HELP! sound question (need input before i dig in)

[-=BoYo=-]

alright, i got a werid noise coming from my engine you hear it as my RPM comes down form a rev. ZZZZzzzzzzz... lol at first i thought it sounded like the spool on the turbo was hitting the housing but after checking both turbos i found out they were fine, alot of work for nothing. So i went back and really listened, now it sounds like like the left cam shaft but im not sure.. could it be???

and i also asked a friend and he says sometimes when you put intake and exhaust on car the stoke waste gates and recirculating values start to make werid noise is this true?

What could it be guys....

[-=BoYo=-]

and its running a ruff, and its not b.c of vacume leaks cuz i check system is pretty sealed. HELP PLZ.....

[evildky]

could be a bearing noise, when was the timing belt last changed? how many miles on the car? was the tensioner or idlers changed as well? alsi there is an idler next to the ac compressor and Ive seen that little bugger go bad more than one, easy to pull it off and see if you get silence, if it's a tensoiner or idler bearing, park the car and fix imediately, one of them seizes and youre buying a new motor

[-=BoYo=-]

i did the timing belt but i didnt replace the timing belt tensioner, and im pretty sure that the belt isnt to tight. but whats this idler u speak of...?

[evildky]

how many miles are on the car? did you check the tensioner for any play or noise? there are 2 idlers on the timing belt, one kind of opposite the tensioner and one in the middle above the thermostat

the other idler that could make a noise but not under the timing cover is right next to the a/c compressor, it's the tensioner for the ac belt, you cna pull the ac belt and find out if the noise stops

[-=BoYo=-]

130,000 miles runs good just little anoying problems. im gonna check what u said 2 soon when i do my alternator belt. ill post when i find the problem thanks man...

[evildky]

I hope for your sake it's just the ac idler, at 130k you really should have replaced the tensioner, i am concerend your gonna find the noise is from the tensioner or timing belt idlers, which means taking it all apart again, and if they sieze your engine is history so procede with caution till you know for sure taht the problem isn't one of the timing belt idlers ro tensioner

[SilverTwin]

Were the VTC springs replaced when the timing belt was done? If not, that's likely the source of the noise if it's happening just off of idle and again at around 2500 rpm just as you let off of the gas.

I very strongly agree with evildky though, the tensioner and idlers are both to be replaced at 120K. I have never seen just a timing belt fail, it's always been the result of either a failed tensioner, idler or idler stud. I know service intervals on some items tend to be conservative but from what I've seen these are ones that should be taken seriously. I've probably done around 200+ Z32 timing belts and at 120K the bearings in the idlers are typically noisy which is a sign of pending failure, not to mention the leaking tensioner. As a side not, Z32 tensioners are clearly noted as a "one time use" item in the service manual and are not to be reused. The seal is often damaged when compressing the tensioner.

Just my $.02

Tim

Tim

[-=BoYo=-]

I’m so stupid, I just remembered I did do the tensioner but, I did not do the idlers they looked fine. Should I have done the idlers?? And could it be possible that the belt is too tight??? Does any one have any other ideas on what it could be the sound kicks in around 3000rpms, not to say you guys are wrong just giving me more things to look at b4 i "dig In"

[-=BoYo=-]

Could it be the cams? and the VTCs were fine 2.

[SilverTwin]

Could it be the cams? and the VTCs were fine 2.

Explain how the VTC's were fine? If the springs were not replaced they were not fine. They gradually loose tension over time allowing the rattle just off of idle and at the rpm range you are describing.

[-=BoYo=-]

And what usually goes first to make a 300 run ruff, i was thinking injectors, and if so how do you check the injectors…???

[SilverTwin]

And what usually goes first to make a 300 run ruff, i was thinking injectors, and if so how do you check the injectors…???

Injectors are the most common culprit. They loose their electrical resistance, there's several theories on why.

To test them, remove the harness and use a multimeter to ohm test for resistance. If they test above 14 or below 11, they are toast. Another common problem is corrosion on the harness connectors, clean them while they are removed to test the injectors.

Tim

[evildky]

timing belt can't be too tight, the tensioner is automatic

[-=BoYo=-]

ite thanks guys in a day or two im gonna put it away for the winter and im gonna start all new project ill post back to tell you guys what it was..

[SilverTwin]

timing belt can't be too tight, the tensioner is automatic

Unfortunately that is not true. I have seen people set the tension using a pry bar with the tensioner already bottomed out. This is actually fairly common, it almost sounds like a supercharger or gear drive from the whine when the car is started. I think this is also the culprit for the broken idler studs which is also getting to be very common.

[evildky]

wow!? I guess if someone tries hard enough they can do anything wrong

[-=BoYo=-]

Damnnnnnnnn... would it sound like the car had timing work donee??