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?

 

[brrrnntsshhhh]

heres what i have.
1g head on a 2g
mitsu metal headgasket (slightly thicker)
recently done timing belt job, can see the little color fade on the outside of the belt. (i thought that this was a sign to replace the timing belt, but seing as i just did it less than 100 miles i figure its normal?)
* the auto tensioner mitsu gave me didnt look like the one on the vfaq or the one that was on before, but it fit. *

here's whats going on.
my car has had some trouble to start it, either it would start up right away, or it would take alot of cranks, a break, and then another try. it also sometimes stalls right away. could this be caused by a timing jump?

now here's my question.
will a timing belt with alot of slack make it difficult to start up if the timing had jumped? however after i cranked it wasnt loose anymore between the cam gears.

I set my tensioner to spec when i replaced the timing belt, and I read that having some slack between the 2 cam gears is fine because at the right position when turned off the intake cam gear goes ccw and the exhaust cam gear goes cw.

 

[sonicnofadz]

1.) Turn the motor over by hand at least 6 times, and make sure that you can feel no resistance for rotation. Also double check the all the timing marks, it can look like everything is dead on but you can still be off by 1 tooth.
2.) If you have a 7 bolt block, make sure you have the right hydraulic tensioner (I forget the part #). Take off the tensioner (take off the belt while your at it) and show them to the dealership. Make sure you have the right belt and tensioner for your block. There shouldn't be any slack on the belt.
3.) If all else fails, take your car to a real mechanic.

If you are lucky, you didn't damage your valves. If you are unexperienced with automotive work, it is not recommended that you try to do something like change a timing belt, because severe engine damage can occur if it is not done properly.

 

[brrrnntsshhhh]

the tensioner i have is different than what all the pictures of tensioners i see, and it was different than the one that was on there before, i have a 7 bolt block. i figured that mitsubishi changed thier design in them since the part numbers match and everything, i am thinking this is the problem though. lucky for me all marks lined up at tdc and i didnt jump any teeth. i will take it to them tomorrow.

 

[sonicnofadz]

I don't often do timing belts on 7 bolts, but I would definitely be weary of a tensioner that was different than your stock tensioner. Good thing you caught it now, and not after your engine was destroyed.

 

[myeclipseisnice]

hey sorry for bring this thread up from the grave, but i have the same problem. i wont be able to test my car untill i get back to work tomorrow. but i want to click on that link to see what it is but it isn't working... defiant can you explain or maybe post a link that works now (2 years later) thanks... bye

 

[jnf63]

I have noticed a good amount of slack in my timing belt between the cam gears. I am an admitted novice, yet I have looked through many threads about the topic of timing belt slack. The one thread (Timing Belt Slack Explained [Merged 6-7] loose cam sag sagging sprockets gears) stated that slack occurred due to the cam gears rotationally moving towards each other with the engine turned off for a while. This made me feel better since it also stated there could be an alarming-looking amount of slack. I also read that the slack might show 1/2" or 3/4" of play. However, I am concerned because the mechanic that is presently repairing my A/T doubts that the slack concept (of the 3g63 exhaust cam) accounts for all of my slack. I used the information in the threads, and I turned the exhaust cam clockwise by hand which tightened the belt better. Later, I also used the starter to turn over the engine (without letting it completely start). Immediately after doing this, my timing belt is not so loose. My concern exists because a previous "performance shop" had installed 264 cams, and a titanium springs/retainer kit (as well as an FMIC and a fuel system upgrade). Unlucky for me, the previous "performance shop" did not properly fasten the I/C piping, or the automatic transmission cooling lines/cooler (and I have been told that the fuel parts are also poorly routed/set [idling issues]). Needless to say, after driving less than 80 miles (2 days) my A/T oil lines popped off the cooler (while driving on a major highway) and created a BIG mess. Put simply, my new IPT A/T is cooked, and several of the pieces on my engine are burned (A/T oil fire). Due to the carelessness of the previous shop, I am concerned that my timing belt may be too loose since they handled it to install the upgraded head parts. My fear is that many of my new engine parts could be in jeopardy from the previous shop's sloppy work. I have (had?) a new SBR engine/head (with a new oil pump housing, a new timing belt kit, a new water pump kit, all new belts, ect) meaning that the tensioner and belts should be (had been?) strong. I really hope that I did not bend any brand new SS valves, or get any piston damage due to an overly loose timing belt. The present mechanic (who is mainly a transmission specialist) looking over my GSX believes that my valves are bent based on how loose my timing belt looks. To illustrate my concern, I shall try to include photos showing the loose belt, and how it changed after moving the cam gear, as well as after turning over the engine. I hope some experienced DSM people can give me some feedback about my timing belt worries. My profile has been updated to show what has been recently added to my GSX. Thank you in advance for meaningful explanations. (By the way, I just successfully won a small claims judgment against the "performance shop" for the A/T replacement, the A/T oil line repairs, and the wiring repairs [burned].)

 

[snowborder714]

The first three pictures definitely are too loose. The last two look better. If you push down on the belt between the cam gears, how far can you push it (normal pressure, nothing he-man)? If you grab the belt in that same spot and try and rotate it, how far does it rotate?

Also see if you can check these same things between the cam gear and each pulley. I believe my belt will typically rotate about 45* or so. There is a FSM value for depression if you'd like me to look it up, but I usually don't follow it. As long as it feels tight (but not so tight it's really hard to depress/rotate), I'd say it'd be fine.

 

[VETTE_50_TH]

Those two pics look like you could take the belt off. How the hell did the car run like that? I bet your tensioners are bad. Or not even tensioned.

James

 

[jnf63]

Brian,
Thanks for the information.

After writing your brother an e-mail, I checked the tension of my timing belt. I got power to the starter to make the engine turn over without it starting. Immediately after turning over the engine, the portion of the belt between the cam gears twists 40-45 degrees. This same portion moves up and down a little less than 1/2" under some "normal" pressing/pushing pressure. As for the other portions of the timing belt, I have not yet removed the timing belt covers in those areas. Nevertheless, I reached inside the cover using a wooden dowel to check the amount of play. On the portion of the timing belt between the (intake?) cam gear (gear closest to the radiator) and the tension pulley, there is about 1/2" of movement away from the "stretched" (resting) position when using "normal" pressing/pushing pressure. On the portion of the timing belt between the (exhaust?) cam gear (gear closest to the windshield) and the next pulley, there is about 3/8" of movement away from the "stretched" (resting) position. Since the belt covers (plastic) block me from checking the other belt portions, I could not check them. Also, I did check these same portions prior to turning over the engine tonight, and the portion between the cam gears had only slightly more slack (compared to after turning over the engine [I had turned over the engine the day before]). The slack between the intake cam gear and the tension pulley had a similar amount of slack. In contrast, the slack (immediately prior to tonight's turning over of the engine) had been about 5/8" between the exhaust cam gear and the next pulley. So, this portion changed the most tonight. I hope this helps explain the things that you were asking about concerning my overall slack.
Jim

 

[jnf63]

James (vette_50_th),
Your thoughts are the same as the present mechanic's feelings. My GSX drove about 80 miles with the timing belt in its present condition. The belt seems to tighten better once the engine is briefly turned over. The top three pictures illustrate how the belt looked after being towed to my house and setting for several days. The bottom two pictures show the belt's tension after briefly turning over the engine.

I am hoping that all I need is to check/adjust the tightening of the belt. If it needs another new tensioner, then so be it. However, I hope to not have to replace new valves and/or pistons because of sloppy workmanship. Going back to small claims court to get funds for getting these possible problems fixed might not be as easy as the A/T problems were proven to be poor workmanship.

Anyway, I also would like to compliment you (James) on the 8/8/09 DSM meet that you have been administrating. I shall be one of those attending without a DSM vehicle. My GSX will not be running that soon (it should have been ready, except for bad workmanship). So, I guess that I shall have to park my truck in another lot.
Jim

 

[snowborder714]

Do you have any idea when the last time all the timing components (belt, 2 pulleys, tensioner, etc.) were replaced?

As bad as this may sound, I would feel most comfortable taking it completely apart and checking every component. Or just replace them all. I know you'd probably rather not replace them all (and I wouldn't if I was you going through all the crap you have lately). But a belt should not lose tension like that, even if it sits for a few days.

It sounds like you really need to have someone who knows what they're doing look at it. Tow it over to our place

 

[VETTE_50_TH]

I just learned how to time dsms and evos now, and can do it relatively quickly. I would help too. I would bet its the tensioner pulley if i were to guess right now. Which is fairly simple to change/tighten. Download or buy the manual and go through the steps of tensioning the car with the belt on. If you need help, give me a pm and ill help you over the phone.

James

 

[VETTE_50_TH]

I would also crank the car manually and see if you're able to line up the timing marks at all. Or see how bad they are off.

James

 

[954TalonTsi]

Looks to me like it is your tensioner. Thats the only thing that i can think of.

 

[jnf63]

The timing belt components were all new in May 2008, and the components have about 2100 miles on them. The replaced (OEM new) parts were the belts, tensioner, water pump, oil housing (oil pump kit), harmonic crank pulley, idler pulley, tensioner pulley, cam gears (to adjustables), and all the covers. Basically, when I got the new SBR engine, SBR recommended that I replace everything associated with the timing belt and the harmonics of the engine (and also to replace the old radiator with a Koyo). I took their advice, and I did it all. Of course, any one of these new parts could be defective, especially the tensioner, as you guys have mentioned as a likely culprit.

Coincidentally, the idea about the alignment of the cam gears is one of the things that I was e-mailing Brian's brother about (in post #4). Eric and Brian have been providing ideas about all the problems my GSX has shown since getting it back from the previous "performance shop" that messed up my A/T (and several other things, like this timing belt thing). I am going to try to do the cam gear alignment procedure to check the placement of the cam gears and all (like James [post #9], Brian, and Eric have advised).

I greatly appreciate the information that all of you are providing. Please feel free to add any more ideas.