Fitting a catch can to a modern turbo diesel is extremely important. I wrote a post some time ago, covering this, and mentioning that I installed a catch can from HPD, or High Performance Diesel. You can read more about this here – Is a Catch Can important on a modern turbo diesel?

Many of you know that I am extremely thorough in my research, and like any products I fit to my Dmax, I spend a lot of time researching and weighing up the pro’s and con’s of each option before I lay my hard earned down.

I detest buying things twice, and will pay for a quality product the first time over several cheaper units that don’t work as well.

Even well before buying the Dmax, I was doing research into what people recommended, and catch cans were high up there on the list of first modifications you should do to your 4WD. Unless you plan on selling your vehicle after a few years of ownership they are a great idea for longevity.

I read a myriad of forums, commercial posts, sales spiels and comments from owners of MUX and Dmax’s online. The overwhelming majority of people recommended the HPD, with a few people mentioning the Provent 200 as well.

Beyond that though, the HPD unit comes in a complete kit with all the brackets, had a great reputation, was Aussie made and was supposed to work well.

There must be thousands of these fitted to various 4WD’s in Australia. They’ve got to be good then, yeah? Well, maybe not…

What’s the purpose of a catch can?

The single purpose of a catch can is to filter blow by gasses from the crankcase, and remove as much oil/fuel/water vapour/carbon soot as possible.

If you fit a catch can or separator and it doesn’t do this, or it does it poorly then you’ve essentially bought a paper weight.

Beyond this, it needs to separate the fluid without creating a pressure drop. In other words, the air needs to flow into the catch can, through it and out the other side with as little as possible restriction, or this can cause other issues.

Diesel oil catch can pros and cons

Long term, there really is no reason why you shouldn’t install a good quality catch can. It’s the only legal way to keep your vehicles EGR working and your intake manifold clean. This helps maintain good fuel economy, power and ultimately reliability. 

The only con is that they cost money to fit, and there’s a lot of them out there which are poorly engineered and don’t catch much.

Catch can efficiency testing

Not long after writing the post, I received an email with a study from Curtin University, where they tested 12 common catch cans for their ability to catch oil, and you know what? The HPD catch can was the forth worst performer. Consider this a Catch Can Comparison test, with the major brands tested.

To make things worse, it wasn’t even remotely close to the performance of many of its competitors. In terms of a catch can review, the HPD faired very poorly. I was very intrigued by these results, having a strong interest in identifying the best catch can.

When I first read the report, I was pretty gutted. I’d blown $385 on a HPD catch can and it was barely working. How could I, and so many people get it wrong in recommending the High Performance Diesel catch can?

In the report, the Flashlube catch can pro, Provent 100 and 200 are the best performers by a country mile. I always suspected the Provent’s would filter a lot more than the HPD, but had no proof. If you want to compare the Flashlube catch can vs Provent, here’s your answers!

Thinking about it logically, it makes sense. A German engineering company making a catch can with a proper fibrous filter is always going to catch more than a catch can with 4 sets of mesh with an aperture of around 0.5 – 0.8mm on the inlet and outlet.

In fact, the results show the Provent catches vapour 5 times more effectively.

In summary though, here’s the catch cans filter quality factor:

1. Flashlube Catch can (CF 1.2)
2. Mann and Hummel Provent 200 (CF 2.1)
3. Mann and Hummel Provent 100 (CF 1.1)
4. Mann and Hummel Provent 150 (CF 1.5)
5. Unbranded wire mesh catch can (CF 2.3)
6. Unbranded fibrous element catch can (CF 1.3)
7. Unbranded Fibrous element catch can (CF 2.2)
8. Unbranded wire mesh catch can (CF 1.4)
9. HPD catch can (CC1)
10. Taipan wire wool catch can (CC2)
11. Calibre catch can (CC3)
12. Mann and Hummel Cyclone with no element (Cyclone)

In terms of pressure drop, capture efficiency and quality factor the Provent 200, and Flashlube take the cake overall.

Of course, this publication has been put online, and you can read it for yourself here – Catch can study. You will have to sign up to download it, but the report is free. You will get an invoice for $0.00.

In the interest of being completely transparent and sharing everything I’ve learnt, I will mention that the funding for this study at Curtin was provided by Mann and Hummel (the manufacturers of Provent). They paid for a completely independent test to be done, so there would be no conflict of interest.

Some of you might say its incorrect data, but the chances of Curtin Uni risking their reputation on a study are slim to none, and my results agree with their data too.

My independent results

I’ve had the HPD catch can fitted to the Dmax for 27,000km. It was fitted when the Dmax hit 2000km. When I first installed it, the hose clamps supplied by HPD didn’t clamp their new hose onto the OEM barb properly and it did weep a bit of oil out.

I fixed it with proper worm drive hose clamps, and have removed all of the oil recently. It’s caught just 65ml of oil. That’s 24ml of oil for every 10,000km, and is a terrible result. Consider this my HPD catch can review.

EDIT: The Provent wins by a country mile

I ended up running the HPD catch can for 34,000km, then swapped to a Provent 200 Catch Can. I collected the oil caught in both catch cans and meticulously recorded their results.

The difference between the two catch cans is chalk and cheese. Check the full post out here; Provent vs HPD Catch Can.

Finding the best catch can was pretty clear cut in this instance!

What does the Provent catch?

By my research, Provent’s fitted to the 4JJ1 motor (same as mine) are collecting 100 – 300ml of oil every 10,000km. That would line up with the 5 x better filtration than the HPD I have experienced!

Obviously, there are a lot of variables at play here – engine oil viscosity and age, engine condition, how the engine is driven and many more. Despite this, from what I have seen on new 4JJ1 motors (under 50,000km), the Provent catches a LOT more.

Since having the Provent fitted for about 35,000km, I’ve collected 1200ml of oil, and that’s pretty incredible.

Other things to think about

When you buy a catch can, there are other things to consider. Obviously how effective it is at removing vapour is a huge consideration, but  consider these too:

Ease of draining

Before you buy a catch can, look at how they are emptied. The Provent has a drain on the bottom, which most people attach a hose to that comes out near the inner guard. Every so often you get a container under the hose, crack the tap and let it empty.

The HPD catch can has a metal bowl on the bottom which you are supposed to unscrew. There is no chance in the world I can get this undone without removing the catch can.

If you have small hands or a filter wrench you can undo it, but the much easier way to empty the can is to suck it out using a big syringe and tube.

Physical size and mounting position

One of the reasons I didn’t get the Provent 200 to start with was their physical size, and where they mounted in off the shelf kits for the Dmax. The only custom Dmax catch can kit that was sold for my model put the catch can where our secondary fuel filter had to go, which created a problem.

If you put a traditional dual battery setup in your Dmax or MUX you have an even bigger problem, as the Provent, secondary fuel filter and battery all need the same space, so what do you pick?

Of course, I’m more than able to knock up brackets to mount it elsewhere, but the Provent 200’s are seriously big and finding somewhere under the engine bay near the crankcase outlet that isn’t going to interfere with anything else is a mission in itself.

Cost of changing filters

The Provent’s have separators (fibrous filters) that need replacing. The recommendation is somewhere between 40,000 – 75,000km. They are about $80 a pop. The HPD has no filters, and therefore no ongoing costs.

You’ll find this is the biggest grudge that people hold who own Provents, but if you take a step back and actually weigh up how much it adds to your overall maintenance bill, its not much. Lets say you replace it every 50k; its $1.6 every one thousand kilometres.

Some people cheap out and install mesh filters into their Provents, or buy the cheap copies. If you do the first, you’ll lose most of its filtering ability, and the latter can result other issues you really don’t want to deal with, like blown rear main seals. 

Pressure on the motor

You don’t want to put any back pressure on your motor. This is done by fitting catch cans that don’t allow enough air flow through them, or allowing them to fill up and block up.

Hoses (or inlets/outlets) that are smaller than the factory ones are a sure way to identify a catch can not suited to your motor. The Provents are sized based on recommended industrial engine CC’s, at high load.

I have spoken to Mann and Hummel, who tell me the Provent 100 is more than suitable for a standard 4JJ1 motor. That said, if you can fit a Provent 150 or 200 it is a better option in terms of offering longer separator/filter/element life.

I would suggest if you have substantially more power and torque than stock, or you work the motor hard (towing something heavy for example) get the Provent 150 or 200.

Provent catch cans come with a relief valve that opens if the pressure builds up too much. HPD have nothing like this, but because the filters are much less fine the chances of back pressure is substantially less.

There is a chance of the dipstick on the HPD popping out under pressure, as long as the hose outlets aren’t over the top of it.

I don’t know what sort of pressure you’d need to do this though, as they are quite tight around the 0 ring.

Quality of construction

The HPD kit is well made, there’s no doubting that. However, they do lack in some areas:

The bracket holding the catch can up rubs on the brake lines unless you bend them over. This could have easily been rectified in the design phase (or at least mentioned in the instructions). I simply bent the brake line a tiny bit.

The air intake hose clamp (under the catch can) rubs on the catch can unless you rotate it, which is not mentioned in the fitting instructions.

The plate on the bottom of the bracket to make it sit level is not exactly the right thickness (out by around 0.5mm on my vehicle), which puts extra stress on the panels. I have seen a photo of someone’s cracked inner guard where the catch can bracket bolts to.

I suspect it is due to the uneven surface, but also because the bracket can move back and forth over corrugations. A lot of people report vibrations/noises coming from the inner guard after fitting a HPD catch can, and I concur with this. Even though they are aluminium, they are still a heavy unit.

The hose clamps that came with the catch can was not suitable for the hose they provided. You could easily pull the hose off the crankcase hosetail even with their clamp on, and this meant that oil would weep out as well, all over the side of your motor.

I put up with it for a while, but eventually changed the clamps to worm drive ones and it never leaked again.

The kit that suits 2012 to 2016 Dmax’s creates a nasty vibration occasionally on take off. I have verified this with my own vehicle, and another one. Remove the catch can from HPD and it goes away. Obviously something isn’t quite right with the kit.

I can’t comment on the quality of the Provent as I’ve never had one, but they are one of the most common catch cans world wide across everything from light vehicles to heavy machinery.

Where to from here?

I’m not really sure. I feel pretty bummed to be let down by the HPD catch can given how it was marketed to me, but I’m going to remove it and try something else.

I was specifically told that these catch nearly as much as the Provents, which obviously is false. In my opinion removing as much oil from the intake is critical on vehicles that run an EGR system, and I want to change it to something else that is going to catch as much as possible.

I could go down the EGR delete path, but really want to keep it completely legal.

Ryco have just released a catch can (although I hear its actually bigger than the Provent 200!), and I have heard good things about the Seper8tor as well. I’d like to fit a Provent 200, but will need to spend some serious time trying to see if it will fit, and making up a custom bracket.

EDIT: If you are looking for a Ryco catch can review, there are a few people running them now, and their own website claims they are better than the Provent 200. As far as I know, there has been no independent testing to back this up though, but its entirely possible.

There is some more testing going on behind the scenes at Curtin University too, which will hopefully result in some more useful information I can pass along.

Update June 2019

A few months ago, Western Filters released a dual mounting bracket, which allowed me to install a Provent 200. The Provent unit goes on one side near the firewall, and the fuel filter (which was in this spot and stopping me from installing a Provent) goes on the other side of the bracket.

With a larger battery its a tight fit, and not the easiest installation, but its done, and now I know I have a quality catch can installed. 

I’ve documented all of the kilometres, and collected all of the oil from the HPD catch can. In due course, I’ll do another write up with the results, and how they compare.

In short though, if you look at the catch can filter its pretty obvious which one will catch more oil!

Please don’t be upset with the findings

If you own a HPD catch can, I understand you are probably not too happy reading this right now. I’m sorry; I really am. I feel the same way. I write this purely to share what I’ve found. I get no financial incentive either way.

You can agree or disagree with what I’ve written; that’s your call. This is just my findings, and the research laid out for you to read. Do me a favour though, and leave a comment below with what catch can you run, and how much oil it catches.

The HPD Catch can is a decent, Australian made product that works, just not nearly as well as some of its competitors.

What catch can do you run? Are you happy with it?

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