[mgkuhn20]

Hey all, I have a question, I think I know the answer but wanted more opinions. I have a 96 with the 3.3, I was coming home and it just died, no codes nothing. The car would not restart at all, has plenty of spark, crank and cam, sensor were good, good fuel, however it was backfiring thru the intake.
Yesterday I removed the timing chain cover and discovered that the chain had jumped and the cam was 180 degrees out from the crank. I replaced the sprockets and the chain and guess what, same no start but backfiring thru the intake.
So my guess is that the valve stems must have gotten pounded by the piston since it was exactly 180 degress out, so this would mean a complete rebuild. So any one who knows more about cars than I do, which will be most of you, tell me what you thing, and if what I have said sounds right.

Thanks,
Mike

 

[Lafrad]

That sounds very right.

I had an '87 Olds with an interference 3.0L engine... stripped a timing gear. Bent all 16 valves, and all 16 pushrods.... but the valve guides and rockers were all still good. there were some scratches on the pistons.. but nothing that was unsafe.

Sounds to me like you need to do the same thing. New Valves, and new Pushrods. Rockers should be fine.. and the valve guides *should* be ok... I don't know how strong they are on the 3.3....

 

[ladelberg]

Assuming your analysis is correct, you should just have to pull the heads and have them redone if they actually hit (I am not sure if the 3.3L is considered freewheeling or not as they don't usually provide such designations for chained timing).

Let me say this and please understand I am not trying to be disrespectful. In 20+ years of working on cars, I have NEVER heard of a chain skipping EXACTLY 180 degrees. I HAVE in the past made similar observations and found I misunderstood something (as the Fonz would say "I was WRUH-WRUH-WRUH" - OK, I am old ). But here is what I know from working on the 3.5L we have, the 3.8L in our Caravan and the 2.0L in our Breeze, if you pull the cam sprockets off, you need to lock the cams down with the cam alignment tool before you reattach or your timing will be way off. I have had the sprockets off of the cams and they are S-L-O-P-P-Y on the D mounts, several degrees play either way.

Once you do that, run a compression check to see if your valves are screwed (I don't think they will be but not really sure). Your valves may very well be bent and then you need to pull the heads and do a valve job.

 

[Lafrad]

The 3.3's and 3.8's are your run of the mill, Interference engines. if you strip the chain.. you most likely will bend some valves.

180 degrees almost makes sense.. as that is the next point on the rotation that the valves won't be in contact with the pistons.

 

[mgkuhn20]

Thanks, One question, the Haynes manual said that the cam sprocket should be at 6:00 and the crank should be at 12:00, does this sound right, because if it is then when I pulled the cover off the cam was 12:00 and the crank was 12:00 also. The chain was tight on the drivers side and had 1-1 1/2 inch play on the passenger side.

Thanks,
Mike