Oh No!! Jumped Teeth with stage II cams

[haydenm315]

Anyways I did a 60k a little over a month ago. I had trouble with the belt whining from being too tight. I loosened it after 3 weeks since the noise didn't go away entirely.

The whine was gone after loosening and the car felt powerful. Everything seemed good for a couple days, then I noticed a drop in power after filling up. The car still had power, but felt like it was in the hole a little. I thought it could be the fuel since I noticed Sunoco is sticking it to me with 10% ethanol. I feared a loose timing belt so tore into it today. The belt is loose at one part in the rotation of the crank. I noticed the cams are 4 teeth behind the crank.

I ordered a new belt and tensioner. THe engine didn't sound bad like things were getting tore up so I hope everything is still ok. I'm praying actually. What are the chance I messed something up with the valves? How much do the cams and crank have to be out of whack for bad things to happen with my motor?

 

[shomesomesho]

Well, Stage II cams do make it an interference motor. . . .

 

[jedhead]

Thats true the Stage 2 cams make the engine an interference motor. Hopefully none of the valves contacted the pistons.

Bob

 

[haydenm315]

How would I know if the valves hit the pistons? I watched some engine animations and I think I'm ok. I am no expert though. If 1 set of valves hits... (exhaust/intake) those valves will be damaged for each cylinder since each cylinder will be the same amount out of time. I'd imagine things wouldn't sound very good.

Here's what I think. The intake valve closes when the piston reaches bdc on the intake stroke and the exhaust valve closes when the piston reaches bdc on the exhaust stroke. I think this is right? Since the valves close when the piston is in the down position, there is still configurable timing for the valve to open before the pison comes back up. I think things would have to be more out of whack to cause damage.... like maybe almost 180 degrees or a belt breaking, sending the cams spinning uncontrollably no doubt smacking the pistons a couple times before grinding to a halt and saying no mas.

They sell adjustable cam sprockets that lets you play with the cam timing some. If I'm correct, there should be some play in both directions.

 

[Mr Anonymous]

Easiest way is to run a compression test, that will tell you if there was any piston and valve collision.

 

[haydenm315]

Ok... so I tore into it this morning. It turns out I was lucky. I didn't skip any teeth. I mixed up the marks on the crank pulley and read the 60 DBTDC mark. The timing belt was loose though... frighteningly loose. The belt was wearing on the case. I suspect it was walking around. Before I took it off, I turned the engine a couple times to note the difference in tension at the noted point of most slack. I think it's gotta be pretty hard to jump teeth after this little incident.

I tore it down, replaced the belt + tensioner, put her all back together, and had my tools all put away in about 4.5 hours. Probably a personal best. It's 26F outside today and I was working on the street.

The car seems better. I'm sure I got the tension procedure right this time. I can rest safely now

 

[1993MTXSHO]

Ok... so I tore into it this morning. It turns out I was lucky. I didn't skip any teeth. I mixed up the marks on the crank pulley and read the 60 DBTDC mark. The timing belt was loose though... frighteningly loose. The belt was wearing on the case. I suspect it was walking around. Before I took it off, I turned the engine a couple times to note the difference in tension at the noted point of most slack. I think it's gotta be pretty hard to jump teeth after this little incident.

I tore it down, replaced the belt + tensioner, put her all back together, and had my tools all put away in about 4.5 hours. Probably a personal best. It's 26F outside today and I was working on the street.

The car seems better. I'm sure I got the tension procedure right this time. I can rest safely now

wow 26... your dedicated hope all goes well

 

[SHOtime2511]

i guess ill be double,no triple checking everything on my 3.2L w/stage2 cams im building.and a new tensioner is in order i think!

 

[haydenm315]

i guess ill be double,no triple checking everything on my 3.2L w/stage2 cams im building.and a new tensioner is in order i think!

I'm a little more at ease now on jumping teeth since it didn't jump with the belt way loose.

I think the key is tightening the tensioner on that first mark on the crank when it's 60 degrees before TDC. There's something about there being the most amount of slack on the tensioner side of the belt. I was skeptical about this, but it is true.