Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

 
 Reply to this topicStart new topic
> throwing belt..., alternator belt keeps flying off??
crash914
post Jun 2 2006, 05:37 AM
Post #1


its a mystery to me
***

Group: Members
Posts: 1,827
Joined: 17-March 03
From: Marriottsville, MD
Member No.: 434
Region Association: MidAtlantic Region
anyone have this problem?

It all started when I replaced my gas tank.. before that I never had a problem.

Now I have thrown the belt 3 times in 3 days....

I did advance my timing a little bit. Could I be revving too fast?

this is not a stock motor... I just don't know if there are shims or other things to look at. Fan is tight and balanced..

I guess I could back off the timing, but what fun would that be...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
davep
post Jun 2 2006, 05:46 AM
Post #2


914 Historian
*****

Group: Benefactors
Posts: 5,214
Joined: 13-October 03
From: Burford, ON, N0E 1A0
Member No.: 1,244
Region Association: Canada
It could be the belt is loose or damaged. More likely would be the alternator alignment or perhaps the alternator bearings.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
crash914
post Jun 2 2006, 05:54 AM
Post #3


its a mystery to me
***

Group: Members
Posts: 1,827
Joined: 17-March 03
From: Marriottsville, MD
Member No.: 434
Region Association: MidAtlantic Region
reply would not take...

I threw the old belt and the new belt twice. I thought that I did not have it tight enough...but not the second and 3rd. time.

The alternator seems ok, spins ok and smooth.

I run it up to 6500 rpm. i did this before I advanced the timing with no problems very frequently. Now with the advanced timing, I am thinking that it spins up more quickly. thus the problem. I am guessing but at 6500 engine rpm, the alternator must be spinning at close to 12000 rpm...anyone? anyone?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
VegasRacer
post Jun 2 2006, 05:59 AM
Post #4


ELVIRA
*****

Group: Benefactors
Posts: 8,707
Joined: 27-March 03
From: Between Scylla and Charybdis
Member No.: 481
Region Association: None
I had the same problem on my 4 cyl. race car. I could toss the belt at will at 7K RPM. My solution was to add a tensioned roller. Never had the problem again.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
GBallantine
post Jun 2 2006, 06:58 AM
Post #5


Member
**

Group: Members
Posts: 74
Joined: 12-October 04
From: Toronto,Ont.Canada
Member No.: 2,930
I had the same problem on my race motor. Tried all kinds of size belts no cure. Finally removed the alternator and ran an Odssey 8 lb. dry cell battery. Just charge up at the end of a track day.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Bartlett 914
post Jun 2 2006, 07:07 AM
Post #6


Advanced Member
****

Group: Members
Posts: 2,218
Joined: 30-August 05
From: South Elgin IL
Member No.: 4,707
Region Association: Upper MidWest
My belt kept coming loose. I have the motor out and I can see the pulleys are not aligned correctly. It looks like the alternator bracket is holding the altenator crooked. Check to see if both pulleys are in line and straight.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Matt Romanowski
post Jun 2 2006, 07:31 AM
Post #7


Senior Member
***

Group: Members
Posts: 878
Joined: 4-January 04
From: Manchester, NH
Member No.: 1,507
Hey Herb,

I don't know if you remember, but I had this problem at NHIS. My car actually broke the long bracket that goes up to the fan shroud. It must have been cracked for a while and moving around before breaking. Hope this helps.

I've also talked to a few people that soak the heck out of the belt with dressing. It weakens it enough to keep it on.

Matt
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
draperjojo
post Jun 2 2006, 08:14 AM
Post #8


sixstrings
**

Group: Members
Posts: 411
Joined: 26-December 05
From: Salt Lake City Utah
Member No.: 5,317
I think Bartlett nailed it. Generally when you start throwing belts you need to look at belt tension, belt condition, alignment, and condition of pulleys. In this case you would probably need to check alternator bearings also, and it sounds like you've done that. After a number of years, the belt profile in the pulley wears and the belt doesn't ride where it should, it rides lower in the groove. The horsepower is carried through the sidewall contact in the pulley, not by it bottoming out in the bottom of the pulley groove. Throw road dust into the picture and its like polishing compound. Someone else mentioned checking the brackets for fatigue and alignment. Good idea!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mark Henry
post Jun 2 2006, 08:39 AM
Post #9


that's what I do!
***************

Group: Members
Posts: 20,065
Joined: 27-December 02
From: Port Hope, Ontario
Member No.: 26
Region Association: Canada
All of the above plus I also found I always threw belts that had the ribs on the outside, I use the gates belt with no ribs.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
davep
post Jun 2 2006, 10:26 AM
Post #10


914 Historian
*****

Group: Benefactors
Posts: 5,214
Joined: 13-October 03
From: Burford, ON, N0E 1A0
Member No.: 1,244
Region Association: Canada
The pivot hole in the alternator can get worn out and ovaled. So can the pivot bracket and the pivot pin. Then the alternator does not sit straight and the belt walks off of the pulley.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
crash914
post Jun 2 2006, 12:19 PM
Post #11


its a mystery to me
***

Group: Members
Posts: 1,827
Joined: 17-March 03
From: Marriottsville, MD
Member No.: 434
Region Association: MidAtlantic Region
Thanks all! good ideas and it seems that I am not alone...

Now why would this occure after replacing my gas tank?

I think that it is a little bit of a red herring...

hi matt! just to let you know, throttle bodies are still in sink and this motor runs like stink...I am using it for my daily driver down here....
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Matt Romanowski
post Jun 2 2006, 02:26 PM
Post #12


Senior Member
***

Group: Members
Posts: 878
Joined: 4-January 04
From: Manchester, NH
Member No.: 1,507
Herb,

I HATE you!! Not really, but my car isn't done yet. I'm heading up this weekend and should have everything on the chasis done. Then over to Mark's to finish the motor.

Matt
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
KenH
post Jun 2 2006, 02:50 PM
Post #13


Senior Member
***

Group: Members
Posts: 680
Joined: 16-January 03
From: Gilroy, CA
Member No.: 156
I had the same problem till I got the CORRECT meteric sized belt.

FLAPS belts are not right.

Have not lost one now in years.

Ken
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Dave_Darling
post Jun 2 2006, 04:40 PM
Post #14


914 Idiot
***************

Group: Members
Posts: 15,062
Joined: 9-January 03
From: Silicon Valley / Kailua-Kona
Member No.: 121
Region Association: Northern California
At one point my car started doing that, too. I futzed with the alternator bracket, and then it would only throw them at the rev-limiter. I futzed with it again, and it would throw them all the time. I futzed with it again, and they started staying put. No problems since then.

I got really tired of trying to get a wrench in between the alternator and the body. And of halfway-removing the alternator...

--DD
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Cire
post Apr 27 2009, 05:25 PM
Post #15


Member
**

Group: Members
Posts: 279
Joined: 12-March 09
From: Tucson, Arizona
Member No.: 10,155
Region Association: None
QUOTE(davep @ Jun 2 2006, 04:46 AM) *

.... or perhaps the alternator bearings.


How could it be the alternator bearing? Is there a way to test that?

My belt has popped off 3 times now as well.
BLEH!

Eric
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
McMark
post Apr 27 2009, 05:45 PM
Post #16


914 Freak!
***************

Group: Retired Admin
Posts: 20,179
Joined: 13-March 03
From: Grand Rapids, MI
Member No.: 419
Region Association: None
Old Thread REVIVAL!!!! (IMG:style_emoticons/default/mueba.gif)

Installing your alternator pulley on backwards will pop the belt off at random times.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 8th December 2024 - 09:47 PM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...