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View Full Version : The effect of a catch can on oil leaks



Trav_1980
24th August 2019, 12:41 PM
Just wondering what everyone's experience is with regard to oil leaks post fitment of a catch can?

In a previous post I asked how easy it is to DIY a replacement rocker cover gasket and injector sleeves on a ZD30DDTi due to some oil leaks. Just wondering what effect fitting a catch can will have in reducing the probability of said leaks occurring again.

I would have thought by having the intake vac pressure reintroduced to the crankcase via the can that oil leaks would be less likely to happen.

Anyone had experience with this conundrum?

Currently the PCV pipe is just vented to the ground on the vehicle and it's making a mess everywhere.

The intention when I bought the vehicle was always to fit a can but space is and issue that I think I have rectified. http://www.nissanpatrol.com.au/forums/images/imported/2019/08/141.jpghttp://www.nissanpatrol.com.au/forums/images/imported/2019/08/142.jpg

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0-TJ-0
24th August 2019, 12:54 PM
Oil leaks are due to old/worn gaskets. Never heard of anyone installing a catch can to fix an external oil leak.

Trav_1980
24th August 2019, 12:55 PM
Just wondering what everyone's experience is with regard to oil leaks post fitment of a catch can?

In a previous post I asked how easy it is to DIY a replacement rocker cover gasket and injector sleeves on a ZD30DDTi due to some oil leaks. Just wondering what effect fitting a catch can will have in reducing the probability of said leaks occurring again.

I would have thought by having the intake vac pressure reintroduced to the crankcase via the can that oil leaks would be less likely to happen.

Anyone had experience with this conundrum?

Currently the PCV pipe is just vented to the ground on the vehicle and it's making a mess everywhere.

The intention when I bought the vehicle was always to fit a can but space is and issue that I think I have rectified. http://www.nissanpatrol.com.au/forums/images/imported/2019/08/141.jpghttp://www.nissanpatrol.com.au/forums/images/imported/2019/08/142.jpg

Sent from my SM-G965F using TapatalkYeah nah that's not the objective really, I'm replacing the rocker cover gasket and injector sleeves anyways. Was just wondering if anyone had notice a reduction in leaks post can fitment?

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the evil twin
24th August 2019, 01:37 PM
PCV shouldn't be vented to atmosphere, that defeats the whole purpose.

The whole concept of PCV is that the gas blow by from the cylinders into the crankcase is 'positive' vented back thru the induction to be burnt and not dumped direct to atmosphere.

There should be a PCV valve in the vent line from the rocker back to the induction point and the Catch Can has the job of capturing the oil condensate so it doesn't reach the induction and foul the engine intake.
When you fit the Catch Can you still need the downstream flow after the Can to go to induction not atmosphere

Trav_1980
24th August 2019, 01:47 PM
PCV shouldn't be vented to atmosphere, that defeats the whole purpose.

The whole concept of PCV is that the gas blow by from the cylinders into the crankcase is 'positive' vented back thru the induction to be burnt and not dumped direct to atmosphere.

There should be a PCV valve in the vent line from the rocker back to the induction point and the Catch Can has the job of capturing the oil condensate so it doesn't reach the induction and foul the engine intake.
When you fit the Catch Can you still need the downstream flow after the Can to go to induction not atmosphereYep I'm aware of all that, my D40 has a Provent fitted and it works great, that's why I'm fitting one to this vehicle I have purchased which doesn't have one and needs one. The previous owner had just vented the PCV pipe to the atmosphere and hadn't fitted the can due to lack of space but now I'm onto it and itll be plumbed as it should be back into the intake.

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mudski
25th August 2019, 09:25 PM
PCV shouldn't be vented to atmosphere, that defeats the whole purpose.

The whole concept of PCV is that the gas blow by from the cylinders into the crankcase is 'positive' vented back thru the induction to be burnt and not dumped direct to atmosphere.

There should be a PCV valve in the vent line from the rocker back to the induction point and the Catch Can has the job of capturing the oil condensate so it doesn't reach the induction and foul the engine intake.
When you fit the Catch Can you still need the downstream flow after the Can to go to induction not atmosphere

Not to mention its illegal to vent into the atmosphere and if caught, hefty fines apply.

Trav_1980
25th August 2019, 11:12 PM
Not to mention its illegal to vent into the atmosphere and if caught, hefty fines apply.That's it, and it makes a mess everywhere!

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MB
25th August 2019, 11:49 PM
Carbon footprints :-)
Plenty an old farmers vent into their chassis rails for 50+ years atmospheric corrosion protection.
Who needs a new steel, rubber, plastic expensive tractor?


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thebrod
26th August 2019, 04:48 PM
The catch can will have zero effect on your oil leaks from the rocker cover or injector seals.

RickGQ
29th August 2019, 12:40 PM
I recently fitted a Provent to my TD42, not to stop oil leaks, but partly to catch oil before it got back to the inlet manifold and partly to monitor the amount of blow-by that was occurring.
Very impressed with the Provent. There's no more oil in the inlet manifold and hardly any oil dampness in the Provent.
When fitting the Provent I replaced the standard hose with 16mm hose, maybe that's helped improve flow and reduce crankcase pressure.
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