S50 rattle?

[ck_taft325is]

Alright, the S50 is out of a '94 (04/'94 build date) with 133xxx on it. Original Greg and I figured it was bad gas making it idle like crap. And by that, it has a pretty noticable/significant "knock/rattle" at idle. The idle itself (as per emissions testing screen) jumps between 780-800. I'm noticing a slight lop, or low spot as well when at idle.

When on the throttle, not WOT just basic acceleration, it's not losing power, or hesitating at all.

Spark plugs? Coil pack? Injectors? Any help or where to start would be appreciated.

It's the wrong section entirely, but the trans (Zf320 -> S3.46) makes a huge whine at nearly any speed or in neutral while moving. At highway speeds it's pretty damn loud. Shifting into second is notchy and just about any gear except 5th at lower RPM's has a *clunk* 'ing sound.

Normal and I'm imagining things or should I start looking around?

[dude8383]

Do you have a vid of the noise that its making? Sounds like a faulty vanos unit...you probably have the early design too.

[MattM]

hopefully this is obvious, but have you checked the fluids in the ZF? they do tend to be noisy when low

[ck_taft325is]

hopefully this is obvious, but have you checked the fluids in the ZF? they do tend to be noisy when low

I haven't yet. To be honest, this was supposed to be a project car into a DD after everything was squared away and went straight from project to DD with like... 2 hours inbetween.

So the ZF's do whine a bit when low? I'll get on that ASAP and check. Here's a question... how? ;)

Well the engine after it's second tank of Premium (Dinan chipped for 93 octane) has definately smoothed out a bit. I'll run another couple through and see if it continues to improve. It's still there, but it's not like stuttering when it's idling.

[ck_taft325is]

Do you have a vid of the noise that its making? Sounds like a faulty vanos unit...you probably have the early design too.

Missed this reply. Stupid smart phones.

Faulty VANOS unit sounds like... a lot of money. The engine noise definately sounds more from the *cringe* bottom end of the engine. I'd put it at the fourth cylinder back from front.

[Fusion]

Including right after startup and throughout engine temps?

[MattM]

undo the bolt on the side of the tranny (passenger side of tranny IIRC). stick your finger in and feel for fluid, should be right at the base of that hole if the car is sitting level.

[Fidhle007]

How long was the motor sitting before you installed it? They have hydraulic lifters that will go dry if they sit for awhile so warming it up and doing an oil change might not be a bad idea if it's been stationary for awhile.

[ck_taft325is]

Pinned down the trans noise. While fluids will be checked and freshened... It's sadly not the trans. It's the 3.46lsd. I didn't want to admit it, but Greg confirmed it last night with me.

Not sure how long the engine really sat. We'll be doing the knock sensor as ecen with a stock chip it's throwing the same code 1121216 iirc.

Vanos rattle on high rev, but it's almost not even there. We'll see what the knock sensor replacwment yields.

[Fidhle007]

Do you have solid subframe and diff mounts and/or a rear seat?

[Roland H]

94.6% chance it's your VANOS.

Cheap fix, but time consuming.

https://www.beisansystems.com

[ck_taft325is]

Do you have solid subframe and diff mounts and/or a rear seat?

Negative on the subframe or diff mount. Yes on the rear seat.

[ck_taft325is]

94.6% chance it's your VANOS.

Cheap fix, but time consuming.

www.beisansystems.com

Would VANOS rattle come from the bottom end of the engine? Keep in mind the damn thing will blow its own doors off if put at wot.

[Roland H]

Would VANOS rattle come from the bottom end of the engine? Keep in mind the damn thing will blow its own doors off if put at wot.

VANOS rattle comes from under valve cover.

a failed VANOS won't effect top end power, only low-end and mid-range.

If the VANOS hasn't been serviced ever on that motor, it's shot. Period. It's a cheap fix, and makes the motor run a lot smoother and quieter. Also gives it more low end snap.

If the noise is coming from under engine, could *maybe* be a tensioner.

If it only occurs when the clutch pedal is out and the car is running, you have a gearbox issue. These gearboxes do whine when low, and they tend to get low if the selector shaft seal is leaking (common). And a little diff whine is normal. My 3.38 does when I have the seats folded down in my E36.

Pour a full can of seafoam into the crank case and drive 150 miles.

[ck_taft325is]

MORE low end snap? I couldn't imagine, honestly.

The VANOS only rattles at all after a very hard rev and Greg and I have gone over most of it. While I would definately service it myself shortly here, it's not quite the rattle/stutter that's coming from the bottom'ish end.

The gear box is solid. It's most definately the diff. I didn't want it to be, but it is. The diff isn't really whining as much as almost screaming.

I'll definately pop some Seafoam in it over Christmas while we're going between Orting and Renton and see what results I get.