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?

 

[jonheslop]

Can anyone help me with this problem??? Every once in a while when I stop my car the timing belt will be extremely loose on top of the two cam gears. It's like all the tension came out of the belt. However, every time I check the belt it has perfect tension and all the gears are timed correctly. My thought is that the cams simply stop at a certain point where they don't stretch the belt out all the way because if I hand move one of the gears a tooth or so the belt tightens up. It's like the cam stops on a wierd part of a lobe and takes tension out. Any ideas???

 

[ROOKIE1]

Some looseness is normal . I do not suggest your test though . Move it tooth or so , your valves may not like that . If it is loose enough to pull off , it may be time for new tensioner .

 

[sb7775]

There is some loose spots but in no way should you be able to move it a thooth. Sounds like something isn't installed right or the parts are worn.

Steve

 

[jonheslop]

I think I've figured it out. My hydraulic tensioner isn't from the dealer and I think with all the timing problems I've been having lately I've crushed it in a C-clamp too many times. I think that tensioner is ruined. I bet when I first install the belt everything seems fine. However, once the car runs and compresses the tensioner, it doesn't expand back out once the engine stops. I think that's the problem so I will just have to suck it up and buy a new tensioner from the dealer. Does anyone know a place cheaper than slowboy to get a tensioner?

 

[jonheslop]

The belt is only a few days old. Every single part has been replaced except the hydraulic tensioner, which is new, but from autozone. I even changed out the bracket that the tensioner pulley bolts to and the hydraulic tensioner pushes against.

 

[ROOKIE1]

Yeah I'd say that is right . You have to compress it slowly , it is not like a brake caliper . If you did it quick , it is ruined . Thats how we learn .

 

[sb7775]

Out of all the parts to buy from the Zone the tenshioner would be last. On a car i was doing a belt job on the arm that the tenshioner pushes up on was worn to the point that it would not hold any tenshion. Just double check the arm. Good luck.

Steve

 

[oldman]

As long as the timing marks are still lined up and the loose part is only between the two cam gears, it is perfectly normal.

 

[oldman]

http://www.dsmtuners.com/forums/showthread.php?t=126376&highlight=timing+belt

 

[jonheslop]

I've already replaced the arm. The hydraulic tensioner wore a divot into the arm and no longer springs out far enough to keep tension so I had to replace that whole arm. It's fine now. I just need to get a new tensioner. That's all it is I think.

 

[GVR4592]

Why don't you check for proper tension and to see if your timing marks are lined up before you buy the tensioner, it's better than just assuming it's bad.

 

[jonheslop]

I have already checked the proper tension and timing marks over 10 times. I have taken this belt off and put it back on many many times. It's the same story every time.

 

[GVR4592]

Can you take a picture of the slack in the belt?

 

[jonheslop]

I guess I could. I'll put the pic on later today.

 

[jonheslop]

As you can see the belt is just loose enough to slip a tooth. Is that too loose to be just from the auto tensioner or can that tensioner make that much of a difference if it's broken.

 

[andymoraitis]

Whoa! That looks like a bit too much. Go ahead and replace the tensioner. I too have slop in the belt but mine doesn't rise up like that and come off the cam gears. While tension isn't measured between the gears, that looks excessive.

Let us know how it goes,

Andy

 

[GVR4592]

Can you get another picture with the timing marks lined up and only rotate the engine in the normal direction of rotation. I really don't think that's a tensioner problem.

 

[TimG]

That is not normal. I'd be replacing a tensioner tonight and I wouldn't be driving that motor to get there.

 

[GVR4592]

Can someone explain to me how the tensioner can cause excessive play in the belt at the top of the cam gears if the belt hasn't slipped a tooth? I'm not saying you guys are wrong, I just don't get it.

 

[oldman]

Can someone explain to me how the tensioner can cause excessive play in the belt at the top of the cam gears if the belt hasn't slipped a tooth? I'm not saying you guys are wrong, I just don't get it.

Can't be 100% sure without looking at it, but I suspect that either you're right and the belt has skipped or the exhaust cam will rotate CCW once the belt is properly tensioned.

 

[jonheslop]

The reason there can be that much slack even if it hasn't slipped a tooth is because when you put tension in the belt the exhaust cam gear will be pulled a little bit while the intake gear stays still and that stretches the belt back out. Both gears have a little play in them and the tension is the only thing that keeps them aligned right.

 

[jonheslop]

I don't know what is wrong now. I replaced that hydraulic tensioner with a brand new one from the dealer and I still have the same problem. The belt is fine and tight when I run the engine. But after it has cooled down the belt loosens. I think it is just the way that the cams land when they stop spinning. Does this sound right?

 

[ROOKIE1]

Are you sure you installed the tensioner pulley correctly . Are you also sure you have the correct timing belt . Find a part number on it and check .

 

[steve]

Can someone explain to me how the tensioner can cause excessive play in the belt at the top of the cam gears if the belt hasn't slipped a tooth?

I also think that belt is not only not tensioned correctly but off a tooth. There is no way that much slack is from the cams relaxing. If the belt is pre-loaded correctly there isn't enough play in the auto-tensioner to allow the belt to get than loose between the cams.

Jon,

How much clearance do you have in the auto-tensioner pin when you tension the belt?
I'd still like to see a picture of the timing marks right after you turn the engine over by hand a few times and the belt is "tight".

Steve

 

[jonheslop]

I don't mean to sound like a jerk but I'm not stupid...I know how to line up the timing marks and they are all perfect. I checked again yesterday when I put the new tensioner in. Everything is put on perfectly, the belt is the right one straight from slowboy and I have double checked part numbers on everything. Every time I notice the belt loosening I am able to turn the intake cam gear a couple degrees clockwise. I don't know if it should be able to move this much because the exhaust gear is always perfectly tight. Now I am thinking that maybe one of the lifters is not working and not keeping the cam still. As soon as I turn the gear a couple degrees it tightens right back up perfectly. And incase I didn't clarify, the belt is not off a tooth. I took my precious time when putting the belt on and went perfectly by the factory service manual. I'm really thinking it's something in the head. Does that sound right? Maybe a lifter isn't working? They are brand new revised lifters so they should be fine.