2JZGTE - Crank Ventilation

There are two crankcase ventilation routes in this engine.

One leads to the intake after the throttle plate, and the other leads to the intake before the compressors. They perform the same function ultimately, but operate in different ways, so they should not be connected together as some half-baked 'experts' proclaim.

The first one faces various degrees of vacuum, and occassionally strong boost conditions. That's why it connects to the camcover via a one-way valve, otherwise under boost it would be pressurising the camcover (and the crankcase by association). That would be a bad thing.

Here is Toyota's general description of their PCV system (Positive Crankcase Ventilation)

The modification described here deals only with the second route. Being before the compressors, this one is always under vacuum. Generally speaking the higher the engine load, the stronger the vacuum. (note that the opposite is true for the other route, they are complimentary)

This catch-tank came from eBay. Good price and suprisingly good quality. Nice, thick aluminium that will help cool the crank gases so the oil solidifies even easier (the other reason is the sudden pressure drop as volume expands). The top and the bottom can be dismantled which is useful when 'dialling' the body for the shorterst possible hose route, while still keeping the level indicator visible.

The dimensions are just right for it to fit behind the airbox.

 

This is a cheap base material to cut out a fine metal filter, if we so wish later on (perhaps to keep the scourer bits together) Just be careful not to leave any loose particles, because they might be sucked in the engine.
This is an equally cheap base material to fill the catch tank so that the gases will have an even more torturous path and are forced to deposit even more oil droplets. Wash them first to make sure there is nothing loose.
Bracket from DIY store that can be quickly adapted to secure the catch tank (a bench drill and some spare bolts will also be needed)

 

Catch tank with top open and the kitchen scourer in place.

Fits very neatly indeed, and the level indicator is straight in the line of sight. This catch tank was sold as 'turbo' model and it has 15mm hose endings (as opposed to the 10mm of non-turbo) This is important because tuned 3litre turbos produce a lot of gases, especially if they are of a certain age and blowby is an issue. We want to keep the volume of hoses as large as possible and their length to a minimum, avoiding kinks and sharp turns if possible.

 

	These are the two new hoses to and from the crank ventilation. Note that these are heavy-duty braided 12mm (ID) normally sold for fuel systems. They have metal springs inside so they can't kink. They are also very resistant to heat and abrasion. They are not cheap, but it is best to avoid usin cheap silicon hoses in this application.
The hoses directly connected to the catch tank are 15mm (ID) as the other ones wouldn't fit of course. The connectors make sure that the routing is short and efficient. We now secure the catch tank and Job done!
Once in place, it is hard even to see the retaining bracket. Thankfully there is already a drilled/threaded hole from the factory just under the catch tank (fits standard 10mm bolts) So we just have to secure our bracket to the one coming with the catch tank. If you have trouble positioning the bolt, just use a 1/4" rachet extension and a blob of grease to hold it in place until it starts screwing. Very nice and tidy.

 

 

 

On to 2JZGTE Cam optimisation.....