PCV Mystery

[calebsullivan3]

Hey all,

I have been fighting PCV issues for the last few weeks and my patience is wearing thin. To start, I was driving my 2014 Sonic 1.4L Turbo 6spd manual LT (89k miles) to work a few weeks ago when I noticed a very loud whistling noise from the engine bay. Much like the last whistling noise I heard two years ago when I ended up having to replace the valve cover. Being a novice mechanic I figured "same symptom, same fix" so I replaced the valve cover. Not only did the whistle NOT go away, it started smoking out of the tailpipe and idling terribly. A few days into troubleshooting and researching, I noticed a buzzing sound coming on then going off repeatedly from the battery side of the engine bay which I have now determined to be the brake booster pump coming on and off. Didn't think much of it and determined that all my other symptoms must be stemming from issues with the check valve in the intake manifold. I should also note I was getting multiple codes when scanned with an OBD tool. Took off the manifold and orange nipple was gone. Installed the intake manifold mod kit from the CruzeTalk forum and most symptoms went away. No more white smoke and idle is perfect. Car even runs perfectly and has plenty of boost. All I am left with at this point is a chirp in the engine that does not start until after the car has ran for a few minutes sounding like it is coming from one of the pullys, a check engine light, a p0171 code, and the brake booster STILL going on and off constantly every few seconds.

Does anyone have any ideas at all? Please be mindful I am just learning these engines, but my personal (inexperienced) theory was that maybe my main front seal was letting vacuum escape thus my brake booster pump needing to kick on and off to build pressure. In your alls opinion would the main front seal being bad be consistent with the issues I explained above? I should mention that I have driven the car at speeds up to 70mph since repairing the intake manifold and I do not have any issues with brakes at this point.

Any guidance or input is MUCH appreciated!

 

[BigLee]

The "chirping" noise usually indicates the front crankshaft seal needs to be replaced.
With the engine at idle, lift the dipstick up and see if the noise goes away. If it does, it's time to replace the crank seal.

 

[calebsullivan3]

Thanks for the response BigLee. I also felt it was probably the crankshaft seal since I replaced the valve cover and modified the intake manifold, thus ruling out most of the other PCV components. I also ruled out the line/check valve that comes off the manifold and goes to the turbo. The chirp does go away when the dipstick is pulled.

Do you think a leak at this seal would make the brake booster pump kick on and off like I described in my post? That is my main concern because I am worried I am going to burn the pump up and lose my brakes...

 

[panos7]

The brake booster pump kicks on and off all the time. It is normal for these engines. As soon as it detects that the engine doesnt produce the needed vacuum, it kicks in to help. So as long as it doesnt constantly work, it's probably okay.

 

[calebsullivan3]

That is why I am afraid. The pump is kicking on and off every few seconds constantly while the vehicle is running. It never done this before I started noticing the chirp and had the PCV issues so I am wondering if a leaky seal could rob enough engine vacuum to cause the pump to go on and off like this. I ordered a seal and should have it tomorrow. Plan to install Thanksgiving week when I have some time off work.

 

[panos7]

If it's like you're describing it and it kicks in even when not using the brakes....then it's a leak that causes it. I also recently changed the front cam seal but not because of a chirp...it was slowly leaking oil and smearing everything around it...I wasn't getting any code or anything but I did it anyway. It's super easy and cheap. 10 minutes job max. Keep us posted if it sorted the problem.

 

[calebsullivan3]

Update: I drove the car 5 hours to my mom and dad's house for the holidays where I would have a garage and plenty of tools. It had been a week or two since I had been in the car and when I started it up engine light was no longer active. Drove it 5 hours to their house and replaced the crankshaft seal on Friday along with the serpentine belt while I was at it. Fired up the car and the chirping was MUCH worse AND the vacuum pump for the brake booster is still going on and off continuously. Spent the entire day in the garage on Friday trying anything I could think of to address this chirp but had no luck whatsoever. Drove back home and the car is really running great. My fuel economy is even fine and is where it used to be before I had the intake manifold issues. That said I decided I was just going to drive the car to work/etc. as normal until I figure out what is going on. On the way home from work today the engine light came back on and the chirp was still insane. I decided to put the valve cover on it that was on it prior to finding the issues with the intake manifold like I described above. Note that this one was an OEM one. The one that was in service prior to today was an Amazon special since the local union was on strike and GM told me they did not have any valve covers and didn't know when they would have them. Put the OEM valve cover back on and drove the car a bunch and cannot get the chirping to come back. The vacuum pump for the brake booster IS still kicking on and off continuously so I am wondering if that is a separate issue altogether. It is just odd that all of these issues occurred at once. I did buy a vacuum gauge today and at idle I have around 10 inHG. Not sure what the normal range should be.