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Discussion Starter · #1 ·
Could not find an answer to this with search....

During a track session, my crankcase develops enough pressure to pop the dipstick about 4 inches out. It mists a little oil on the bottom of the engine cover (annoys me).

It started doing this immediately after I installed the block-off plates for the big vent tube on the front of the engine. I am not running catch cans, also no intercooler. I have read all the discussion about that tube and TurboPhil's assertion seems to make sense. The whole timing chain area is open...etc.. so it's not needed. It does seem like a big coincidence if my car developed enough blow-by to start doing this exactly when I made the change.

Guess I could re-install that tube, but the bottom is a real pain. It pretty much requires removing the SC. Car just turned 30K and gets tracked pretty often, but runs great and has had mega-maintenance. No oil leaks or problems with the rest of the engine.

Any similar experience? Something to worry about? Easy fix?
 

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I was on a dyno once when the tech didn't "click" the dipstick all the way. Blew off at high rpm (small block chevy), hit the ceiling with oil, and caught fire when gravity brought the oil back down on the hot headers. Pretty dramatic, but an easy fix. Is this a consistent problem for you? Any chance it could be as simple as the dipstick coming out easier than intended?
 

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Discussion Starter · #3 ·
I was on a dyno once when the tech didn't "click" the dipstick all the way. Blew off at high rpm (small block chevy), hit the ceiling with oil, and caught fire when gravity brought the oil back down on the hot headers. Pretty dramatic, but an easy fix. Is this a consistent problem for you? Any chance it could be as simple as the dipstick coming out easier than intended?
Every track session.... I always leave the car running for a bit to cool off hot spots, open the engine cover to let heat out and have a look (I like my aerocatch). Pushing the dipstick back in and wiping off the oil mist are now part of the routine before checking tire pressures.

Your scenario sounds scary! At least my dipstick is opposite the exhaust header.
 

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Boosted motor will pressurize the crank case. You'll need to either vent or install a catch can with a low enough restriction to prevent blowing out the dipstick.

On turbo cars, you actually need pretty large hoses to the catch can with a large vent to prevent that from happening.

BTW, having a pressurized crank case will lower the power output, efficiency, and gas mileage, as well as can cause the seals to fail.

It is better to have the crank case vented to the intake (before the supercharger/turbo) so the suction from the intake can create a vacuum in the crank case, which increases power and mileage. The trick is keeping the oil mist out of the intake.
 

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Discussion Starter · #5 ·
Boosted motor will pressurize the crank case. You'll need to either vent or install a catch can with a low enough restriction to prevent blowing out the dipstick.

On turbo cars, you actually need pretty large hoses to the catch can with a large vent to prevent that from happening.

BTW, having a pressurized crank case will lower the power output, efficiency, and gas mileage, as well as can cause the seals to fail.

It is better to have the crank case vented to the intake (before the supercharger/turbo) so the suction from the intake can create a vacuum in the crank case, which increases power and mileage. The trick is keeping the oil mist out of the intake.
That helps... probably time to install a catch can. Thanks.
 

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If you are developing that much crankcase pressure you may want to check your rings via a leak down test or a compression test as blow by gases can cause that. A Catchcan would be in good order.


Sent from AutoGuide.com App
 

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"The whole timing chain area is open...etc.. so it's not needed."
I rebuilt my engine this week, the front timing cover is "outside" the crankcase and sump, this assertion is not correct.
Over here a friend did the tube delete bit with Phil's blanking plates on his Rev 400 motor. We put the Pipe back as it caused similar issues. I think it is worth putting it back and yes I know it is a real pain.
 

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Discussion Starter · #8 ·
"The whole timing chain area is open...etc.. so it's not needed."
I rebuilt my engine this week, the front timing cover is "outside" the crankcase and sump, this assertion is not correct.
Over here a friend did the tube delete bit with Phil's blanking plates on his Rev 400 motor. We put the Pipe back as it caused similar issues. I think it is worth putting it back and yes I know it is a real pain.
Hmmm... Thanks Richard. I kind of thought others would have seen the same thing. Well, I will have the clam off in the next few weeks and can do this much easier. Will install a catch can too. Having that hose off did make it easier to access the alternator bolts and brackets so I may modify that top hard pipe piece at least.
 

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I'm not going to retype the explanation that's in the other thread. The block off plates are not the problem.

I think your time would be best spent ensuring proper ventilation for your motor/setup. You can add a catch can from the existing breather port and then add another breather port in place of the PCV valve, which could nearly double the crank ventilation. This strategy will only work in a vent to atmosphere strategy of course...

-Phil
 

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The BOE catch can is very practical and has good inner diameter. If you continue to have the dipstick pop out or experience odd oil leaks you will want to do a leak down test to make sure the piston rings are ok.
 

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Discussion Starter · #13 ·
The BOE catch can is very practical and has good inner diameter. If you continue to have the dipstick pop out or experience odd oil leaks you will want to do a leak down test to make sure the piston rings are ok.
Thanks man. Yep, I have one "on the way". Figure I will get the engine properly vented and see where I am at.
 

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Discussion Starter · #15 ·
Installed the BOE catch can and took my car to the track for a nice Father's Day. Same result.... still blew the dipstick out and some oil. There is no oil in the catch can yet, so that seems a little odd. It is quite a large line that goes from the valve cover to the catch can and I made sure that is clear. Phil mentioned the possibility of another line using the PCV port. I guess that would also go into the catch can with an additional fitting?

I passed some people I know in their Vettes, Porsches, etc :)D) so I got to ask them if there was any smoke coming from my tail pipe. Nope, all clear. The car is running great and I was very close to my personal best on that track config in spite of a hot day and a passenger. I guess it is time for a leak down test.
 

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Discussion Starter · #17 ·
So What numbers will you use for passing and failing?

A leak down test won't hurt, and is a good baseline, but it is seeming like you are not expecting the dipstick to get blown out??
Not really sure on the pass/fail numbers. Maybe it will show a clear problem on one cylinder? Hopefully no issues at all, but at least I would have a baseline.

Is it not reasonable to expect the dipstick to stay in? I have dozens of track days where it did not blow out and only the last 4 where it does. A properly vented crank case would not build that much pressure, right?
 

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Not really sure on the pass/fail numbers. Maybe it will show a clear problem on one cylinder? Hopefully no issues at all, but at least I would have a baseline.

Is it not reasonable to expect the dipstick to stay in? I have dozens of track days where it did not blow out and only the last 4 where it does. A properly vented crank case would not build that much pressure, right?
Knowing what to expect for leak-down might be wise.

What does properly vented mean?
You changed the breathing to the new and improved version and then the problem started right?
While correlation does not prove causality... There is correlation.
A lot of boosted cars eject the dipstick, but it is not optimal.

Richard Cooper has some wisdom and he offered a suggestion.
 

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The 2ZZ is just not a well vented motor with such a small breather of just over 1/2" and depending on the dipstick, they may not take much pressure to come out when combined with vibration with a motor that has a bit extra blow by. Blow by can be consequent to rings and normal combustion or to some detonation as well, FWIW....

Try removing the PCV valve and replace with the biggest barb you can. a 3/8 NPT to 5/8" hose barb and you will significantly lower the crank case pressure.


-Phil
 

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Try removing the PCV valve and replace with the biggest barb you can. a 3/8 NPT to 5/8" hose barb and you will significantly lower the crank case pressure.

-Phil
which valve is this? the 1/2" or the smaller one? I believe i have this same issue and am not sure where the real problem is, but having better pressure relief is a good think IMO.
 
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