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nissan
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Discussion Starter #1 (Edited)
Is a Catch Can Really Necessary After EGR Block?

The gunk buildup inside the intake is attributed to having oil vapour mix with exhaust gas. If you remove the exhaust gas from the equation (EGR Block), does the oil vapour just pass harmlessly through to the combustion chamber? I would have thought that it might provide a good bit of lubrication to the intake side of the turbo and also the intake valves.

There seems to be a lot of knowledgeable Patrol owners on here that block the EGR and still run catch cans. What am I missing?

I just finished installing my EGT and Boost Gauges so the EGR block is happening shortly and I'm trying to plan what other mods are essential without being a needless spending exercise.

Thanks in advance for your thoughts.
 

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bit cold out it seems
nissan
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no.

The EGR is dumped into the intake manifold, well after the turbo.

the crank case ventilation is dumped in prior to the turbo.
 

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2001 TB48 GU Patrol
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Hi mate I thought the same as you And I have been running blocked egr and no catch can for a few months so far and hav not had any problem
 

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nissan
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Don't need it from the point of view that it is no longer mixing with the EGR soot making black goop..

Yes from the point of view that you do not want oil vapor / droplets going into the turbo which is spinning at up to 160,000rpm, it can damage the blades over time.

Also yes from the point of view that it will make the aftercooler less efficient (it will take longer to cool down if there is oil in it) which is probably another reason why the ricers run a catch can on their engines.

:cheers:
 

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Grenade Master
GU4 05
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I would have thought that it might provide a good bit of lubrication to the intake side of the turbo and also the intake valves.
That's the stupidest think I've heard sorry, your diesel motor intake doesn't need lube and intake valves get the lube where it belongs via existing engine oil lubrication system.
The intake will still gunk up with the crap courtesy of the idiotic crankcase ventilation design by Nissan and the other vehicle manufacturers, diesel or petrol engines included! Either make it free to breathe or use catch can. Cheers
 

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nissan
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The intake will still gunk up with the crap courtesy of the idiotic crankcase ventilation design by Nissan and the other vehicle manufacturers, diesel or petrol engines included! Either make it free to breathe or use catch can. Cheers
Whats a better design? are you referring to the fitment of a catch can from the factory?
 

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nissan
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just run the breather hose down and have it dump deside the chassie. it barely drops any oil, mainly mist .nearly all the trucks used this method until the euro 4 emmisions crap came out and there wasnt a problem with getting on the road , clearly im not a greenie! and im sure ill get a heap of people saying its not the right thing to do... meh
 

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Enemy of Reality
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That's the stupidest think I've heard sorry, your diesel motor intake doesn't need lube and intake valves get the lube where it belongs via existing engine oil lubrication system.
The intake will still gunk up with the crap courtesy of the idiotic crankcase ventilation design by Nissan and the other vehicle manufacturers, diesel or petrol engines included! Either make it free to breathe or use catch can. Cheers
That's the stupidest, unwarrented nasty response iv'e heard in a while; but at least you apologised.

But you are right. Use a catch can.

FWIW, i don't think it's idiotic at all.
 

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nissan
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I am completely confused by the idea of why you would block off a pollution device that does not effect performance in any way :confused:

If you are recirculating unwanted by-products there is really something fundamentally wrong with your engine.

I understand budget concerns prohibit fixing the real issues like rings etc. but if you fix the underlying problems all works spectacularily :crazy:
 

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nissan
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I am completely confused.
Correct.

The engine has been designed to recirculate unwanted by-products,nothing fundamentally wrong there. yes it is a pollution device, and by removing it is wrong. (NoX generation)

Does it effect performance? yes as your diluting your intake charge with exhaust gasses.
 

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It only works on part throttle, not under full load ;)
Yes this most likely correct but has anyone actually proved this? do you have logged data to show the exact conditions the EGR system is operating under? eg. When I kick down the auto does the valve snap shut? what is the response time?

Sorry for going off topic.
 

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I thought it is a 3 step motor which opens (or closes) in relation to the throttle position.

If Chaz reads this he will know. He did tell me but lack of sleep is affecting my memory.
 

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Yes this most likely correct but has anyone actually proved this? do you have logged data to show the exact conditions the EGR system is operating under? eg. When I kick down the auto does the valve snap shut? what is the response time?

Sorry for going off topic.
Oxides of nitrogen are created when you lean the mixture out during light throttle/cruise. By introducing recycled exhaust gas into the combustion chamber, combustion is cooler and the reduced burning temp reduces the NoX :)

Million for performance gainers plug them as they think exhaust gas is being recirculated in all throttle openings.

This is not true.

If you snap the throttle, the EGR system stops working as the cooler richer mixture reduces the NoX.....

If you have oil, water, scum or fuel in your inlet manifold your poor car is telling you there is a blow by, fuel system or cooling system issue :idea:

I hope this helps :)
 

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"If you snap the throttle, the EGR system stops working as the cooler richer mixture reduces the NoX....."

No such thing as a "mixture" in a diesel.......
Fuel gets injected directly..
No such thing as "lean out" either...they are running very lean all the time.

EGR is introduced to reduce peak combustion temps and usually does not happen under high load conditions.
As for the catch can, if you're not in the habit of slightly overfilling, it is probably not necessary as there is already an oil separator built into the rocker cover.
You will find the under normal conditions very little oil accumulates in the catch can. Mine has been in for about 30,000 km and it would have about 4mm in the bottom of the can, hardly worth the effort.
 

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you still need a catch can.
first of all to stop oil mist fouling the MAF.
also to stop the oil puddling in the IC and more importantly stop it lubing the intake hose. with no oil they stick and pipes don't slide off.
the oil is also fuel, unmetered and also breathed in. it can ignite early causing a bit to much heat.
If you snap the throttle, the EGR system stops working ......
not quite. you snap the throttle, egr starts to close bit by bit and the exhaust gases get less and less. point being its actually slow. there is a response time for the EGR system.
then theres the problems of the valve sticking open. these don't have a position sensor on the egr valve so the ecu ASSUMES its in the correct position.
 

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not quite. you snap the throttle, egr starts to close bit by bit and the exhaust gases get less and less. point being its actually slow. there is a response time for the EGR system.
then theres the problems of the valve sticking open. these don't have a position sensor on the egr valve so the ecu ASSUMES its in the correct position.
Agreed, however in full power (WOT) the EGR does not work ;)

Again, will anybody own the fact that if you have anything but air and exhaust fumes in your inlet that there is a serious problem :D
 

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normally, at full power EGR is off. however as its slow to turn off it can run at full noise. and more often than you would think, they stick open and run at full throttle with some very high EGT's.
 
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