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Resolved 1G - Evo 8 timing belt on 1g walking

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
So I'm trying to use my An OEM Evo 8 timing belt on my 6 bolt 1g. The engine is "built" and I've heard that Evo 8 belts are a good Upgrade from the gates replacement and even an update to the OEM 1g Mitsu belt.

-balance shaft deleted with the OEM Mitsu spacer that replaces balance shaft gear behind crank.
-OEM Evo Belt is brand new from the package (albeit a couple years old)
-Gates OEM replacement is a roughly 2 years old with like 100miles on it.
-Both idler and tensioner pulleys were new with the gates belt.
-none of the pulleys have any excessive play in them, in and out nor side to side.
-OEM 6 bolt tensioner
-engine Is turned over fully 6 times after each belt

My issue is that ONLY when using the Evo 8 belt, it walks to the inside edge of the all the gears (both cams, oil pump, and crank). It sits basically flush with the edge or just barely over. This worries me because of premature wear on that side of the belt, this motor is going to make 800wheel or so, so any faults I want to correct..

When I use the gates belt it sits basically dead even in the middle of the cam gears and doesn't walk.

I have tried flipping the belt so lettering faces inwards instead of our and same Issue.
I've tried using the tensioner tool both pushed down on the tensioner pulley and pulling up to see if that effected pulley at all.

I checked the tensioner arm and there's a small amount of play, but nothing serious IMO:
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OEM spacer:
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Before turning over
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After turning over
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Tensioner position
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Who's got any suggestions? I don't really feel like paying $100 for a timing belt to "just try" another Evo belt.

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Solution
So oddly enough, I swapped the pulleys out with new OEM pulleys and now the Evo 9 belt rides dead center.. maybe it was a combination of everything? This was after 10 full Rotations.
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1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
And you say that the tensioner arm isn't sloppy or loose on its pivot? I have seen this happen when the arm has some play in it from a wore out bushing and it lets the belt "walk" like yours is showing. That is the only time I have seen it happen but it would do it with ANY belt, which makes your situation different.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
And you say that the tensioner arm isn't sloppy or loose on its pivot? I have seen this happen when the arm has some play in it from a wore out bushing and it lets the belt "walk" like yours is showing. That is the only time I have seen it happen but it would do it with ANY belt, which makes your situation different.
I don't want to say it doesn't have ANY slop or play but it's not much in my opinion. This is the only tensioner arm I've ever dealt with so I have nothing to compare it to. I've attached a video of the tensioner arm play in my original post too I'd you want to check it out.

It is very weird that it only does it on the Evo Belt. I thought maybe one side of the belt was slightly short than the other as a defect, but when I flipped the belt so the letters face away from me rather than towards it did the same thing.

I have a Brand New Evo 9 belt as well that I will try and see what it does.
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
We talked about this issue in this thread
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
In my rebuilds of these, it is the tensioner arm "play" that made the belt not run true. I have horded a few used arms and the front mounts just in case I have a rebuild that has the same issue that you are having.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
In my rebuilds of these, it is the tensioner arm "play" that made the belt not run true. I have horded a few used arms and the front mounts just in case I have a rebuild that has the same issue that you are having.
Yeah I wish I had more. I don't know if maybe it's the extra tension or the Evo belt vs the gates belt that causes it to flex or what.

Now, I wonder if it's the post on the mount that might be worn, or if it's the bushing that is.

Dsm machining sells some replacement "oilite" material.. maybe I should do that?


I did also make sure to grease the bushings and the stub on the mount when installed as well.
 

Mello

15+ Year Contributor
1,484
642
Jul 4, 2003
Albuquerque, New_Mexico
Both my 2G's belts are not perfectly centered either. They seem to ride a little offset towards the engine like your pictures show after rotating. This is after running my motors and not just hand rotating. As long as there is some gear teeth visible past the edges of the belt I wouldn't worry.
 

talonesi95t

Supporting VIP
211
40
Sep 5, 2009
prosser, Washington
Not sure if this helps, but when i used the oem spacer on my 7 bolt the metal plate for the crank sensor would rub. So i ended up taking off the spacer and just used the balance sprocket. it seemed as the spacer is slightly thinner then the sprocket was.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
Both my 2G's belts are not perfectly centered either. They seem to ride a little offset towards the engine like your pictures show after rotating. This is after running my motors and not just hand rotating. As long as there is some gear teeth visible past the edges of the belt I wouldn't worry.
So mine sit either exactly flush with the edge or sometimes over if I take the tension off and recenter it. As it sits right now with the Evo belt on, I can easily catch my nail on it sticking over the edge and feel it with my finger. There's no edge of the gear sticking out at all towards the engine side.
 

Mello

15+ Year Contributor
1,484
642
Jul 4, 2003
Albuquerque, New_Mexico
This picture isn't after rotating?
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1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
I use the Evo belts and also the stock balance sprocket on my 4g builds just to clarify.
Most of mine are 6 bolt but I have built 2 7 bolt motors and just did a BSE and stock sprocket.
I would worry only if the belt kept walking the more the motor ran.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
I use the Evo belts and also the stock balance sprocket on my 4g builds just to clarify.
Most of mine are 6 bolt but I have built 2 7 bolt motors and just did a BSE and stock sprocket.
I would worry only if the belt kept walking the more the motor ran.
Should i try the stock balance shaft sprocket? Instead of the spacer?
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
At this point, if it isn't to hard to swap, I'd see if it made any difference at all. Maybe the aftermarket spacer isnt "true".
Its just a test.
 

Vegas Smith

20+ Year Contributor
5,037
2,915
Dec 2, 2002
Houston, Texas
Usually when you install the wrong oil pan bolts underneath the timing belt they touch the belt and push it out. However, yours is going in, but make sure you don't have the long bolts in the oil pan underneath the belt.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
Usually when you install the wrong oil pan bolts underneath the timing belt they touch the belt and push it out. However, yours is going in, but make sure you don't have the long bolts in the oil pan underneath the belt.
I actually only have a few bolts in the pan right now. The ones in the front case aren't in
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
At this point, if it isn't to hard to swap, I'd see if it made any difference at all. Maybe the aftermarket spacer isnt "true".
Its just a test.
So I swapped on the Evo 9 belt and it's much better. The entire belt stays on the cam gears.

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DSMPT

DSM Wiseman
2,207
1,798
Jun 12, 2014
Japan / Mexico, Arizona
When the belt doesn't have enough tension or strength (soft-ish), the tensioner arm would slightly move like your video. Did you put enough tension or remove the grenade pin from the tensioner when you took the video? And did you bleed all the lifters?
Should i try the stock balance shaft sprocket? Instead of the spacer?
I have been using the OEM spacer instead of balance shaft sprocket the same as yours but it doesn't cause this.
I've heard that Evo 8 belts are a good Upgrade from the gates replacement and even an update to the OEM 1g Mitsu belt.
That EVO 8 OEM belt in the pic is NOT a upgrade from DSM OEM belt. They are the same. What you want to use is the EVO 9 belt. That's the one contains kevlar like aftermarket belts.
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
When the belt doesn't have enough tension or strength (soft-ish), the tensioner arm would slightly move like your video. Did you put enough tension or remove the grenade pin from the tensioner when you took the video? And did you bleed all the lifters?

I have been using the OEM spacer instead of balance shaft sprocket the same as yours but it doesn't cause this.

That EVO 8 OEM belt in the pic is NOT a upgrade from DSM OEM belt. They are the same. What you want to use is the EVO 9 belt. That's the one contains kevlar like aftermarket belts.
If I remember right I moved the tensioner arm while there was no tension on the belt. Now that you mention it, I did NOT remove the grenade pin but I didn't want to because the belt was walking and I didn't want to fight with putting it back in if the belt continued to walk.

Lifters are all bled.

After doing some reading today about the belts I did read that the 8 belts are actually the same part number as the OEM dsm one. And the Evo 9 ones are, like you said the upgraded one.
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
And those are the belts I use. The ones with Kevlar in them. They are strong belts. :thumb:
But we all know you have to keep an eye on the timing side of these motors..
 

Anfurnyy

Supporting Member
388
320
Jul 4, 2020
Rapid City, South_Dakota
And those are the belts I use. The ones with Kevlar in them. They are strong belts. :thumb:
But we all know you have to keep an eye on the timing side of these motors..
Yeah I thought I had read somewhere that the Evo 8 belts were the kevlar ones. Oh well! This is acceptable to me!

I guess to close out, it looks like this evo 8 belt and my engine just don't jive together, or the belt was defective.
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
It'd be rare but I guess a belt could be a little thicker on one side if quality control missed it.
 

1990TSIAWDTALON

Moderator
9,866
5,743
Nov 14, 2013
Independence, Kansas
Got a point there.
 
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