It probably insn't a problem. It happenned to me once (10,000 miles ago), and then never again. At the time my oil was overfilled and I was using a oil catch that did not recirculate back into the valve cover. I still really don't know if the oil catch was a factor. My compression is perfect.

It freaked me out too. Let us know if it ever happens again. Then, you might have to do a couple of things.

 

That is a good fix, but I think he (and me also) is interested in finding and understanding the root cause for the problem.

I mean, we know it pops out because of excessive pressure, but why is the pressure there ??

 

We finally have a real solution for the dipstick problem. I have a prototype billet alluminum locking dipstick that once Im done with testing and convinced it works as well as its supposed to, we will be selling. We took a completly uncrushed dipstick tube and put the new alluminum dipstick in it and pressurized the tube to 60 ft lbs of pressure before it blew out. It has a handle and a release lever so all you have to do to easily remove it is pull up on the lever and it slides out with ease. Once we have some ready to sell, Ill let you guys know and we will also put them up on our webpage.

 

There is a hose that runs from the valve cover to the intake tube to draw out the crank case pressure. If you run a oil catch can, it's not drawing all the pressure out. Another thing you could do is drill out the pcv valve to help releave some of the pressure if your running a catch can.

 

I figured the hose was there to help draw down the crankcase pressure using the vacuum effect created by the intake.
That is why I was always amazed that some folks would remove the hose and install a little fuel filter.

I have a catch can, but I have it plumbed with both hoses; from the cover to the can, from the can to the intake.
I would be my assumption that even with the can inline, I was still getting the "suck" created by the intake.

Still, if my dip stick was popping out (which it isn't so far [crosses fingers]), this is really a secondary effect
that is pointing to another problem.
Unless it is the concensus that excessive crankcase pressure is normal for DSMs ??
I know it's common, but should it be acceptable ??
I would want to understand (and hopefully fix) the root cause.

And although a locking style dipstick would be really swank, it's kind of a "finger in the dike" solution, yes ???

 

Hi,

Yeah, if you read some of the catch can threads, look for the posts by Mark at Quantam. Good info. Also see what Timzcat says about plumbing the "pcv" side into the catch can in addition. You can also have two separate catch cans.

Anyway, it should route back to the intake (unless that has been eliminated by an aftermarket intake) to help with breathing as well as relieving crankcase pressure or something like that.

FB

 

thanks for all the help everyone. i will keep everyone updated. I am going to clean the engine bay today and drain just a tiny bit of oil, and run a compression tests for safe measures...i am a worry wort.

 

did a compression test and everything checks out

cylinders

#1 177psi
#2 176
#3 175
#4 176


so i guess everything is cool. Something funny to think about is when i called the SHELTON in CT....the service advisor said "...so you want a new dipstick" and i just lauged...he had noooooooo idea what was going on. it is quite funny how the people on this board no more than the people that are working on our cars.

 

here is one option that was given to me by a local shop that specializes in turbocharged mustangs. they suggested actually hooking a vacuum pump up to the valve cover to simulate the suction originally produced by the intake for the turbo relieving pressure without the risk or getting oil into your i/c. they stated that this is a regular mod for the cars they build.

 

If it happens again, just tie down the dipstick. No big deal

 

true, that's what I do currently, just use a zip tie to secure it.

 

Definitely keep us posted, or me anyways.

 

Under boost, you're putting 19psi above 1 atmosphere into the pistons, adding fuel, and igniting. That makes for enough pressure to push a car -- quickly.

Some of that pressure is going to get past the rings into the crankcase. (No engine will hold pressure perfectly.) While oil is pressurized to pump it around the moving parts, you don't want pressure or vacuum on the crank side of the pistons. The "internal combustion" pressurizes the cylinder side of the piston to move it (and to push compression stroke pistons up). You don't want pressure on the crank side fighting the movement of the pistons.

In ye olde days, the crankcase was simply vented to the outside air. However; since the crankcase is full of oil, some oil gets mixed with the gasses venting from the crankcase. Thus the oil-vapor separator (charcoal cannister) or catch-can, to remove the oil from the gasses so it doesn't drip all over the engine bay. Because the crankcase gasses also pick up hydrocarbon elements which the vapor separator won't catch, these gasses are passed back into the intake so the engine will burn them, rather than simply pumping them (smog) into the air.

I had a similar problem on an old Alfetta GT. Between condensation (or imperfections in the head gasket), water can get into the charcoal cannister. On the Alfetta, that water froze in the cannister, blocking the crankcase vent. The dipstick was well seated on that car -- like crimping the dipstick tube. As the crankcase pressure built up, the car ran progressively worse. Then *BANG*, a huge noise from under the hood -- and then the car ran fine. When I got to work, there was an oil streak down the side of the car, and I found the dipstick lodged under the overflow tank. The crankcase pressure had blown the dipstick (and about a quart of oil) clear out of the dipstick tube.

From then on, I kept the hose clamp at the top of the cannister loose in winter.

You don't want the crankcase perfectly sealed. Ideally, it should vent through the provided equipment. But if the supplied vent fails (clogging of the cannister or pinched hose), you want the pressure to blow off somewhere that isn't going to take a lot of oil out with it. Today's cars (unlike the Alfetta) tend to have long dipstick tubes that rise to the top of the engine, so oil is less likely to exit if the pressure releases there -- provided it doesn't build up too high before it releases. If you want to seal the dipstick (which does, after all, connect at the oil-filled pan), then make sure you have an excess pressure release somewhere at the top of the valve covers -- say, by loosening the clamp on the crankcase vent hoses. Engineers call this a planned failure -- or just a safety valve.

I haven't checked, but I don't think they use charcoal in the vapor separators these days. Charcoal cannisters, once contaminated, became even more prone to clogging, so you had to replace them after a while. I don't think one oil bath will kill your separator, but if you get this issue repeatedly, you might need to replace the separator.

The old Celica GT4 didn't have a cannister at all -- it simply vented the crankcase to the intake, so if you overfilled the engine oil, you'd get a bit of oil smoke in the exhaust for a while. (The PCV kept a backfire from igniting the crankcase gasses.)

So the first lesson here is don't overfill the oil level. But beware sealing the crank too well, or when pressure finds its own way out (and it will) it'll likely blow a lot of oil out with it.