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Premature Timing Belt Failure - Solved

 
Old 09-02-2010, 09:25 AM
  #46  
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Ethre,
You say you can see the wear on the surface of the cam gears and from what you are saying they are aluminium. If you have aluminium gears they will be the later round tooth design. Make sure you get the right setup on your car. As Greg has already said a miss match of round and square teeth is not a good way to move forward. The steel gears can also wear but will not show a shiny surface like the aluminium gears and it is best to check them by feel and using a straight edge with a feeler gauge.
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Old 09-02-2010, 10:37 AM
  #47  
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The water pump's a rebuilt one which was working fine. Since the belt hadn't broken, but rather slipped and exhibited excessive wear, I'm guessing it shouldn't have been the cause of belt issues.
I haven't had a chance to read into the issues to which Landseer refers.

Roger - I was referring to the gear shown in MrMerlin's photograph. I had at first thought it to simply show surface wear, but after looking over the photos several times (and asking numerous questions of Blown - thank you by the way), I think I was visualizing it from an incorrect perspective. The gear appears to be worn in a relatively smooth curve (as opposed to a solid track) though - the cause of which I do not quite understand.
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Old 09-02-2010, 10:53 AM
  #48  
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As the pumps were rebuilt interference tolerances were not held on shaft/impeller connection. Separation created essentially milling tools. These WPs use the block as part of the pump, unlike typical water pumps that companies rebuild that fully contain the impeller. This happened across rebuilders based on discussions revealed here over the last 3 years.

Meanwhile, $99 China knock offs became available on the market. Very bad units.

If I see evidence of cost cutting on a TB job, I assume immediately that the mentality extended to the WP.

Therefore, I replace with the solutions that have been made available during the last year and a half (mainly by efforts of Roger).

Surgical 'fix just what's broken" cost engineering/optimization is a path to avoid if possible on these. That's really the main point. A non professional, or a cost-avoiding owner fixed your car based on what is found to date, therefore all becomes suspect beneath those covers. You can't baseline off anything in there. Not uncommon.
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Old 09-02-2010, 11:21 AM
  #49  
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Yes, its becoming painfully obvious that his repairs aren't exactly up to spec. Unfortunate, but such is life.

It may take a while, but I do hope to get everything back to good condition (like everyone hopes to I guess). Priority will go to "what's broken" though (followed by about to go, . .. . and ending in frills/cosmetics).

I can see where a metal head spinning across the block could do some damage.
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Old 09-02-2010, 01:26 PM
  #50  
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Originally Posted by ROG100 View Post
If you have aluminium gears they will be the later round tooth design.
My '81 had square tooth aluminum gears. The gears were changed sometime in '80 from steel to aluminum, keeping the same part number, 928 105 545 04. (PET 7.1 103-05 #19)

In '83 they went to the HTD gears, 928 105 545 10.



Note that there are three versions of 32V cam gears with two part numbers. 928 105 530 00, and 01. Early '85 has 00, late 01. '86-'95 use 01 with six holes.



Late '85 has 01, without the small mystery locating holes, although IIRC, the boss is cast on the 5-8 rear cover.



Mystery boss on 5-8 rear cover which aligns with one of the small holes at TDC#1.

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Old 09-02-2010, 01:40 PM
  #51  
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Ken,
Very interesting as the gears we have here direct from Porsche 545 04 are steel.
They have about 24 in Germany but that is all.
Greg was saying earlier that they were NLA so I wonder if he meant the aluminium version.
I learn something new every day about these cars.
What about the oil pump gear - did the early version change to aluminium as well. We have steel here.
The later I know changed back to steel.
Roger
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Old 09-02-2010, 02:14 PM
  #52  
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Originally Posted by ROG100 View Post
Greg,
The change from steel square tooth to Aluminium round tooth happened in 82. This normally related to the production of 83 MY cars which started in August/September 82 after the Summer vacation.
All my pre 83 cars (7) had reusable old design square tooth gears and they stay that way.
Upgrading is very expensive to some users if the original equipment is servicable. If worn then that is another issue especially if the crank gear is worn. However for those financially challenged a good used gear from Mark would be an OK option.
Not all owners can make the upgrade and providing the original equipment is servicable this is an OK option.
Roger
I see the communication problem we are having. You think there are two versions of cam gears. There are actually three.

All of the 1982 square tooth cam gears were aluminum, not steel. I actually think this started in 1981, but I'm not sure.

No question that the 1983 and 1984 gears were "round" aluminum.

There are therefore three versions of cam gears...not two, for the 16 valve engines.

This car should have the aluminum square tooth cam gears.
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Old 09-02-2010, 02:39 PM
  #53  
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Greg,
I think we are all on the same page when it comes to the form of tooth on the gears - square or round.
From 78 to 82 the part number for the cam gears is 928 105 545 04 and they were square tooth. From my end I was interested in the fact that you said they were aluminium and from my side all I had seen were steel. As already said I have new factory Porsche cam gears 928 105 545 04 here and they are steel. Ken points out that he has seen aluminium cam gears with the square tooth design and that Porsche changed from steel to aluminium in 81. The same part number applies 928 105 545 04 whether it is steel or aluminium which in itself is certainly strange as I would have expected an issue change in number at the very least to show the difference.
So we are in agreement that there are three versions of the cam gears but only two part numbers.
I guess I need to go put a magnet on one of the cam gears on my 82 cars.

I just went back in the Porsche parts list and found that 545 03 superceded to 545 04 I wonder if the 03 was the original steel gear as fitted 78 through 81.
As I say I learn something everyday so thanks for the information.
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Old 09-02-2010, 08:41 PM
  #54  
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Interesting. I haven't ordered that "04" part number, in many years, because they always came in aluminum. Figured it was better to go get some used steel gears than buy another aluminum gear, so I quit ordering them. Now they apparently send steel gears, as they get to the "bottom" of the pile. Germans...

Once new/decent crank gears got hard to get, I converted everything to the later style, round tooth design. Hell, if you are buying two cam gears and an oil pump gear anyway, a crank gear doesn't add all that much money. The round tooth design belt is much stronger and on a two valve engine, you can almost install it and forget it.


Originally Posted by ROG100 View Post
Greg,
I think we are all on the same page when it comes to the form of tooth on the gears - square or round.
From 78 to 82 the part number for the cam gears is 928 105 545 04 and they were square tooth. From my end I was interested in the fact that you said they were aluminium and from my side all I had seen were steel. As already said I have new factory Porsche cam gears 928 105 545 04 here and they are steel. Ken points out that he has seen aluminium cam gears with the square tooth design and that Porsche changed from steel to aluminium in 81. The same part number applies 928 105 545 04 whether it is steel or aluminium which in itself is certainly strange as I would have expected an issue change in number at the very least to show the difference.
So we are in agreement that there are three versions of the cam gears but only two part numbers.
I guess I need to go put a magnet on one of the cam gears on my 82 cars.

I just went back in the Porsche parts list and found that 545 03 superceded to 545 04 I wonder if the 03 was the original steel gear as fitted 78 through 81.
As I say I learn something everyday so thanks for the information.
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Old 09-03-2010, 12:16 AM
  #55  
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The bottom line here is that if you think a hard part may be bad, take your time to think about how bad they really are while you are putting new parts on the car.

Not a real issue for me.
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Old 10-10-2010, 08:04 PM
  #56  
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Looks like it does indeed track down to a shot gear.

http://picasaweb.google.com/lh/photo...eat=directlink


Those pictures make a lot more sense now, after I got to feel and see this gear myself. The edges are a good deal sharper than they look. I'll have to check the crank gear to see if that's worn too, and then get a replacement. Thank you very much for the comments in this thread - they have been very helpful.

(More pictures here)
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Old 10-10-2010, 08:42 PM
  #57  
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Originally Posted by Ethre View Post
Looks like it does indeed track down to a shot gear.

http://picasaweb.google.com/lh/photo...eat=directlink


Those pictures make a lot more sense now, after I got to feel and see this gear myself. The edges are a good deal sharper than they look. I'll have to check the crank gear to see if that's worn too, and then get a replacement. Thank you very much for the comments in this thread - they have been very helpful.

(More pictures here)
Mine looked like yours very sharp. Landeer and I just finished changing all gears.
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Old 10-10-2010, 09:14 PM
  #58  
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is the thrust washer missing?? there should be 2 of them?? one on the front and back of the the Timing Belt drive gear
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Old 10-11-2010, 09:56 PM
  #59  
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Well, crank gear's gone. Unfortunately it doesn't seem like anyone has any new ones. I'd really rather not add a used one, but that may be the only option.

Do you mean this washer Mrmerlin?
http://www.autoatlanta.com/porsche-p...=92810212502#a

The gear shown is the oil pump gear. The two washers indicated in the parts catalog (one larger, one very small) are present in front. I can't see or feel behind for the inside one, but it seems to align correctly. Is there supposed to be another washer somewhere?
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Old 10-11-2010, 11:07 PM
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yes those are the thrust washers they are actually belt guides,
once they crank bolt is tightened.
it didnt look like they were on either side of the crank drive gear
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