I have tried to attach a photo of an engine part whose name I don't know; underneath the accelerator cable drum cover, looks like a "vacuum tree". While doing some other maintenance I noticed that there are three horizontal nipples on the vertical metal pipe. The top two nipples have vacuum lines attached, but the bottom nipple has no hose, and no plug covering the end. To me this would seem to be a vacuum leak, but after looking all over the engine compartment I couldn't find any orphan hoses that were unattached.

Car is a '94 850T.

Should there be a hose attached to this nipple, and if so where else does the hose attach? If there is no hose, should this open nipple be covered with a plug? Or is it supposed to be open?

Thanks in advance for any help!

probably a spare but needs plugging off.

Try plugging it off and see if there is any change in the way the engine runs.

Firstly, it is not supposed to be open. You are leaking vacuum that way.

Secondly, Volvo had the tree with extra branches to accommodate owner's fancies - some like to have an independent boost meter up in the cabin, with feed direct from the engine, so they can tap it from here, etc.

What you could do, is purchase the vaccum-cap. I hope its cheap there, cos it costed me some RM5 for a NEW one, here.

Alternatively, for the time being, you can fit in a rubber hose, with the end plugged by a long and big screw, to stop the leak.

I plugged the open hole and initially there was no noticeable change in operation. But after a day the check engine light has come on. I haven't had a chance to see what the code is, due to my 17 year old always using the car, but will try to take a look tomorrow morning (since he won't get up until at least noon!). I'll report on what I find if it seems it might be related.

Thanks for the suggestions! This forum is great!

Hi! I just removed this same part you are referring to from my 94 850 Turbo sedan with a 2.3L engine and automatic transmission. I have other more serious problems! The nipple on my vacuum tree is capped off, so i assume yours should be as well. There exists an open communication between all of the nipples, so if yours is not capped, you will have a vacuum leak.

dkiernan,

Your ID sounds familiar. :)

Anyway, what are your more serious problem?
If not related, could you start in a new topic?

Thanks!

I pulled the codes and got a 3-2-5 (ECU memory loss) and a 4-1-4 (turbo boost pressure too high). Can you think of any reason that plugging the open hole would give me either of these codes? I guess the real question is what do I do to correct these problems? I haven't really had a chance to drive the car to see how it performs since plugging the leak, so I don't know if there is a change in performance. Anyway, I'd be happy to hear any advice about the two trouble codes.

Pluggin the hole in the vacuum tree SHOULDNT be giving you there probalems, shouldnt.

OMG! plugging that nipple will not harm any function on the engine, toss any codes, or affect drivability. What it will do is stop the vacum leak that is truly affecting the performance and turbo boost levels. If you are getting a 3-2-5 (ECU memory loss) and a 4-1-4 (turbo boost pressure too high) it is because the battery was disconnected while the acc function was used, mechanic error, and your turbo pressure was recorded, stored, and modified by the ECU all the time that nipple was open, in acceleration that tree's vac flow reverses, and everybody knows how the 850 boost and wastegate systems run. The code may have appeared due to a imediate change in the boost, you closed a leak, no telling how long your leak existed.
The Bear is right and in no way wrong. Clear your codes. Clear your check light. Clear the Tcm, Clear everything, start fresh, then see what pops up. I had the early issue, old codes, mis-codes, ect.

I have already cleared the codes so the check engine light is off again, but I don't know how to clear anything else. What is the "Tcm" that you mentioned?

I think this leak has probably been here for some time, so if there is anything I need to do to get everything working correctly again I'd love to know what I need to do.

Thanks again for all the input!

Swed,
:thumbsup:




Tom,

The TCM is the Turbo Control Module.
As for the leak, how long ago, exactly was that?
I've seen someone reset and fixed a "leak of 12 months" and still ran great afterwards... Try it.

Alternatively, i hope someone who has faced this issue before, and got the light stuck on, can also share how was it fixed. :)
(Aside from pulling out the plug, of course...)

I wish I knew how long the leak has been there. I only discovered it because I had to replace the starter, and in the process pulled the plastic cover off the vacuum tree and saw the open nipple.

The check engine light is on again, with the 3-2-5 code showing up. Ideas about what might be going on here? Also, is it necessary that I reset the TCM and if so, how do I do that? I looked through my Haynes book but found no references or information regarding the TCM.

that 325 code is memory loss, try looking for crimped, damaged, or wet harnesses indirect to the ECU. that code stores due to loss of current and signals while running. And TCM i meant was transmission control module (computer), although, the turbo control module is a not a bad idea, in fact, needed.
At this point my advice is for you not to worrie bout "clearing" the codes, tackle the problem.
to clear the codes, push and hold the button for 6-7 seconds, release and as soon as the LED comes on push and hold the button for another 6-7 seconds. Now push the button for one second and read the codes again, you should get 1-1-1 (no faults). You Must Read All Codes before Clearing. Turn the ignition off and then start the car, the check engine light should be out.

One thing I want to add as far as maintenance. Check the integrity of your pvc system while you are there, if you do not know, Volvo changed the flame trap from metal to plastic. If yours is metal, you should upgrade. As far as turbo 850's I dont know a whole lot about them because mine is non-turbo.

+1 to swed and Xpiece,

And hope tom gives an update.
:)

Since the car never seems to be home (the perils of having a 17 year old) I haven't been able to do anything further yet. I left the check engine light uncleared. When I do my diagnostics I am always using socket #2 on module A of the diagnostic unit. Should I be a diagnostic using any other of the sockets at this point? Haynes doesn't do a very good job of telling when to use the various sockets.

Where do I find the flame trap that xpiecemealx mentioned? And for you turbo owners, is this an issue with my car?

I'm going to look at the ECU as swedseed850 suggested once I have access to the car.

Thanks again for the help!