Turbo Diesel Registry
Issue link: http://read.uberflip.com/i/594528
18 www.turbodieselregister.com TDR 90 NOISY ENGINE START Recently when I started my '06 Turbo Diesel 3500 with 88,000 miles, I heard a mid-range squeal from the engine compartment and immediately shut the engine off. I opened the hood and found nothing out of the ordinary. I re-started the engine and there was no squeal and I have driven my truck several times since with no unusual sounds. B.G. Smith, Port Neches, TX The sound is possibly from an accessory belt drive component. Remove the serpentine belt and inspect each component for smoothness of operation. I learned something while replacing a water pump on a friend's '07 Turbo Diesel. With the serpentine belt removed and while I was inspecting the belt driven components, I noticed that the alternator used a one-way clutch pulley called Overrunning Alternator Pulley (OAP) or Overrunning Alternator Decoupler Pulley (OADP or ADP). I recognized it since I had recently replaced one on my wife's '06 VW TDI alternator. The symptoms on the VW were very similar to yours. A one-time squeal and then everything seemed to be fine. It took me several weeks to figure it out. With the engine idling, it seemed a little rough and I also noticed excessive movement of the tensioner pulley at idle speed. Apparently, the squeal was a slipping one-way clutch on the alternator until it locked up and worked like a solid pulley. I replaced the pulley with another OAP and the tensioner pulley was steady at idle and the engine idled smoothly again. Your truck's alternator may have this one-way clutch pulley. If it does have one and it is locked up, I don't think it should be a problem to continue driving the truck until you figure out the problem. It would behave as a solid pulley and I don't think you could tell the difference when your engine is at idle since larger engine displacements would probably hide the symptoms as compared to a smaller 1.9-liter VW TDI engine. If you remove the plastic cover, you will probably see a female spline with about 30 teeth that accepts a special removal tool and will indicate that you have a one-way clutch pulley. petersonj, Scotts Mills, OR I haven't heard any more unusual noises. The overrunning clutch reminded me of an incident a couple of weeks ago. One of my friends said her Chrysler Town and Country was making a terrible noise. After probing and listening under the hood with a stethoscope, I determined it was the alternator bearings and replaced the alternator. I noticed that the pulley on the alternator had a plastic cover where there is usually a nut holding the pulley in place. I checked my truck's alternator and it also has a plastic insert in the end of the pulley. B.G. Smith, Port Neches, TX Don't remove the plastic cover unless you are ready to change the pulley. It won't stay on after you disturb it. I checked my '06 Turbo Diesel and it is equipped with an alternator decoupling pulley (ADP). I replaced an ADP unit on my '02 Chrysler Town and Country yesterday. I researched the ADP and have learned quite a lot about them. In the process of researching ADP theory I found several threads on a Town and Country forum describing the strange noises that a failing ADP can make. I also heard a strange noise in my '02 Chrysler Town and Country, which sounded like a bearing knock; however, at 110,000 miles, I found that to be highly unlikely so I disconnected the drive belt to see if I could pin it down. I armed myself with a replacement ADP kit, and as a back-up, a complete alternator with pulley in case something went wrong. I also purchased a Lisle ADP removal tool set for $39.00. The pulley cannot be removed without a special tool set. mwilson, Lincoln, ME The dealer installed an ADP on my '05 Turbo Diesel after I brought it in for throwing the serpentine belt once while still in warranty. seafish 2016 TDR CALENDAR CONTEST PHOTO Richard Osborn's entry. Coverage of '03 to '07 Model Trucks Web Site Correspondence Edited by Bill Stockard.