P80 PCV System Repair on a Volvo 5-cylinder (-1998)

[bmdubya1198]

This is why I've been extra careful in making sure every little problem is taken care of while I'm in there.
And while I'm on here, thanks jblackburn! I just completed this job yesterday, and (aside from attempting to fix the previous owner's "mechanic's" shoddy work... I'm disgusted, to say the least) it went well! Haven't done a glove test yet to make sure there is no more positive pressure, but it seems to run better already. I changed the oil as well, and it doesn't look like there is any oil trying to pass the oil filler cap seal (which is also new).
Now onto the timing belt!

[1997volvo850]

Justin,

Over the years I've read a lot of "I've got smoke coming out my dipstick" followed by "you need to replace your PCV system".

There are quite a few individuals who then perform the PCV system repair only to find they still have smoke coming out of their dipsticks.

After reading a lot of the experiences on this site I'm beginning to believe the smoke test alone does not indicate the need for a PCV replacement. While blow by gases increase with the age of the engine I don't believe this smoke alone is a clear indication of excessive pressure.

In my case a few years back cleaning a completely blocked PTC valve eliminate the excessive pressure in my breather system without performing the complete PCV system repair/replacement.

I believe the glove test over the old fill hole (Saw this on Robert DIY) is a good indication of excessive pressure.

Even if the glove test shows excessive pressure it might be a good idea to suggest cleaning the PTC valve PRIOR to replacing the entire PCV system. This worked once in my case.

The PTC has an opening the size of a pencil eraser head and is a critical component for current operation of the breather system. Examining the PCT also gives you insight as to what you might find when you do the PCV replacement.

If your PTC is clogged and the vacuum hoses disintegrate in your hands then it's likely time for the PCV system repair. If they are in good shape and cleaning the PTC reduces the pressure then you might be good for another 40-60k.

I just wanted to toss this out there. I'll be doing a complete PCV repair in the near future. My PTC was clogged (now cleaned) but the main hose from the breather box cracked near the PTC valve. (or I may try some duct tape).

I'd suggest adding the glove pressure test to the tutorial. If pressure test is positive I'd suggest cleaning the PTC before making the decision to perform the complete PCV replacement.

[tryingbe]

The PTC has an opening the size of a pencil eraser head

I drilled mine out bigger to a size of a nickle with a unibit. It works much better.

[jblackburn]

Agreed. Seeing smoke @ idle is not indicative of a totally clogged system.

HOWEVER, smoke should suck down when the system is under increased vacuum (higher RPMs). Glove test is also a good one.

I've heard many say that drilling out the holee in the PTC helps. It makes sense that it would - it increases the vacuum that the intake side of the turbo can provide.

[1997volvo850]

My sense is when some folks see smoke or do the glove test and see pressure they go ahead and replace the PCV. I'm recommending starting with the weakest link in the breather system and checking/cleaning the PTC valve.

Have other members measured the vacuum at idle and higher RPMs? From reading other posts it seems the larger hole in air intake has vacuum at idle and tiny tube to intake manifold has vacuum when higher RPMs. I'm wondering how the vacuum at the air intake hose hole compares to the tiny hose coming from the intake manifold. I'm sure it's been discussed and the tiny tube from intake manifold would indicate there is much higher vacuum. I'm just wondering how the vacuum value from the air hose compares to intake manifold at idle and higher RPMs. I may have to find my vacuum gauge.

[jblackburn]

My sense is when some folks see smoke or do the glove test and see pressure they go ahead and replace the PCV. I'm recommending starting with the weakest link in the breather system and checking/cleaning the PTC valve.

Have other members measured the vacuum at idle and higher RPMs? From reading other posts it seems the larger hole in air intake has vacuum at idle and tiny tube to intake manifold has vacuum when higher RPMs. I'm wondering how the vacuum at the air intake hose hole compares to the tiny hose coming from the intake manifold. I'm sure it's been discussed and the tiny tube from intake manifold would indicate there is much higher vacuum. I'm just wondering how the vacuum value from the air hose compares to intake manifold at idle and higher RPMs. I may have to find my vacuum gauge.

Made an edit to the PCV post per your recommendation:

If you own a turbo, it is a good idea to clean the PTC nipple periodically every 40-50K miles or so (see step 7 and pictures further below in this post), or get rid of the flame trap if your N/A car still has it installed. *You may want to start here if you see excess pressure; then re-evaluate replacing the rest of the system once clear.*

[reluctant_mechanic]

This is a hack I made to reduce pressure until I can get around to replacing the PVC system ( I don't know how to post the pictures, but I got them): I got an oil filler cap at the boneyard, disassembled the interior metal from the plastic outer cover of the cap, drilled out the plastic outer cover to accommodate a grommet for a 70's style breather element and drilled four holes in the inner metal part of the filler cap. Then, I assembled the entire thing and put it on the engine, it clears the hood and have driven around for about 50 miles, highway included. Because the metal and plastic parts of the filler cap are not liquid-tight, I used a bit of accordian hose from a wet and dry vac between the grommet and the metal part of the filler cap, to capture and oil returning to the inside of the valve cover; it gives a tight fit but it might be better to use a section of hose but I didn't have any handy.

During the course of this exercise, I think I located an actual cap that was made for this application, but I am unwilling to misdirect any of my friends here, in case I'm wrong.

What I'd like to do is transfer this breather assembly to the rear blank cap on the engine, the cap that corresponds to the filler cap at the front of the engine. I'd like to drill this plug thing out and put the hot-rod style breather cap there. How difficult is it to remove this?

Thanks. Hi Matt, and everyone else.

[erikv11]

A few people over at Volvospeed have beat this idea to death, including in some very creative ways. Here is a nice example that just drills that blank cap, without removing it: http://volvospeed.com/vs_forum/topic/12 ... s/?page=54

[reluctant_mechanic]

Very nice. is it possible to post a pic here at MVS, or do I have to link it to another site? My "fix" is simpler that those other "fixes" and the whole thing is assembled on the cap itself. Thanks for the info.

[bmdubya1198]

Very nice. is it possible to post a pic here at MVS, or do I have to link it to another site? My "fix" is simpler that those other "fixes" and the whole thing is assembled on the cap itself. Thanks for the info.

I'm interested to see what you did. If you click "post reply" and scroll down under the text box, you will see an option for "attachments." Click that, and you can add pictures.