Strange. Oil smells of gas, van runs great.

[platinumzombie]

My 1990 has recently, when I check the oil prior to driving, began to smell of gas. I read a bunch on this forum, tested my o2 sensor and FPR, both of which seem to be working. I pulled off the air filter box and when I did I noticed gunk (oil?) With a slight odor of gas inside on the AFM side. I cleaned it up with a rag and it was a bit hard to come off. Could this be causing the gas in the oil and drop in MPG? Like I said, the van runs fine, just drop in fuel economy.
Am I looking at a more serious engine problem more suited to a professional?
Thanks for any advice.
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1990 Westfalia

[E1]

Have there been any recent incidents of gas flooding?

Is it running any hotter than normal?

It’s possible you have a problem, or not. Especially if running rich, or shut off after just a minute or two, I’ve occasionally smelled this over the years as well on three different engines… but only if I make the effort to notice it.

I just smelled my dipstick after sitting overnight, and it does smell like gas a tiny bit, though it’s not running rich. If the O2 has failed or is about to, the spark plugs should show it in being wetter or darker than normal — and mpg will drop as a result.

If there’s indeed a problem, pull the stick and point it straight down. If way gassy, the oil should flow off of it like it’s thinned out. Probably best tested when as cold as possible, and at consistent oil level on the stick. I just checked for you, 15/50 synthetic, about 65 here, turned dipstick straight down and it took about 2.5 seconds to drip. My dipstick level is right at the bottom notch where I like it best.

Lots of possible variables to change that timing, but a starting point of questionable value, or not.

FWIW, and very OT or not, when I was a pinstriper and sign painter I’d use this very test to determine my paint/thinner mix when dripping from a screwdriver. The timing between drips was *everything* and the noticeable difference was maybe a couple percentage points difference in mix.

Yes, that was oil-based *paint* with pigment. But even if only me, I see parallels in this test, and if there’s a concerning amount of gas in your oil the oil will run straight off the dipstick instead of collecting as a drip.

I believe also that once the key is turned off, a small amount of gas is left in the combustion chamber. Whether that’s enough to quickly circulate into the oil as a mass, I suspect not but can’t say for sure.

Hope I’m right and that yours is no major issue. Others will know better.

Be careful, let us know, and Best!
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Howesight]

Engines with the early generations of EFI, like the Vanagon 2.1 Digifant, are more prone to this problem than more recent systems like, for example, the direct-injection 2.0 Audi engines that Audi lables "TFSI" (Turbocharged Fuel Stratified Injection). But even a TFSI engine will, if only or mainly driven short distances, suffer gasoline dilution in the engine oil.

A cold gasoline engine must use a richer Air Fuel Ratio (AFR) when the engine is cold in order for the engine to run smoothly until up to operating temperature. The main reason for this is that the fuel in the atomozed fuel-air mixture falls out of suspension when it contacts the cold intake manifold, ports, cylinder walls and the piston. This excess gasoline then is scraped by the rings (which are also cold and thus allowing more blowby) into the crankcase and dilutes the oil there. If the vehicle is then driven for a sufficiently long time that the oil temperature rises to operating temperature and stays at that temperature long enough, then most, but not all, of the gasoline in the motor oil gets "boiled off" and ends up in the crankcase gases that are then sucked into the intake manifold to be burned instead of being released into the atmosphere.

Most gasoline vehicles from the Vanagon era specified in the owners manual a shorter oil change interval for vehicles that are only operated for short hops or mainly in cold weather or both. The main reason for that recommended short oil change interval was the cold-start oil dilution and the fact that there was no opportunity in those cases to boil off the excess gasoline.

So, after you do an oil change, try to avoid short-hop driving as much as possible. This is not easy for most Vanagon owners since the Vanaqon is seldom a daily driver and seems always to be in the way in the driveway or garage and thus gets moved around - - for short distances - - a lot.
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'86 Syncro Westy SVX

[platinumzombie]

No flooding, just had oil change, drove for 20 minutes out the highway at about 90km/hr and smelled gas on the dipstick. Just pulled the stick and held it up. A drop fell off instantly.
Just fired it up and pulled the wire of the o2 sensor and grounded it, this should alter the RPM, yes? It doesn't. I checked the wire by page 24.62 chart in the Bentley and it checks out. I'm lost.
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1990 Westfalia

[platinumzombie]

[E1]

In my opinion, pulling the O2 wire will only tell you anything if having run a minute or two already, from startup, once the ecu becomes active in the fuel mixture. The few times I’ve done that, I’m not sure I noticed an RPM change so much as a “quality of firing” change.

In our vans to date, a minute or two after firing I can tell when the computer comes online: for me a slight and brief hesitation followed by smoother idle and sound. Then you know for sure that the mix has changed.

I do not know for sure if a shutdown when hot resets that process if started right back up, but suspect once hot it goes straight to a regulated fuel mix.

What’s your oil level? And viscosity? Both are factors in my Billybob test, and I can’t speculate how 10/30 would react but would definitely drip faster. I seriously doubt it would just “run off.”

The higher it is the quicker the drip, but off hand yours sounds too fast. I also wonder if a valve may need adjusting, going back to maybe checking the plugs.

You’ll get more help for sure, and hope I have. I suspect there’s a lot more to this than my knowledge allows.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[DanHoug]

[platinumzombie]

[E1]

Meant to add that I’ve never *not* seen minor residual oil in the intake rubber, a natural by-product of the crankcase breather design.

And Yes, it hardens.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Ahwahnee]

You mentioned a 'drop in fuel economy'... do you have an mpg figure?

[zerotofifty]

How about replacing the oxygen sender? They are cheap and are considered a regular consumable item, make sure the wires for the sender are good.
Running a suspect bad sender is false economy if you also run a catalyst. A bad oxygen sender can quickly ruin a good catalyst, and the catalyst if very expensive.
If you are running rich, you are harming the catalyst, if the oil is contaminated with gasoline, that harms the wear surfaces inside the engine also.

Also assure that the ignition is correctly working, a miss of the spark or weak spark can cause unburnt fuel to contaminate the oil, and the excess oxygen from the not fully burnt cylinder charge will fool the oxygen sender into commanding a richer mixture to be delivered, with further compounds the rich running issue.
A faulty injector can also be an issue. an injector with poor spray can cause poor ignition of the not fully atomized mixture, which will do similar, i.e. fool the oxygen sender. one or more clogged injector can throw the whole system off to run richer. likewise an intake leak can fool the oxygen sender to command a rich mixture.

So replace suspect O2 sender, confirm the wires to it are good.
Check the injectors for flow volume and good spray pattern.
Check plugs, spark wires, coil, cap, rotor, make sure all four plugs give good strong blue colored spark
test for intake leaks using the flammable aerosol can method on all intake related hoses, and joints.

Have fun!
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Give peace a chance. No American war with Russia!

[Geato]

I can speak from experince on a V8. If one one (or more) injectors are stuck open then you will be washing your cylinder walls down with gasolene and the gas will easily pass by the rings. This will remove lubrication from the rings and you will very quickly, have wear on the cylinder walls. So I suggest not to run the engine untill you get this sorted.

If all 4 injectors are open then that speaks to a problem with the SCR in the ECU. Start by pulling the injectors and jumpering the fuel pump relay to check for leaks.

[brickster]

Verify that your thermostat is working properly. Is it reaching operating temperature and staying there?
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1984 Campmobile Automatic

[Vanagon Nut]

[platinumzombie]

[platinumzombie]

[platinumzombie]

[Wildthings]

A bad TSII sensor or its wiring would cause the engine to run rich. The coax for the O2 sensor is also a well know problem as it ages.

[SCM]

Maybe try pulling your spark plugs to see if they're wet with gas. If you have one fouled plug that would point to a different cause (bad injector) than if all four are wet.
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[TornadoVan]

I used to do emissions testing in both California and Fairbanks, Alaska, and fuel dilution was, without a doubt, the number one cause of vehicles failing a test. The possible causes of dilution are few, but here are the most common.

1) Coldstarts. The colder it is when you fire up the engine, the worse the seal between the rings and cylinder wall, allowing for blow-by. The air-fuel mixture is literally blowing past the rings until the engine warms up. Usually a consistent problem that doesn't "just start" to happen. It will happen every winter. The fix is not all that simple. Letting the engine warm up fully before driving really helps, but long drives that allow all the fuel in the oil to "cook" off is really the only thing that solves this issue.

2) Worn piston rings. Same results as coldstarts, blow-by. Usually gets worse and worse as the rings wear out. Nothing short of a rebuild will really fix this, ALTHOUGH, I have made numerous vehicles with worn rings pass an emissions test by using a product called "Restore". It comes in 4,6 and 8 cylinder size cans and you put it in the crankcase before you add the oil during an oil change. It has a ceramic in it that will fill the scoring and wear in the cylinder wall then get "cooked" into a cured state by the engine/combustion heat. After 500 miles you change the oil again, as normal, and it will give you a restored cylinder surface for 10,000 miles or so. I am not kidding, this stuff actually works on "Old Smokey" type emission failures caused by worn rings/crankcase dilution. It was always my "Last Chance, Dude!" attempt to get a customers car to pass before condemning the engine.

3) In systems that have a spring balanced PCV (Positive Crankcase Ventilation) valve, the spring/plunger/ball can become stuck blocking ventilation of the crankcase. The valve or associated hoses can simply be plugged. The entire point of a PCV valve is to remove fuel from the oil. In the case of plugged hoses the problem usually comes on slowly and gets worse over time. In the case of a stuck spring/plunger/ball the problem can happen quite suddenly. Replacing a stuck PCV valve if it is stuck is the best fix. They can also be cleaned out with carb/brake cleaner. Some systems only have a narrow orifice instead of a valve. These plug up faster than valves. Making sure all the hoses flow freely is important.

4) Artificial Rich condition. A lazy O2 sensor can cause this, but the problem starts slowly and gets worse over time. From my own experience, the usual cause of this on a Bosch system is the airflow sensor flap gets gummed up with oil and other crud and doesn't move freely, sometimes never going back to it's "relaxed" state (like when the engine is off). If the airflow sensor is in an incorrect position, it can cause both a rich condition, or more rarely a lean condition. The airflow sensor problem can happen suddenly (a chunk of crud broke loose from somewhere and got wedged in the flapper) or it can happen slowly as crud builds up, creating resistance in travel, much like rusty door hinges. Both the O2 problem and the Airflow sensor problem will also cause decreased fuel efficiency. The fix for the airflow sensor problem is take the sensor off and give it a good cleaning with BRAKE cleaner (leaves zero residue behind. I use Napa part number 4800 brake cleaner). Make sure you get the BACK of the sensor door cleaned well. On "Hot Wire" type airflow sensors, crud can build up on the two wires (Reference/Sensor) that air flows over skewing the signal back to the ECU. A simple, CAREFUL cleaning of the wires will usually restore function. There will usually be some "crusty hard" stuff on the wires as the wires are literally heated to glowing hot by electrical current and will turn oily gunk into a hard crust. The fix for a lazy/dead O2 sensor is simple replacement. Make sure you use a BOSCH sensor. I've had shitty luck with other brands on a Bosch system.

5) The WRONG OIL! Even though I am a retired mechanic, I still take all my vehicles to the local Pennzoil Quick-Lube as I hate dealing with waste oil. I've been going to the same guys for 20 years but one time they had a new, young buck that just started working there do the oil change on my Vanagon and he inadvertently put 5/30w in it. I didn't realize it until I drove up a long mountain road, going uphill for about ten miles. The engine heated up pretty good and the oil light came on. Immediately pulling over, the first thing I did was check the oil. It was actually a bit HIGH on the stick because it had so much fuel in it. It was also VERY thin, running down the stick like water. Apparently, with oil that is too light, there is a LOT of blow-by past the rings and fuel built up faster than the PCV valve could deal with it. The oil light came on as the temp thinned the oil. I let the engine cool off, fired it up and the light was off (the oil had thickened back up), and went straight home to drop that oil. 20/50 is pretty damn thick oil. The fix is obvious--Change the oil with the right stuff.

6) Any basic fuel system failure, such as wonky injectors, etc that is causing a Rich condition. Too many possible causes to really help you out here. If you don't know how to diagnose Bosch systems, take it to someone that does.

Hope this helps!