DIY: 1998 Volvo S70 GLT PCV Mod: no more smoking dipstick!

[matthew1]

Slated for Repair Database inclusion.

CN, another killer DIY writeup.

[precopster]

Great write-up CN90!!

I too had a smoking dipstick (but not pressurised smoke) on my '99 NA V70 (now gone) after replacing the cylinder block with one from a 70K mile engine and thoroughly cleaning the rings with carby cleaner by lifting the cylinders repeatedly while spraying and soaking the piston tops then rotating the crank to loosen the debris. It was clean as a whistle when finished.

The compression was 195-205 psi BEFORE doing all this so I really didn't understand why I still got the smoking from the dipstick using new PCV and ensuring all ports were clear. There was no lip at all on cylinder bores.

It wasn't a high pressure output as on my high mileage 960 with VERY large lip on cylinder walls but smoke nonetheless.

Next time I do a PCV job this is how it will be done.

[hankbates]

I have been thinking about this subject for a while now, as the sophisticated PVC system Volvo has used on these cars cannot adjust itself to compensate for increased blowby as mileage builds up.

I did the"normal" PCV job on my 96 855T a little over a year ago after I had started to get some driveway spots from the rear end of the engine. It cured this temporarily, but the leaks came back about 30k later, and I had the RMS done then.

I have had the nagging thought, that if the capacity of the pcv system is still insufficient after cleaning and replacement, then I can expect (as I saw) more rapid RMS wear in the future.

The use of the 5/8" heater hose looks like a great improvement, but since the greatest restriction to gas flow in this line exists in the small orifice in the PTC itself, why not modify it at the same time? Should the opening in the PTC be opened, perhaps in the same ratio as the increase in hose diameter?

I'm thinking that it probably also a good idea to do this even if the hose (as in my case) is still the restrictive old one....

In the case of my 96, the small vacuum line from the PTC to the intake manifold runs from a branch on the PTC, but I have noticed that on later models, the PTC doesn't have this connection, and the line runs to a port on the intake pipe. Less chance there, I guess, for it to become plugged up. I plan to get a complete intake pipe assembly with the later configuration and put it into my 96, after slightly enlarging the hole in the copper ptc heating plate.

Anyone else done this?

[cn90]

...The use of the 5/8" heater hose looks like a great improvement, but since the greatest restriction to gas flow in this line exists in the small orifice in the PTC itself, why not modify it at the same time? Should the opening in the PTC be opened, perhaps in the same ratio as the increase in hose diameter?...

Interesting idea.

Whatever the cause is, I know for fact that the 5/8" hose fixed the smoking dipstick because I checked the engine before and after the 5/8" hose mod.

I am attaching the PTC photo from "jblackburn" PCV thread for everyone to see.
Personally, I don't know how we can "mess around" with the PTC w/o damaging it.
I would leave the PTC valve alone.

[jblackburn]

I think you could drill a *slightly* larger hole in the plastic, but I'm not so sure it would make any great difference. While you're at it, drill a bigger hole in the vacuum port too.

[cn90]

Does this drilling business mess up the PTC valve? Just curious.

Since I don't know the inner working of the PTC Valve, I'd not mess with it.
Also IIRC, the PTC Valve is not sold separately, but rather together with the pipe.

[jblackburn]

There's a metal washer embedded in the plastic. There's enough room to go up a drill bit size or two on both ports. Hit it with the drill fast and don't snag it at low speed and twist it around, you should be OK.

If you screw it up, you can always find a "new" one at a junkyard - and since they'll have no idea what it is, probably give it to you for $2-free.

[JP850R]

I am going to try this mod. I just replaced the PCV trap, cleaned the block ports, changed the upper hose from trap to cam cover, and cleaned out the rest of the lines. To my surprise the dipstick and oil cap filler are smoking exactly the same before & after. I have a 2000 V70 Non Turbo with 115k. I noticed while testing under throttle the smoke almost goes away. I just got this car but am surprised at 115k it is smoking pretty good. I am wondering of the lower oil passage to pan is clogged. Time to take it all back apart again..

[hankbates]

I have always thought that the early PTC's (used only on turbo models) are basically tees with a heated copper orifice plate, and the later ones (without the small vac line connection) are just connectors with the same heated orifice plate.
Good idea to enlarge the inlet port also when enlarging the orifice.

Guess it is time to dissect one.....

[rgcustom]

Is this essentially the same as over hauling the PCV system? Just not buying a pre-assembled kit? And where would I (or others) go about finding these seperated parts, by part numbers givin?(the clamps are really hard). Sorry for so many questions, this is my next project. Going stage 0.