• This one, top exit. The outlet faces up and the hose leaves vertically. It keeps the hose off the rocker cover and away from the manifold side of the engine, and it is the shortest run if the catch can sits high. It needs clear air above the breather.
• Side exit. The outlet faces out to the side and the hose leaves horizontally, across the bay. Pick that one if something sits directly over the breather, intercooler piping or a brace, and a vertical hose would foul it or kink. See the HPD Side Exit Crankcase Breather.
• Neither one clears a factory top-mount intercooler. Both are for engines with the top-mount gone. On this one the outlet projects upward, so overhead clearance is not optional.
• Everything else is the same. CNC alloy, 4JJ1 and 4JJ3, and both take the HPD -10AN push-in adapter if you are plumbing to a catch can with AN fittings.

• Replaces the factory breather outlet. A straight swap on the rocker cover. No coolant to drain and nothing major to pull off.
• Routes crankcase ventilation upward. The outlet points up, so the hose leaves vertically and stays out of the way instead of running along the top of the engine.
• CNC-machined alloy with an anodised finish. Made by HPD Special Parts in Thailand. Alloy will not crack, warp or go brittle from underbonnet heat the way the factory plastic breather does.
• Set up for -10AN catch can plumbing. The adapter is sold separately.
• Suits OEM and HPD alloy rocker covers. All 4JJ1 and 4JJ3 variants.
• It does not add power. What it gives you is tidier crankcase ventilation routing and an easier catch can install. Anyone selling it as a power part is having you on.

4JJ1-TC 3.0L turbo diesel, 2007 to 2020:

• Holden Rodeo RA7. 2007 to 2008.
• Holden Colorado RC. 2008 to 2012.
• Isuzu D-MAX (4JJ1). 2008 to 2020.
• Isuzu MU-X (4JJ1). 2013 to 2020.

4JJ3-TCX 3.0L turbo diesel, 2020 onwards:

• Isuzu D-MAX (4JJ3). 2020 onwards.
• Isuzu MU-X (4JJ3). 2020 onwards.
• Mazda BT-50 (4JJ3-TCX). 2020 onwards, the Isuzu-platform BT-50. The older Ford-based BT-50, 2011 to 2020, uses different engines and does not suit.

4JJ3 installs need 4 x 8G (4.2 x 16 mm) stainless steel screws for mounting. They are not included: order them separately or pick them up locally before you start. 4JJ1 installs typically reuse the factory hardware or need a different screw spec.

Rocker cover compatibility: OEM factory rocker covers across all 4JJ1 and 4JJ3 variants, and HPD alloy rocker covers.

Not compatible with a factory top-mount intercooler. The top-exit outlet projects upward and will interfere with the standard top-mount. This breather is for vehicles running a front-mount intercooler, or with enough overhead clearance in the bay. Check what you have before you order, and send us a photo if you are not sure.

• 1 x HPD top exit crankcase breather. CNC alloy, anodised finish.

Not included:

• Mounting screws for 4JJ3. 4 x 8G (4.2 x 16 mm) stainless steel.
• The -10AN push-in adapter. Available separately: HPD -10AN push-in breather adapter. If you are running a catch can on AN fittings, order it at the same time and save yourself a second delivery.
• Catch can hoses and fittings.

• Unscrew and lift out the factory breather from the rocker cover.
• Clean the mounting surface so it is free of debris before the new one goes on.
• Fit the HPD breather and secure it with the right screws. 4JJ3 needs the stainless screws listed above.
• Run the hose from the top outlet to your catch can or vent point and make sure every connection is sealed. A leaking breather puts oil mist through the engine bay and can cause running problems.
• Thread locker on the mounting screws so vibration does not loosen them.
• Time: 15 to 30 minutes for someone comfortable with basic mechanical work. Any diesel mechanic or 4x4 workshop can do it if you would rather not.
• Tools: a Phillips or hex driver depending on the screws, plus the -10AN adapter and braided hose if you are running AN fittings.

• Free express shipping Australia-wide, trackable to all Australian addresses.
• Dispatch: orders placed before 2 PM AEST on a business day go out the same day when the part is in stock.
• Buy now, pay later: Afterpay, Humm, Klarna and Zip. All major credit cards accepted.
• International orders: contact us with your location for a shipping quote. We send HPD parts worldwide.

• Usually in stock and ready to ship.
• Some batches run 1 to 3 weeks behind because of manufacturing schedules in Thailand.
• Pre-orders. If it is temporarily out of stock we can take a pre-order and give you an estimated arrival date from our Thailand supplier.
• Urgent order? Message us first and we will confirm stock and the actual dispatch time before you pay.

The intercooler decides this one. The top-exit outlet stands up, so on a 4JJ1-TC still running the factory top-mount intercooler it will not fit. If that is you, either look at the side exit unit linked above or sort the intercooler first.

Returns need the item unused and in its original packaging, so confirm your vehicle and your intercooler configuration before you open it. HPD parts carry the manufacturer's warranty against defects in materials and workmanship, and your rights under the Australian Consumer Law are unaffected either way. If anything is wrong with the part as supplied, tell us.

Q: What is the actual difference between the top exit and the side exit?

A: Which way the outlet points. Top exit sends the hose straight up, side exit sends it out horizontally. Top exit gives a shorter, cleaner run when the catch can sits high and there is room above the rocker cover. Side exit is the one for tight overhead spaces. Both are linked to each other so you can compare the photos.

Q: Will it fit both 4JJ1 and 4JJ3?

A: Yes. It fits 4JJ1-TC (2007 to 2020) and 4JJ3-TCX (2020 onwards) the same way. The difference is hardware: 4JJ3 needs 4 x 8G (4.2 x 16 mm) stainless steel screws, which are not included. 4JJ1 usually reuses the factory hardware or takes a different screw spec.

Q: Is it compatible with the factory top-mount intercooler?

A: No. The outlet projects upward and interferes with it. Front-mount intercooler, or enough overhead clearance, or this is not your part.

Q: Does it suit the BT-50?

A: Only the 2020 onwards Mazda BT-50 that runs the Isuzu 4JJ3-TCX on the D-MAX platform. The older Ford-based BT-50, 2011 to 2020, uses different engines and does not suit.

Q: Will it fit my HPD alloy rocker cover?

A: Yes, and the OEM cover as well.

Q: What size hose does it take?

A: It is designed around the HPD -10AN push-in adapter, which takes -10AN braided hose, the usual catch can plumbing size. Without the adapter, use appropriately sized rubber or silicone hose with hose clamps.

Q: Do I need the -10AN adapter?

A: Only if your catch can runs -10AN fittings. It gives you a proper sealed connection. Otherwise suit the hose to whatever your catch can uses.

Q: Can I vent it to atmosphere instead of running a catch can?

A: Technically it will work, but we would not do it. Venting crankcase gas straight out puts oil mist and vapour into the engine bay. A catch can traps the oil and lets the clean air out.

Q: Where do I get the screws for the 4JJ3?

A: Any hardware or fastener shop stocks 8 gauge (4.2 x 16 mm) screws. Get stainless, because they live in an engine bay. Ask us when you order and we may be able to put them in the box.

Q: Can I fit it myself?

A: If you can use a screwdriver, yes. Pull the factory breather out, clean the surface, screw the HPD unit on, seal the connections. No coolant draining and no major components to remove.

Q: Is the alloy unit actually better than the factory plastic one?

A: For durability, yes. It will not crack, warp or degrade from engine heat. It does not change how the engine runs.

Q: Is it genuine HPD?

A: Yes. HPD Special Parts, made in Thailand, imported direct by us. The finish is CNC-machined alloy, anodised, smooth and corrosion-resistant.

Q: What else goes with it?

A: If you are building the engine bay out, the HPD alloy rocker cover, HPD rocker cover bolts and the -10AN adapter are the usual companions.