Cam Gear Movement

[DJ Robu5t]

Dumb question but couldn't find the answer. Is it normal for your cam gears/timing belt to move after your engine has been shut off? As in a good minute after it was shut off.. I was looking around the engine bay at the vacuum lines trying to figure out where one of the hoses off the purge control valve should go and I hear a noise and look over and the cam gears spin for a few seconds. Is it the engine cooling down or a bad tensioner or am I just crazy?

 

[pauleyman]

They can adjust position slightly becsuse of valve spring tension on the lobes but its very very small. Not like a tooth or something.

 

[SrKegler]

If you saw the cam move chances are you lost all tension, if the cam moved, bet you skipped a tooth on the belt.

 

[DJ Robu5t]

So.. maybe the timing tensioner is going bad? It's tight and doesn't slap around when driving, doesn't seem loose when off either. It just moved on it's own after the car was shut off. It was sort of freaky, and it was probably a good 4 teeth of movement. Would explain the rough idle and the car trying to lope then sounding like it's overlapping itself. If the timing is off say a tooth and is loose this would explain a lot of my smaller issues..

On a side note when I say cam gear movement, I mean both cam gears and the belt moving together rotating probably 3-4 teeth. Then it stopped.

 

[pauleyman]

No. Stop driving the car its a time bomb. You may have already done damage. A timing belt job is in order before the car goes any further.

 

[SrKegler]

The only way possible for the cams to move that much is if the car is in gear and parked on a slope. Low compression might allow the engine to rotate from the weight of the car. In any case, check things out, verify the timing marks are correct before starting the engine again. No sense trashing a head.

 

[pauleyman]

I disagree. Cam lobe alone will rotate a cam several teeth if the belt gets slack enough. Car does not have to be in gear etc.

 

[DJ Robu5t]

The car is acting the same way it's acted since I've got it, so it couldn't have skipped more, I'm thinking maybe it's always been off a tooth, I'm just trying to figure out if it moving while off means it's loosening, tightening, etc.? The car was in a gear in my driveway, which is barely a slope but is still a slope, perhaps that would be the answer.. Verifying timing marks on the cam gears.., I would need to make sure that the lines on each cam gear are in line with each other correct?

 

[pauleyman]

If it slipped 3 or 4 teeth there is no way it wound run the same. Now if the whole motor turned over 3 or 4 teeth thats different. You're making it sound like only one cam slipped.

 

[DJ Robu5t]

Sorry I was trying to clarify it and in doing so made it more confusing. It definitely did not slip, the whole thing turned what I'm thinking would be 3 or 4 teeth. Not just one cam, so I guess you would say the whole motor turned over..

 

[boost97gst]

You just have really good compression. Maybe thats it. Its stopping on an upswing and its enough to push it back down. Stock valve springs?

Big question: Does it do it 100% of the time after shutting it off? I bet not...

 

[DJ Robu5t]

No I've never really seen or noticed it before. But I'm not always sticking my head in the engine bay when I shut it off (even though it's natural for dsms ) It's a built block with around 5,000 miles on it, so I'm guessing that could be it. Not sure about the valve springs, we tore into the bottom of it, have yet to take the valve cover off, will be doing that this coming week. I know it has bc 272 cams

 

[pauleyman]

Dont park it in gear. If you want to check cam position then do so.

 

[DJ Robu5t]

Is that bad? Damn I've done that with all my cars.. now I have to fix my ebrake

 

[pauleyman]

On an interference motor I wouldn't. At the very least put it in the gear the car would move in. What I see is people put it in first on a hill or driveway but car rolls backwards and spin motor backwards.

 

[boost97gst]

Is that bad? Damn I've done that with all my cars.. now I have to fix my ebrake

haha, you kiddin? Me too bro. I ALWAYS parked in 1st and hardly ever used my ebrake. Done this on every manual tranny car ive owned. Lmao.....
Guess we were living dangerously

Edit: obviously not on a damn hill. Only on a small incline or on flat areas. If i park on a hill i let it roll back and let the tranny take the load, then pull the ebrake up. On that note, always turn your wheels so you will roll back in to the curb and not into the road if something ever let loose. But thats another topic..

 

[DJ Robu5t]

Ah I see.. and it's not a hill I live in Florida so we don't have hills, it's a slightly inclined drive way I'm no engineer but I'd say 5 degrees maybe less. But makes sense, lesson learned. Thank you guys