High Noack Oils and Dirty EGR Valves...

[SonofJoe]

Just for completeness, it might be worth asking the question, do the additives in gasoline contribute to EGR valve fouling?

This has nothing to do with engine oil as such but the composition of these additives is far more oil-like than fuel-like, so these with suffer exactly the same partial combustion fate as engine oil carried through the PCV system. Given that EGR valve fouling, if you're unlucky enough to get it, is something that builds up over the long term, this is a fair question. In the case of TGDI engines, which use EGR, it would indeed be ironic if gasoline additives caused EGR valve fouling when they do nothing on GDI engines to prevent IVD deposits!

 

[SonofJoe]

This was the article I read about VW engines suffering EGR failures post applying the software fix needed to fix the dodgy emissions...

http://www.autoexpress.co.uk/volkswagen/...ted-latest-news

IMO this kind of thing is totally outrageous!

 

[zeng]

Originally Posted By: SonofJoe
Semi-synthetic 10W40s are interesting. You typically might need 20% Group III just to meet 13% Noack but 40 to 50% might be needed to get an 'honest' TU5 A3 pass (not all passes were IMO honest but you just can't accuse people of cheating). That might drop the Noack down to say 10.5-ish. Factor in ACEA B4 and you might up the Group III even more.

Am I right to suggest a typical Euro 10W40 A3B4 SM/SL carries more Group III than a non-Euro 10W40 SM/SL without A3B4 and hence is of higher performance level ?

 

[SonofJoe]

Originally Posted By: zeng
Originally Posted By: SonofJoe
Semi-synthetic 10W40s are interesting. You typically might need 20% Group III just to meet 13% Noack but 40 to 50% might be needed to get an 'honest' TU5 A3 pass (not all passes were IMO honest but you just can't accuse people of cheating). That might drop the Noack down to say 10.5-ish. Factor in ACEA B4 and you might up the Group III even more.

Am I right to suggest a typical Euro 10W40 A3B4 SM/SL carries more Group III than a non-Euro 10W40 SM/SL without A3B4 and hence is of higher performance level ?


Yes. A typical SM/SL 10W40 might be wholly Group I/II based with a Noack of up to 15%.

 

[zeng]

Thanks, mate.

 

[SR5]

Originally Posted By: Gokhan
Originally Posted By: SR5
You mention 15W40 mineral oils and Euro 10W40 A3/B4 semi-synthetics as being fairly low in Noack.
What would their typical Noack values be ?

I haven't seen much data on them.

Thanks.

http://www.pqiamerica.com/June 2014/consolidated HDEO 2015.html


Thank you Gokhan,

Castrol GTX Diesel 15W40 has a Noack of 11.8% is good middle of the pack example, and the Oz version is common in shops around me.

 

[SR5]

Originally Posted By: SonofJoe
Originally Posted By: zeng
Originally Posted By: SonofJoe
Semi-synthetic 10W40s are interesting. You typically might need 20% Group III just to meet 13% Noack but 40 to 50% might be needed to get an 'honest' TU5 A3 pass (not all passes were IMO honest but you just can't accuse people of cheating). That might drop the Noack down to say 10.5-ish. Factor in ACEA B4 and you might up the Group III even more.

Am I right to suggest a typical Euro 10W40 A3B4 SM/SL carries more Group III than a non-Euro 10W40 SM/SL without A3B4 and hence is of higher performance level ?


Yes. A typical SM/SL 10W40 might be wholly Group I/II based with a Noack of up to 15%.


Thanks Joe, Thanks Zeng,

I have only ever seen A3/B4 10W-40 oils, so good to know their Noack and also how they may differ from API only 10W-40 oils.

But just to clear, all the 10W40 oils around me in Oz are semi-synthetic ACEA A3/B4 and API SN.

In North Americia it looks like they still get mineral API SN 10W-40 oils, surely these SN oils should be better than the Group I/II oils referred to above, as I often hear to pass API SN the oil needs to be fully Group II or maybe even contain a small amount of Group III. Probably less Group III than a Euro A3/B4 semi, but it's not uncommon now days to hear about "conventional" oils claiming some level of synthetic fortification. The GTX 10W30 UltraClean comes to mind here.

 

[CR94]

Originally Posted By: SonofJoe
... These heavy hydrocarbons do not burn well and partial combustion can leave behind very heavy, sticky deposits. This stuff can find it's way past the rings and leave deposits in the piston grooves. In extreme situations, this can cause an oil control ring to stick (unlike the top two rings, the OCR is not self-cleaning). Once this happens, your engine's oil consumption is likely skyrocket as oil gets pushed passed the top ring and directly into the cylinder.
...

I am now wondering if there's another potential impact of high Noack oil in that over time, partially burnt oil can foul Exhaust Gas Recycling (EGR) valves? ...

What I find ironic is that EGR (especially cooled EGR), in lowering the peak combustion temperature, might make the problem of partial combustion of vapourised oil even worse, so you end up with MORE deposits with EGR and more sticky gunk, just waiting to gum up your EGR valve?
...
For what it's worth, I keep seeing reports of Prii with 2-3X the mileage of mine suffering from severely clogged EGR coolers. Whether that occurs before oil consumption "skyrockets," or only as a result, is unclear. The cooler (heat exchanger) is a lot more expensive and difficult to clean or replace than the EGR valve. I assume many of those cars are using TGMO 0W-20 or something similar.

 

[SR5]

Originally Posted By: SR5

http://www.pqiamerica.com/June 2014/consolidated HDEO 2015.html

Castrol GTX Diesel 15W40 has a Noack of 11.8% is good middle of the pack example

And just to be fair to thin oils, here is a link to a recent (2017) PQIA test of Caatrol GTX 5W20

http://pqiadata.org/Castrol_GTX_5W20.html

The SN and GF-5 GTX 5W20 has a Noack = 11.6 %
That is very close (better in fact) to the 11.8% for the GTX 15W40.

Sure you can find other examples of 5W20 with much higher Noack, here is a 2017 PQIA test of Phillips 66 Trop-Artic 5W-20 with a Noack of 14.9 % (also SN & GF-5).

http://pqiadata.org/Phillips66_Trop_Artic_5W20.html

Looks like a lot of diversity in this grade, and it would be important to select the correct 5W20.

 

[53' Stude]

Originally Posted By: SR5
Originally Posted By: SR5

http://www.pqiamerica.com/June 2014/consolidated HDEO 2015.html

Castrol GTX Diesel 15W40 has a Noack of 11.8% is good middle of the pack example

And just to be fair to thin oils, here is a link to a recent (2017) PQIA test of Caatrol GTX 5W20

http://pqiadata.org/Castrol_GTX_5W20.html

The SN and GF-5 GTX 5W20 has a Noack = 11.6 %
That is very close (better in fact) to the 11.8% for the GTX 15W40.

Sure you can find other examples of 5W20 with much higher Noack, here is a 2017 PQIA test of Phillips 66 Trop-Artic 5W-20 with a Noack of 14.9 % (also SN & GF-5).

http://pqiadata.org/Phillips66_Trop_Artic_5W20.html

Looks like a lot of diversity in this grade, and it would be important to select the correct 5W20.



Thank you SR5 for your work and info. Do we know for a FACT the NOACK % for Magnatec 5w20&30?

 

[SR5]

Hi Car51,
Always good to hear from you, unfortunately I have not seen any solid numbers for Castrol Magnatec, only Edge and GTX, which would be the best indicators at this stage.

I notice in a recent post of yours, you scored some of the good stuff recently.

Originally Posted By: car51
Castrol GTX "super clean" 5w20, was $16.27-$3.00 manufacturer coupon I used today at Wal Mart


Nice work.

 

[53' Stude]

Originally Posted By: SR5
Hi Car51,
Always good to hear from you, unfortunately I have not seen any solid numbers for Castrol Magnatec, only Edge and GTX, which would be the best indicators at this stage.

I notice in a recent post of yours, you scored some of the good stuff recently.

Originally Posted By: car51
Castrol GTX "super clean" 5w20, was $16.27-$3.00 manufacturer coupon I used today at Wal Mart


Nice work.






Yes, may go grab another jug as co worker knows I'm a "oil nerd" and gave me coupon

Since I have some 5w20 Magnatec I'll try it after GTX "superclean"

 

[Gokhan]

It looks like clogging by hard carbon buildup always happens at the EGR-valve port -- not in the EGR-valve pipe or the intake-manifold side of the EGR-valve port. That was certainly the case with me. My theory is that the HC in the exhaust pipe suddenly cools down when it expands through the EGR valve into the intake manifold and starts solidifying right there.

Here is the port of a Maxima EGR valve. They seem to be prone to clogging. But then Maximas seem to be prone to all sorts of mechanicals breakdowns:

In my case it seemed to be very hard black carbon. I didn't notice grayish ash deposits (SAPS part) like you see on spark plugs.

It's caused by engine problems. Was my oil consumption back then a major source of it or was it because of carburetor issues etc.? Was it because my ignition timing was advanced too much? It's hard to say.

Just like what VW did today, to increase the low-throttle horsepower, it was common in these cars for the EGR valve to be disconnected by disconnecting the vacuum hose to it and plugging the hose end to prevent vacuum leak. I found that this causes excessive engine pinging, which is probably not good for the engine. I found that the best setting is to run about 3 or 4 degrees more advanced with the ignition timing and EGR valve connected to reduce pinging. This increases the low-throttle power and fuel efficiency without excessive pinging. Ideal setting is when you hear light pinging during ow RPM and moderately high throttle. However, advancing the ignition timing by even three degrees seems to almost double the HC emissions but mine passes the smog anyway.

Regarding oil consumption, there was a study that compared the three sources -- transport (rings/valves), evaporation (NOACK), and blow-by (PCV). Evaporation and blow-by become important at high loads but they are negligible at low loads.

The Contribution of Different Oil Consum...gine (PDF link)

If you have your EGR valve clogged, have your engine repaired. There is too much HC in the exhaust. Even if oil is contributing to the HC, NOACK won't make much difference. Besides, synthetic oil may actually produce more HC when it burns but I don't have a study at hand for this.

For the fun of it, this is from my factory repair manual, explaining how EGR works:

 

[BrocLuno]

I just let the EGR plug itself up and tune accordingly

Seriously, we had pumped AIR injection in 1966 on my Malibu V8. EGR came into general use soon after. It's been around a long time. May be new on diesels, but not on gas engines in Cali ...

 

[Silk]

Originally Posted By: SonofJoe
Just for completeness, it might be worth asking the question, do the additives in gasoline contribute to EGR valve fouling?

This has nothing to do with engine oil as such but the composition of these additives is far more oil-like than fuel-like, so these with suffer exactly the same partial combustion fate as engine oil carried through the PCV system.


Mitsubishi were one of the first with production GDI vehicles in the mid '90's. They came here as used imports from Japan, and were giving trouble straight away. Most would be running on ''oil'', and our lower grade of fuel...but apparently even our premium is a long way off what they would've got in Japan.

I had a GDI Chariot in a few weeks ago - smoking ! and missing. By playing the shell game I confirmed it was no coil, plug or cyl failing, any plug would foul up if idled or driven slowly. An elderly owner, cleaning the manifolds and ports would cost more than the car is worth...so I used Shumma.

Shumma is a Mitsubishi only product, and was developed by someone who now works for Mitsubishi NZ, although when he did it he was living in another country and did the job as a consultant. Mitsubishi obviously realised they had an engine loading up intakes pretty early on. I sprayed it into the intake manifold and left it overnight. Clouds of smoke the next day, and running sort of ok. He was in ealier this week, and said it's running fine and no smoke.

GDI and fouling manifolds is certainly not a new thing...at least not around here.

 

[Gokhan]

Originally Posted By: Shannow
Joe,
a couple of data points while I process...

* EGR was early applied on petrol engines to reduce NOx on those carburettered at part throttle...usually had some strange pneumatic interlocks that wouldn't apply it until engine was at temperature (and usually locked out vacuum advance until top gear enabled as well).
* Recall Monash University in the '80s trying to replace a Camira engine with an OPEL 1.3, high boost turbo, and controlling using EGR, and the vacuum slide/guts of an S.U. carby to avoid throttling losses...worked OK, but when it didn't ... Bang, it destroyed pistons...we've come a long way with electronics.
* My ex Navara, with the ZD30 turbodiesel had two intake valves per cylinder, one high swirl, with EGR, the other for volume air flow, no EGR...a little butterfly closed the high volume ports, and a main butterfly partially choked the engine to get the EGR to flow (differential pressure)...the inlet manifold on those engines is incredibly wet with oil...the High swirl port was invariably black with carbon, or worse...no inlet valve deposits on the wet but clean port, deposits on the wet/dirty/egr port.
* AUDI had a patent (and I can't find it) that modified the chemistry of the oil to prevent (and remove) Intake Valve deposits. The inference was that it cleaned them, rather than (for example) lowering NOACK to reduce carry through.

This is what I mean on the ZD30 ports...not mine, I blew away the photos when I sold it.


Mine was a black paint like sheen, not the fluffy crusty stuff...Car spent most of it's life on synthetics (Castrol/Mobil 0W40), followed by 5W40s (Castrol and Mobil GrIIIs), then Edge 5W30 A3/B4 with a 20% edge 25W50 booster...just for reference.

Yes, EGR had been standard in gasoline engines long before it became common in HD diesel engines in the 2000s during the API CI-4/CJ-4/low-sulfur-fuel transition. Both the gasoline and diesel versions of my 1985 Corolla has EGR.

With regard to the problem that you encountered, in diesel exhaust you get so much soot and other junk that I wouldn't even worry about oil-burn-off components.

Again, it looks like the clogging happens when the exhaust gas suddenly expands and therefore adiabatically cools off exiting the EGR-valve port. It was entirely contained within the EGR-valve port in my case and nothing got through the intake manifold hole where it is attached to. There was also nothing the EGR pipe because that stays hot.

It usually seems to happen quite fast if it happens and probably indicates some engine malfunction or tuneup issue than anything else (oil, NOACK, additives, etc.). With diesel I would guess it's much more common given how dirty these engines run.

 

[Gokhan]

I have a theory.

When I discovered my clogged EGR valve, I also discovered that my EGR vacuum modulator had its diaphragm torn. An EGR valve will not open if the diaphragm of the EGR vacuum modulator is torn. So, mysteriously the EGR valve was clogged despite not being used.

It was also brought up here that VW discovered a lot of issues with EGR valves immediately after they started using them regularly, instead of in a very limited manner.

I mentioned that the clogging happens when the exhaust gas expands through the port and suddenly adiabatically cools off. This is the same physical process (adiabatic cooling) that happens when the refrigerant flows through the expansion valve in an A/C.

If the hole is restricted, there will be more sudden cooling. In my case with the EGR vacuum modulator failing, EGR valve would only open partially, increasing the adiabatic cooling and therefore speeding up the phase transition of the vaporized HC in the exhaust gas into a solid. In the VW scandal, they operated the EGR valve in a limited manner, which may have increased the cooling off of the exhaust gas in a similar manner, increasing the gunk buildup. This is in some ways analogous to running the spark plugs too cold (choosing a too low heat rating), which would foul them very quickly.

Therefore, perhaps, the reason for the EGR valves clogging is the EGR valve not fully opening or not fully operating, which increases exhaust-gas cooling and speeds up the hardening of the HC vapors at the exhaust port, leading to EGR valve clogging in a very short time period. It may have nothing to do with oil, fuel, or mechanical problems in the engine other than problems in the EGR system.

 

[Silk]

Having cleaned both GDI and diesel manifolds - it's the same stuff. Small diesel engines had EGR in the '80's...although our engines didn't have it, all the UJDI's from the '80's, petrol or diesel, had EGR.

 

[Shannow]

Originally Posted By: Gokhan
I mentioned that the clogging happens when the exhaust gas expands through the port and suddenly adiabatically cools off. This is the same physical process (adiabatic cooling) that happens when the refrigerant flows through the expansion valve in an A/C.


ummm...no, there won't be enough to even measure, let alone do what you describe.

and it's a pressure drop across an orifice...it's equally "sudden" regardless of whether it's blocked or not...sudden just being a word for effect in this case.

Well do a naturally aspirated first, take exhaust pressure as 1.4 bar, intake pressure as 1 bar, exhaust temp of 300C (573K)...gamma for CO2 is 1.3, N2 is 1.4, so well split the difference at 1.35.

T2, the "expanded" exhaust gasses are 140C...

Dew point of natrual gas fueled engine exhausts are of the order of 60C, and clearly no part of the intake tract is going to be operating under 60C with the engine at operating temperature, so there's no "cold wall" effect either.

Now we'll do a diesel, operating (obviously) unthrottled, give the exhaust 2 bar, and the intake 1.5 bar. Same gamma (Cp/Cv), and same 300C.

Only cools to 258C...clearly above the dew point.

If there was a phase change during the expansion (your expander valve mention), then obviously the effect is much bigger, but simply expanding gasses through orifices isn't a very efficient way of making cold.

So YES, it's much more likely to be lubricant/fuel/design/operation related than the adiabatic cooling effect causing dewpoint problems.

 

[Shannow]

Originally Posted By: Silk
Having cleaned both GDI and diesel manifolds - it's the same stuff.


Re the same stuff....

https://energy.gov/sites/prod/files/2014/03/f10/pm009_lance_2012_o.pdf

Basically hydrocarbon molecules that have been partially pyrolised during low temperature combustion and haven't lost all of the hydrogen to become soot...so it stays tarry and sticky.

Could be the stuff boiling off the upper ring lands and bores, or fuel related bottom ends in the quench crevices...note that hot they created it intentionally was to operate at idle, with HIGH EGR, and retarded timing.