PCV: Oil Separator Box Return Hose
 

So, IPD says

We highly recommend only replacing this tube when you have the oil pan off of the engine.

It is usually not possible to extract the old tube because they get very brittle and will fall apart if disturbed.
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So, I chewed it up on top end...screwed again....and strongly suspect it can't be removed on top side when it becomes hard.

So, any tricks to avoid removing oil pan? Like fishing out fragments from oil drain hole when done?

When I went to service the oil separator box and found the return hose completely clogged and was unable to clear it. I did this: https://forums.turbobricks.com/showthread.php?t=338673
Has been working fine.

Blow-by is not the issue...I wanted to install a new Oil Separator Box Return Hose

Most likely, I'll have to remove oil pan....

Yup. That hose will come out in many hard, brittle pieces.
It goes through a clamp/bracket which is attached to one of the oil pump nuts.

Thanks for clarification...

I don't know how you could hope to replace it correctly without removing the oil pan to have access from below.

The tube is held in place down below and IIRC the only way to make certain it is held / fixed in place correctly is by being able to eyeball it while guiding it into place in the clamp / bracket from below with the oil pan off.

Blowby wasn't the issue with my car. Without being able to return the oil to the sump. You have no separation of gases and oil. Thus no crankcase ventilation. It is much easier to do what I did than remove the oil pan for 'fixing it right'.

If you do remove the oil pan to 'fix it right'. Then you also have to replace the oil pump transfer tube seals while in there. With so many miles and the age on these engines. In my opinion if you are going to do all that. Then just remove the engine, put it on a stand, and refresh the whole engine.

I can't find it to link to anymore. But Stealthfti used to recommend that you shorten the oil drain back hose so it's only about four inches long. That way the hose can't clog as easy and is easier to clean if you need to.

After we put my engine together, including the return hose, we found threads suggesting to cut the hose shorter. To help in staying unclogged.

I could see how it would help as the hose gets narrower toward the end. I wouldn't think any harm could come, as long as it's cut after the bracket.

Edit. Well darn, ya beat me to it. (Read before you post...) I didn't do this before. But I wish I had.

100k engine...1990 240...runs fine, plenty of power....previous retired owner died, but he was a Swedish Volvo-ist, who maintained it,

Top cover part of PCV box was separated from lower part, and head's rear cap is fine...so I'm not sure about this issue.

Now that I think about it, possible rings shot....ever heard of PCV box separating at top?

The aftermarket ones split often enough that the rule of thumb response is volvo only on the oil separator box. I've resealed the top seam on the aftermarket ones with a soldering iron and they lasted fine after that.

The issue with those drainback hoses are the end at the bottom is flattened thus making it easy to clog with the pcv garbage that forms. If the car has done a lot of short local driving it doesn't surprise me that the hose clogged.

If I recall correctly Stealthfti suggested making it even shorter and not use the support bracket on the oil pump for the hose.

I don't have personal experience with trying that mod, but I know that the OEMs almost always extend their PCV system drain below the engine's normal operating oil level. I believe the thought process is that the crankcase pressure would otherwise be entering from below as well and disturbing the airflow/ability of the PCV to separate out the oil, although that's an assumption on my part.

Not that stock is better, I usually find those hoses kinked where they go through the bracket. A metal tube would be a much better solution.

Blow-by would represent oil and combustion gases, so a portion of them would condensate-or be absorbed-within engine's oil in the oil-pan.

Recirculating these gases in crankcase area would increase blow-by gas....in previous days, a blow-by pipe vented them to atmosphere.

One forum member used mechanical fuel-pump-port to vent blow-by. But, engine should be re-ringed if it gets this bad.

But first, warm up engine and stop, remove spark plugs, rotate crank until all cylinders are half way down, then add Johnson Evinrude OMC Engine Tuner 777185, and let it soak for several hours...and slightly move rock crank back/forth a pinch a number of times.

When done, run engine for a while, and change oil/filter. Do once more if needed...still got issues, then rebuild engine.

:lol:

The idea from volvo is to have the returning oil be below the level of the crank so it's not dripping oil against the splash of the crank. I agree some kind of return hose setup that would be more easily serviced would be great. I think that is why strealthfti suggested a shorter hose to get it above that internal area of the engine. That would let the oil fall back but not be an issue with the splashing oil from the crank.

Sounds like using the sea foam treatment for cleaning the rings. I did try the restore stuff on an 81 245 I had in the 90s. It was smoking like crazy and wouldn't pass emissions. Kjet with the early emissions cam L or F? It also had a 3.31 rear and was slower than a turtle. This car was the first one I did this PCV mod to. It had a completely clogged pcv system and if you know the kjet setup for that year it is not convenient to service. Once the pcv was enhanced by that method. It passed emissions after driving for a bit to clear out the cylinders. I bought it for 600$. Sold it for 800 a couple years later.

What a dog that car was. I guess it was a Monday assembled car. Let's see:
The firewall cracked where the clutch cable passes through.
The power wire to the kjet lambda box was recessed in the connector so the controller never powered up. The lambda relay was also bad. So none of the engine controls powered up like the control pressure regulator, aux air valve. lambda valve, etc.
The main pressure pump also failed intermittently letting you drive 15-20 mins away then would have failing pressure making a slow car even worse. I had to put a fuel pressure tester on it and drive around till it happened so I could see what the pressure was doing. Bad pump.

I guess you could say I learned a lot on that car, too. :lol:

81 VW Rabbit Pickup - Bosch used a RPM relay, where fuel pump is shut off when relay does not sense RPM.

I bought it from a neighbor with same issue as yours, and a mechanic couldn't fix it...worked fine when he "worked" on it. I installed a jumper wire at relay terminal, issue gone; so I fetched a replacement relay from auto salvage, and never had that issue again.

That is classic kjet stuff. :lol:

Footnotes

Art's Page - http://cleanflametrap.com/oilpan/

Removing (1) Air box.., (2) PS-Pump and AC, (3) drooping down steering rack, (4) battery, and (5) bracket for PS-Pump and AC makes it easier. I found a few loose bolts along the way.

Suspension's cross-member has a guide-bushing between two bolts on each side, and only driver's side needs bolts removed; with other side, just loosen until several threads are left in.

I used a floor jack on driver's side to raise driver-side's body, along with a cherry picker to raise engine on a concrete floor, with all tires about 6" above floor. I used a big screw driver to separate suspension from body on driver's side

Front of oil pan is pointed towards driver's side wheel...about 90° or less to engine block when removing/installing.

Since gasket was attached to engine block, I lightly cleaned it off, and cleaned oil pan, and then used Permatex Form-A-Gasket No. 2 Sealant on oil pan. It doesn't take much...just a thin layer.

I use a quarter inch ratchet to tighten pan's bolts. I didn't look up torque spec, but I suspect around 10 ft.lbs. or so. I've always hand tightened with 1/4" ratchet on oil/transmission pans with a somewhat firm hand torque.

I don't think it was needed to remove oil pan to replace the tube....but it may be best.

I found passenger side engine mount was busted...so replacing engine mounts, along with changing transmission filter/oil while vehicle is 6" above floor.

Well done! That is the way to do it. If you are going to change the return hose. Then you're miles ahead to do that other work. Should pass the glove test easily now.

In this photo, what was the idea here with that large hose, upper left: Volvo 949701?

What is attached on its ending?

A better "mouse trap" for excess blowby?

It looks like one of those little crankcase vent / valve cover filters.

Blowing blow-by back into valve cover would serve no purpose, and would increase blow-by pressure in crankcase.

Sort of looks like a traditional blow-by pipe...distributor appears to have a vacuum advance pot, which would suggest a much older Volvo.

I think you misunderstood what I was thinking of? To me it looks like this thing:

https://cdn.shopify.com/s/files/1/00...g?v=1571754780

aka a vent to atmosphere.

No need for a filter...here's how to vent to atmosphere, like in pre 1970s vehicles in below pic

I'd sure like to see a pic of that Volvo setup. I suspect there was a "metallic air filter" at the end of it, which caused cooling of vapor, which condensed to oil droplets. Otherwise, there would be an oily mess where vapor condensed.

What causes Engine Blow-by?

https://static.wixstatic.com/media/3...20blow-by.webp

That looks like an early 80s B23FT or B230FT pcv setup.

1975-244 just dumps it back into intake manifold....iirc, via valve-cover cap, like on your wagon, with a hose going to intake manifold.