7M-GTE Timing Belt Loose After 2nd Gear Pull - not broken

[jdemara]

Hey all, I will start by saying this is a STOCK 7M-GTE engine - and ran beautifully until this problem occurred.

After doing a pull in 2nd gear, I came to a stop and the engine was running rough as if it were some sort of vacuum leak or misfire.

Cut to the chase here... its a cam timing issue. I managed to remove the upper timing belt cover bolts and have a look inside. The belt is not broken, but it can be easily pushed down between the two cam gears. I have not had time to drain coolant, remove the waterneck and upper rad hose to fully get the upper cam gear cover off, but I can see the tensioner seems to be still in tact.

As well, I tried checking the timing with a timing light (yes with the jumper in place!), and I believe the timing is so far out I am unable to see any line at all. (I have done this in the past, and it WAS set to 10* BTDC with jumper in place).


Any ideas as to what would cause the timing to go out of wack, and the belt to go loose all of the sudden like this?

Your help is appreciated!
Thanks guys

 

[mkiiichip]

Timing is out of wack because the cams are not aligned.

The 7m does not have a self adjusting timing tensioner, so as the belt stretches it becomes loose.

How old is the belt? Was it installed with the proper tension?

 

[jdemara]

Clearly the timing is out of wack from the gears not being aligned anymore. They HAD to have skipped some teeth from the belt being loose. I have read something to do with a guide on the pulley breaking off, or a bolt even breaking causing a pulley to become loose - but would like to see what others have to say about this.

The belt has always been tight since I have had the car, and I have never had an issue with timing in the past.

Belt is fairly new (less than 40,000km)

 

[JStoked]

Ok I have seen this before. On the cam there are three dowl pins and a bolt that hold the cam gears on. Please correct me if I'm wrong. But on the motor that have seen that had the similar prob the dowl pins had wore out and broke off the cam leaving only the bolt to hold it and that won't work. So that will give you a starting point to look at. I'll go take a look at that motor tomorrow and to make sure I'm telling you the rite info.

 

[kneedragger85]

Check the length of the tensioning spring...

 

[Quin]

Check the length of the tensioning spring...

I'd put my money on this, or the bolt on the tensioner coming loose. I've never heard of those dowel pins breaking but I have seen people forget to put them back in. I can't see you making it this many miles without this happening if you forgot to put em in though.

Either way, time to yank that cover off.

 

[CajunKenny]

My money is on the belt being loose enough to jump some teeth.

 

[jdemara]

welll... easy fix tensioner pulley separated into two somehow! time for a new one and a new belt and I'm set.

99% of the time I am one to do the work myself on my car, but with the lack of daylight and amount that I am at work, I have no time for this - so It had to be taken to a shop.

Tomorrow when I get it back, I'll see if they were smart enough to actually get all the timing set properly!

 

[Poodles]

Hope they torque the tensioner bolt properly...

 

[jdemara]

Haha! I printed out the timing belt portion out of the TSRM for them, and HIGHLIGHTED the torque for it... Was very clear with them about not over torquing.

Hope they listened!

 

[shaeff]

For what it's worth, I had a similar problem several years ago. It ended up that the tensioner was actually bent, and would keep the belt tight during rotation by hand/socket wrench, but would lose time as soon as the motor was started. Drove me nuts for about fifteen minutes until I figured it out. New tensioner and I was on my way.

 

[Nick M]

Timing is out of wack because the cams are not aligned.

The 7m does not have a self adjusting timing tensioner, so as the belt stretches it becomes loose.

How old is the belt? Was it installed with the proper tension?

To add to chips post, as it ages, the spring needs to be checked for length and replaced when it is too long to prevent the slipping you describe.

 

[jdemara]

Here was the problem!

 

[Nick M]

Here was the problem!

Toyota still sells them new, and the spring. Get both.