Rough idle, oil loss, PCV crankcase ventilation issue on B20

[everyhumanvovo]

First, how is the oil trap or crankcase breather removed on a B20? Brute force? No hexhead or anything to grip with tool. It does not seem to budge when I try to twist or pull out. Does seal ring need to be replaced if I pull this out? Have been doing a lot of searching online and in manuals, but seems there is a lot about newer Volvo PVC issues and not much on earlier models.

Second, suddenly engine started to run poorly and die on idle. Thought it might be clogged fuel filter as have felt this type of sudden and violent engine shake and die going 90 on the highway before. Fuel filter fine. Then I noticed more oil on the engine and collected on valve cover perimeter. Leaking oil since this started and notice when or after running for past week. Now have not been running as I do not want to blow out seals or other damage. Changed PCV valve (did not see clogged metal mesh at oil trap opening), checked all hoses and nipples between front carb to oil cap, and PCV valve up into area below and between the two SU carbs. All looks clear for air flow. The PCV valve replaced did not look clogged at all. Have not removed front carb air filter to check the "smaller air filter" for the PCV system.

It is a B20 transplant with dual SU's, HS6's from a B18 I think, and the PCV set up is like the B18. Oil cap outlet to front air filter nipple; and PCV valve to middle area between carbs (rocker cover). The only reason I mention this is if I am wrong on issue being the PCV system. It has run great for over 7 years and about 20,000 miles and have not ever had to replace burning or leaking oil to speak of. Have not ever cleaned oil trap (crankcase breather). I read on brickboard someone else had PCV air flow issue only when it gets cold outside, and it has gotten little cooler as in 40F and have still been driving before winter arrives. Any insights very very much appreciated!

 

[dl242gt]

You can improve the pcv with thicker oil. If the system is clear and it's still a lot of vapors then the engine may be worn. You can get an idea of the engines health with a compression check. I used to use 20-50w oil in my B18B to help with the pcv.

 

[everyhumanvovo]

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[c1800]

Hi, enough with the Lucas stuff! The proper zinc and phosphorous oil is perfectly adequate. Here’s a link to a good source outlining the PCV systems on classic volvos. Suggest if you have a B20 set up yours with that system. There is a bolt holding the crankcase breather on the left side of the block. It has a square o ring to seal it. And there are 2 sizes of o rings. There’s no such thing as a smaller air filter, unless it’s been added aftermarket. You don’t need that. Just hook it up as per factory. B20’s from factory don’t use a PCV valve. 40 deg weather shouldn’t be a problem, when it gets to -20 or more there’s a possibility of vapor freezing in the hoses.

http://www.sw-em.com/pcv_diagrams_and_notes.htm

 

[alschnertz]

It's good advice to do a compression check first.
Not sure I'd use 20-50W in lower ambient temperatures.

 

[dl242gt]

It's good advice to do a compression check first.
Not sure I'd use 20-50W in lower ambient temperatures.

Good point Al. I usually used 10-40w in my pushrod redblocks. But a problem engine
I'd use the thick stuff. Synthetic 20-50w won't have any issue in cold weather. In my turbo
I use 15-50w M1 all year.

 

[spock345]

Hi, enough with the Lucas stuff! The proper zinc and phosphorous oil is perfectly adequate. Here?s a link to a good source outlining the PCV systems on classic volvos. Suggest if you have a B20 set up yours with that system. There is a bolt holding the crankcase breather on the left side of the block. It has a square o ring to seal it. And there are 2 sizes of o rings. There?s no such thing as a smaller air filter, unless it?s been added aftermarket. You don?t need that. Just hook it up as per factory. B20?s from factory don?t use a PCV valve. 40 deg weather shouldn?t be a problem, when it gets to -20 or more there?s a possibility of vapor freezing in the hoses.

http://www.sw-em.com/pcv_diagrams_and_notes.htm

If you set it up in the B20 manner sans PCV valve you will want the proper intake manifold hose fitting with a restriction inside. VP has them.

 

[alschnertz]

Good point Al. I usually used 10-40w in my pushrod redblocks. But a problem engine
I'd use the thick stuff. Synthetic 20-50w won't have any issue in cold weather. In my turbo
I use 15-50w M1 all year.

Me? I use 5W-30 high mileage synthetic blend in everything I own. That's Volvo B16, B18, B20, B230FT, B5234FT to B4204T3.
Then throw in the Mazda MPV, Ford Focus, Honda Prelude and Civic.

Too many cars, too many options. So I try to keep it simple.
If an engine is so tired it needs thick oil, I rebuild it.

 

[everyhumanvovo]

Hi, enough with the Lucas stuff! The proper zinc and phosphorous oil is perfectly adequate. Here’s a link to a good source outlining the PCV systems on classic volvos. Suggest if you have a B20 set up yours with that system. There is a bolt holding the crankcase breather on the left side of the block. It has a square o ring to seal it. And there are 2 sizes of o rings. There’s no such thing as a smaller air filter, unless it’s been added aftermarket. You don’t need that. Just hook it up as per factory. B20’s from factory don’t use a PCV valve. 40 deg weather shouldn’t be a problem, when it gets to -20 or more there’s a possibility of vapor freezing in the hoses.

http://www.sw-em.com/pcv_diagrams_and_notes.htm

Thank you very much for link. The "filter" is how I saw it described somewhere else. Autopress 122 manual calls it "Intermediate Piece for Crankcase Ventilation" or in later manual a "Cleaner Insert" located in air filter assembly receiving a breather hose. This piece bolts on with air filter and is sandwiched between air filter and the front SU carb. A crankcase hose attaches to it coming from the oil filler cap. It is about 3" x 6" x 6" triangular shape with rounded corners and only about 1/2" thick and has round opening at center for the air intake. If PCV system is blocked up somewhere, I think it is either this piece or the crankcase breather oil trap. Do you know socket size of oil trap bolt? - was having trouble finding any size to fit and thought might maybe have to use wrench.

 

[everyhumanvovo]

Hi, enough with the Lucas stuff! The proper zinc and phosphorous oil is perfectly adequate. Here’s a link to a good source outlining the PCV systems on classic volvos. Suggest if you have a B20 set up yours with that system. There is a bolt holding the crankcase breather on the left side of the block. It has a square o ring to seal it. And there are 2 sizes of o rings. There’s no such thing as a smaller air filter, unless it’s been added aftermarket. You don’t need that. Just hook it up as per factory. B20’s from factory don’t use a PCV valve. 40 deg weather shouldn’t be a problem, when it gets to -20 or more there’s a possibility of vapor freezing in the hoses.

http://www.sw-em.com/pcv_diagrams_and_notes.htm

Thank you very much for link. The "filter" is how I saw it described somewhere else. Autopress 122 manual calls it "Intermediate Piece for Crankcase Ventilation" or in later manual a "Cleaner Insert" located in air filter assembly receiving a breather hose. This piece bolts on with air filter and is sandwiched between air filter and the front SU carb. A crankcase hose attaches to it coming from the oil filler cap. It is about 3" x 6" x 6" triangular shape with rounded corners and only about 1/2" thick and has round opening at center for the air intake. If PCV system is blocked up somewhere, I think it is either this piece or the crankcase breather oil trap. Do you know socket size of oil trap bolt? - was having trouble finding any size to fit and thought might maybe have to use wrench.

 

[hiperfauto]

2 bolt SU filters don't have a provision for the breather and used the sandwich adapter. We have them ultrasonically cleaned as there's no easy way to get the muck out.

http://hiperformanceautoservice.com/images/418970.jpg

3 bolt filters have a provision for the breather.

http://hiperformanceautoservice.com/images/672280.jpg

The bolt holding the breather box to the block has a 7/16" (11mm) head. It's very close to the box so you need a thin wall ?" drive socket.

 

[everyhumanvovo]

Right on! Got the breather box off and not much inside box, but hard to tell if mesh is blocked up. Surface looks fairly clean, Sprayed some carb cleaner on mesh and thinking I could push wire through to clear; maybe not. Seems air may be good to blow this mesh out if is mucked up.

Thinking issue is the sandwich adaptor. After idle turned bad last week, noticed after parking that smoke was wafting from front air filter/carb. Checked dashpot oil (may have been empty) and overfilled and tried to syphon out what I could. Back carb dashpot oil seemed fine. Wonder if this dashpot oil overfill caused more of a breather issue with sandwich adaptor. Read excess will just burn off, but wondering.

Can I send this sandwich adaptor in to be cleaned? Or, do you sell these sandwich adaptors, breather boxes or know where to find them new or refurbished? Thinking I should start searching "SU HS6 2-bolt sandwich adaptor" instead of sifting at the classic Volvo parts places. Thank you much for detail on breather box bolt! I thought my sockets were possibly too thick.

 

[hiperfauto]

The breather box is just an empty can. The "filter" is a flame trap that's supposed to be replaceable but is now NLA so you'll need to clean it or remove it and run without one. To clean the box, cap the small nipple and fill with carb cleaner and a bunch of nuts and/or washers and shake vigorously with your hand covering the open end. It will probably take several times to get it clean.

http://hiperformanceautoservice.com/images/419771.jpg

We sell the ultrasonically cleaned sandwich adapters for $60. We can have yours cleaned for $20 + shipping or you can find a local place that does ultrasonic cleaning.

 

[everyhumanvovo]

Thank you! Does it work to keep only hose going from breather box to rocker cover, eliminating sandwich adaptor and using one of those little air filters attached to oil fill cap?

Or, and, also, is capping rocker cover nip, and having breather box let a little go to ground (which appears to be virtually none based on looking inside my breather box), or set up an oil catch box? Wondering what is better for engine breathing and most simple longer term solution.

 

[everyhumanvovo]

The breather box is just an empty can. The "filter" is a flame trap that's supposed to be replaceable but is now NLA so you'll need to clean it or remove it and run without one. To clean the box, cap the small nipple and fill with carb cleaner and a bunch of nuts and/or washers and shake vigorously with your hand covering the open end. It will probably take several times to get it clean.

http://hiperformanceautoservice.com/images/419771.jpg

We sell the ultrasonically cleaned sandwich adapters for $60. We can have yours cleaned for $20 + shipping or you can find a local place that does ultrasonic cleaning.

Hello, checked hiperformanceautoservice site and looks to be great future source. Like to send sandwich adaptor and breather box in for thorough cleaning and o-ring seal for box if available. Thank you much.

 

[Stiggy Pop]

It's good advice to do a compression check first.
Not sure I'd use 20-50W in lower ambient temperatures.

I had 15w 40 in my 945 years back and after a night of -15* the starter couldn't even turn the engine over. Pulled the dipstick and it was like cold molasses.

 

[hiperfauto]

Thank you! Does it work to keep only hose going from breather box to rocker cover, eliminating sandwich adaptor and using one of those little air filters attached to oil fill cap?

Or, and, also, is capping rocker cover nip, and having breather box let a little go to ground (which appears to be virtually none based on looking inside my breather box), or set up an oil catch box? Wondering what is better for engine breathing and most simple longer term solution.

Yes, you can eliminate the sandwich adapter and run a small filter on the breather cap. The air being sucked into the engine just needs to be filtered somehow.

Venting the crankcase to atmosphere isn't recommended. It was done before emissions standards were implemented. Besides, the fumes find their way into the cabin and it isn't pleasant.

Hello, checked hiperformanceautoservice site and looks to be great future source. Like to send sandwich adaptor and breather box in for thorough cleaning and o-ring seal for box if available. Thank you much.

I'm more than happy to clean the breather parts for you but I think you have another problem. The rough running indicates a mechanical malfunction or possibly a carb flooding. Figure out what's causing it to run rough first. As suggested a compression test and if you have access to one a leak down test will reveal a lot about the condition of the rings and valves. Pull the valve cover and look for anything out of place (ie. bent pushrod, broken valve spring, etc). If it all looks good crank the engine over with the starter and look for a flat cam or any unusual valve movement.

 

[everyhumanvovo]

Great, thank you. So, to confirm, it is fine or better even to only run the hose from breather box to rocker cover with oil cap filter and eliminating sandwich adaptor?

Well, it was only intermittently rough. It did run well for a day last week and thought I solved issue after I adjusted the idle on both carbs. I also need to truly sync the carbs. Now have the air filters pulled off. But, will definitely do a compression test and pull the valve cover and look for what you describe.

I will still send both the sandwich adaptor and breather box for ultra sonic. Also, like a new breather box o-ring if available. Do you sell those K&N oil cap filters? I believe I have the early model B20 and oil cap with nip. I have a note and the hi performance address ready to ship with items. Should I make it to the attention of yourself? Best regards, Mike

 

[hiperfauto]

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