Help with a piston soak problem aka did I destroy my engine?

[jsean]

This is on a Passat with the 3.6 CDVB engine.
It was burning a quart anywhere between 300-700 miles depending on how I drove it.
Decided to run a couple of tanks full of Yamalube before I did this.

Started yesterday, went though 7 cans of B12 over 24 hours. Rotated the crank by hand at 4hrs, 8hrs and 12 hrs mark. At 24hrs, I rotated the crank by hand and verified it was ok. Vacuumed out cyl3 which was the only one with any B12. Rest had leaked down to no fluid. Blew all the carbon chunks out. Again verified crank rotation by hand. Added about 1tsp of oil down each of the cylinders and rotated the crank about 20 times. Verified that there was no standing oil in the cylinders at TDC on each of them.

Put the plugs and after the usual long crank/misfiring/ lots of smoke, the idle evened out. This whole thing took about 30-35 mins. The last 10-12 mins the engine ran great and I had idling at 2,000RPMs. Turned the car off and restarted it. Started and idled smooth. Ok great, figured I change the oil.

Changed the oil and oil filter (old oil filter had a bunch of crud in it). Poured in 6qts (owners manual calls out 5.8qts). Tried turning on the car - each time it turns on, stumbles and misfires really really bad - as in you can hear and feel the misfiring on the driver’s seat. The low oil light illuminates and dipstick claims I’m low?! Below the cross hatch marks despite filling 0.2qts more than factory fill spec.

So what gives? Did I destroy the engine?

 

[jsean]

Video showing what’s going on. For whatever reason, the webpage is not letting me upload the link like it usually does.

 

[TijY_]

So you ran your engine with six cans of B12 in the crankcase? That is a totally new kind of bravery to put it mildly.

Put in new plugs and verify your oil pressure.
Oil level sensor probably got damaged, be happy if that is the only thing.

 

[Pablo]

I’m thinking your spark plugs are fouled

 

[goblin]

This ^^^
Doesn't account for the missing oil though. Unless there's some sick procedure for oil level checking in these engines.

 

[jsean]

So you ran your engine with six cans of B12 in the crankcase? That is a totally new kind of bravery to put it mildly.

Put in new plugs and verify your oil pressure.
Oil level sensor probably got damaged, be happy if that is the only thing.

Ha! I’m not the brave. I started this adventure when it was a quart low. I measured the dipstick before I fired up the car (pre oil change but post piston soak) and it was just a smidge over the cross hatching on the dipstick. Unless the dipstick reading was off, I wasn’t significantly off on how much was in the crankcase.
Verified by measuring what drained out - about 5.8qts or take.

 

[jsean]

I’m thinking your spark plugs are fouled

That’s a good suggestion. Could the plugs have fouled when the car sat for the hour or so when I was doing the oil change? Meaning they got hot during the post soak startup, ran fine and now are completely gunked up?

 

[Pablo]

That’s a good suggestion. Could the plugs have fouled when the car sat for the hour or so when I was doing the oil change? Meaning they got hot during the post soak startup, ran fine and now are completely gunked up?

Unknown but you should pull them anyway

 

[TijY_]

Wouldn't be clogged cat would it? How long time did you have excessive oil consumption?

 

[jsean]

Unknown but you should pull them anyway

Turns out they’re fouled pretty bad. Just coated in thick layer of carbon.

 

[jsean]

Wouldn't be clogged cat would it? How long time did you have excessive oil consumption?

Possibly? But wouldn’t that have been an issue before this all happened? I got it to run smoothly immediately post piston soak and pre oil change. I’ve had it for about 5k miles, no idea how long it’s been consuming oil before my ownership. Previous owner is no more unfortunately for me to able to ask questions.

 

[jsean]

Ok, so quick update. Put in brand new set of plugs and it does exactly the same. Starts up, idles kinda ok for a second or two, then gets progressively worse and starts misfiring badly before just dieing.

Maybe I’m reading into this too much, but why does the low oil light keep popping up? Makes no sense to me..

 

[Pablo]

Ok, so quick update. Put in brand new set of plugs and it does exactly the same. Starts up, idles kinda ok for a second or two, then gets progressively worse and starts misfiring badly before just dieing.

Maybe I’m reading into this too much, but why does the low oil light keep popping up? Makes no sense to me..

It must be throwing some codes. no?

 

[2strokeNorthstar]

Ok, so quick update. Put in brand new set of plugs and it does exactly the same. Starts up, idles kinda ok for a second or two, then gets progressively worse and starts misfiring badly before just dieing.

Maybe I’m reading into this too much, but why does the low oil light keep popping up? Makes no sense to me..

Is the oil low or is it just the light? Maybe the b12 put the level sensor out of its misery. Could also be a coincidence. Ive had BMW oil level sensors fail after an oil change for no good reason

 

[Kupplung]

20/20 hindsight but you can't leave B12 in the crankcase after a piston soak. Needs to drain out completely and then put in new oil and run for a short time and change again. Who knows what happened at this point. Also, if B12 is still leaking down, it means rings are still not sealing. Sorry your having troubles. Start from ground zero with a compression check.

 

[Cujet]

B12 is a very strong solvent. It should never be in the crankcase. Ever. It dissolves gaskets.

No idea why your engine is misfiring, there is some chance of contamination on a sensor. Mass airflow sensor, O2 sensor, etc.

Make sure you have enough oil in the engine. Are you sure that's the oil level light? It could be oil pressure light with such low RPM.

Will it run if you step on the gas?

 

[jsean]

It must be throwing some codes. no?

Didn’t check, kinda beat and defeated after today. The CEL isn’t illuminated when the car is running - but maybe there are some stored codes? I’ll run my scanner tomorrow

 

[jsean]

Is the oil low or is it just the light? Maybe the b12 put the level sensor out of its misery. Could also be a coincidence. Ive had BMW oil level sensors fail after an oil change for no good reason

My understanding of this era of VWs is that a red oil warning light is an actual malfunction like no or low pressure. While the yellow oil light is for low oil level or a bad oil sensor? Quite possible that the oil level sensor failed and is a separate issue than the misfire and not running problem I’m having.

 

[jsean]

20/20 hindsight but you can't leave B12 in the crankcase after a piston soak. Needs to drain out completely and then put in new oil and run for a short time and change again. Who knows what happened at this point. Also, if B12 is still leaking down, it means rings are still not sealing. Sorry your having troubles. Start from ground zero with a compression check.

Good point about the B12. I read quite a few threads about B12 soak on TN and Audi world. Seems like folks changed it immediately and other drove the car spiritedly for 30-40 mins and then did an oil change. I was not comfortable with the latter and decided to just run it in P revving it to 2,000RPMs.
If I had bad compression, wouldn’t the engine have run poorly like it is now even with the prior b12+oil in the crankcase?

 

[jsean]

B12 is a very strong solvent. It should never be in the crankcase. Ever. It dissolves gaskets.

No idea why your engine is misfiring, there is some chance of contamination on a sensor. Mass airflow sensor, O2 sensor, etc.

Make sure you have enough oil in the engine. Are you sure that's the oil level light? It could be oil pressure light with such low RPM.

Will it run if you step on the gas?

I poured in a 5qt jug and a 1qt jug of the oil. I’ll double check in the morning, but those were the oil containers that I poured in. Both were new and sealed.

It does run if I step on the gas - haven’t tried it more than a few seconds. When I let go of the throttle, the revs fall and that’s when it misfires really bad. Is it safe for me to step on the gas and keep the revs up when I try this again?