Plastic Check Valve (10mm OD)

This innocent-looking piece is a miracle cure for popping dipsticks! For years and years, DSMers have been plagued with an annoying? (maybe a lot worse than merely annoying, but we digress . . .) problem. Under certain conditions (usually spirited driving under high boost, high revs, etc) the dipstick has been known to pop out of the dipstick tube in which it sits and allow oil to shoot out all over the underside of the hood, over the engine, etc. This is not fun! It could also be extremely dangerous as it can (and has!) led to engine fires.

There are solutions to be had. One of the most common is to replace the dipstick with a new one. The idea being that as a dispstick ages, the rubber plug at the top of it (which exists to seal the dipstick tube closed) gets hard, cracked, what have you, and is no longer an effective seal. Another option is to "pinch" the top of the tube with pliers or a similar tool to give a tighter fit for the rubber seal on the dipstick.

These solutions have been known to work in many cases and under many circumstances, but not all. When the boost, rpms, etc are especially high, these solutions prove inadequate. So what is a DSMer to do, you ask? Well, it turns out that many of the previous assumptions about the causes of the popping dipstick phenomenon are not necessarily true.

It had always been assumed that high crankcase pressure was the root cause of the problem. And that's certainly true--it IS the root cause. WHY the crankcase is ever "allowed" to build excessive pressure has not been so well understood. It was more or less assumed that some kind of design flaw, inherent condition, etc in the 4G63 turbo engine was to blame. The school of thought was "well, the 4G63 engine is just a blow-by monster, nothing we can do about the root cause, we'll just have to treat the symptoms". Turns out this appears not to be the case. The 4G63 engine may have been falsely accused!

Evidence seems to show that the crankcase ventilation system is really to blame. And, specifically, the PCV valve itself! It appears that under high boost (and maybe not so high boost) the PCV valve has been found to "leak" some of the boost pressure into the valve cover (and so into the crankcase). This is NOT supposed to happen. The PCV valve is supposed to be a "one way" valve. That is, it is supposed to allow air to pass in one direction only. In this case, that's supposed to be from the valve cover into the intake manifold (when the intake mani is under vacuum). When the intake mani is NOT under vacuum (when under boost, for example) the PCV valve is supposed to close and not allow pressure into the valve cover. It appears to fail to do this in many circustances. This is true of BRAND NEW PCV valves as well as used. It is also true of OEM Mitsu versions as well. It appears the sealing system within the PCV valve is simply unable to properly seal under higher pressures. It's as simple as that!

So what's the solution you ask? IT'S AS SIMPLE AS A BETTER ONE WAY CHECK VALVE! (forgive us our shouting please). One that has been proven able to contain high pressure. Let us introduce you to this simple, very inexpensive solution to the "DSM popping dipstick" phenomenon. We just call it the Plastic Check Valve. Somehow we feel it should have a more regal name, but nothing else seems to fit.

This check valve simply does what check valves are SUPPOSED to do: allow air to pass in the one direction ONLY! (seems simple enough, right?) We know of many hardcore, knowledgeable DSMers who swear by this little valve. Many use it INSTEAD of a PCV valve (it afterall performs the same function), others choose to plumb it in series with the PCV. We'll let you decide. (RTM also carries a fancy fitting to aid those who wish to plumb their check valve into the valve cover vent without a PCV. For details, please refer to the "Related products" link near the bottom of the page).

We should point out that this valve will not cure ALL crankcase pressure problems. Boost pressure, normal combustion pressure, etc. can find its way into the crankcase past the piston rings. This valve IS amazing, but it CAN'T restore life to worn piston rings. Anyway . . . Even if you don't believe this little valve can do what we claim it can, for less than $3, you aren't willing to see for yourself!?

NOTE: There's a little arrow cast into the plastic on the centre portion of the check valve which indicates the direction of air flow. This arrow should point toward the intake mani.

Sold individually.