Timing belt slipping

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Phantom240

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Oct 1, 2008
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I may be able to pick up an MKIII 7M-GE Supra fairly cheap, clean body and interior... but he says that the timing belt keeps sliding forward off the gears when he goes to start the motor.

Any ideas what could be the issue? Maybe bad tensioner?
 
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jgcable

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Jul 26, 2008
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Milford, CT
Phantom240;1145422 said:
I may be able to pick up an MKIII 7M-GE Supra fairly cheap, clean body and interior... but he says that the timing belt keeps sliding forward off the gears when he goes to start the motor.

Any ideas what could be the issue? Maybe bad tensioner?
Click to expand...

yes..
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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IJ.;1145540 said:
They do?
Click to expand...

Happened on mine (Cuel called it. IIRC, he'd seen it before too)... but the belt didn't ever come completely off and it took a lot longer than just starting the car for the belt to move a half inch. It's been mentioned here a couple times. Not common by any stretch. I threw out the old pulley last weekend... I'll see if I have any pics.
 
mkiiSupraMan18

mkiiSupraMan18

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Apr 1, 2005
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^ Very. But I don't know why the gears themselves would be bad...

I would guess thet the tensioner bolt wasn't tight. Mine did this when I forgot to tighten it.
 
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AJ'S 88NA

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Jul 26, 2007
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Could be improper installation of the belt, it has to be turned over a couple of revolutions by hand then checked for the marks to line up. Shouldn't be necessary to change all the gears. CRE did have the washers on the crank gear come loose, they are just tacked in place.
 
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figgie

Supramania Contributor
Mar 30, 2005
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timing belt moving forward based on crank gear missing guides? NO!



Unless the prior owner put a dremmel to the entire crank gear guide, unlikely.

OP

check the oil crank pulley and see if it is "wobbling". More than likely that will be your cause if the bolt sheared.
 
Jaguar_5

Jaguar_5

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Feb 7, 2006
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mkiiSupraMan18;1145704 said:
^ Very. But I don't know why the gears themselves would be bad...

I would guess thet the tensioner bolt wasn't tight. Mine did this when I forgot to tighten it.
Click to expand...

Never overtighten the tensioner bolt either though!

Stick with stock spec, and follow the TSRM procedure for setting tension before you tighten it
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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The guides aren't even tack welded, they're just crimped. The stocker was only crimped on in 6 points the new one in about 12 points on each side.



I replaced every other part and the belt still moved... if you guys insist it can't happen, well, I guess you need to have a chat with my engine because it doesn't believe you either. Maybe there's enough movement in my crank to cause the belt to want to move, I dunno.
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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Denver, CO
Phantom240;1145842 said:
I'm waiting on the guy to send me pics, so I can take a look at this engine before I take a trip to go get the car and find the entire engine bay is trash.
Click to expand...

A wise decision.

As for the timing belt coming off, I do find it highly unlikely that it would be able to come off completely unless there was a LOT more wrong than just a pulley issue or even a loose crank bolt. Bad tensioners (from what I've read, I could be wrong) are more likely to eat a belt than cause it to come off.
 
F

figgie

Supramania Contributor
Mar 30, 2005
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grrrrrr!!

get your terminology correct folks!

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EM&P=22

Crank timing pulley, oil pump drive pulley, idler pulley.

What the hell is this "crank" guide!!

The Crank timing pulley, the two "guides" are not crimped on. They are one with the crank timing pulley iteself!

Do not deviate and start making up names for things that do not exist. Now with the TSRM in place.. what are you folk talking about? The first one that say oil pump drive pulley and previously said crank guide is going to get stomped! :madfawk:
 
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