Thread: squealing noise from crank pulley area? PCV issue?

helping a buddy with a n/a 3.8 series II in his rivi, just go the motor back together and after a couple days of driving, it started making this weird squealing noise from crank pulley area. took belt off to make sure it wasnt a pulley. made no difference in sound. When you first start it up, you dont hear it, then you hear it a little, then i gets louder and louder. used a ghetto stethoscope aka breaker bar, and could not track down the noise anywhere but right at the crank pulley. I told him, maybe something weird happen like one of the reluctor ring on the back of the crank came slightly lose or bent or something got in it idk, so we pulled the crank pulley/balancer off, and didnt see anything weird really, looked like the seal was leaking a tad maybe and there was a visible score mark/line on the pulley snout where the seal rides, but figured that is probably normal for almost 200k or so.

So anyway I started doing some research and I found someone that mentioned something about getting what seems to be a similar noise if you are having a pcv system problem, like missing the o ring on the pcv or pcv valve not in right or something weird like that, you could be experiencing negative crankcase pressure which causes air to want to suck into the motor the easiest place it can, which is usually either the front or rear crank seal.... and to me, this would explain why it takes a min or two for the sound to appear after the car is running (crankcase is building negative pressure), then it overpowers the seal and lets air suck in around the front seal creating the noise and the noise does change with the rpm's (different tone) which could make since because different rpm's would cause slightly different pressures and slightly different amount of air trying to get past the seal. and what i believe is the biggest thing backing this theory up is the sound still happens for a second or two after the car has shut off which could be because there is still a negative pressure inside the crankcase and it takes a second for the pressure to equalize again......

Thoughts on this? I just found like one person bringing this up on another forum real briefly when trying to find a noise....We are going to check out the pcv valve carefully tomorrow and make sure there is no other ovious problem with the pcv system and then put a new seal on and see what happens.....I also wondering if once its running again, I could remove the oil fill cap and put my hand over the hole/oil fill neck and see if i feel a suction. If I do feel a suction, I believe that would be a problem because if I am thinking about this right, you should always have just a slight positive pressure (air blowing out) with the car running.....of coarse blow by could also throw things off a tad. lol

Sounds like the PCV is putting vacuum to crankcase which is normal but the vent passage is plugged. The noise will go away immediately if you take of the oil fill cap. This happens alot on people swapping from gen 3 to gen 5 superchargers because the vent porting is different. Not sure on a NA but I would guess the vent port goes through the upper composite intake into the throttle body. it is probable plugged some where. Was the throttle body or intake removed and reinstalled? Did RTV get into some of the ports on the throttle body?

P.S. You should have slight vacuum at the oil cap. A lot of vacuum is is a blocked vent port.

On the pcv..there's an oring that sits on it below the lip and seals the bottom, then an o-ring on the cap that seals the top. Make sure you have both.

To test it.. simply start the car and get it to whine like the little pig that it is. Pull the valve cover cap. If the noise stops, it's usually pcv.

In your diagnosis, there was an interesting post not long ago about a similar issue. I want tot say that on the LIM thw two "hidden" bolts that are inside the manifold were left out on an LIM swap. Once the bolts were put back in..the vacuum from the intake tract stopped being a problem.

As for the oil by the HB, don't worry about it. The HB seals to the seal and you'll see oil there, looking like it might want to leak.

Originally Posted by BillBoost37

In your diagnosis, there was an interesting post not long ago about a similar issue. I want tot say that on the LIM thw two "hidden" bolts that are inside the manifold were left out on an LIM swap. Once the bolts were put back in..the vacuum from the intake tract stopped being a problem.

Aww, dangit Bill, I was hoping I'd beat you to it!!!

Anyways, yes, make SURE you put those 2 bolts back in the intake manifold. When someone had my car apart they forgot to put them back in and it left me with a situation VERY similar to yours (that being negative pressure on the crankcase and a HORRIBLE noise from the belt side of the engine).

I'd almost go as far as to say that's your problem. It just sounds too much like my problem for it not to be....plus it almost fits since you said you recently had the car apart.

-Edit-
One more thing, does the car smoke white a lot? If it doesn't check your oil level and make sure it's filled to the correct marks. My car only produced white smoke after the oil was topped off. Reason? Because the car was low on oil it was sucking air up into the intake from the crankcase (creating the negative pressure or vacuum you refereed to)....but once the oil was topped off it was sucking air AND oil into the intake and trying to burn that combo which (obviously) resulted in the tons and tons of white smoke.

Yea my buddy just got done doing the heads on it......so its a great possibility he either forgot the bolts or something got misplaced in the pcv system or some rtv somewhere or something. Gives us a place to start looking here. I thought about the removing valve cover thing but it was after we pulled the balancer. Lol and there was actually oil on the inside ring by the reluctor ring that had seeped past the seal, I figure its kinda dumb not to go ahead and replace it while there....

That appeared to be the problem, I told him to check for the o ring on the pcv and he said there wasn't one so he put one on it and put the new crank seal and the balancer back on and no more sound and no crazy negative pressure comming from the oil fill cap/neck. Thanks guys.