Thread: Engine squeal, vacuum related *UPDATE* Problem Solved (see last post)

Rough idle, runs fine otherwise? I've heard vacuum leaks whistle, but not squeal. A common leak is right off the lower intake manifold near the alternator.

Might be a long shot, but unplug the mass airflow sensor and see if it runs different. Maybe a clogged fuel filter? Fouled spark plugs?

I will definitely try unplugging the MAF sensor, I don't think it's a fuel filter or plugs, but the MAF sensor is worth a shot.

I would describe it as more of a squeal than a whistle. It actually sounded like I had a pulley seizing up, but I've since ruled that idea out. It produces the noise with or without the serpentine belt on the car.

Yes, it does idle rough due to the vacuum leak, but it runs absolutely perfect down the road when it has the leak.

If the vacuum leak (the drilled hole in the oil fill extension) is left untouched (i.e. it still has the leak) the car has no signs, symptoms, or other hints of anything other than the vacuum leak being wrong.
If you start it up with the leak it will obviously idle rough but as soon as you plug the hole it will produce this God-awful squeal for about 3 seconds, then it will go away and idle fine. Then if you unplug the hole it will (again) produce the same noise which also lasts for 3 or so seconds. After the 3 or so seconds it won't make the noise anymore, but will start to idle rough again due to the vacuum leak.

Just to make it perfectly clear, the car runs down the road PERFECT if the vacuum leak is left untouched. In fact, it will not produce the noise at ALL if the leak is left untouched from engine start to stop. With the leak unplugged, the ONLY thing that seems wrong with the car is the rough idle (which is caused by the vacuum leak of course). But if you plug the leak it turns into a whole different ballgame.


Anybody think it would help if I tried to get a video of the problem?

Didn't see the updates yesterday. I wanted and overall pic because sometimes a guy will do something and it'll be old enough to look stock etc. and we may pick up on it.

Pull the oil cap off and plug that hole. Start it up. Clearly you have the cap off so there's a big hole. Put your hand over it. Does it have vacuum or pressure? It sure sounds like the crankcase isn't ventilating properly. The UIM has a hole that comes up from the ctrankcase in the LIM to the bottom of the PCV, then it comes up through...and into another passage and into the UIM in a tube in the top of it. Try and check that tube or passage by blowing air into it. If there is restriction then that would build pressure in the crankcase. Also take a tube and try to pull air up through the bottom of the pcv area to see if there is a clog in the LIM leading to the pcv. Might be a bit of a stretch, but it sounds like the pcv system is blocked somehow.

Originally Posted by BillBoost37

Does it have vacuum or pressure?

It's got vacuum, and plenty of it. It wants to suck your finger (or hand) down the oil fill cap, it's got that much vacuum.
I don't mean to try and shoot you down when you're trying to help, but I don't think anything could be plugged because, if I'm thinking correctly, that would build excess pressure, not excess vacuum.

Plainly said, somebody was pretty darn smart to figure out that by allowing the crankcase to take in air (i.e. the vacuum leak in the oil fill) it would prevent the car from making the noise. It's just my own opinion, but somebody was trying to cover something up by giving it the vacuum leak (which could explain why the hole was drilled into the extension). Now it's just a matter of figuring out what they were trying to cover up.....

Ok, just an update here...

Now, I almost bet somebody is going to say something along the lines of "I told you so!" but I'm gonna say it anyways.
Just ran up to the auto parts shop and bought a $3.18 PCV valve, came home, put it in and Viola! no more engine squeal.

I'm not out of the woods yet, still need to fix the vacuum leak, but at least it doesn't make noise anymore.

This car is still probably going to end up torn apart though as today I checked oil and it was roughly 2 quarts low (which I realize is pretty low). I added 2 quarts of oil just for the time being, waited several minutes for it all to drain down, checked oil level again and, upon seeing it was where it should be, started it up. Then I proceeded to watch it fill the whole garage up with white smoke . Even with the new PCV valve and the hole plugged in the oil fill extension something still isn't right.
Dad says it's gonna get torn apart, so yay...

Ok, finally figured out the problem as to why there was vacuum in/on the crankcase. After taking off that plastic intake thing (don't ask about how that went...) we were welcomed by oil...and lots of it. At this point it was like "W-T-F?!" how/why is there a standing pool of oil IN the intake .
After a bit of checking through service manuals we found the problem: someone had taken the intake off and had forgotten to replace 2 bolts that sit inside the intake. It just so happens that if these two bolts are missing (which they were) you have two direct passages from your intake to the crankcase. With the hole in the oil fill extension plugged the car was trying to suck air, which was now oil since the hole was plugged, up from the crankcase through these two holes into the intake where it was burning the oil....thus fogging half the county up with white smoke.

So, after I get those 2 bolts replaced and the intake back together (along with draining all the oil from the intake and replacing fluids etc etc) I'm HOPING that this car will finally run right.

Awesome.. there's always an answer to the oddest issues. And it's logical once found.