850 and S/V/C70 non-turbo vacuum lines

Post by **John850GLT** » 29 Dec 2014, 09:00

If your #3 line is off-white and thin (as in picture with flame trap insert) you should have elbows at the flame trap and front passenger side of manifold (have to put your nose down in there to get a proper view). Check condition of both. Line is behind manifold, but doesn't need to be.

joe_pinehill · Post by **joe_pinehill** » 29 Dec 2014, 09:07

John850GLT wrote:If your #3 line is off-white and thin (as in picture with flame trap insert) you should have elbows at the flame trap and front passenger side of manifold (have to put your nose down in there to get a proper view). Check condition of both. Line is behind manifold, but doesn't need to be.

My line 3 is rubber the entire length, its got an insulating foam over the part under the intake manifold

Post by **erikv11** » 29 Dec 2014, 09:07

joe_pinehill wrote: ... Can line three be replaced without taking the fuel rail and intake manifold off? Can I snake a new line under intake manifold? Will the original have clamps on it under the manifold or should the line simple be able to be pulled out by pulling the end attached to the intake manifold nipple?

In the factory (or OEM replacement) configuration, line 3 routes from the nipple then under the intake manifold where it is jacketed with the thicker PCV pipe, then it exits the jacket to connect to the flame trap housing. So you can't necessarily pull it out of there until you get the manifold off, I would try just a bit then if no luck just unhook the ends and then leave it alone, maybe snip off the accessible sections.

Yep you can route a new line any way you want. I have gone under the manifold or over it, without removing the intake. The end at the nipple by the PS pump is a hassle but you can do it, I use those super long nose pliers. The fuel rail cover just snaps off by prying forward, that helps for routing it above the manifold like in the pics.

Post by **erikv11** » 29 Dec 2014, 09:11

John850GLT wrote: ... P0133 code (slow O2 sensor Bank 1 sensor 1) ... lets me know my vacuum tree is correctly done ...
... If anyone has this code issue, and any insight, would much appreciate help. ...

Sounds very pesky. I might smoke test all vac lines at this juncture, I have seen small leaks from the base of the vacuum tree for example.

Post by **John850GLT** » 29 Dec 2014, 12:09

Thanks for the input; will check tree out.
Just replaced (probably unnecessarily) the O2. Tip was white-ish, if that indicates anything.
Exhaust from tailpipe at idle feels barely there. seems previous cars were different. Indication of an exhaust leak?

dorvin · Post by **dorvin** » 30 Dec 2014, 05:55

Awesome write up! This will aid me in preventative maintenance when I decide to go through and replace the 19 year old lines in my car.

goVolvo · Post by **goVolvo** » 10 Feb 2015, 22:50

FLXC90 wrote:On the back side of the air cleaner housing, there should be two vacuum nipples in what looks like a clamp. Number two is the upper nipple. the lower will route down to the the bottom of the airbox, where the preheater duct comes from the exhaust. (#6 in the pictures) This connects to the preheat air thermostat for the airbox.

Thanks for the great pics. This is engine vacuum 101!

I don't understand something. #2 goes from air box top to vacuum tree, what is the use of it? Does it bypass the MAF this way? Ah I am so silly. Seems all hoses on vacuum tree are before MAF. They only hold vacuum normally and don't pass air. If for some reason cannot hold vavuum, then it leaks air into intake.

So looks only #3 and #4 could leak air into intake, right? In normal condition #4 is also used to suck the accumulated fuel fume into engine and burn it. Could too much fuel fume cause rough idling?

mika · Post by **mika** » 12 Feb 2015, 15:13

I also have a question about #3 routing..could I just connect it to the vacuum tree instead of the trap housing?

Anyone do this?

Post by **erikv11** » 12 Feb 2015, 19:41

About #4 and rough idling I don't know but I doubt it, my guess is that the largest effect you might see is the engine running just a hair richer.

Yes, some people cap off #3 or route it directly to the tree, but then in either case #3 doesn't do its job under vacuum of helping to pull crankcase gases out of the oil trap.

Post by **erikv11** » 24 Apr 2015, 08:42

Here is another factory, non-turbo setup that came up from MVS member TBrown00:

: vac hose diagram; vac_hoses_code1.jpg (126.07 KiB) Viewed 2484 times

This car is probably emissions code "1" and Motronic 4.3 (see http://new.volvocars.com/ownersdocs/199 ... n1996.html) but regardless one interesting thing is, it is a slightly simpler setup, with only:
- lines 1,4,5,7,8
- a simpler alternative for line 3, directly from flame trap housing to the vacuum tree (no PITA nipple on the intake manifold!)
- one additional route, one line from the tree to the EGR solenoid then a second line from there to the EGR itself.