Timing Belt Slack Explained [Merged 6-7] loose cam sag sagging sprockets gears

[defbear]

I was just wondering if its normal for the timing belt to have some slack after its been sitting over night. I have been checking it for the past few days. When the car has just been shut off and for a few hours after its nice and tight with virtually no play. But in the morning when I check it there is some, not alot, but some play. More than just after its been driven. The timing belt and tensioner were replaced about 2000 miles ago. Anyone have any ideas?

 

[91talontsiturbo]

i have the same problem but mine wasnt resently changed its been on there for'a while in i dont have a clue as to when the last time its been changed , mine looks tha same as in the pictures thow

 

[Defiant]

Since it seems that no one is reading the link, here's a cut-and-paste:

That slack is normal for the timing belt. When stopped, the cams are being pushed on by the valve springs. When it stops at just the right point, the intake will be being forced CCW, while the exhaust is being forced CW, making for the slack you found. The slack's taken up by the crank before the engine fires, but it's also what's hardest on the belt, and why it's so common for a belt to fail at startup, shutoff, or during idle.

 

[50trimtsi]

Thank You Defiant. I appreciate all the help. No longer worried

 

[blackGSX2g]

That slack is normal for the timing belt. When stopped, the cams are being pushed on by the valve springs. When it stops at just the right point, the intake will be being forced CCW, while the exhaust is being forced CW, making for the slack you found. The slack's taken up by the crank before the engine fires, but it's also what's hardest on the belt, and why it's so common for a belt to fail at startup, shutoff, or during idle.

Sorry to bring this back from the dead, but my new 6-bolt does this too. If that amount of slack is normal in the belt on startup, is it normal to see the belt flap up and down at different RPM points when you rev it? It just seems like that would be hard on the belt.

 

[notractiongst]

Sorry to bring this back from the dead, but my new 6-bolt does this too. If that amount of slack is normal in the belt on startup, is it normal to see the belt flap up and down at different RPM points when you rev it? It just seems like that would be hard on the belt.

it shouldnt be flapping id get that checked asap if not sooner

 

[blackGSX2g]

Yea, thats what I figured. I haven't driven it yet, I shut it off as soon as I saw that. I took off the auto tensioner and looked at it...doesn't look like its leaking or anything, but I can push it on the ground enough to put the pin through the hole. I went back and found my 2g tensioner and its solid as a rock. I had to really crank it in a vice to put the pin in it. Is this my problem?

 

[TwoLiterV8Eater]

Yes, get a new tensioner immediately. Good thing you noticed it.

 

[1fast97gsx]

yea definitly take that sumabitch apart and figure out whats wrong. An interesting fact though that I learned the hard way when I did my 6 bolt swap .... the tensioner pulley has 2 small holes in it and then 1 hole in the middle. Well the 2 small holes when you do a 2g timing belt job sit horizontally BELOW the center bolt. On a 1g the pulley gets rotated so they sit above the center bolt horizontally. I didn't pay attention to this and did my timing belt the 2g way. Well what happens is the tensioner pulley doesn't freely spin because it hits the arm and you see the belt lose / gain slack and I actually skipped timing by a few teeth. I took it apart and realized what I did wrong after staring at it for a while. Luckily nothing broke and I fixed that and it also fixed the belt issue. Just something to think about. Good luck.

EDIT: Just read your last post. You shouldn't be able to compress it like that ... you need to stick it in a vice and really crank on it to get it to compress. Replace the tensioner.

 

[blackGSX2g]

Thanks guys, I'll go get a new auto tensioner tomorrow.

 

[BGRIPTP]

Mines also like that, but it goes back to normal when it starts up... well atleast it did last time it ran in November...

 

[750_sport]

That belt looks ok. You want some slack in the belt. As the engine heats up it expands. You need some slack to take up the expanding motor. Most belt slack up from wear on the belt teeth and the gear cogs. Yeah you should tighten it. But you want some slack!

 

[Prez]

THAT BELT IS NOT NORMAL. I REPEAT IS NOT NORMAL.

The very first time I did a t-belt mine came out like that. I had a veteren DSMer come over and he was like woah.. thats not right so we took it all aprt. Turns out I installed the Tensioner pully incorrect and jumped 3 teeth. ON the tensioner pully there are two holes. Those holes need to be at 11 and 1 o'clock when you tighten the bolt. This will take up the slack. My new motor has been sitting on an engine stand for 2 weeks and has next to no play in the timing belt.

THE BELT SHOULD NEVER BOW OUT TO THE TOP. NEVER.

 

[RamenPride]

when I was changing my valve cover, I noticed that mine was the same. it's been like that for a couple thousand miles now...

 

[Prez]

when I was changing my valve cover, I noticed that mine was the same. it's been like that for a couple thousand miles now...

Personally I would be tearing the timing apart and checking the hydro tensoner and the tensoiner pulley. But hey I don't like spending a couple grand to rebuild my engine when a 100 dollars and some sweat would have saved me from it.

 

[RamenPride]

Personally I would be tearing the timing apart and checking the hydro tensoner and the tensoiner pulley. But hey I don't like spending a couple grand to rebuild my engine when a 100 dollars and some sweat would have saved me from it.

I did happen to have the timing covers off at one point in time after this, and everything was fine down there

 

[Defiant]

THAT BELT IS NOT NORMAL. I REPEAT IS NOT NORMAL.

The very first time I did a t-belt mine came out like that. I had a veteren DSMer come over and he was like woah.. thats not right so we took it all aprt. Turns out I installed the Tensioner pully incorrect and jumped 3 teeth. ON the tensioner pully there are two holes. Those holes need to be at 11 and 1 o'clock when you tighten the bolt. This will take up the slack. My new motor has been sitting on an engine stand for 2 weeks and has next to no play in the timing belt.

THE BELT SHOULD NEVER BOW OUT TO THE TOP. NEVER.

Go back and read Post #13.

 

[Defiant]

That belt looks ok. You want some slack in the belt. As the engine heats up it expands. You need some slack to take up the expanding motor. Most belt slack up from wear on the belt teeth and the gear cogs. Yeah you should tighten it. But you want some slack!

Uh....

no, nevermind.

 

[Catbox_95]

I put my car together last night from a 2 month break-down. I'm not a newbie when it comes to timing belt installation and tension setting. Drove it around for about an hour to check things out, get home, things are fine. This morning I go out, pop the hood and grab the timing belt between the cams and if feels loose, much looser than last night.

So, I start it up, pull it in the garage and shut it down. I feel the timing belt, and it's tight-feeling again.

Is it normal to loosen up while just sitting there? Can someone (who doesn't have a belt cover of course) go out and feel yours if your car has been sitting over night and see if it feels loose?

 

[gsxboostin]

I have had that too man, I didn't worry about it it never skipped teeth or anything so I think its ok. later -Matt

 

[Strm Trpr]

The reason it feels loose after it sits for a while is because when you shut your engine down at least one of the pistons is on a compression stroke which causes the piston to creep downward turning the crank, which then turns your exhaust cam toward your intake cam causing some slack between your cam gears.
At least that's what I was told when I posted the same exact question a while ago.

 

[Catbox_95]

Yes, that makes sense. I am a little paranoid about it because, the cause of the 2-month break-down was a slipped timing belt, hence 12 bent valves. But the timing belt slipped because the balance shaft belt broke and got lodged between the timing belt and the crank pulley.

This is my luck.

So a saggy timing belt did cause some concern, but for now I will be satisfied with the "compression-stroke engine-backlash exhaust-cam-creep towards the intake-cam" theory.

Thanks guys..

 

[project_tsi]

I recently did a timing belt job on my 91 Laser. I replaced the timing belt, hydraulic tensioner, and both idler pulleys, and also removed the balance shafts, so no belt there. however, I notice that when the engine sits and cools back down my slack on my timing belt gets to be alot. This may not have anything to do w/ the temp of the engine, I actually dought it does. When its "Loose" and I just tap the key, the belt tightens back up immediately, kinda like maybe my hydraulic tensioner is the problem, just loosens up from sitting? I dont know, it may not be a big deal since it does tighten back up immedietly whenever the key is turned. It has approximately 1000 miles on the timging job. I just dont want it to be too loose one day and jump timing. take a look for your self.

 

[Staytuned]

You may need to rotate your tensioner pully a bit more to take up that slack. The auto tensioner may not be able to remove enough of that slack on it's own.

 

[blackGSX2g]

When the motor stops at a weird position where the cams have some tension from the valve springs, they will sometimes roll back putting some slack in the belt. This is why a high number of timing belt failures occur during startup.

As long as the belt has solid tension after its started up, it should be fine. Just make sure the belt isn't flapping up and down when you rev it a bit.

 

[project_tsi]

yeah the adjustable pulley may need to be adjusted, i never thought of that. the hydraulic tensioner may be "maxing out" upon some startups.

Also, the timing belt is otherwise perfectly fine while the engine revs, i had the hood opened and revved her up and no flapping or anything, looks like it should, nothing suspicious.