Choice of oil & EGR

[Ramblin Fever]

Does one's choice of oil have anything to do with an EGR Valve & passages getting clogged?

Just strictly out of curiousity.

This particular vehicle only uses 1/4qt in 3k miles and has 146k miles.

 

[Malaclypse]

Considering that most engines burn infinitely more fuel than they burn oil, I'd say that clogged EGR passages is more affected by which brand/octane of fuel you use and its additives.

Also in question is whether or not your injection system is working as it should.

 

[Quest]

In addition to Malaclypse's point, EGR's longevity has a lot to do as to how "hot" you maintain your combustion chamber/exhaust.

Most EGR valves are choked to death (causing leaks) due to carbon deposits. Where do they come from? frequent short trips (not enough time to bring the combustion chamber + exhaust to normal temp range, coupled with lack of maintenance (tuneups, sparkplug replacements, etc.) and also poor gasoline (leaving lots of deposits behind).

As for ICV's longevity due to oil fumes, yes, the more volatile the motor oil is, the more likely the IAC/ICV, MAF, thermalcouple (heating wire type) based MAS, etc. will becomes "sticky" due to oily films deposited on their moving/sensing parts.

To clean these components is to use some throttle cleaner spray (do not do this on thermalcouple based MAS, that calls for electical "dry" based spray) and then immediately wipe clean.

Using FP or Techron or similar on a regular basis, with proper long distance drive (hiway) will keep your EGR valve running nicely.

 

[G Peen Jr]

I have the same question regarding ICVs (idle control valves) which are exposed to PCV oil fumes. Do oil volatility, additive and ester content, etc. affect their longevity?

There is also some mention that Redline SI-1 fuel additive 'cleans' cats, egrs, icvs, and o2 sensors. Comments?

 

[G Peen Jr]

> Considering that most engines burn infinitely
> more fuel than they burn oil, I'd say that
> clogged EGR passages is more affected by which
> brand/octane of fuel you use and its additives.

Malaclypse, EGR passages are designed knowing that more fuel is being burned than oil. So, I would say that if one is burning more oil or fuel than is expected, this may cause a problem.

Older Audi engines typically burn 1 qt of oil per 2000 miles, and run rich, and their sparkplugs and emissions equipment appear fine. Maybe unburned fuel cleans EGR passages.

 

[G Peen Jr]

Quest, I would agree with you regarding the cause of EGR deposits. So you believe EGR-beneficial fuel additives survive combustion. Redline claims their high-temp additives do.

Regarding ICVs, maybe oil fumes from high-ester or AN oils keep ICVs clean. Any papers on this?

 

[nickmckinney]

"I became interested in this when my 96 Saturn SL was kicking nasty fumes back through either the EGR or PCV fresh air hose that collected on the throttle plate making it sticky."


EGR and PCV are behind the throttle plate when compared to the air filter. If you have alot of oil on the front (air filter) side of the throttle plate you have excess blowby from the piston rings (which it sounds like you do). I have found Mobil 1 combined with a full bottle of VSOT to do wonders with sticky piston rings.

 

[G Peen Jr]

> EGR and PCV are behind the throttle plate
> when compared to the air filter. If you
> have alot of oil on the front (air filter)
> side of the throttle plate you have excess
> blowby from the piston rings (which it sounds
> like you do).

Audi V6 PCV is before or "in front of" the throttle plate - EGR after the plate. Excessive blowby would soil the front side, as you said.

 

[IslaVistaMan]

Same thing with Toyota's newer 2.4L VVT-i engines -- but these have two PCV circuits, not one.

The first PCV circuit is upstream from the throttle body (drawing from a baffle in the valve cover), and the second (which is primary) feeds into the intake manifold just before the cylinder bank, via the PCV valve itself.

Two of these fixed the gumming and carboning problem real quick on my car:

http://www.accmachtech.com/pcvcatchcans.htm

Expensive, but highly recommended. Ask for an extra 5-foot length of hose when ordering so you can mount the cans optimally.

 

[nickmckinney]

"The first PCV circuit is upstream from the throttle body (drawing from a baffle in the valve cover)"


Thats technically the breather circuit.


"Audi V6 PCV is before or "in front of" the throttle plate - EGR after the plate"


I would need to see this to believe this.

A PCV valve cannot work without direct engine vacuum (try it sometime), it has to be connected to the intake manifold (behind the throttle blade) and has been on every car I have ever worked on. The vent (breather) for the engine internal pressure feeds to the front of the throttle blade. the PCV is not a "vent" and is a seperate circuit.

If you mount a PCV valve to a line between the air filter and the throttle blade, and it works, then you have a severely restricted air filter system.

 

[IslaVistaMan]

Yes, a breather circuit does more accurately describe it, Nick. Nevertheless, Toyota's factory service manual refers to it as PCV.

More importantly, the can that's plumbed into the middle of the "breather" is definitely catching some crud -- but nowhere near as much as the can on the primary PCV circuit. That one is a candidate for draining every two months or so, and seems to scavenge very aggressively.

Now that I can see how much these units are keeping out of the induction system, I'm glad I got them. Kudos to AccMach for coming up with a practical design that's easy to service.

No interest, just a satisfied customer.

 

[nickmckinney]

"More importantly, the can that's plumbed into the middle of the "breather" is definitely catching some crud -- but nowhere near as much as the can on the primary PCV circuit."


Those cans in the breather circuit are usually noise reducers. Extreme race cars use the exhaust or external oil pump to force feed a vacuum into the engine crankcase as well (makes more horsepower) I run a filter for an air compressor on the PCV of every car I own now, works real good.

 

[eljefino]

I became interested in this when my 96 Saturn SL was kicking nasty fumes back through either the EGR or PCV fresh air hose that collected on the throttle plate making it sticky.

I tried synthetic oil, 15w40 Pennzoil LL, chevron supreme, GTX, all burned 1 quart per 800-1000 miles and all collected and hardened on the throttle blade about the same. That needed GUMOUT every 2000 miles, very annoying. I assume the lousy carbon I found there to be the same found in EGR passages.

Incidentally, I also cleaned the EGR valve every 12-20k miles.

My reading BITOG actually began looking for higher quality oil for the saturn, a known oil-sensitive vehicle. Nothing stopped or really even affected the burning or coking though.

 

[G Peen Jr]

> "Audi V6 PCV is before or "in front of" the
> throttle plate - EGR after the plate"

> I would need to see this to believe this.

For all but idle, PCV is before plate.

 

[nickmckinney]

I should have stated PCV "valve" This is what most mechanics consider the PCV, not the breather line.

That Audi PCV system above only difference to a regular system has the "PCV valve" also become a breather at low to zero vacuum, there it is called a "float valve". However if you look closely at the above explanation you will see the "float valve" sends the gases to the intake >behind< the throttle blades when under vacuum, just like a regular PCV valve system. Otherwise you are only venting the crankcase at idle and cruise, not actually "sucking" the crankcase air, and the EPA in America frowns heavily on this.

Basically the only difference to the complex system above is the PCV valve segment is actually a 2 way valve instead of an off/on. The PCV valve converts to a crankcase breather under low vacuum conditions.

 

[DSteven]

On a 97 Stratus V6, I blocked off the EGR with a plate where it goes to the intake. A check engine light is on with a code showing no EGR function, but everything in the intake has stayed as clean as the day I decarboned everything to a like-new condition. The engine operates exceptional with above normal MPG, and has been this way for nearly 50,000 miles. Regarding this topic: Is this bad for the engine? The intake, coolant and under hood temps have lowered since doing this. Maybe this is only an issue for emissions related items? UOA are better with EGR blocked, too. Is this hard on anything?

 

[Alex P.]

It's hard on passing inspections in some places.

 

[eljefino]

Re: my 96 Saturn, I even tried running a breather filter on the fresh air inlet to the PCV system. By all theories that should have stopped the gunking on the throttle blade. Interestingly there was more gunk on the BACKSIDE. I hypothesize that when the car is shut down the last bit of oily air in the intake manifold condenses everywhere including the back of the throttle blade. That oily air could have come from the PCV and combined with soot from the EGR for a nasty paste.

Regardless, I've sold the car and never found an oil that cut down on the problem.