Suicide hose & catch can

[Cuppa]

I gather the main reason folk fit them is to prevent the engine's blow-by oil getting sucked into the turbo & getting baked on in places whee it is not desirable - ie. a means of keeping things clean & extending the turbo's lifespan.

Fitting a catch can wasn't something I had ever really thought about until I lifted my bonnet in the company of a couple of mates last weekend, both experienced diesel owners & mechanics, although not specifically with Patrols.

On opening the bonnet they both immediately commented upon the fact that I still had the 'suicide hose' fitted. I had no idea what they were talking about!

Turns out they were referring to the breather hose which goes from the rocker cover to the air inlet pipe between air filter & turbo. They explained that in certain circumstances, usually when giving the motor some welly up a hill, that it can become impossible to shut the motor off with the ignition key because the motor can continue to run on the 'blow-by oil, rather than diesel, after the fuel solenoid has cut off the diesel supply. Although rare, both claimed to have known of occurrences. When it happens apparently the only way to stop the motor is to block off air, not an easy task & fraught with the danger of injury as engine suction is extremely strong.

The suggested preventative solution was to fit a catch can mid hose to separate oil from air.

I have no reason to doubt what I was told, but in looking at catch cans I have seen no mention of reasons other than for engine cleanliness.

Nevertheless I have now bought one (a Provent 200 copy) & have spent this arvo making a bracket to hang it from.

Interested in any comments about what I was told.

[the evil twin]

Hmmm... dunno why you would want to shut off the engine in the middle of giving it a huge bit of welly up hill.

Once it is back at idle the blow by is usually quite low and the donk will shut off.

Diesels 'running on' certainly happens but I would think it is more likely a dodgy fuel cut or a very worn engine with lots of blow by at idle.

IMHO the best reason for a catch Can remains that of keeping the grunge out of the EGR system... but... would be happy to accept either as a good reason to fit one.

[Cuppa]

The way it was explained to me was that engine revs could potentially continue to rise & with no ability to turn off the motor revs could rise to the point of destruction, but I imagine that if this is possible it could only be with a very worn motor & a huge amount of blow-by

Seeings I've bought the catch can I guess I may as well fit it. If the EGR were also blocked would this be an issue?

[4bye4]

That would be a lot of blow back. I have heard of this happening but usually a mechanical fault allowing fuel or oil into the intake. A mate told me of an occurrence years back on a cray boat when routine maintenance started the engine with the air intake pipe to outside the engine room, a bit like a snorkel, disconnected. Engine ran until someone covered the air intake. Brave man to under the deck to the engine room with a Perkins going off like that. Never heard the expression of 'suicide hose' though. As ET says, the best reason for a catch can is to try and keeo the intake clean.
This example off the internet.
https://youtu.be/Cqb7l-_P_nE

[Bidja]

The way it was explained to me was that engine revs could potentially continue to rise & with no ability to turn off the motor revs could rise to the point of destruction, but I imagine that if this is possible it could only be with a very worn motor & a huge amount of blow-by

Seeings I've bought the catch can I guess I may as well fit it. If the EGR were also blocked would this be an issue?

Cuppa, go ahead and install the catch can, its function is to filters out and retain the majority of the oil vapour that is vented from the engine crankcase.

The catch can will catch better than 98% of all oiley fumes entering the inlet manifold of your Diesel. A very good mod and you will be surprised how much oil it collects and IMO empty CC each oil change. I change my oil approx every 5000km.

After installing CC good idea to remove inter cooler, inspect for oil residue (oiley gunk deposit) give it a flush/dry to clean it (good idea if grotty). Have a look at your induction piping as well, some do inlet manifold justy depends how bad things are.


Whether the EGR is blocked or not, it is always beneficial to install a CC.

[Sprock]

I hope your prevent copy is better than the 1 I originally got , the plastic was of poor quality & the lid never screwed on straight & wouldn’t stay on - I ended up making a ‘clamp’ type thing to hold it on , the filter was just stainless mesh - not a fibreglass wrapped looking thing as in the genuine Provent I now have .

[Cuppa]

I hope your prevent copy is better than the 1 I originally got , the plastic was of poor quality & the lid never screwed on straight & wouldn’t stay on - I ended up making a ‘clamp’ type thing to hold it on , the filter was just stainless mesh - not a fibreglass wrapped looking thing as in the genuine Provent I now have .

I'm hoping too!
Time will tell if the plastic is any good, but it feels solid enough. The lid feels like it screws on ok, has an o ring in it which seats at the end of screwing the cap on (when there is a final 'click' which feels like it 'locks' the lid into place). The filter is just stainless mesh which I'll wait to see how well it works, fabric wrapped filters are available *if* genuine Provent ones fit aftermarket copies.

This is the one I bought https://www.ebay.com.au/itm/Pro-200-...72.m2749.l2649

[threedogs]

Anything thats makes the engine run cleaner and more effircient has to be good eg. blocking the EGR
I thought it was to keep the MAF a bit cleaner

[Hodge]

Catch can has a few benefits Cuppa. Your motor will thank you for it.
I must admit that was the first time I've heard of blow by oil keeping a motor running away. But it makes perfect sense.
I have a Provent 200 ready to fit in. Been sitting on the bench for a while now. I'm in the process of finding some matching hoses, without bulky 25mm hose barb reducers.

I am keen to see where you have fitted yours. What bracket contraption you've come up with.

As some above have mentioned please be wary of imitation catch cans. There are varying degrees of "quality" of a copy. Keep an eye on yours.

Work friend had a provent copy on his 105 cruiser. It looked fine and dandy on the outside.
We sometimes use sump oil caught in a catch can to get a camp fire going, and that day we decided to empty his one out.
His one has a clear drain hose at the bottom of it. And inside the hose there were bits of black plastic fragments. When we opened the catch can we noticed the catch can has just about been eaten from inside out. This includes the outgoing hose barb. Meaning many plastic fragments ended up in the air intake post-filter.
Hence they're all in his crank case now .
It just seemed like the plastic it was made out of was not oil resistant. Could have been the heat too. Either way it wasn't good.
Same goes for hoses. Make sure the hose is oil resistant. On my 3L Patrol I had a hose from a XE Falcon heater with flared ends. It matched the 25mm catch can barb, and the 16mm motor side perfectly. Looked neat and tidy. After a while, I noticed oil drops from somewhere.
It turns out the hose was literally sweating the oil out, as the oil eventually made it's way through the skin of the hose.

[Cuppa]

Hi Hodge,
Unless I started moving other stuff around under the bonnet I really only had one choice of a place to put the can, on top of the passenger side wheel arch. It once had an aux battery fitted there, but I removed it so had that space. Without that space available I reckon it would have been too hard & I wouldn't have bothered!

I made a rather 'utilitarian' (ie. not pretty) mount from pieces of aluminium I had sitting around, glued (Soudal TRex) & riveted. Bolts to the wheel arch using two existing threaded holes & a third nut & bolt through a plain hole. I have demounted it for the time being until I have the hoses. I bought a couple of silicone hose reducers - for $24 which I'm waiting to arrive.
https://www.ebay.com.au/itm/AEROFLOW...72.m2749.l2649 The ad says 'not recommended for fuel & oil' but I reasoned that I have brass hose joiners so if I take care & cut the reducers accurately to length, little, if any, of the reducers will be exposed to any oil. I'll buy new 16mm oil hose. If I end up with a problem like you had with your heater hose I guess I'll grumble & cough up for a pair of Provent silicon hose reducers. I'll be keeping a close eye on the whole affair until I'm happy it is problem free.


Here's a pic of my "agricultural' mounting bracket sitting (not bolted) in position. Work of art eh?