Author Topic: Tired of Truck Vibrating  (Read 246 times)

Offline Harmon

  • Registered Users
  • *
  • Posts: 134
Tired of Truck Vibrating
« on: October 09, 2018, 08:53:26 PM »
86 C 10

Ive seen this a few times in posts online, but couldnt find it when I seared the forums, so I apologize if this has been asked again.

When I turn AC on, truck vibrates like its going to die.  Usually when I turn AC off, it is fine.  I have no issues when im driving down the road.  It works great then.  When I come to a stop it vibrates like heck.  AC belt vibrates as well.  This is the 3rd AC compressor I have had on there and they have all done the same thing.  Im tired of it.  Any ideas.

Offline bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 4990
Re: Tired of Truck Vibrating
« Reply #1 on: October 09, 2018, 09:21:37 PM »
Through poor engineering, the A/C compressor belt develops a standing wave at low RPM...

A/C Compressor Replacement and Pulley Alignment

Sometimes tightening the belt will help.  Often the idle speed needs to be adjusted a little higher.  Does the engine have an idle speed solenoid and is it working correctly?
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 17074
Re: Tired of Truck Vibrating
« Reply #2 on: October 10, 2018, 04:48:30 AM »
Also check the mounting brackets and bolts
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

Offline MIKE S

  • Newbie
  • Posts: 14
  • Newbie
Re: Tired of Truck Vibrating
« Reply #3 on: October 11, 2018, 11:11:59 AM »
There was a GM bulletin back in the day to replace the clutch pulley on the compressor. The original is to light and will cause a vibration. I had 1987 GMC that I bought new that had that problem and had it replaced under warranty at the time. I took away about 90% of the vibration. That pulley is no longer available from GM. On my 1987 that I am restoring now I purchased a new GM compressor and it has the newer pulley on it. If I remember the original pulley was very lightweight and kind of tinny. The new pulley was heavier and had more meat on it. The compressors you are buying may have the lightweight pulley on it. Also it is important that you make the belt pretty tight. It should not bounce. If you are not used to tightening V belts you may not be making it tight enough.


#88-413-1B: MOAN NOISE WITH A/C ON INSTALL NEW COMPRESSOR PULLEY - (Apr 16, 1989)

Model and Year: 1985-88 LIGHT DUTY TRUCKS AND VANS WITH R-4 A/C COMPRESSOR AND WITHOUT SERPENTINE BELT DRIVE



TO: ALL CHEVROLET DEALERS



Chevrolet Dealer Service Bulletin 88-176-1 B dated March, 1988 is being cancelled and superseded by this bulletin to include "P" model trucks. All copies of 88-176-1 B should be discarded.

An A/C moan on vehicles equipped with one of the engines listed below can be addressed by replacing the A/C compressor pulley.

NOTICE: Prior to ordering the new pulley, visual verification should be made that the vehicle is equipped with the R-4 compressor and is not serpentine belt driven.



YEAR MODELS ENGINES ---- ------ -------- 1985 C/K 4.3L 5.0L 5.7L 6.2L Diesel M 4.3L G 4.3L 5.0L 5.7L P 4.8L 5.7L

1986 C/K/P 4.3L 5.0L 5.7L M 4.3L G 4.3L 5.0L 5.7L

1987 R/V/P 4.3L 5.0L 5.7L G 5.7L (LT9 ONLY)

1988 R/V/P 5.0L 5.7L G 5.7L (LT9 ONLY)

The new pulley, P/N 6552402, is a single "V" groove high inertia pulley, which is heavier than the original "V" groove pulley
« Last Edit: October 11, 2018, 11:18:59 AM by MIKE S »