...

probably due to replace ALL the rubber components in the suspension, front
and back...

 

[mjc13]

how difficult is it to replace those bushings? I have much the same symptoms
in my '89 240 wagon, and with the age and milage, wouldn't be surprised if I
need to do the same... easy enough for a shade tree mechanic? or do I need
special tools, expertise?...

probably due to replace ALL the rubber components in the suspension, front
and back...

IIRC, you need to buy or improvise a tool to press the bushings in
and out. We had a shop do it. I don't remember the cost, but most 240
repairs seem to cost about $300. ;-)