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Too much cranckcase pressure even with a catchcan?

greatestntm

greatestntm

New member
Joined
Aug 28, 2018
Location
France
Hi everyone,
In January, I did some work on my car and some of the modifications I did were a set of redblockpowered chips and a Yoshifab catch can.
I used the car mostly for city driving for a while like this with no real problem.
But a couple of days ago I was on a going on vaccation with my car which is a 1996 940 with a B230FK. The drive was about 8 hours of highway and in the middle of my journey I noticed that the engine was puking oil from the oil cap.
At this point my PCV setup was a yoshifab catchcan only routed with the stock block vent and return and the top port that goes to the air intake right before the turbo.
About 2 hours before I was supposed to arrive, the oil filler cap popped eventough it was tight and all of my engine oil leaked everywhere in my engine bay.
I found some oil and filled it back up and also installed my yoshifab vented oil cap that was actually in my trunk.
Even with the new cap, oil still found it's way trough the seal.

After I arrived to my destination, I did a proper oil change and cleaned everything up but the oil cap still leaks eventhough I tried with 2 different gaskets.

Do you guys have any idea of what might be the source of my problem?

Also, is it normal that even turned all the way closed the Yoshifab oil cap feels way loser than the stock cap?
 
The oil drain hose under the oil trap box can clog with crap and cause high crankcase pressure. You can clean it out with a very stiff bristle brush like a rifle brush. Also be sure the port for the small hose on the intake is clear. Also check that the hose that goes to the intake pipe by the throttle body isn't filled with crap.

The tabs on the oil filler cap may need to be very slightly bent so they pull the cap tighter to the valve cover. At least that works with the stock cap. Not sure if that would work on the yoshifab cap. Try getting an oem gasket for the cap as it may be thicker than the aftermarket ones.
 
dl242gt said:
The oil drain hose under the oil trap box can clog with crap and cause high crankcase pressure. You can clean it out with a very stiff bristle brush like a rifle brush. Also be sure the port for the small hose on the intake is clear. Also check that the hose that goes to the intake pipe by the throttle body isn't filled with crap.

The tabs on the oil filler cap may need to be very slightly bent so they pull the cap tighter to the valve cover. At least that works with the stock cap. Not sure if that would work on the yoshifab cap. Try getting an oem gasket for the cap as it may be thicker than the aftermarket ones.
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Thank you for your answer!

I will clean the return and the block vent tomorrow.
The 10 AN hose that goes from the catch can to the intake between the MAF and the turbo is brand new.
As for the small vacuum hose that was going from the flame trap to the intake manifold, I thought it wasn't used anymore since it is not mentioned anywhere on yoshifab's website or on Dave Barton's installation of the catchcan.

I will also try to bend the tabs on the oil cap. I already have an OEM gasket which is indeed thicker than the one that was provided with the Yoshifab cap.
 
The small hose on the intake manifold is used to provide vacuum at idle to improve the pcv flow. It's not totally necessary as the 240 turbos didn't use it. But every bit helps and it's stock on the B230 turbo engines.
 
dl242gt said:
The small hose on the intake manifold is used to provide vacuum at idle to improve the pcv flow. It's not totally necessary as the 240 turbos didn't use it. But every bit helps and it's stock on the B230 turbo engines.
Click to expand...

That hose was deleted on 240 Turbos by Volvo. I assume the same for the 700-900 Turbos. If you're going to add this hose, consider adding a one-way valve so boost cannot flow into your crankcase when you have boost.

Dave
 
And if by chance you're using the brass filter thing, try removing it.

w01331904108mtc.jpg
 
Thank you for the information Dave.

I had a vacuum line like this going to the intake manifold with the stock PCV system but I deleted it when I installed the catch can.

This morning I cleaned the return plastic tube that goes in the block and it seemed like it was in fact clogged.
After that I bent the metal tabs on the Yoshifab filler cap and now when it goes on it's much snugger.
I then went for a test ride of about an hour and when I opened my hood, it was way better than before. One or two tiny little drops of oil had leaked out of the filler cap but that was all.
 
The 940 turbos have the vacuum line.

I'm having the same problem, but I have a Holset HE351CW and I'm running 25PSI. I'm in the process of building a serious PCV system with a McNally catch can, Yoshifab block adapter and a Ford Evap pump which will be boost referenced to turn on and off.
 
I added a another catch can so I have the factory oil trap going to one catch can and a B20 vented cap going to another one, I also put some black gasket maker on both sides of the valve cover gasket. This has cut down considerably on my oil leaks.
 
The boost pressure that does try to go down the small hose is sucked back to the intake of the turbo by the large amount of vacuum at the turbo intake when under boost level of flow. So there was not a one way valve used in the pcv small hose.

I like the method Stealthfti used to improve crank case ventilation. He added a fitting to the pcv breather box and then ran both large hoses to a catch can. From there a vacuum hose to the turbo intake hose. https://pbase.com/stealthfti/pcv
 
dbarton said:
Do they use a one-way valve?
Click to expand...

The only valve in a 7/9 turbo vacuum system goes to the climate control hose.

This might be an obvious statement, but if you had a lot of engine wear it would manifest as a lot of smoke on acceleration. Like if you were pressurizing the interior of the engine, ask me how I know haha. Must be a gasket problem. Hope the oil cap thing fixed it.
 
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dbarton said:
Do they use a one-way valve?


Can you point us to this Ford Evap Pump? Googling finds quite a variety.
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They do not use a one-way valve or check valve.

Search secondary air pump in Amazon or Ebay. They're everywhere.

Here it is installed and with my hand for a reference.
 

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2turbotoys said:
This might be an obvious statement, but if you had a lot of engine wear it would manifest as a lot of smoke on acceleration. Like if you were pressurizing the interior of the engine, ask me how I know haha. Must be a gasket problem. Hope the oil cap thing fixed it.
Click to expand...


Yeah with all this pressure, I was expecting to see smoke at the tailpipe but to my surprise, it didn't smoke at all.
The oil cap seems to be OK now I'll have to drive a bit more to confirm that.
 
I haven't seen it mentioned, but how good is your ring seal? Have a recent compression test?
 
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