Timing belt

  • denhamfly
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06 Jul 2011 08:11 #5430 by denhamfly
Timing belt was created by denhamfly
I started working on my timing belt yesterday, I was following Dwayne’s excellent procedure, the only problem is that Dwayne’s car is an 87 while mine is an 85 so far the only difference I have found is the marks on the cam gear, the 87 has a indention on it and mine does not. I think mine is marked on the inside of the gear with a pill shaped make. Can anyone confirm this?

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06 Jul 2011 08:21 #5431 by srshaw3
Replied by srshaw3 on topic Timing belt
Sounds right, can you get a photo to post?

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06 Jul 2011 08:26 #5432 by srshaw3
Replied by srshaw3 on topic Timing belt
Here is a document that Wally P. created, perhaps this is for your year?:
www.928oc.org/pdf/T-Belt-1.pdf

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06 Jul 2011 08:50 #5433 by denhamfly
Replied by denhamfly on topic Timing belt
Stan would it be alright to e-mail you the picture, I can't figure out how to post it.

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06 Jul 2011 08:53 #5434 by srshaw3
Replied by srshaw3 on topic Timing belt

Stan would it be alright to e-mail you the picture, I can't figure out how to post it.


Sure, you can send it to This email address is being protected from spambots. You need JavaScript enabled to view it.

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06 Jul 2011 10:25 #5437 by Landseer
Replied by Landseer on topic Timing belt

I started working on my timing belt yesterday, I was following Dwayne’s excellent procedure, the only problem is that Dwayne’s car is an 87 while mine is an 85 so far the only difference I have found is the marks on the cam gear, the 87 has a indention on it and mine does not. I think mine is marked on the inside of the gear with a pill shaped make. Can anyone confirm this?


Hi. I have familiarity with 85 and 86 cars and might be able to help you.

USA 32V car, right?

The 85 cam gears should indeed have tiny indentations that face the engine.
Looks almost like a cut, the width of a saw kerf. They align with marks on the rear backing covers when engine is positioned at O/T mark (top dead center, cylinder 1).

If engine is positioned at 45 deg BTDC, which is the desired "safe/recoverable" position when removing and replacing the belt, then the little marks are not visible IIRC!

Will see if I can find pictures to help you, or threads where I've previously posted them.


It would be most helpful for you to post pictures of each gear, as well as the harmonic balancer while at TDC to give us a baseline. Am assuming the belt is still on the car.

If not, post pictures of that stuff as it now is postioned.

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06 Jul 2011 10:49 #5438 by denhamfly
Replied by denhamfly on topic Timing belt
I will get out my best glasses and look again for the mark, I did not see them, but will look again. I do really appreciate this help!

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06 Jul 2011 10:54 #5439 by Landseer
Replied by Landseer on topic Timing belt
Below are a few pictures to help.

One shows the passenger cam gear mark, typical half tooth off, while drivers is dead-on.

Another shows the tensioner arrangement.
(IIRC, Dwayne's writeup might have not shown that washer labeled #4.)

Tensioner arm changed slightly after your 85 model year. Different casting, different offset dimensions so that the line of force applied to the tensioner roller put less twist on the pivot bolt. I mention this only to prevent you from worrying about very minor difference from Dwaynes pics on that subject.

Attached files [img]media/attachments/5579=643-85 Tensioner Image3.jpg[/img] [img]media/attachments/5579=642-timing gear indentation mark OC size, 85.jpg[/img]

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06 Jul 2011 10:57 #5440 by srshaw3
Replied by srshaw3 on topic Timing belt
The Porken timing tool allows setting the timing dead on, as I recall, so that would help as well.

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06 Jul 2011 11:18 #5441 by Landseer
Replied by Landseer on topic Timing belt
In your pictures that Stan shared with me the car is not at TDC.

The rotors should point roughly to the three O'clock position when at TDC (one is slightly different than the other, but close to 3 O'clock). Then, at that position, with harmonic balance at O/T, the nicks become visible and aligned.



Your rotors, as shown in your pictures, are more like the 10 O clock position.
I show below the position of the passenger rotor at harmonic balancer O/T (TDC).
Hard to see due to resolution, even by zooming with ctrl key / spinning mouse wheel -- but my rotor points sort of towards 3 O clock, in line with the timing warning wire that is hanging there.

The marks on the front of the cam gear are not relevant. Those pill shaped indentations mean nothing to the alignment.

The alignment nick-marks on the rear edge of the cam gears, behind them so-to-speak, are what you are looking for. These critical nick marks are not visible until the car is more closely approaching TDC. Your's might be closer to 45 deg btdc in your pictures.


One fact that bothers me about the process --- with crank locked per instructions at 45 degrees before TDC, when removing and replacing belt---- you don't have visiblity to the cam gear marks to ensure one camshaft didn't move while the belt was off. So most of us make separate reference marks on front of gears with a magic marker --- just to confirm they didn't move relative to each other while you are doing all the other work before putting the belt back on.

Attached files [img]media/attachments/5581=644-TDC and rotor postion.jpg[/img]

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06 Jul 2011 12:11 #5444 by denhamfly
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Thanks< I guess I missed seeing the mark I will check it out when I get home.

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06 Jul 2011 13:40 #5446 by Landseer
Replied by Landseer on topic Timing belt
Let us know.

Also, as a precaution before you get started with the project, take a hard look at the harmonic balancer for proper fitment/orientation.

When you stand in front of your car and face the engine, the white numbers printed on the harmonic balancer should be oriented for easy reading.
They should not be "upside down" when reading them.

(The unit fits both ways --- but it will indicate wrong crank positions if upside down --- making a world of problems for the "next guy replacing the timing belt" --- read "you". Gotta check that before disassembly)

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06 Jul 2011 16:46 #5451 by 928mac
Replied by 928mac on topic Timing belt
Here are some pictures from my profile page

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Drivers side

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Passenger side

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07 Jul 2011 09:04 #5456 by denhamfly
Replied by denhamfly on topic Timing belt
I have found the timing marks on the cam gear, now I am in the hope and pray mode, because they were off by a lot. This story started when I brought my car to a shop for the water pump and they changed the belt also. The car ran great when I picked it up ,but when I was driving it the next day the timing belt tension light came on and the car would barley run, when I checked out the belt it was really loose. I KNEW BETTER THAN TO GO BACK TO THE SAME SHOP SO I PARKED IT. Now that I have time to work on it, I am hoping things did not get bent. Thanks for ya’ll advice and I might have to ask for more. At the club’s next event if I can make it, I volunteer to donate and cook a big Cajun jambalaya.

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10 Jul 2011 20:46 #5495 by N2O-928
Replied by N2O-928 on topic Timing belt

In your pictures that Stan shared with me the car is not at TDC.

The rotors should point roughly to the three O'clock position when at TDC (one is slightly different than the other, but close to 3 O'clock). Then, at that position, with harmonic balance at O/T, the nicks become visible and aligned.



Your rotors, as shown in your pictures, are more like the 10 O clock position.
I show below the position of the passenger rotor at harmonic balancer O/T (TDC).
Hard to see due to resolution, even by zooming with ctrl key / spinning mouse wheel -- but my rotor points sort of towards 3 O clock, in line with the timing warning wire that is hanging there.

The marks on the front of the cam gear are not relevant. Those pill shaped indentations mean nothing to the alignment.

The alignment nick-marks on the rear edge of the cam gears, behind them so-to-speak, are what you are looking for. These critical nick marks are not visible until the car is more closely approaching TDC. Your's might be closer to 45 deg btdc in your pictures.


One fact that bothers me about the process --- with crank locked per instructions at 45 degrees before TDC, when removing and replacing belt---- you don't have visiblity to the cam gear marks to ensure one camshaft didn't move while the belt was off. So most of us make separate reference marks on front of gears with a magic marker --- just to confirm they didn't move relative to each other while you are doing all the other work before putting the belt back on.


This is correct all 32 valve engines use the exact same gears, and they are different from the 16 valve gears. The marks on the outside facing edge have nothing to do with valve timing.

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