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

[Ben850]

This small hole is the first bottleneck. If the hole is not enlarged or the flame trap remains in place, you can have a 1 foot diameter pipe coming from the PCV and it won't matter:)

That small plastic pipe outlet in this fitting does not look like a 5/8 diameter. It may be slightly more than 3/8, if not 3/8. That is the next bottleneck. Can someone measure the inner diameter and report back?

These are the first pieces to leave out of the equation on an N/A.
Smooth sailing pretty much after that.
Also, the turbo hose to the PTC nipple has no "flame trap".
5/8" tubing simply makes things easier to route without kinking.

A simple hose clamp brings the diameter tight to the fitting.
Not Rocket science.
Matty Moo, of Midwest ABS, contributor here utilizes copper tubing to do this bypass.
I believe that is a better way to go as well if you have the patience.

It is not written in stone to be 5/8" heater hose.

Oil separator.jpg (50.35 KiB) Viewed 1880 times

[Redneck]

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[cn90]

...@cn90, What is the diameter of the opening in the oil separator where you attach your hose? What is the smallest opening diameter near the intake where former flame trap was located? Unless these openings are enlarged the 5/8 hose will have no benefit at all. You only risk squeezing it under the manifold contrasting the air flow. At least the plastic pipe can't be squeezed...

I would say take 5/8" and subtract 1mm on each side (the thickness of the outlet port of the oil trap):

https://www.matthewsvolvosite.com/forums ... =1&t=55470

[erikv11]

All setups have a small restriction, about 3/8 (oil trap) or smaller (PTC nipple or flame trap). The flow rate/capacity discussion is an interesting sideshow, for me it is not worth arguing those details. It doesn't really matter, the basic premise of using some kind of bulk hose is a good idea regardless.

Using a bulk 5/8 hose is a great alternative because it is cheap and easy and works, just drive to a local store and pick up what you need for moderate cost. No pricey and slow online orders of specialty piping. As pointed out many times in many places, there are better choices than cheap heater hose, e.g. fuel line or copper tubing, for insurance against kinks. Or use something cheapo but route it carefully. Whatever your choice, just install and move on, keep those crankcases breathing!

[Ben850]

They were doing Bernoulli calculations involving turbulence and boundary conditions on 5/8th diameter hose assuming that it was the smallest diameter along the way. This assumption was incorrect.

What is the smallest inner diameter of the plastic fittings/outlets that the 5/8 hose slides onto? Is it much larger than the existing plastic 3/8 in pipe?

The fitting/outlet out from the oil separator may also be much smaller than 5/8 and closer to 3/8in. Nobody can modify that outlet. If the inner diameter is 3/8, then sliding larger diameter hose over it won't make any difference. The flow rate will be the same. This is just a common sense:)

It is like putting a 2inch diameter hose over 3/4 inch faucet hoping that more water will come out:)

The smallest diameter in the duct is the limiting factor that if increased may reduce some of that pressure from the crankcase. However, the pressure reduction may be still insignificant because flow rate may be similar or almost the same but with increased velocity via a smaller diameter opening.

This is all fine.
If you would like to discuss the Volvo, "White Block" PCV system, you must also indicate normally aspirated, or Induction enhanced, Turbo, supercharged, N2o.

Once these variables are put into said equation, Bernoulli may speak to that.
As far as the normally aspirated internal combustion engines go, the numbers may remain static.

Maintenance history, neglect, deterioration of organic items...

Other said variables were non existent when The savior Bernoulli began his equations.

Understanding full well his comprehension of air pressure, Fluid dynamics ETC..
It is a non argument as to his view on the PCV bypass fix To a five cylinder Volvo.

[Redneck]

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[Redneck]

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[Ben850]

@Ben850. The only thing that matters is the pressure inside the crankcase and the smallest diameter opening that lets the air out from the crankcase. It does not even matter what kind of car it is.

If the smallest diameters along the way of the PCV duct can be enlarged, then more air will flow out from the crankcase at the same velocity without increasing pressure in the crankcase to push the excess air out.

How is that going for you? I absolutely agree with that statement.
I am fine with my vehicles.

[Redneck]

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[Ben850]

I don't have the problem yet, but It got me thinking as the car gets old, there is more blow-by. If I still have the car 8 years from now, I may look into this suggested solution. It is actually hard to know if I dont have the problem of high pressure already. The pressure buildup will happen when driving for extended period of time on a highway with high revs. I may not see much smoke from the dipstick when testing on the parking lot. It will take some time for the crankcase pressure to build up. I may at least look at the flame trap fitting to see if I can enlarge any of the holes to make them at least 3/8 as the existing pipe diameter. I don't worry much about the camshaft seals, but the rear main seal is the one to worry about:)...It was a good brainstorming session:)

I have just rebuilt my alternator, starter, replaced the radiator, pulley, adjusted AC compressor shim.. I like doing everything at the same time in groups. Tomorrow I will finish bolting it all back.

Well, I did enjoy our banter today.
I must say you had brought up some very good points normally overlooked by the average daily wrenching mechanic.
Please enjoy your holiday season and feel free to PM anytime as to speak without audience.