98 S70 Timing belt off one notch on exhaust cam

[kevins s70]

Today I decided to replace the timing belt idler which has be squeaking for a while. When I was lining up the timing marks prior to removing the belt, i noticed that the exhaust cam is out one full tooth (lagging). It has been driven at least 15k this way and seems to run fine. Wouldn't being out one tooth be a problem??

Thanks

[erikv11]

One tooth has been posted about before, it will put the engine out of time but will not cause valve interference. If you correct the timing the fuel economy may improve and the car may run better.

You will want to make sure it is really off by a tooth, e.g. there is also a small chance that a combination of a stretched belt (very common as they age) and altered cam timing (sprocket(s) moved on the end of the cam(s)) makes it appear to be off a full tooth when it was actually set correctly.

I would eyeball the slots on the back of the cams when the sprockets are on the timing marks, just to be sure. The slots should be parallel to the surface/seam of the head. A little extra work to see them but worth the trouble here.

[kevins s70]

Thanks Erik. I just read through the post in the database and it does answer my initial question. As far as checking the cam sprocket I don't see slots you are mentioning. Where are these located?

[FLXC90]

He's referring to the slotted holes on the face of the sprocket, some sprockets have them to attach with. They allow adjusting the cam timing to an extent, without disassembling everything. What he's saying is verify the true cam position at the back of the head ( under distr. and cam sensor) Then if the sprocket timing has been adjusted, the timing mark may be off, if the belt is stretched, the cams probably won't line up properly at the back-end.

[kahl]

here is a picture

[erikv11]

What those guys said. Here are the cam slots, from the inimitable Tracey's head gasket tutorial

[broken images removed]

Volvo 5-cylinder: How to Replace the Head Gasket

Set the slots, that is how the engine came from the factory. Then check the cam gear marks, if they are off then you can correct them by loosening the cam sprocket bolts and putting them where they need to be. Install a new (unstretched) belt and you are good to go.

[rspi]