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jmfixitman · 01-31-2023, 04:49 PM

So I have a 2009 Cummins 425 ISL. Are there any Diesel mechanics out there that can tell me the flow direction of the draft tube attached to the oil separator on the crankcase filter housing in this pic?

I assume crankcase blowby is coming up that tube and into the filter, then ingested by the intake after filtering? The small lines are oil drains, so I know those go back down to the oil pan.

Thanks!

WILDEBILL308 · 02-01-2023, 11:08 AM

Ok, I bet it flows just like that. So why does it matter as long as it works?
Bill

jmfixitman · 02-01-2023, 12:11 PM

Quote:

Originally Posted by WILDEBILL308

Ok, I bet it flows just like that. So why does it matter as long as it works?
Bill

Getting what I feel is extra oil on the crankcase filter and was thinking of installing a catch can.

Bruce Anthon · 02-01-2023, 05:08 PM

I wasn’t aware the catch can was being used on DPF engines. The filter on the valve cover captures the oil in the breather pre exiting out the tube if I understand it correctly. Maybe someone else can comment on appropriate use of the catch can.

Caliber · 02-01-2023, 05:58 PM

Quote:

Originally Posted by jmfixitman

So I have a 2009 Cummins 425 ISL. Are there any Diesel mechanics out there that can tell me the flow direction of the draft tube attached to the oil separator on the crankcase filter housing in this pic?

I assume crankcase blowby is coming up that tube and into the filter, then ingested by the intake after filtering? The small lines are oil drains, so I know those go back down to the oil pan.

Thanks!

The blow-by comes from the valve cover than passes thru the filter, crosses over to the oil separator than down the road draft tube and is expelled to the atmosphere just above the starter.

WILDEBILL308 · 02-01-2023, 06:27 PM

Quote:

Originally Posted by Caliber

The blow-by comes from the valve cover than passes thru the filter, crosses over to the oil separator than down the road draft tube and is expelled to the atmosphere just above the starter.

There are no fumes being released to the atmosphere on the OPs coach.
Bill

jmfixitman · 02-01-2023, 06:44 PM

Quote:

Originally Posted by WILDEBILL308

There are no fumes being released to the atmosphere on the OPs coach.

Bill

That's why I was wondering where that tube goes or comes from... I was thinking of venting the crankcase to the atmosphere via a catch can that had a filtered vent. I had thrown a code for crankcase pressure, and saw the filter was coated with oil when I changed it. But now I realized they overfilled my oil by two quarts during the last service. So that could be the cause of the oil on the crankcase filter. I'll be doing my own oil changes from now on...

Caliber · 02-01-2023, 06:49 PM

Quote:

Originally Posted by WILDEBILL308

There are no fumes being released to the atmosphere on the OPs coach.
Bill

Yes there is, this is a tier 3 engine, the tier 4 has closed crankcase ventilation.

WILDEBILL308 · 02-01-2023, 08:38 PM

Quote:

Originally Posted by Caliber

Yes there is, this is a tier 3 engine, the tier 4 has closed crankcase ventilation.

The OP has a 2009 engine. I have a 2007 in my 2008 and it doesn't vent to the atmosphere.
Bill

mackwrench · 02-02-2023, 05:47 PM

OP, over filled with oil will restrict crankcase filter. If you changed filter, hopefully oil level is correct as well?

Depends on year engine was built as to what emissions it has, if the pics you posted are from quickserve using your engine S/N then it looks like you have a "draft hose" it only functions as a crankcase vent once the filter is restricted....like when your DTC popped on.

The other hoses that drain back to crankcase are for crankcase "air" from blowby and any liquid (oil) that may pass though the filter.

96 Wideglide · 02-02-2023, 07:25 PM

The overfill has probably caused your issues.

I replaced my filter at about 52,000mi, and it was clean enough I wondered why I bothered!

FIX-IT-BOB · 02-02-2023, 07:44 PM

GOOD EVENING ! I also went down this road and heres the fix I found to work perfectly

1) Where does the tube go? It goes ( tucked tight ) down near the oil pan..... its goes outta to atmosphere...... and add a length of rubber heater hose to it to keep the oil residue off of everything...
2) The older cummins engines vented from front timing cover to atmosphere and sometimes used a plastic catch can... for any crankcase blow by
3) the crankcase filter located in valvecover of your engine tends to be a restriction and causes the "check engine light for crankcase pressure" typically after using engine breaking .... Replace with "lifetime unit" from cummins OR remove the filter media with cutoff wheel and reinstall .... after replacing mine three times with new filters and getting the high crankcase pressure..... I went this way and absolutely perfect fix. ( Also removing the bypass valve and making FREE FLOWING 100Precent
4) normal crankcase pressure flow goes up thru filter media and first separates air/oil and drains back oil to cyl head..... next up is it leaves the valve cover and goes thru the plastic air/oil separator ( black funnel looking ) there it flows the air out but also gets what it can for oil and drains back to the oil pan....

Good luck. Ive had no further issues with filter removed .... Furthermore the crankcase filters on semi trucks offer " life time filters " with the elements removed Which I suspect is because the " idea" of a crank filter sounds better on paper then living with it day in day out