The egr does not become activeuntil normal temp is reached i think. That would coincide with the temp parameter. Can you see if the hole is bigger. It sure seems like a high pitched intake type whistle. When the egr is commanded on the hole would become an active leak. Your swap of the ufo pcv is easy and will take care of that scenario. Have you verified the corrugated line from the ufo valve to the elbow to be intact

 

Hi, yes ive changed the pipe going from the PCV to TB not too long ago. I sprayed some sensor cleaner on all the lines prone to cracking or causing leaks. The only place where I noticed change in rpms was the egr pipe which I know for sure is leaking. Rest evidently checked out.

Egr pipe leak has been there for a while. Unfortunately, the part has been back ordered and ive had to drive around with the egr pipe leak. I just clear the codes and fortunately for the car don't need to do any lengthy driving for work. But, this high pitched whine or whistle, is a rather recent occurrence, despite the egr pipe leak. I will be away this weekend so I will try to swap the PCVs next week. The injured cat can rest for a bit.

Im looking forward, hopefully, to that genius feeling of accomplishment when I'm able to resolve this issue. Had it once before when I got a strangers dog to sit on my command.

 

Its a weird sound. It seem to get louder as you went towards the back of the motor with the phone. It didn’t increase with the rpm when you gave it gas so It sort of rules out supercharger. Sounds like something is either vibrating like the fuel pressure regulator or maybe it is acoustic like when you blow into a wind instrument and the read flutters. Since you mentioned you had an EGR leak I’m wondering if maybe high pressure in that tube could make it vibrate and flutter from a cracked stainless steel flexible tube?? I’m not sure the vacuum to the PCV could do that but who knows. Maybe disconnect the vacuum line going to the big space a PCV valve creating a massive vacuum leak which we drop the pressure. If you had that big line disconnected and the sound was coming from a leak in the line it should go away or change because theres now a difference in pressure and it should change its characteristic if it was in that line

 

Watched the video clip again. Problem is worse at low RPM, right?

Two thoughts come to mind:

Intake manifold vacuum is strongest at idle or deceleration. Not sure about effect from the supercharger, though. Did you ever pull the dipstick, as previously mentioned? That should change the vacuum equation, and thus the sound.

Still sounds electrical in nature, at least to me. I'm thinking some actuator is hunting rapidly due to a power supply issue. If your alternator has a bad diode, it will pump out rapid dirty spikes instead of the normal clean DC. At high RPM, the spikes tend to blend together, disappearing to some extent. At low RPM, they have more separation and are more pronounced. Loosen or remove the serpentine belt momentarily to test this theory. If the alternator isn't spinning, the battery will be the only source of electrical power, with no spikes.

On a related note, how old is your battery? One very important function of the battery is to act as a giant capacitor to smooth the normal ripples from the alternator. This capacitance (or lack thereof) is rarely an issue because the battery typically dies from other causes first. But in rare cases, capacitance can be a factor. The remote location of the battery makes the situation worse, as the spikes are not immediately dampened. I'm not saying rush out and replace it, but do tell how old it is.

You can also test for AC ripple with a voltmeter, but not all types and brands are capable of picking up this problem. Do you have a multimeter, and if so what brand and model?

 

good point. This is something I'd like to try. I will be replicating the sound then I'll try to sway the pcv valve or at least disconnect it. It is a weird sound indeed.

 

I did pull the dipstick as I thought maybe crankcase ventilation was hindered, but it didn't really make a difference at all to the sound. I should've pulled off the hose going into pcv but it didnt occur to me at the moment.

As for the battery, it's not new but it's not old either. Being in Canada, the harsh winters decrease the life expectancy of batteries by quite a large margin. I normally change my batteries out every 3 years. The one currently in the car is about 2 y.o.

I do have a dewalt multimeter. I will give this a go as well. The interval and tone of the sound definitely leads to the hypothesis that it may be electrical. No doubt about it. However, if you search "high pitched whine caused by bad pcv" on the youtube, you will hear engines making an eerily similar sound with a faulty PCVV. I will also be removing the serpentine belt to rule out pulleys and modules such as alternator and PSP (extremely unlikely to be steering related).

 

Quick update. I took the car for a drive and as soon as the sound occurred, I pulled over and took off the hose going to the PCVV from the TB. As soon as I did this, although the engine idle became understandably rough, the high pitched sound ceased immediately. As soon as I clicked the hose back into the PCVV, the sound began again.

Process of deduction leads to crank case pressure or the ability to regulate thereof as the issue, most likely due to a faulty PCVV. I've ordered a replacement. Hopefully that will be the end of the horrible sound.

 

Excellent. Be aware that even a new good one will make a slight hiss. It has been discussed many times on here and i have persoal experience to draw on. With the engine cover on it is hard to here

 

Good job! I will be watching to see if this fixes it but I think you found the cause.
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Duly noted. Cheers.

 

Hey Clubairth! Its been a while. If it's not the PCVV then im afraid ill be dishing out for a new engine or new car LoL. The only other thing in my mind that causes excessive crankcase pressure is a head gasket leak whereby pressure could enter the oil system.

I'm sure there might be less problematic ways that cause high pressure in the crankcase. I've learned it's best to be realistic about a two-deacade old, well-aged British performance sedan. I've pondered the idea about taking the car to my local dealership and getting a quote for a new engine, transmission and everything else in-between. Essentially to make it brand new including getting a nice new paint job.

In my mind the cost of doing this would equate roughly around the price as a new car anyway. I love the car. I could see myself driving it for the better part of my life. If it had the room maybe put in the 5.0L supercharged V8 out of the XKRs for wome extra kick.

 

All good points! But there is a quick test for blown head gaskets? Some chemicals that turn color if there are combustion gases in the coolant.
The 4.2L is a tough engine and not known to blow head gaskets at all but it can happen.
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I think you are fine. The ufo valve hose is under vacuum created at the induction elbow. When the charger becomes active it increases exponentially. The ufo valve semi regulates it i think. We have never fully figured out its operation other than it uses a diaphram. The other hose that goes to the other side would be the one to really assess blowby. The ufo diaphram on yours must have failed and started vibrating a lot similar to what aarcuda said compared to a reed woodwind music instrument

 

the ufo is just an oil separator valve like the things the german cars use

 

thank you. That was my thought after i took my old one apart a couple years ago

 

So what meters the crankcase vacuum? Just all the seals in the engine? Or does sn engine need anything to regulate crankcase vacuum?

 

I think the big thing is being forced supercharger induction needing all the vacuum it can get under full load conditions while at no boost it regulates itself i guess like you say. I know when my ufo went bad i did not catch it in time and excess pressure made a small leak happen in the front timing cover gasket or sealing compound right below the alternator. So somehow it can restrict vacuum when bad when the charger is boosting and creating more internal pressure needing the super vacuum to keep up. In my case the weak spot was the front cover and not a front or rear crank seal as is more common i would think. Mine probably leaks about 4 oz every 1000 miles. Not enough to take the front cover off for me. Especially when i drive the car about 7000 miles a year

 

I doubt the head gasket leak as well. I had a friend do a compression test not too long ago plus no other signs of blown head gasket. Oil is silky clean, exhaust does not produce any weird, fruity smelling smoke. I get the new PCVV soon. I'll report back after some use.

 

LoL my thoughts exactly. I always understood the positive crankcase ventilation valve to be just that, a positive feedback loop whereby engine vacuum draws the blow-by gases from combustion chamber back into engine rather than releasing them into the atmosphere acting as an emissions control device of sorts.

 

Update on the issue. Changed out the PCVV and drove around aggressively trying to replicate sound. I ended up hearing it but this time a lower pitched wheeze almost, as I lifted off throttle. I fully expected the sound to stay present as it normally does after it occurs once but it didnt. After hearing it the one time, I couldn't replicate it again. Not sure if it went from constant to intermittent but I'll have to keep monitoring next couple days. Normally once it starts, the only way to make it stop is turn off the engine and wait a couple minutes. Guess it's definitely an improvement but I will drive around the next couple days to make sure what's, what.