The Brick-yard Homepage Brickwerks
Forum Home Forum Home > LT, Crafter & Sprinter Section > LT, Crafter & Sprinter Tech
  New Posts New Posts RSS Feed - Alternator noise fixed!
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Alternator noise fixed!

 Post Reply Post Reply
Author
Message
Monster LT View Drop Down
Yardie
Yardie
Avatar

Joined: 02 Jan 15
Status: Offline
Points: 392
Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Topic: Alternator noise fixed!
    Posted: 31 Mar 19 at 23:55
Alternator issue update....
I had an undiagnosed alternator noise for over 1 year! It would start after the engine was started  and battery light on the dash was put out by depressing the throttle pedal. It would then last a couple of minutes and then suddenly stop. I took it to a local alternator repair shop and they bench tested but couldn't find anything wrong nor any noise so I re-fitted it (pita if you do this in the dark!) and lived with the metallic noise. Recently my battery died with a bad cell not charging and previously my Webasto's ECU also died for NAR. I decided to test & take the thing apart to find out what the problem noise was and if it may have caused the death of batt & ECU. I first checked with a multimeter at the new battery to see if alternator was charging properly and if any significant AC ripple. Low AC ripple so that ruled out. The alt won't start putting out full charge to 14.2V until a few minutes after engine is started and as soon as the metalic noise stops it puts out 14.2V. To get it apart you need to remove 4 really long M5 Philips head machine screws. I used penetrating oils WD40 etc. heat gun, impact gun a few other tricks but ended up just rounding them . They wouldn't budge. Thankfully they are not protected in the middle so out came the grinder. Once apart I managed to slowly get them moving with vicegrip pliers.. took f'in ages an 8th turn at a time. When I took off the pulley though - low and behold - there was no woodruff key! I thought it must have fallen out but I searched even using a large magnet to no avail. Turns out It wasn't there to begin with. I checked the rest of the internals and all OK - diodes, brushes, windings, slip rings, bearings etc except for the voltage reg iteself.  So I sourced a replacement woodruff key from VAG and some similar bolts this time with allen heads (although a bit higher) I put it back together but the bolts weren't quite snugging it tightly as the threaded part was not cut far along the shank enough. I added washers that I had to drill out a little and crossed my fingers when I put the fan back on as I might be touching the bolt heads. A little more tightening gave enough room between the fan and the heads that it could spin without touching. So back in the truck and tested... Still the same charging pattern but no more noise! Thumbs Up



Edited by Monster LT - 19 Apr 19 at 12:46
LT45-TD-ACL-intercooler-4x4-1993
Back to Top
Monster LT View Drop Down
Yardie
Yardie
Avatar

Joined: 02 Jan 15
Status: Offline
Points: 392
Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Posted: 18 Apr 19 at 12:39
After all the above the noise has returned. Same pattern as described above but not as loud and high pitched. So probably not due to the missing woodruff key. My next step may be to replace the voltage reg. However the replacement ones seem to have an exposed resistor (if you look at photos) which my original bosch reg does not have. A bosch replacement is around 50quid and I may find it's not the root of the problem after all. Voltage regulators are difficult to test unless one has the correct equipment and even then this sound anomaly may not show itself with testing.
Is the charging cycle timeframe I have described normal for these alternators? It's the 90amp.
So here it is again:
No charging until engine rev'd over 2000rpm and rev counter starts to work and charging is 12.4V creeping upto 12.9V (revs at idle 800rpm) for 2-3 mnutes, suddenly voltage jumps to 14.4V and engine revs increase slightly as if a load has been removed.



Edited by Monster LT - 18 Apr 19 at 12:40
LT45-TD-ACL-intercooler-4x4-1993
Back to Top
Monster LT View Drop Down
Yardie
Yardie
Avatar

Joined: 02 Jan 15
Status: Offline
Points: 392
Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Posted: 19 Apr 19 at 12:53
Another update. There was alot of vibration that was coming from the alt. I re-adjusted loosened then tightened all and the excessive vibration and the noise have now disappeared and hopefully wil not return.
I'm still interested to know if others out there are not getting charging upto 14.2V until a couple of minutes of the alt getting excited.

LT45-TD-ACL-intercooler-4x4-1993
Back to Top
nooberdoober View Drop Down
Yardie
Yardie
Avatar

Joined: 23 Apr 12
Location: Cambridgshire
Status: Offline
Points: 271
Post Options Post Options   Thanks (0) Thanks(0)   Quote nooberdoober Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 19 at 09:13
I'll test mine soon and update you.
I got me a 2.4 straight Six......and it's a soundin JUICY!

1984 LT40 2.4 petrol Coachbuilt Autotrail Motorhome
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

The WebThis site