What'a that sound, very odd have a listen

[JimP]

I noticed this new sound lately, checked all accessories, belt, pulleys, removed belt and the sound was still there. I've also eliminated the supercharger bypass valve. The sound seems more noticeable around drivers side front tire and only after car has reached full operating temp. I can feel suction / vacuum as I place the oil cap back on and proceed to tighten it. Car has 2 pcv valves one on each cam cover.

What has me stumped is when I remove the oil fill cap the noise goes away, upon replacing the cap it returns as can be seen and heard in this video.

Any ideas?

https://youtu.be/5JDxuVF4cxk

[Zack]

Most likely a vacuum or pcv issue

[JimP]

Most likely a vacuum or pcv issue

Thanks Zack, I went around with a stethoscope and I can isolate it just above the power steering pump but I don't see anything. There is quite a bit of vacuum pulling on the oil cap into the cam cover when I put it back on. I checked plumbing to procharger and there is no sign of oil getting into the tubes or intercooler.

I'm a bit stumped, car runs amazing, going to get my hands on a smoke tester but if you have any suggestions I'd love to hear them.

Jim

[justbob]

Why do you have two PCV valves? It is probably suffocating for air.

Are you sure the passenger side wasn't gutted and just used as a hose connection? (Assuming this is the modded version posted years ago)




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[JimP]

Why do you have two PCV valves? It is probably suffocating for air.

Are you sure the passenger side wasn't gutted and just used as a hose connection? (Assuming this is the modded version posted years ago)




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Good point, I'll have a look and see. There's hoses running from both pcv's I'll have a better look. I'm a bit slow, I had back surgery last month so I'm not as bendy as normal.

[justbob]

I know all too well about back issues.. Take it easy.

Here is the write up of the mod.

http://www.mercurymarauder.net/forums/showthread.php?t=25641


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[Zack]

I skipped right over the 2 pcv valve info.
That is definitely a no-no and will cause this

[sailsmen]

Why did you install a second pcv?

[JimP]

I just checked the link justbob posted and the second comment in the thread is from a former member snowbird. It just so happens that I now own his MM, I found it lost and forgotten last year and scooped it up. Going to go through the setup and see exactly what it has been done, it is an FIT procharger install. My buddy I also dropping off the smoke tester Tuesday. I'll post my findings for sure.

[JimP]

Gave the car a once over today, the pcv mod as mentioned has been done as per the link justBob had posted.

I smoke tested the car, found two small leaks which I fixed, and also found a mystery vacuum hose. It attaches at the firewall area, no idea where it's supposed to go, can't find anything which looks out of place. Noise still there until I either unscrew the oil cap or pull the hose from the procharger to the pcv.

So definetly an issue with too much crankcase ventilation as I can feel suction pulling down the oil cap, I'm stumped.

First two pics are of the hose, where it connects close to firewall, and end which is not connected to anything, where does it go??

Last three pics are of pcv mod.

[Mr. Man]

I thought the inlet on the DS cam cover was to let air in as it is hooked to the CAI. Not a S/C guy so not sure why you need 2 PCV's.

[JimP]

I thought the inlet on the DS cam cover was to let air in as it is hooked to the CAI. Not a S/C guy so not sure why you need 2 PCV's.

Yup was supposed to be hooked up to intake, passenger side had a pcv. This car has the FIT pcv mod done to it, followed the link justbob posted, seems to have been done correctly. Fitting on driver's side cam cover seems to just be gutted out, passenger side cam cover has a corba pcv valve which goes to the procharger.

Anyone know where this mystery vac line I took pictures of goes too?

[JimP]

In case anyone was wondering, I installed an oil separator catch can between the two cam covers, the noise heard in the video is now gone.

The pcv mod which the car had was creating a ton of negative pressure within the motor hence the odd sucking noise from the video. I haven't introduced any unmetered air this way either being a flow through supercharged set up.

I'm thinking of converting to a blow through with a blowoff valve instead of the bypass valve setup now.