Mmr1

A mechanic removed my oil filler cap with motor running , he showed me there was suction pulling it back down, he said it’s a bad PCV valve . Is this true ? I have no smoke or other symptom, oil changed at 5000m but bought used at 37000 miles. It has over 75000 now, I have changed the oil but I don’t know about previous owner. It makes no noise , maybe intake gasket ?
I see nothing in the Glk maintenance manual on even checking the PCV valve going out to 140,000 miles. I’m getting it replaced today.

John CC

Depends. A little suction is a good thing; it helps prevent leaks. A lot of suction is not so good; it can suck dirt past the seals and increase oil consumption.

There should be no positive pressure.

Mmr1

There isnt much oil consumption , maybe 1/2 quart in 5000 miles.

John CC

There' probably a spec for crankcase pressure.

calder-cay

No vacuum please ... example :

Odd Piggy

37,000 miles is extremely early for a crankcase vent valve failure on M276. Most go 150,000 miles, some never fail. A noise that sounds like a belt slipping is usually diagnostic of that failure along with a high vacuum at the oil filler cap. If that is the only failure, it does not set the CEL. Maybe yours has just started to fail and hasn’t developed enough vacuum for you to hear the screeching.

Mmr1

I was not clear, I bought it with 37000 now it has maybe 75000 , could it be intake gasket or something else making vacuum?

Chris1979

It will absolutely be your PCV valve. Go to FCP euro and buy the package for that. It comes with the 3 cam plugs, oil breather cap, oil drip pan, oil separator, and 2 hoses!!

Mmr1

I already got the Pcv from fcp, I didn’t see a kit, it should be fine. Thanks

Mmr1

Approximately how many hours to replace a PVC valve ?

OnlyoneMB

I replaced my wife’s 2013 GLK last year at 60K miles. There was oil in the filter box and this fixed the problem.

habbyguy

Yeah, a new car is one way to fix a problem... ;-)

Mmr1

It’s finished , replaced, the hole a hose was attached to was enlarged naturally. No more sucking in the oil cap. Go check your Glk !

John CC

What does this mean?

habbyguy

Thanks - I thought maybe I just missed something. ;-)

Mmr1

I didn’t check autocorrect spelling. Sorry.

John CC

Maybe I'm dense, but I still don't get the naturally enlarged hole...

Mmr1

I’ll look for a photo, the photos you see are the top and it’s bolted down , on the bottom is a about 1” hole with rubber washer that connects to the motor, the rubber washer on the pvc wears, I guess from vibration and a leak develops. I threw the old one away. A poor design and poor placement as it’s like an 6-8 hour job to replace.

Mmr1

It’s just normal Wear and tear on the gasket, that is in the hole, on the bottom of the pvc. The wear will happen to all pvc and can’t be fixed . I should have worded it differently, and I can’t find a photo of the underside of pvc to show the gasket and hole . A vacuum check of the crankcase is needed to verify it’s bad . I don’t have the vacuum spec. But moderate pull on your oil cap , when you loosen and lift it, with motor running indicates an issue. A mild vacuum is normal. Its something that needs monitoring on old engines.

Mmr1

This is the bottom view, the big center hole is what connects to the motor, the center is a gasket that fits tight but loosens over many miles . Then it leaks.

habbyguy

I'm still struggling here... ;-)

Are you saying that the metal (?) hole that the PCV valve "nose" sits in had been worn somehow? Boggles my mind to think how that could happen...

Chris1979

I see what you mean!! I have a 2011 which is the M272 and it doesn't have the same PCV, similar but not the same. On mine I changed the PCV and the oil drip pan which is to what the PCV attaches to. I also changed the oil separator which sits on top of the engine drivers side along with it's hose. Which by the way when I took off the hose it actually came apart lol. Glad you got that fixed.

Silver Shadow

The hose passes through a rubber grommet. The grommet wears/stretches out with age.

John CC

Too bad you can't just replace the grommet...

Mmr1

It’s really to bad it wasn’t made simple like a US 350 v8, a 3$ part and 3 minutes to replace. This thing was insane to get to. Remove the intake , high pressure oil pump and more ! That’s MB .