1996 850 PCV Problem - Simple Fix?

[sleddriver]

Our 850 is now failing the glove test and we just don't have time to do a full PCV job - maybe in the Spring. I currently have the dip stick out a bit.........I am really tempted to cut hoses (where ever?) and put in an old style PCV valve.

Before you do anything, be sure that the hose that provides vacuum to the oil sep. box has not cracked. Not only will this give you a large vac leak but engine vacuum is necessary for the PCV system to operate.

As I have a T5, I'm not sure how a NA intake is plumbed. On turbo systems, it's all-too-common for the large and small hard plastic pipes inside the foam sleeve, that run from the intake pipe @ the turbo inlet, to the oil sep. box, to crack. Mine did so right below the distributer even though I replaced this pipe new about 6 yrs ago.

Robert and others have replaced this cracked-prone-line with either aluminum or copper or the updated line from a newer car. It seems Volvo updated this system.

Mine is currently patched with a 4" piece of silicone vac. hose until I can get in there and do Robert's update.

So in summary, you may not need to replace the ENTIRE system, just the hose supplying vacuum to the box. With that said, all ports, orfices, hoses, etc. need to be free of gunk/sludge/blockage as well.

I've used 100% syn oil since the warranty was up and have never found any blocked passages, ports, orfices, etc. Just the two cracked rigid plastic lines.

[Ozark Lee]

I've been reading, should I drill out the PTC valve?

You don't have a PTC on a N/A car. From what you said you already chucked the flame trap which is the same choke point on the system.

...Lee

[PeteB]

Oh, thanks for the info, didn't know that.

[PeteB]

I bought an extra oil cap on ebay and I'm going to drill a hole through it, stick
a Elbow fitting into it and run a vac or 1/4" ID line down to road level.

Inside diameter of vac line elbow is 3/32" and for a 1/4" elbow 5/32, I'm inclined to
use the 1/4" with 5/32" elbow but is that too much, will it throw a ECU vac leak code?

Why doesn't the ECU throw a code when we do the glove test with the oil cap off, that
would be a large leak?

Any advice on which size will vent enough so that seals do not blow but not cause engine
running problems?

[abscate]

Most codes need to be detected over multiple drive cycles before they are stored, so the glove test wont trip a light if the test is short

[PeteB]

I see, If I use too large of a hole and it sets a vac leak code will it clear on fixing
it or will I need the scan tool to fix it?

We have not tried this yet so I don't know if it will cause an ECU code.

Here it is used the 1/4" ID line. I like this because my son can put back the old cap
without having to fuss with a splice in the original hoses. I also might leave it in
since it provides some safety against blowing a seal at anytime down the road:

OIL-CAP-TOP.jpg (290.05 KiB) Viewed 1446 times

OIL-CAP-BOTTOM.jpg (292.78 KiB) Viewed 1446 times

[PeteB]

This did not work, since the new hole in the center is in an area that vents outside through the
half circle holes around the perimeter. Oil leaked out through those holes and we are back to
the old cap with the dip stick out a bit.
I need to make the vent continuous from the hole in the bottom side, if I even want to bother
with it. Then I wonder how much oil will run out the hose, would like to avoid too much.

The design of this cap is a bit of a mystery to me, It looks slightly spring loaded - good,
but it must be so tight that the engines blow out seals rather than it doing its job -bad.
There does not seem to be any path from the inside metal area to the perimeter vent
holes in the normal configuration of the cap - what are they for?
Edit: On a closer look this is not designed to be a pressure relief vent of any kind and the
perimeter half circles have nothing to do with venting in normal operation.

[sleddriver]

Not sure why you think this solution is better than just pulling out the DS a bit? Am I missing something here?

I suggest first determining if engine vacuum is being applied where appropriate (Do NA's have a separator box?) then check if you have any clogged ports or hoses or to see if any hoses are disconnected. Troubleshooting this is straightforward.

[PeteB]

I didn't intend to suggest that this was any sort of a permanent fix, just to get by until
the full PCV job was done.
I didn't think there was much to diagnose, I looked at it in the past year when I removed
the flame trap and the hoses seem in fragile condition and now something is clogged
since the glove inflates. Seems the PCV job just needs to be done. We don't get any
vac leak codes. But that is good advice and I will look over things the next time I have
the car. My son and his girlfriend might forget to leave the dip stick up and if this vent
worked well we might have gone until Spring before doing the full job. I also thought
that the dip stick might spray some oil, and that the cap being up high might be less
prone to venting of oil along with the gases, but that does not seem to be the case.

This 850 needs boots on the axle shafts and struts, so combined with the PCV job, I'm
not sure if it is worth doing. It consumes about a quart every 1K miles and also drips
oil - probably the crank seal.

[cn90]

You may want to try "vented oil cap":

http://forums.turbobricks.com/showthrea ... 469&page=2