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

[ShaverNS1]

I used the 5/8" heater hose to replace the long run to the turbo pipe and replaced the spaghetti tube from the intake manifold with 5/32" I believe with some larger silicone tubing as adapters for the nipples.

Been trying to track down a good size hose to replace the vacuum line when I do the mod. To clarify, what type of hose did you use and how did you connect it to the silicone tubing to adapt to the nipples?

Has anyone used anything else?

Per usual, appreciate the help.

[erikv11]

Matthew1 posted the generic vacuum line solution before this thread even started, it is still a good solution: https://www.matthewsvolvosite.com/forums ... hp?t=47383

[bob850]

Would simply enlarging the PTC hole make a big difference in flow? I don't want to do the entire PCV job for a while since I did it about 30K miles ago, but was thinking I might just pull the PTC and enlarge the hole if it would be a big help in getting more flow through there.

[Clemens]

Don't think this is a good idea, I just remember way too little of fluid dynamics to explain why.
The critical part usually is the hose diameter of the plastic hose, not the hole in the ptc (unless clogged).
Also, doing the pcv is a great time to clwan the iac and replace the throttle body gasket along with the injector o-rings. I redid the whole pcv after a few months because i still had positive pressure and the large hose finally got good vacum. It is an easy, pretty hassle-free job, it just takes a while.

[bob850]

I am referring to the PTC hole in the copper heating element, not the tiny PTC vacuum port hole. Which hole are you referring to?

[erikv11]

Would simply enlarging the PTC hole make a big difference in flow? I don't want to do the entire PCV job for a while since I did it about 30K miles ago, but was thinking I might just pull the PTC and enlarge the hole if it would be a big help in getting more flow through there.

This idea has indeed been tossed around a lot in the forums, for example see page 2 and onward of this very thread (although ignore the discussion about if the larger hole would mess up "the PTC valve" as it is not a valve at all, just a plate with hole in it), or hit up the search button. I know some people have done it and like it, for example I think tryingbe has.

There seems to be no strong argument against trying it: short term it isn't gonna kill ya, long term if it doesn't work out you can just grab another PTC from the junkyard.

[V701987]

Hello,
I have a question regarding this mod. I have a 1999 Volvo V70 and I am replacing the PCV. I can't seem to find the crankcase vent hose (PN - 1270321, https://www.fcpeuro.com/products/volvo ... se-1270321) anywhere as it is discontinued. Would I be able to use this mod for my car? How exactly would I do it? One end is clamped to the top of the PCV box, what do I do with the other open end? Thank you!

Jeff

[VolvoWildman]

Great writeup! Thank you! I don’t know if anyone pointed this out already, but something I’d like to add for the N/A models is an additional small modification where the heater hose goes back into the intake. I noticed that the intake piping that attaches directly to the throttle body has another point of constriction. I’ve added some pictures of what I’m talking about. I used a stepped drill bit to widen the hole and allow the proper airflow.

[abscate]

The PTC nipple is a maintenance item that should be cleaned every 60,000 miles. If it is plugging up faster than this, you have blow by or a badly slugged engine to address.

Changing the size of the hole is changing the balance of the vacuum from the intake manifold on overrun, and the snorkel during boost operation.

[ChadLee]

Heater hose modification done and week 2 in the books. No more smoking dipstick and I am no longer burning through a quart of oil every 1000 miles. Thank you for the knowledge to make this possible.