[xxmrman1991]

I have a 1990 300zx NA 2+2. The engine sounds as if it were cranking but the cam shafts do not rotate!??! The car was bought as a project from a guy who gave up half way through an engine swap...good times. Anyway I am really hoping that it is something simple and not a improperly connected trans.

 

[thor2004]

If it's cranking and cams not turning, I'd say it's a timing belt problem (broken).

 

[xxmrman1991]

That's the strange thing, the timing belt checks out Tip Top.

 

[xxmrman1991]

ok this is very strange. I removed the air intake boots from both sides of the engine as well as the hoses that go along with them and now the cams are rotating, there is spark, and the car started. Go figure. If anyone knows why in the world this might have happened please let me know.

 

[OchnofConcrete]

that just doesn't happen.

your crank is connected MECHANICALLY via your timing chain to the cams.

even if there was a complete vacuum on the intake tubes the failure would be at the piston rings, i'm sure.... or the timing chain.

i think you were mistaken.

what happened that caused you to think the cams weren't moving?

 

[xxmrman1991]

I had a friend tap the starter a few times while I watched the cam pulley.

 

[xxmrman1991]

Oh well, the good thing here is that it does run. I don't have the foggiest notion about what happened here but I shake my head and laugh confused and satisfied. Thank You.

 

[thor2004]

You can't see the cams. They're covered with plastic. To take plastic off you have to already have intake boot and hoses off. Fan off and all belts. Don't make any sence.

 

[xxmrman1991]

you can get them off with small hands and a lot less work than that.

 

[OchnofConcrete]

lets get down to it...

you tapped the distributor CAP????? or the distributor HOUSING????

if the cams didn't move when you moved the CAP, that's normal... that's the distributor spark timing your f^kin with. not good if you don't want detonation or a completely off spark.

if the cams didn't move when you moved the HOUSING, then you've got an effed up distributor gear or housing. maybe stripped gear.. maybe bent distributor shaft ~more likely~

if you cams moved with the distributor, you're fine.

after knowing that...
what happened to make you think that the cams and the distributor.. or the crank weren't mechanically timed. (moving together)

 

[xxmrman1991]

I had the distributor off and was watching a white TDC mark on the right hand side cam. It appeared to not be moving at all. I MUST have been mistaken. I would like to think that I know motors in general pretty well. I am aware that there is a mechanical connection between mostly everything including the crank and cam shafts. There is no way that without the timing belt being stripped out at the main crank gear that the cam would not turn.

I have no idea what happened here, but I guess that's what I get for working on the car for 20+ hours at a time.

The good news is that today I threw some Premium fuel in it and fired it up for a few seconds. It ran quite smooth too.

 

[OchnofConcrete]

oh yeah.. been there... after your 3rd wind goes it gets a crapload more frustrating when you can't find your 10mil socket. heh.

i wasn't sure how much you knew and it just sounded off.

any chance it was a glare on the cam? but just to clarify.. you had the dist. out of the dist housing timing cover and you were spinning the crank to get to TDC and the cam wasn't turning?

 

[xxmrman1991]

ah yes the elusive 10mil. It is very possible that it could have been a glare. I was having someone hit the starter while I observed.