2001 C70 PCV system explanation

perkunas · Post by **perkunas** » 19 Dec 2013, 11:49

Hi,

I own a 2001 C70 coupe. Recently, I've been trying to resolve a rich mixture CEL. One of the suggestions was that it might be a PCV vacuum leak. I expected to find a "classic" pcv system in my car, but what I found was something more similar to the newer models (S60/V70 etc.)

The PCV vacuum system consists of a hose with banjo bolts (Bolts K in the scheme) on the ends and a hose coming off the thermostat housing.

My question is: if the hose with banjo bolts on the ends is the vacuum hose, where does the thermostat hose lead to? I guess it should do the heating part of the system, but I don't really understand the way it works. Why is there no hose leading to the PTC nipple, unlike in the classic system? Where does the banjo bolt connect to (not the intake manifold side, the other end)?

Any comments are welcome.

Post by **mikealder** » 19 Dec 2013, 11:59

The PCV gasses come out of the inlet manifold via the Banjo bolt, the coolant goes back in to the engine on the banjo bolt at the right hand side of your picture (bandstrap E) - Mike

perkunas · Post by **perkunas** » 19 Dec 2013, 12:15

Isn't the bandstrap E the one that goes into the PTC nipple?

Right now it seems to me that the intake manifold vacuum hose just plugs into the thick PCV hose somewhere along the line, but I still have to check this on the car. It might be tough to do though, due to limited accesibility.

i.e. this:

MMT51 · Post by **MMT51** » 19 Dec 2013, 12:27

Here's my take on the workings of this system.

There's a vapor loop and a coolant loop. Each has a banjo bolt on one end and a hose clamp on the opposite end. I'm guessing on the direction of coolant flow.

perkunas · Post by **perkunas** » 19 Dec 2013, 12:36

Seems just about right! Well, at least the connections, I can't say anything about the direction of flow though.

It just seems odd that there is no vacuum going to the PTC nipple anymore. It could have solved my air leak issue due to a missing hose, but now it just got more complicated.

My PCV system seems to be in a good shape. I bought the car a month ago and there is no pressure build up on idle (rubber glove test). There is only a minor amount of oil around the oil cap and the PTC nipple is free of any obstructions. Still, I need to find the reason causing a rich mixture CEL.