Boost gauge and evap system vacuum lines

Cookeh · Post by **Cookeh** » 29 Jan 2021, 04:26

*Please note that due to many errors, both descriptive and relating to conciseness, this first post has been edited*

MVS cardinal sin #1: No part numbers, sorry (that's part of what I need help with!).
MVS cardinal sin #2: Vague topic, sorry (also why I need help!).

I recently recorded an A2 port 232 DTC after the lambda light reared its ugly head on my 1996 850 T5M (RHD). I had a vacuum leak in the white nylon line going to the instrument cluster from the vacuum tree. Simple fix, replace the rubber hose connector joining the two parts of the line. I am assuming these lines separated due to deterioration of the the connector. My question relating to this section is two-fold. Firstly, should there be a connector here, or should it be a straight shot through? Secondly, if this is related to the EVAP system, does it carry fuel vapours or is it vacuum only (answered by Abscate in post #2)?

Also related to vacuum lines, I have a very deteroiated line running from purge valve valve (mounted to the fan shroud) to a barb on the intake manifold by the throttle body. This line is split by what I assume is a check valve, and it is the piece of line post-check valve that I need to replace. Pre-check valve appears to have been previously replaced as it is in mint condition. As per the previous query, I am assuming this line carries fuel vapours, and as such was wondering if it is possible to use fuel hose for this line? I am struggling to track down the part number for this line, and so finding the correct dimensions for replacement. I believe this is a 7.5mm ID line, but my line is so deteriorated that obtaining robust measurements with a set of calipers is proving difficult.

Images of this line follow:

When I woke up this morning I left half my brain on my pillow, but what few brain cells are left in the other half are telling me vacuum lines (silicone or rubber) are not suitable for use with fuel vapours as they'll degrade. But then equally they're telling me that fuel lines are designed to withstand pressure, and not vacuum, so are they sufficient to resist collapsing under vacuum?

Apologies again for the lack of part numbers et al., but on volvopartswebstore none of the diagrams match up with my car (we didn't have all the emissions guff you chaps did) and my factory vac line sticker is long gone. I consider this a most grievous failing on my part.

Post by **abscate** » 29 Jan 2021, 05:20

This is for your 1996 RHD?

How does this diagram match up?

Evap lines carry some fuel vapour but not enough to really degrade them over years in my experience

Your turbo has two ways to purge, the manifold at low boost and the snorkel at high boost, so you get a T on the vacuum lines

Cookeh · Post by **Cookeh** » 29 Jan 2021, 05:46

Sorry, thats MVS cardinal sin #3. Yes, my 96 850 T5, oddly that diagram doesn't match up either, I don't have the pictured 'T' formed from valves and lines at the top of the image (#16 & #26). The ends of the lines don't match up with what Im seeing either, though it may be the same in principle with a different layout. When it eventually stops raining I'll try and grab some pictures.

Cookeh · Post by **Cookeh** » 29 Jan 2021, 10:28

Further apologies incoming, I am being somewhat of a plonker... I'm now 12 weeks into a lockdown, which is clearly getting to me. The white line in the first post appears to be the vac line to the factory boost gauge in the cluster. It runs along the entire front clip, drops down to the crash support bar, then doubles back along the front bumper, along the offside wing, and into the firewall. I will try and edit the first post until it vaguely makes sense. The question now is, will a vacuum leak in this line cause an emissions DTC232? Given it is fed direct from the vacuum tree I suppose it is possible, but would like some confirmation.

: vacuumhoserouting.jpg (185.27 KiB) Viewed 1365 times

The second hose is the evap one I'm struggling with. I only have the one vac line on the fresh air intake, which is connected to the blue port on my TCV. It would appear that they get vented to manifold only? The following attachment is for ME7, so I am not sure if this has any different routings. It also has EGR, which I do not have. Despite this, it most closely matches what I can see in front of me.

: 2000 V70XC Vacuum hose diagram.JPG (125.79 KiB) Viewed 1365 times

The line that is deteriorated is the line from the purge valve to the manifold (post-check valve). I cannot find a part number for it, though based on dimensions I believe it is this item listed in SKANDIX. It would appear 7.5mm hoses are much more commonly available in fuel hoses than they are in vacuum hoses in the UK. Would an internally reinforced fuel hose be suitable for usage here? The internal reinforcement would, I believe, provide sufficient resistance to collapse under vacuum?

Post by **Sveedy** » 29 Jan 2021, 12:57

I have had the white hose that goes from the vac tree to the boost gauge pop off before and all that happened was that the boost gauge stopped working. Never threw a code.
I would think the fuel hose would be more than adequate. The reinforced hose used for fuel injection is really stout.

Umm...stout.....yum.