DIESEL CATCH CANS - Are they really needed? They WON'T stop YOUR intake CLOGGING!

Catch Cans, generally fitted to stop intakes clogging, but do they really work, or do they cause more issues than what their worth?
We jump in, and discuss what causes the intakes to clog, why older cars don't experience these issues, and how to fix!
www.adventurecorp.com.au

[@the510wagon]

I am a qualified marine engineer. I work on some of the largest and most powerful compression ignition engines in the world. I also own a common rail turbo charged diesel vehicle. Almost all of this video speaks the truth. I really don't disagree with much of it.
But there's a few things you didn't mention that I think are important.
1. You can't talk about PCV and blow-by without discussing piston ring & bore condition. One important thing anyone can do to control excessive c/c pressure? Regular oil & filter changes and a bit of thermal sympathy in the mornings, and before switch-off. And regular fuel filter changes combined with injector management (overhaul or replacement at recommended intervals, or as needed). Faulty or tired injectors will wash lube oil away from the ring/bore area which then accelerates wear and allows more combustion pressure into the lower c/c which creates more oil vapour carry-over to the PCV. Or another way put, the more worn/tired your engine becomes the more oil droplets will be present in the PCV vapour. Added to this, poor ring seal will allow faster oil degradation via contamination of combustion products. Oil degradation accelerates wear and on it goes. One of the best things you can do for your hard-working turbo diesel is halve the oil change intervals. The longer intervals quoted by manufacturers these days are about selling more vehicles, or appearing cheaper to own than the competition. But it does your engine no long-term favours. And the longer service intervals and fixed priced servicing are a cynical use of the warranty period by the manufacturer.
2. If you're engine has a larger displacement (say more than 3 litres...) and you suspect the catch can is causing excessive c/c pressure, even with regular draining - don't blame all catch cans. Either fit a larger capacity catch can, or fit 2 catch cans in parallel to double the surface area and halve the restriction. They are still a worthy addition to a modern diesel. And they are fitted as standard to many industrial diesel engines.
3. EGR systems are difficult to defend or justify. They are the result of poorly planned and considered environmental regulations (from Europe & California). No manufacturer would have fitted such a system for any evolutionary benefit. They were forced by the regs. They are a crude solution to a problem that is only perceived. Anyone dancing around the internet saying "well if Toyota's engineers specified the EGR why would you mess with it?" needs a history lesson. The only benefit that might be present (and it's an accidental benefit, not a deliberate one) is slightly lower combustion temperatures. But that alone can be controlled or modified by so many other better methods. The extent that that reduction is beneficial over the long term is unknown. And the real-world evidence out in workshop-land would suggest the opposite - diesels that have a functioning EGR seem to have more problems as the kms rise. Many engines have been destroyed by malfunctioning EGR's - coolant loss is one example.

[@adventurecorp]

Thanks for the input, glad to see your on board and also for added info from a similar industry!

[@turbostyler]

I'm not a mechanical engineer, but I've tinkered with enough IC engines to know what's up. You're absolutely spot on. I ignore manufacturers service intervals and halve them. I've removed the EGR system from my particular engine due to a high degree of catastrophic engine failures due to the egr cooler cracking and dumping coolant and completely agree with replacing fuel filters regularly and injectors at a reasonable time frame to prevent torching of pistons. Also remember that the soot that goes back into the intake is essentially carbon. When that stuff goes past the rings and into the oil its an abrasive. That's why it's important to change oil more frequently.

[@louistiches4810]

Would it matter if I buy a catch can that was designed and only tested on a gas engine? I was looking at a radium engineering catch can

[@glandanit]

I have been building Turbochargers for 35 years, and I have found that 99% of leaking turbo's on an older diesel is caused by the aftermarket catch can, adding to the already high crank case pressure.

[@adventurecorp]

Good to see another industry expert in the comments!

[@johncasspatrol]

The oil going back through the intake also helps lubricate the valves and reduces valve wear

[@adventurecorp]

Also true, thanks John!

[@offroadoffshore153]

The carbon still collects only a bit dryer and is more abrasive. There is more risk of inducing higher crankcase pressure and blowing seals either via bad installation, not servicing or relief valve sticking. The ONLY carbon solution is to blank off the EGR valve either mechanically (with ECU mod to stop fault code) or remap ECU without EGR. Obviously illegal but certain engines like Hilux and Prado 1KD introduction of a restrictor plate (7mm diam hole) between EGR Cooler and Head gets rid of a lot of it and doesn't throw any fault codes.

[@the510wagon]

No. It doesn't.
It actually modifies the combustion properties (cetane, ignition speed /delay, duration, combustion pressure etc). The engine is designed to run on a hydrocarbon fuel that meets a certain set of chemical criteria (viscosity, flash point, cetane etc). These specifications are required, but are given as a range rather than an exact number. When the intake mixture is modified by crank case oil vapour the nature of the combustion changes. A little bit of oil vapour is not going to create a huge effect, but if your 500,000km diesel is drinking it's own lube oil you will have significantly reduced combustion performance.
The intake valve stems might catch a small oily residue, but it's pretty irrelevant. And most engines are arranged so that the residue would need to travel upwards. Against gravity, and the pressurized air flow, and be dragged into the guides to improve lubrication. And the oil vapour is only hitting one side of the stem unless your retainers are rotating the valves? 99% of the valve train lubrication is occurring above the chamber in the camshaft space (in a modern OHV engine that is).

[@adventurecorp]

​@the510wagon we agree, but as you say, the amount of oil that would have to be in the intake tonstart affecting combustion would have to be quite large, so large, you aren't thinking about any of this.

[@Mosesk1988]

Ejecto seato egr = not more slugde in intake 🤙🤙.

[@ianweal3081]

I specifcally installed a catch can from vehicle purchase as I had seen the intake manifold restrictions in my previous vehicles diesel engine.
(Once cleaned and reassembled it recieved a catch can also but that one had a stainless steel mesh gauze that required washing instead of replacing)
Current one has fabric filter that requires replacement. I religiously drained it and replace filters.
Does it attribute to air intake?
To answer that, I have had a new upgraded weld sealed intercooler installed also.
There is zero oil vapour present in my intercooler at any inspection & thats just the way I want it, compressed combustable air without oil mist traces.
I'm confident my intake manifold is much cleaner than if I'd done zero initially.
Final advise, drain frequency, replace filter regularly, and grin knowing your intake is performing at its peak.

[@user-jg2hv8ec6n]

I think your addressing egr related issues and not considering the main reason for an oil seperator. The main advantage of a "catch can" is related to maintaining crankcase vacuum to allow adequate turbo drain back, without such turbo seals fail due to pressure build up. High flow crankcase vacuum is an essential component of any turbo deisel.

[@adventurecorp]

Crank case pressures are discussed within the video.

[@jarrod1687]

Diesels are dead